Project Gutenberg's The Child's Book of Nature, by Worthington Hooker

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Title: The Child's Book of Nature
       Three parts in one

Author: Worthington Hooker

Release Date: December 7, 2018 [EBook #58421]

Language: English

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Transcriber’s Notes

3 Parts in one volume. Part I is numbered 1000 upwards; Part II is
  numbered 2000 upwards; Part III is numbered 3000 upwards.

Pagination starts with each section.

The cover image was created from the original all black cover with
  the title page superimposed onto it and is placed in the public
  domain.

Page 1021: pressents corrected to presents.

Page 3139: added ‘it’ to “while you are looking at it.”

Other minor printer’s errors have been silently corrected.




NOTE.--The three parts of this book can be had in separate volumes by
those who desire it. This will be advisable when the book is to be
used in teaching quite young children (from six to nine years of age),
especially in schools. It will take some time to go through with each
part thoroughly, and the pupil had better, for various reasons, be
introduced to each in its order as a new book.




    THE

    CHILD’S BOOK OF NATURE.

    Three Parts in One.

    PART I. PLANTS.
    PART II. ANIMALS.
    PART III. AIR, WATER, HEAT, LIGHT, &c.

    BY WORTHINGTON HOOKER, M.D.

    With Illustrations.

    NEW YORK:
    PUBLISHED BY HARPER & BROTHERS,
    PEARL STREET, FRANKLIN SQUARE.
    1882.


    THE CHILD’S BOOK OF NATURE

    FOR THE USE OF

    FAMILIES AND SCHOOLS.

    INTENDED TO AID MOTHERS AND TEACHERS IN TRAINING CHILDREN
    IN THE OBSERVATION OF NATURE.

    IN THREE PARTS.
    PART I.--PLANTS.

    BY WORTHINGTON HOOKER, M.D.,

    AUTHOR OF “FIRST BOOK IN CHEMISTRY,” “CHEMISTRY,”
    “NATURAL PHILOSOPHY,” “NATURAL HISTORY,” ETC.

    With Illustrations.

    NEW YORK:
    HARPER & BROTHERS, PUBLISHERS,
    FRANKLIN SQUARE.
    1882.




By Dr. WORTHINGTON HOOKER.


 THE CHILD’S BOOK OF NATURE. For the Use of Families and Schools;
 intended to aid Mothers and Teachers in training Children in the
 Observation of Nature. In three Parts. Illustrations. The Three Parts
 complete in one vol., Small 4to, Cloth, $1 00; Separately, Cloth, Part
 I., 40 cents; Parts II. and III., 44 cents each.

 PART I. PLANTS.--PART II. ANIMALS--PART III. AIR, WATER, HEAT, LIGHT,
 &c.

 FIRST BOOK IN CHEMISTRY. For the Use of Schools and Families. Revised
 Edition. Illustrations. Square 4to, Cloth, 44 cents.

 NATURAL HISTORY. For the Use of Schools and Families. Illustrated by
 nearly 300 Engravings. 12mo, Cloth, 90 cents.

 SCIENCE FOR THE SCHOOL AND FAMILY.

 PART I. NATURAL PHILOSOPHY. Illustrated by nearly 300 Engravings.
 12mo, Cloth, 90 cents.

 PART II. CHEMISTRY. Revised Edition. Illustrations. 12mo, Cloth, 90
 cents.

 PART III. MINERALOGY AND GEOLOGY. Illustrations. 12mo, Cloth, 90
 cents.


Published by HARPER & BROTHERS, Franklin Square, N. Y.

☞ _Either of the above volumes will
be sent by mail, postage prepaid, to any part of the United States or
Canada, on receipt of the price._


Entered, according to Act of Congress, in the year one thousand eight
hundred and fifty-seven, by HARPER & BROTHERS, in the Clerk’s Office of
the District Court of the Southern District Court of New York.




PREFACE.


Children are busy observers of natural objects, and have many questions
to ask about them. But their inquisitive observation is commonly
repressed, instead of being encouraged and guided. The chief reason
for this unnatural course is, that parents and teachers are not in
possession of the information which is needed for the guidance of
children in the observation of nature. They have not themselves been
taught aright, and therefore are not able to teach others. In their own
education the observation of nature has been almost entirely excluded;
and they are, therefore, unprepared to teach a child in regard to the
simplest natural phenomena.

Here is a radical error in education. When we put a child into the
school-room, to be drilled in spelling, reading, arithmetic, geography,
etc., we effectually shut him in from all the varied and interesting
objects of nature, which he is so naturally inclined to observe and
study. These are very seldom made the subjects of instruction in
childhood. And even at the fireside the deficiency is nearly as great
as it is in the school-room.

A similar defect appears to a great extent through the whole course of
education. The study of the wonderful phenomena which are all around
us and within us, is, for the most part, neglected, except by the few
whose inclinations to it are so strong that they can not be repressed.
This defect is well illustrated in a remark which was made by a mother
in relation to her own education. When at school she stood at the head
of her class, and excelled particularly in mathematics. Her remark was,
that she every day regretted that much of the time she had given to the
study of mathematics had not been spent in learning what would enable
her to answer the continual questions of her children. Even when the
natural sciences are taught, the mode of teaching them is generally
ineffectual. The knowledge which the mass of pupils in our higher
schools gain of Natural Philosophy, Chemistry, Botany, and Physiology,
is very deficient.

There should be a thorough change in this respect in the whole course
of education, beginning in childhood. The natural sciences should be
made prominent among the studies even of young children, who, in other
words, should be encouraged and guided in that observation of nature to
which they are generally so much inclined. In the different departments
of natural science there are multitudes of facts or phenomena in which
children readily become interested, when they are properly explained.

In this little book my object is to supply the mother and the teacher
with the means of introducing the child into one department of natural
science--that which relates to the vegetable world, or vegetable
physiology. With this view, I have endeavored to select those points
only which the child will fully understand, and in which he will be
interested. But this selection has by no means shut me up within narrow
limits. I have been surprised at the amount of knowledge in this
interesting study that can be satisfactorily communicated to the mind
of a child. While the fundamental points in vegetable physiology are
quite fully developed in this book, I have avoided as far as possible
all technical terms. These can be learned when the pupil becomes old
enough to profit by learning them. The facts, the phenomena, are what
the child wants to understand; and these can be communicated in the
simplest language, so that a child of about seven or eight, or perhaps
even six years, can readily be made to comprehend them.

I begin with the most simple and obvious facts--those which relate to
flowers--and go on through fruits, seeds, leaves, roots, etc., step by
step, until, at the latter part of the book, the circulation of the
sap, and other points at first view complicated, are made perfectly
intelligible. By this gradual unfolding of the subject, many points
are made clear to the child, which are not fully understood by many of
those who in riper years have studied botany; for in the common mode of
teaching this science the mere technicalities of it are made prominent,
while the interesting facts which vegetable physiology presents to us
in such variety receive but little attention.

The best time to use this book in teaching is during the summer,
because then every thing can be illustrated by specimens from the
field and the garden, and the teacher can amplify upon what I have
given. For example, when the lesson is to be on leaves, the teacher can
request her scholars to bring as many different kinds of leaves as they
can find; and she can point out their differences after the same plan
that I have adopted, but in a much more extended manner. Indeed, if
the teacher catch herself the true spirit of observation, she will be
continually led in her teachings to add facts of her own gathering to
those which I have presented.

I believe that there are few terms in the book that can not be readily
understood by the child. A little explanation may sometimes be
necessary on the part of the teacher, especially when the same word
is used as meaning more at one time than at another. For example,
the word plant is used sometimes, as in the title of this book, to
include every thing that is vegetable; while at another time it is
used to distinguish certain forms of vegetables from others, as in the
expression plants and trees.

I have made such a division into chapters as will place each subject
by itself, and at the same time, for the most part, give lessons of a
proper length for the learner. I have placed questions at the end of
each chapter, for convenience in instruction. Of course the teacher or
parent will vary them as she sees fit, to accommodate the capacities of
those whom she teaches.

  WORTHINGTON HOOKER.




CONTENTS.


  CHAPTER                                                 PAGE

        I. OUR LOVE FOR FLOWERS                             13

       II. MORE ABOUT OUR LOVE FOR FLOWERS                  19

      III. HOW FLOWERS ARE MADE                             22

       IV. THE COLORS OF FLOWERS                            25

        V. THE PERFUME OF FLOWERS                           28

       VI. THE SHAPES OF FLOWERS                            31

      VII. HABITS OF FLOWERS                                37

     VIII. MORE ABOUT THE HABITS OF FLOWERS                 40

       IX. WHAT LIVE ON FLOWERS                             43

        X. MORE ABOUT WHAT LIVE ON FLOWERS                  46

       XI. WHAT THE BIBLE SAYS ABOUT FLOWERS                49

      XII. FRUITS                                           52

     XIII. MORE ABOUT FRUITS                                55

      XIV. WHAT SEEDS ARE FOR                               58

       XV. LIFE IN THE SEED                                 62

      XVI. HOW SEEDS ARE SCATTERED                          64

     XVII. LEAVES                                           67

    XVIII. MORE ABOUT LEAVES                                71

      XIX. THE SAP IN LEAVES                                76

       XX. THE USES OF LEAVES                               80

      XXI. LEAVES IN THE AUTUMN                             83

     XXII. LEAF-BUDS                                        86

    XXIII. THE COVERINGS OF THE BUDS                        90

     XXIV. WHAT ROOTS ARE FOR                               92

      XXV. MORE ABOUT ROOTS                                 95

     XXVI. STALKS AND TRUNKS                               100

    XXVII. THE BARK OF TREES AND SHRUBS                    103

   XXVIII. THE WOOD IN TREES AND SHRUBS                    105

     XXIX. WHAT IS MADE FROM SAP                           107

      XXX. MORE ABOUT WHAT IS MADE FROM SAP                110

     XXXI. CIRCULATION OF THE SAP                          113

    XXXII. THE SLEEP AND THE DEATH OF PLANTS               116

   XXXIII. CONCLUSION                                      118




THE

CHILD’S BOOK OF NATURE.




PART I.--PLANTS.




CHAPTER I.

OUR LOVE FOR FLOWERS.


[Sidenote: Flowers in the garden.]

Every body likes flowers. We like them wherever we see them. How
pleasant they are to our eyes as we see them in the garden! How their
various colors please us as we look along the borders! Some are red,
some are white, some are blue, and some are yellow. All these different
colors, mingled with the fresh green leaves, make a feast for our eyes.

And then we love to look at each flower by itself. Some flowers we like
better than we do others. A pretty little flower that smells sweet, we
like better than we do a large one that has no perfume. The peony is
very beautiful, but we do not love it as we do the little pink with its
delightful fragrance.

[Sidenote: The garden of Eden.]

It was a garden in which Adam and Eve were placed. While they were
innocent and pure God surrounded them with beautiful things, because he
loved them so much. Before they sinned they lived among the flowers and
trees of the garden of Eden. It was more beautiful than any garden that
has been seen since that time. It was so beautiful that God would not
let Adam and Eve stay in it after they had sinned.

[Sidenote: Flowers in the fields.]

As we roam about the fields and the woods, it is pleasant to see here
and there a flower. We should hardly enjoy our walk if we did not see
them. They are like familiar friends that we love to meet. We see them
come every year after the winter is gone, and we like to bid them
welcome. A little girl, finding a wild violet early in the spring,
exclaimed, “How glad I am to see you again! It is a long time since I
have seen you, and you look as pretty as ever!” The delight expressed
by this little girl is felt by every body that loves flowers, as they
come one after another in the spring. How much we should miss them if
they did not come every year!

[Sidenote: The early flowers of spring.]

The earliest flowers that we see in the spring are the most precious
to us. They are very welcome, coming so soon after the cold winter is
gone. They are the first children of spring. They are few. We find them
only here and there. But we know that there will be many more flowers
as the warm summer comes on; and we rejoice to greet the first of the
host of beautiful things that are to delight our eyes in the field and
in the garden.

These early flowers that we love so much are very little flowers. Look
at the sweet little flowers of the trailing arbutus as they peep out
from among its rough leaves. It seems as if they scarcely dared to show
themselves, for fear that old winter had hardly gone. The violets too,
are small, and just lift their heads from the ground. So, too, the
delicate anemones, that are moved by the least breath of air, are very
small.

[Sidenote: Keeping flowers in the winter.]

We are so fond of flowers that we like to have them where we can look
at them in the winter. We are not willing to wait till spring comes. So
we keep them in our warm rooms on stands at the windows. Those who can
afford it sometimes have green-houses, in order that they may keep a
great variety of plants, and have flowers all the time.

[Sidenote: The little girl’s frozen flower.]

People sometimes become very much attached to a few plants that they
keep in their windows. Their opening flowers seem to smile upon them,
and this is very pleasant to them in the midst of the dreariness of
winter. It makes a little summer for them in-doors. And if the plants
happen to get frozen some very cold night, it makes them feel really
quite sad. A little girl became very much attached to a plant given to
her by her mother. She watered it every day, and watched the buds on it
as they opened into flowers. It was one of her pets. But one night it
froze, and the little girl wept over her loss. She felt as if she had
lost a sweet and ever-smiling friend. A kind neighbor gave her another
plant of the same kind; but it was a long time before she could feel
that it was just as good as the one that she had lost.

[Sidenote: The prisoner.]

[Sidenote: The flower in the prison.]

There is a beautiful story in French of a prisoner who became
exceedingly attached to a flower. He was put in prison by Napoleon
because he was supposed to be an enemy of the government. One day as
Charney (for that was his name) was walking in the yard adjoining his
cell, he saw a plant pushing up from between the stones. How it came
there he could not tell. Perhaps some one carelessly dropped the seed.
Or perhaps the seed was blown over the wall by the wind. He knew not
what plant it was, but he felt a great interest in it. Shut in within
those walls away from all his friends, not permitted to interest
himself with either reading or writing, he was glad to have this little
living thing to watch over and love. Every day when he walked in the
court he spent much time in looking at it. He soon saw some buds. He
watched them as they grew larger and larger, and longed to see them
open. And when the flowers at length came out he was filled with joy.
They were very beautiful. They had three colors in them--white, purple,
and rose color; and there was a delicate silvery fringe all round
the edge. Their fragrance, too, was delicious. Charney examined them
more than any he had ever seen before; and never did flowers look so
beautiful to him as these.

[Sidenote: How Charney watched and guarded it.]

Charney guarded his plant with great care from all harm. He made a
frame-work out of such things as he could get, so that it should not be
broken down by some careless foot or by the wind. One day there was a
hail-storm; and to keep his tender plant from the pelting of the hail,
he stood bending over it as long as the storm lasted.

The plant was something more than a pleasure and a comfort to the
prisoner. It taught him some things that he had never learned before,
though he was a very wise man. When he went into the prison he was an
atheist. He did not believe there was a God; and among his scribblings
on the prison wall he had written, “All things come by chance.” But as
he watched his loved flower, its opening beauties told him that there
is a God. He felt that none but God could make that flower. And he
said that the flower had taught him more than he had ever learned from
the wise men of the earth.

[Sidenote: How the prisoner was set free.]

The cherished and guarded plant proved of great service to the
prisoner. It was the means of his being set free. I will tell you how
this was. There was another prisoner, an Italian, whose daughter came
to visit him. She was much interested by the tender care which Charney
took of his plant. At one time it seemed as if it were going to die,
and Charney felt very sad. He wished that he could take up the stones
around it, but he could not without permission. The Italian girl
managed to see the Empress Josephine, and to tell her about it; and
permission was given to Charney to do with his plant as he desired. The
stones were taken up, and the earth was loosened, and the flower was
soon as bright as ever again.

[Sidenote: The Empress Josephine’s love of flowers.]

[Sidenote: Charney takes his plant home.]

Now Josephine thought much of flowers. It is said that she admired
the purple of her cactuses more than the Imperial purple of her robe,
and that the perfume of her magnolias was pleasanter to her than the
flattery of her attendants. She, too, had a cherished flower--the sweet
jasmine, that she had brought from the home of her youth, a far-off
island of the West Indies. This had been planted and reared by her own
hand; and though its simple beauty would scarcely have excited the
attention of a stranger, it was dearer to her than all the rare and
brilliant flowers that filled her hot-houses. She thought a good deal,
therefore, of the prisoner that took such care of his one flower. She
inquired about him, and after a little time persuaded the Emperor to
give him his freedom. And when Charney left the prison he took the
plant with him to his home; for he could not bear to part with this
sweet companion that had cheered him in his lonely prison life, taught
him such lessons of wisdom, and was at last the means of setting him
free.

[Sidenote: Nothing comes by chance.]

Some, perhaps, would say that the seed of this flower got into that
prison-yard, and took root in the earth between the stones by _chance_,
and that this was all very _lucky_ for the prisoner. But this is not
so. Nothing comes by chance. God sent that seed there, and made it
lodge in the right place to have it grow. He sent it to do great things
for the poor prisoner. Little did Charney think, when he saw that
tiny plant first pushing up from between the stones, that by it God
would free him from prison, and, what was better, deliver him from his
infidelity.

 _Questions._--What is said of our love for flowers? Do we like some
 flowers better than others? What is said of the garden of Eden? How do
 we feel about the wild flowers of spring? Why do we like the earliest
 best? Are these large or small? Mention some of them. Why do people
 keep flowers in the winter in their rooms and in green-houses? Tell
 about the little girl and her plant. What is the story of the French
 prisoner and his plant?




CHAPTER II.

MORE ABOUT OUR LOVE FOR FLOWERS.


[Sidenote: Bouquets.]

It is from our love of flowers that a bouquet is always a pretty
present to a friend. The kind teacher is much gratified when a scholar,
with a bright, cheerful “Good morning,” gives her a bouquet. Though the
flowers may be simple and common, the present is a very pleasant one.
It is saying to your teacher, I love the beautiful things that God has
made, and I know that you love them. It is saying more than this. It is
telling your teacher that you love her. It is because you love her that
you give her the sweet flowers that you love so much. And she will feel
that though the flowers will fade, your love to her will ever be fresh.

[Sidenote: Flowers in the sick chamber.]

How grateful are flowers in the chamber of sickness! It would weary the
sick one to see all her kind friends. But they can send her presents to
let her know that they think of her. And what tokens of remembrance are
more welcome than flowers?

[Sidenote: Flowers as ornaments.]

Flowers are much used as ornaments, even among savages. They are more
beautiful than any ornaments that man can make. What is more elegant
than handsome hair dressed with flowers?

As natural flowers droop so easily, we make artificial ones for
ornaments. Sometimes they are made so well that they look like fresh
flowers just picked from the garden.

[Sidenote: Flowers in dress and furniture.]

We like flowers so much that we copy them in the figures in dress
and furniture. Gems and ornaments of gold and silver are arranged
in flower-shapes. Figures of flowers are seen in the patterns on
dresses more often than any other figures. The calico-printer gets
his prettiest figures from the flowers that he sees in the field and
garden. The richest carpets are those in which the figures are flowers.
We often see in the carpet under our feet a great variety of flowers
of the most beautiful colors. We seem to tread on beds crowded full of
roses and various kinds of flowers; and we have no fear of crushing
them as when we tread on real flowers. Flowers, too, are stamped on
the papers on our walls. You often see representations of flowers
woven in table-cloths and napkins. You see the figures of flowers
worked beautifully on articles of silver. You see them too on vases
in which we put real flowers. Flowers are often carved in furniture,
and even the stove-maker has them on his stoves, whether they are
made for the parlor or the kitchen. Thus it is that we have flowers
about us whenever we can. And where we can not have flowers, we have
representations of them.

[Sidenote: Why God has given us beautiful things.]

I said in the first chapter that every body likes flowers. Perhaps
I ought to say that _almost_ every body likes them. A man may be so
wicked and so like a brute that he can see no beauty in flowers. A
man may love to hoard up money, so much, that he will not care about
any thing beautiful. Some men can not see any use in flowers. They
think that potatoes, and turnips, and beets, ought to grow where their
daughters have their flower-garden. They forget that God has given us
beautiful things for the purpose of having us enjoy them. God has a use
for every thing that he has made, and this is the use of flowers. And
he likes to see us love the beautiful things that he has given us, and
make a proper use of them.

[Sidenote: Love of children for flowers.]

Children always love flowers. The baby puts out its little hands to
them before it can hold any thing, and shows that it is pleased by its
smiles and funny noises. And the child that can run about and talk, is
delighted as it runs up and down the garden, and says “Pretty, pretty!”
to every flower.

[Sidenote: Flowers in the school-room.]

There ought always to be flowers in the school-room. The place where
the happy child goes to learn should be made very cheerful. Pleasant
things will make it so, and flowers are certainly very pleasant things.
And then, they are very easily obtained. Scholars can bring them, and
they can be put into vases where all can see them. Pictures would make
a school-room look very pleasant, but they are too costly. Flowers
are cheap, since they commonly cost only the trouble of gathering and
bringing them to school.

 _Questions._--What is said about giving a bouquet to your teacher? Why
 are presents of flowers so pleasant to a sick person? What is said of
 flowers as ornaments? What of artificial flowers? Tell how we copy
 flowers in dress and in furniture. Are there some who do not like
 flowers? For what did God make flowers? How do very little children
 show that they like them? What is said about having flowers in the
 school-room?




CHAPTER III.

HOW FLOWERS ARE MADE.


If you love flowers you will like to know all that you can about them.
It is just as it is when you love a person. You want to know all that
you can about the friends that you love so well. And if you love
flowers, you will like to know what I have to tell you about them.

[Sidenote: What is growing?]

You go out into the garden, and you see among all the flowers there
a large red rose. Look at it, and see how many red leaves it has all
folded together. How did that rose come there? That is plain enough,
you will say--it _grew_ there. And most grown people as well as
children think that this is all that is to be said about it. But what
is _growing_? Do you know _how_ a rose grows? I will tell you something
about this.

[Illustration]

That rose was once a very little bud, such as you see here. Then it
did not look any thing like a rose. It was a little green thing with
nothing red in it. You would not suppose that it ever could turn into a
rose, if you had not seen buds turn into roses before.

[Illustration]

[Sidenote: Rose-buds.]

The little rose-bud becomes larger and larger every day. Soon it begins
to open, as is represented here, and you see the red leaves of the
flower all folded together. It spreads out these leaves after a little
time, and now you see the full-blown rose.

[Illustration]

Here is a representation of a rose in full bloom. How much larger it is
than the little bud from which it came, and how different it is from
it! A great many leaves it spreads out in its bosom. Sometimes the
difference is greater than what you see here. Some kinds of roses are
very large indeed, but their buds at the first are very small.

This rose was _made_. We commonly say that it grew, without thinking
what growing is. It was made from something. There was something that
came to the bud to make it into a rose. What was it that came to the
bud? How did it come there? I will tell you.

[Sidenote: Roses are made out of sap.]

The rose was made from a juice, or _sap_, as we call it. This sap kept
coming to the bud all the time that it was growing larger, and then
all the time that it was changing into a rose. We do not know _how_
this sap can be made into such a beautiful red flower. This we can not
understand. The wisest man in the world can not tell us how it is done.
But God, who made all the flowers and every thing else, understands it.

[Sidenote: How the sap comes to the bud.]

[Sidenote: Sap-pipes and water-pipes.]

But you will ask how the sap comes to the bud. You see that slender
stem that holds the rose. There are little fine pipes in that stem, and
the sap comes through these pipes. All the time that the bud is turning
into a rose, the sap comes to it through these pipes in the stem, just
as water comes through pipes to our houses. These pipes in the stem
are very small, and there are a great many of them. They are so small
that you can not see them, but they are large enough to let the sap run
along through them.

If the sap should stop coming through these pipes to the bud, it could
not become a rose. If you pick a bud, you know that it stops growing,
and never becomes a rose. This is because no more sap can come to it
through the pipes of the stem. It is just as no water can come into a
house if the water-pipe be cut off outside.

The sap from which the rose is made we should suppose would be like the
rose. But it is not. It is not red, as you see breaking the stem. It
does not taste at all like the leaves of the rose.

[Sidenote: Rose-buds are rose-factories.]

It does not seem very wonderful that the little green bud should be
made from the sap in the stem. But it does seem very strange that the
bright-red leaves of the rose should be made from it. Suppose some one
should take some stems, and bruise them, so as to get the sap out of
them. Could he make a rose from this sap? Oh no. This can be done only
in the bud. That is the rose-factory. The sap must go there to be made
into a rose.

 _Questions._--Why do you want to know about flowers? Do most people
 think it plain how a rose-bud becomes a rose? How is the rose
 different from the bud? Is the rose made? What is it made from? How
 does the sap get to the bud? If you pick a bud, why does it not become
 a rose? Is the sap in the stem like the rose? Can any one make a rose
 from the sap?




CHAPTER IV.

THE COLORS OF FLOWERS.


I have told you about red roses. But all roses, you know, are not red.
There are white and yellow roses. And some roses are a very light red,
while others are a dark red. Now, how are all these different colors
made?

[Sidenote: How flowers are dyed.]

If you ask a dyer how he gives cloths different colors, he will tell
you that he dips them into different dyes. He has a dye in one place
that gives a red color, and one in another place that gives a yellow
color; and so for all the different colors. The roses are not colored
in this way; they are not dipped into dyes. But the colors must come
from something. From what do you think they come?

[Sidenote: The colors made from the sap.]

We do not know exactly how these colors are made. The sap seems to be
the same in the stems of all the different roses. It is not yellow in
the stem of the yellow rose, and red in the stem of the red rose. The
stems of all the roses are green, and the buds at first are green. But
in some way all the different colors are made from something. And as
there is nothing there but the sap that comes in the stems, the colors
must be made from this. Air and light have something to do with making
the colors, but they are made from the sap.

I have told you only about roses. But there are many, very many other
flowers with every variety of color. They are all made from the sap
that comes to the buds through the stems. This is true of the flowers
on the trees as well as of those that you see on stalks and bushes.

The sap is different in the different trees and plants. But in none of
them can you find sap that is like the flowers that are made from it.

In some flowers you see different colors beautifully mixed together.
These different colors are made from the same sap. In the garden-violet
you see a purple and a yellow color. In the iris you see a purple, a
yellow, and a blue. These three colors are very unlike, and yet they
are made from the same sap that comes up the stem. In the China pinks
you see a great variety of colors alongside of each other.

[Sidenote: Mixing and shading off of colors in flowers.]

Sometimes the colors shade off into each other beautifully. You see
this in the pink. Sometimes one color is put right upon another in
streaks or in spots. You see stripes of color in tulips. In the
tiger lily there are dark spots of a very different color from that
reddish-brown upon which they are put.

How it is that out of the same sap one color is made in one part of a
flower, and another color in another part, we do not know. Sometimes
two entirely different colors are side by side. In one kind of poppy
the leaves of the flower are white except on the very end, and there
they are red. They look as if all their edges had been dipped in a red
dye. Now how it is that the sap should make the flower white every
where except on the tips of its leaves, and there make it red, we do
not know.

Neither can we tell how one color is made to shade off or run
into another color. This is often so nicely done, that you can not
tell where one color begins and another ends. You see this in the
apple-blossom. The reddish color runs off into a pure white, but there
is no place where you can say the white begins.

[Sidenote: Change of color in some flowers.]

The colors of flowers change some as they open. A flower is not exactly
of the same color when it is partly opened as it is when its leaves
are all spread out to the light. There is a vine called the cobea that
has a singular change in the color of its flowers. When they first
open they are a pale green. They are of this color when they are fully
opened. But after a while they have a rich purple color. It is like the
change of color that you see in some fruits. An orange, you know, is at
first green; but when it is ripe, it is a bright yellow orange.

I might go on to tell you much more about the colors of flowers. But
you can look for yourselves in the garden and in the field, and see how
differently the colors are arranged in one flower and in another.

 _Questions._--Are roses of different colors? How does a dyer give
 different colors to cloth? Do we know how the colors of flowers are
 made? What are they made from? What is said of the great variety of
 colors in flowers? Mention some flowers in which different colors
 are alongside of each other. Is it strange that they are made from
 the same sap? What is said of one kind of poppy? What is said of the
 shading off of colors? Tell about the flower of the cobea.




CHAPTER V.

THE PERFUME OF FLOWERS.


There is another thing in the flower besides the color that is made
from the sap. It is its perfume. How delightful this is in the rose!
And how long it lasts! But you can smell none of it in the sap from
which the rose is made. There is commonly very little odor in the stem
through which the sap comes to a flower, and it is not at all like that
which you smell in the flower itself.

[Sidenote: Some flowers perfume-factories.]

The perfume is not in the stem; but that from which the perfume
is made is there. Something is done to the sap as it comes to the
flower to make it give out the perfume. Every fragrant flower is a
_perfume-factory_.

Some flowers have no odor, while others smell very strong. The lilac
and the syringa, you know, have a strong smell. They are quite
pleasant in the open air; but when they are in a closed room they are
disagreeable, because their odor is so strong.

[Sidenote: Some have no fragrance.]

There is no fragrance in many of our most beautiful flowers. This is
true of the cactus in all its varieties. When you look at a large
cactus blossom, so splendid in its colors, it seems to you that it must
smell sweet. But if you put it to your nose, as a child is apt to do,
you find that it has no smell. Then there are the elegant japonicas, of
various colors, that have no fragrance. The showy red peonies in the
garden look to a child so much like large red roses, that it seems
to him as if they ought to have a pleasant smell. But they have none.
Perhaps you have seen in the autumn some very bright scarlet flowers
standing on a stalk in damp places. It is the cardinal flower. Some
call it eye-bright. This elegant flower has no fragrance. And there is
none in the fringed gentian, another beautiful wild flower of autumn.
It seems enough for such flowers that they are so beautiful.

[Sidenote: Some both beautiful and fragrant.]

But there are some flowers that have both great beauty and delicious
fragrance. This is true of most kinds of roses. Whenever any one gives
you a rose, you put it up to your nose at once. You expect that it will
smell sweet, of course; and you feel disappointed if it does not. The
cape jessamine is one of the most beautiful of flowers, and, at the
same time, it has a delightful fragrance. The pure clear white flower
appears very beautiful among the glossy green leaves. In a southern
climate it is one of the most splendid of flowers.

[Sidenote: Variety in the fragrance of flowers.]

Most flowers have some odor. And the odors of the different flowers
are all different from each other. If you were blindfolded, and a
pink, a rose, an apple blossom, a pond lily, an orange blossom, and
a clover-head, were put up to your nose, one after the other, you
would know each of them by its smell. And so of other flowers. What
a variety there is in the fragrance that the flowers in the garden
and the field send forth into the air! What a multitude of different
perfume-factories has our kind heavenly Father provided just to gratify
us!

[Sidenote: Clover-field.]

Sometimes a great many of these factories of one kind are together, and
then the air is filled with the perfume they make. You will at once
think of a clover-field. How sweet the fragrance as the wind blows over
the field and brings it to you! All this perfume comes from millions of
little factories. For each clover-head is a perfume-factory, as you may
know if you pick one and smell it.

[Sidenote: Grape-vine.]

The fragrance from the flowers of the grape-vine is very delicious. It
is of this that Solomon speaks when he says, “The vines with the tender
grape give a good smell.” When the grape-vines are in bloom the air is
filled with their fragrance; and yet the flowers are so small, and so
near the color of the stem and the leaves, that you would not notice
them, unless you looked particularly for them.

[Sidenote: Unpleasant odor of some plants.]

There are some flowers that have an unpleasant odor. Sometimes this is
because they are poisonous, the odor making us avoid them, and thus
saving us from danger. But in many cases we can not see any such reason
for the unpleasant odor. Why it is that such a splendid flower as the
crown imperial should smell so disagreeable we do not understand. One
thing, however, is true: the bad-smelling plants are few, while God has
given us a multitude of those that smell sweet.

 _Questions._--What else in the flower, besides color, is made from
 the sap? Is the perfume in the stem? Where is it made? Mention some
 flowers that have a strong smell. Mention some that are very handsome,
 and yet have no fragrance. Mention some that have both fragrance and
 beauty. What is said about the different odors of flowers? How does
 this show the goodness of God to us? Tell about the clover-field. What
 is said of the flowers of the grape-vine? What is said of flowers with
 a bad odor?




CHAPTER VI.

THE SHAPES OF FLOWERS.


[Sidenote: Flowers shaped like stars.]

Flowers are of all kinds of shapes. The shape of the flower often gives
it its name. Some are shaped like stars, and are called asters, the
word in Latin for stars. There are many kinds of these asters that grow
wild in the autumn. Some of them are blue, some purple, and some white.
And then there are the China-asters that you see in the garden.

There is a beautiful wild flower called, from its shape, ladies’
tresses. And so, too, we have ladies’ ear-drops, and the lady’s
slipper.

[Sidenote: Butterfly-shaped flowers.]

[Illustration]

Some flowers are shaped like butterflies. This is the shape of the
pea-blossom which you see here. A very beautiful flower it is, though
people seldom think much about it. They think only of the peas which
they are to gather by-and-by. There is one curious thing about the
color of the pea-blossom. Sometimes, you know, it is white, and
sometimes it is a purplish red. Now when it is red, you can see red
spots all the way down the stalk, at the joints where the branches go
off from it. It is as if the sap as it went up to color the blossom,
left some of its red dye in these spots on the way. You see no such
spots on the stalk when the flowers are white.

[Sidenote: Bell-shaped flowers.]

Here are the flowers of the lily of the valley. They are like little
bells hanging from the stem. This is one of the sweetest of all
flowers. The little blue-bells, so pretty, and yet so troublesome in
the garden, have their name from their bell-shape. So also have the
Canterbury bells.

[Illustration]

[Sidenote: Cup-shaped.]

Some flowers are cup-shaped. This shape gives its name to the bright
yellow buttercup that you know so well. The cup-daffodil, as we call
it, has the middle part of the flower in the shape of a cup. The cup
part of it is quite deep. The flower is bent over. If it stood upright,
its cup would be filled with water when it rains. The narcissus, too,
which bends over like the cup-daffodil, has a little cup, as you see in
the figure, in the middle of it. Its cup, you observe, is shallow. It
is something like a bowl.

[Illustration]

[Illustration]

[Sidenote: Funnel-shaped.]

Here is a flower of a funnel or tunnel shape. We see this shape in the
flowers of the cypress-vine, and of the tobacco-plant. The flower of
the morning-glory, which you will see on page 41, has this shape quite
perfectly. It looks very much like a tunnel.

[Illustration]

[Sidenote: Calceolaria.]

The flower that you see here is one of the varieties of calceolaria.
It hangs down like a bag, or pocket, having a round opening above. The
blossom of which this is a drawing was of a bright yellow color with
red spots on it. There are many varieties of this singular flower,
having different colors, and different sizes.

[Illustration]

[Illustration]

[Sidenote: Wake-robin.]

[Sidenote: Calla.]

The flower here represented is the wake-robin, or Indian turnip. It
is found in rather damp and shady places. What you see is commonly
called the flower, but it is not really so. It is a covering for the
flowers of the plant, which are very small. They are on the lower part
of that rounded stalk that stands up in the middle. This splendid
covering or house for the little flowers is green in one variety, and
of a dark purple in the other. In the beautiful calla the flowers are
small, and are on a stalk like that in the wake-robin. That pure white
trumpet-shaped thing that we so much admire is not really the flower,
though it is called so.

[Sidenote: Trumpet-creeper.]

[Sidenote: Catching humming-birds.]

Some flowers are shaped like a trumpet. This is the shape of the
blossom of the trumpet-creeper. The blossom, you know, is very deep.
The humming-bird is fond of going quite into it. I suppose he goes in
after the honey in the bottom of the flower. I have sometimes caught
this beautiful bird by grasping the blossom in my hand when he had
fairly got into it. I only kept the trembling little creature long
enough to let us see how beautiful he was, and how curiously his long
bill was made, with its slender tongue, to gather the honey. I soon set
him free, and he was off again as joyous and as busy as ever, going
from flower to flower.

The blossom of the snap-dragon has a queer shape that gives it its
name. By pressing it together sideways, you can make it open like a
mouth, and there are little white things that look like teeth. And
then, if you let go of it, this mouth snaps together.

You have often seen the golden rod by the road-side in the last of
summer and in autumn. Its golden yellow blossoms grow on a tall stalk
in such a way that its name seems a very proper one. It is truly a rod
of golden flowers.

[Sidenote: Compound flowers.]

There are some flowers that are called _compound_. They are called so
because each flower is made up of a great many flowers. The dandelion
is a flower of this kind. Each blossom has a great number of flowers in
it. These you can easily pick apart. Each one of these looks beautiful
if you see it through a microscope.

[Sidenote: Ox-eyed daisy.]

The blossom of the clover is one of the same kind of flowers. The white
daisy, too, or ox-eyed daisy, as some call it, that you see scattered
over fields among the grass, is a compound flower. I have counted in
one of these blossoms over six hundred flowers.

These flowers are in the yellow part in the middle, that has a row of
white leaves all around it. They are very small. But when you look at
them through a microscope, you can see that each one is a beautiful,
perfect flower. So, then, there is a whole garden of flowers in one of
these blossoms. If these six hundred flowers could be taken out and
turned into large flowers, they would make very much such a show as six
hundred yellow lilies would.

[Illustration]

[Sidenote: Mountain daisy.]

The mountain daisy, here represented, is a pretty little flower of the
same kind. It has in its golden yellow bosom a multitude of little
flowers close together, just as our common white daisy has. And around
this yellow part there is a row of delicate leaves, sometimes reddish,
and sometimes white. This is a favorite flower in England and Scotland,
where it is very common in the fields. There has been a great deal of
poetry written about it. Burns, the great poet of Scotland, has some
sweet verses to this “wee, modest, crimson-tipped flower,” as he calls
it. Here are some lines that some one has written about it.

    “I’m a pretty little thing,
    Always coming with the spring;
    In the meadows green I’m found,
    Peeping just above the ground,
    And my stalk is covered flat
    With a white and yellow hat.

    “Little maiden, when you pass
    Lightly o’er the tender grass,
    Step aside, and do not tread
    On my meek and lowly head,
    For I always seem to say,
    Chilly winter’s gone away.”

Very pretty poetry this is, but I think the poet is wrong in making this
modest little flower praise itself.

[Illustration]

[Sidenote: Tassels of the willow, alder, etc.]

The flowers on many trees hang down, as represented in this figure,
in tassels. The flowers of the willow hang in this way. There are a
great many flowers in each tassel. In the figure, in one of the tassels
the flowers are fully open, and in the other they are not. Sometimes
they are very delicate. They are in the black alder. It is curious to
see how different they look when the flowers are open and when they
are not. When they are open, they look beautiful, as seen through a
microscope. When the chestnut-trees are in blossom, their tassels,
hanging in clusters, give them a very rich appearance.

[Sidenote: Why flowers have such variety of shapes.]

You have seen in this chapter that the variety of shapes in flowers is
very great. It is almost without limit. Now the Creator makes all this
variety of form for the same reason that he gives to flowers such a
variety of colors. It is to feast our eyes and make us happy.

 _Questions._--Mention some of the shapes of flowers spoken of in the
 first of the chapter. Tell about the pea-blossom. Mention some flowers
 that are shaped like bells. Mention some that are cup-shaped. Mention
 some that are shaped like a tunnel. Tell about the calceolaria.
 Tell about the Indian turnip and the calla. What is said of the
 trumpet-creeper? Of the snap-dragon? Of the golden rod? What are
 compound flowers? Mention some of them. Tell about the white daisy.
 Also the mountain daisy. Mention some trees that have their flowers in
 tassels. Tell about these tassels. Why has God given such variety of
 shape to flowers?




CHAPTER VII.

HABITS OF FLOWERS.


Flowers have habits, or ways of acting, just as people do. I will tell
you about some of them.

[Sidenote: Flowers turning to the light.]

All flowers naturally turn toward the light, as if they loved it. You
can see this if you watch plants that are standing near a window. The
flowers will all be bent toward the light if you let the pots stand
just in the same way all the time. By turning the pots a little every
day or two while the blossoms are opening, you can make the flowers
look in different directions.

[Sidenote: The bumble-bee in the tulip.]

There are some flowers that shut themselves up at night as if to go
to sleep, and open again in the morning. Tulips do this. I was once
admiring in the morning some flowers that were sent to me the evening
before by a lady. Among them were some tulips, and out of one of these,
as it opened, flew a bumble-bee. A lazy, dronish bee he must have been
to be caught in this way as the flower was closing itself for the
night. Or, perhaps he had done a hard day’s work in gathering honey,
and just at night was so sleepy that he stayed too long in the tulip,
and so was shut in. A very elegant bed the old bee had that night. I
wonder if he slept any better than he would have done if he had been in
his homely nest.

[Sidenote: Mountain daisies.]

The pond-lily closes its pure white leaves at night as it lies upon its
watery bed. But it unfolds them again in the morning. How beautiful it
looks as it is spread out upon the water in the sunlight! The little
mountain daisy that I told you about in the last chapter, is among
the flowers that close at night. But it is as bright as ever on its
“slender stem” when it wakes up in the morning. When it shuts itself up
it is a little round green ball, and looks something like a pea. You
would not see it in the midst of the grass if you did not look for it.
But look the next morning, and the ball is opened, and shows “a golden
tuft within a silver crown.” And very beautiful it is when there are
so many of the daisies together that the grass is spangled with them
in the bright sun. It is supposed that this flower was at first called
“day’s eye,” because it opens its eye at the day’s dawn, and after a
while it became shortened to daisy.

[Sidenote: Dandelions.]

[Sidenote: Salsify.]

The golden flowers of the dandelion are shut up every night. They are
folded up so closely in their green coverings, that they look like
buds that have never yet been opened. The blossoms of the salsify, or
vegetable oyster, close in the same manner, but not at the same time.
They close always at noon. In the morning their tall, straight stalks
make quite a brilliant appearance, each one having a deep purple flower
at its top. All these are shut up in the afternoon, and you see at
the top of each stalk a large pointed bud. The flowers of this plant
are very much like the dandelion, both when closed and when open. The
seeds, also, are very similar, as you will see in another chapter, and
make together, around the top of the stalk, a similar feathery globe.

There is one curious habit which the dandelion has. When the sun is
very hot it closes itself up to keep from wilting. It is in this way
sheltered in its green covering from the sun. It sometimes, when the
weather is very hot, shuts itself up as early as nine o’clock in the
morning.

Some flowers hang down their heads at night as if they were nodding in
their sleep. But in the morning they lift them up again to welcome the
light.

[Sidenote: Primroses.]

[Sidenote: Four o’clocks.]

Some flowers have a particular time to open. The evening primrose does
not open till evening, and hence comes its name. The flower called
_four o’clock_ opens at that hour in the afternoon. There is a flower
commonly called _go-to-bed-at-noon_, that always opens in the morning
and shuts up at noon.

[Sidenote: Flowers of the cypress-vine.]

Most flowers last for some time. But there are some that last only
a few hours. The red flowers of the delicate and rich cypress-vine
open in the morning, and in the afternoon they close up, never to
open again. But there are always some buds to open every day. It is
delightful to one who loves flowers to see every morning a new set of
these bright blossoms appear among the fine dark-green leaves of this
vine.

 _Questions._--What is said of flowers turning to the light? What do
 some flowers do at night? Tell about the bumble-bee. What is said of
 the pond-lily? What of the mountain daisy? What of the dandelion? What
 is said of the time of opening of some flowers? Tell about the flowers
 of the cypress-vine.




CHAPTER VIII.

MORE ABOUT THE HABITS OF FLOWERS.


[Sidenote: Buds and flowers of the morning-glory.]

You have often seen the flowers of the morning-glory. These last only
from early in the morning to noon, or a little after noon. In the
afternoon they are all closed, and the vines look very dull without any
flowers on them. But look the next morning, and you will see a plenty
of these beautiful flowers. They open before most people are out of
their beds. And, just as I told you about the cypress-vine, there is a
new set of them every day.

[Illustration]

It is curious to see in what way the blossom of the morning-glory opens
and then shuts itself up to die. If you look in the afternoon you will
find here and there a bud shaped as you see in this figure. The flower
part of it, you observe, is twisted at its pointed end in a spiral
manner; that is, something like a cork-screw. This bud will be an open
flower the next morning.

On the following page you see the flower as it looks when it is fully
opened. There are ribs running up from the lower part of the flower.
Each of these ribs comes to a point at the edge. They give firmness to
the blossom. They are its frame-work, its timbers. Without these ribs
it could not stand like a cup on its stem, as it does now, but would
hang loosely down. The open spread part of the flower is very thin,
and the ribs are to it what the whalebones are to an umbrella.

[Illustration]

[Illustration]

[Sidenote: Closing of the flower of the morning-glory.]

In this figure you see how the flower looks as it is partly closed. The
points of the ribs are all turned in toward the middle of the flower.
They bend in more and more, and after a while the flower wilts and
dies. Now it is curious that the ribs of the flower should be folded so
differently when it closes from what they are before it opens. Before
it opens they are folded in a spiral form, as you see in the figure in
the preceding page. When it closes, we would suppose that they would
fold up in the same form. But they do not. They bend straight over, and
the points come together in the middle of the flower.

[Sidenote: Night-blooming cereus.]

There are some flowers that open only at night. That splendid flower,
the night-blooming cereus, is one of them. And it opens only once. It
lets us see its beauty only a few hours, and then it wilts and dies. It
is a very large flower, and its opening is commonly watched for with
great eagerness. It is a rare flower, and it is only now and then that
we can get an opportunity of seeing it. It is very fragrant. It opens
commonly quite late in the evening, and shuts itself up the latter part
of the night. It never lets the light of day into its bosom. It makes
us feel almost sad that so beautiful a flower lasts so short a time. We
should feel really sad if most flowers did not last longer than this.

[Sidenote: The succession of flowers.]

Through spring, summer, and autumn, we have a succession of flowers of
every kind. Some last but a little while, and some feast our eyes for
a long time. They come one after another. Each has its own season, and
opens at its appointed time every year. In this succession of flowers
we are never without some of them before us till the cold weather of
winter comes again. God has thus kindly provided us with beautiful
things to look upon, in the garden and in the field, through all the
warmer months of the year.

In the spring the flowers are small and delicate, but are generally
quite fragrant. In the summer we have very many more flowers than in
spring or autumn. They have every variety of color and shape. They are
commonly very fragrant, so that the air is filled with pleasant odors.
In autumn the flowers generally have bright colors, and are very showy;
but few of them have any fragrance.

 _Questions._--How are the flowers of the morning-glory like those of
 the cypress-vine? Tell about the bud of the morning-glory; also about
 the flower when it is open, its shape, and its ribs; also about the
 way in which it shuts up. What is said of the night-blooming cereus?
 Tell about the succession of flowers. How are the flowers of the
 spring, and summer, and autumn different?




CHAPTER IX.

WHAT LIVE ON FLOWERS.


[Sidenote: Food in flowers.]

Flowers are made chiefly for us to look at. It is to gratify our eyes,
as I have before told you, that the Creator has made them so beautiful,
and has given to them such a variety of shape and color. But they are
good for something else besides this. Many different animals get their
food from them. These animals are very small, and need but little food;
but that little they get from flowers.

[Sidenote: Honey-bees.]

You see many different kinds of insects about most flowers. Most of
these insects, we suppose, live upon the honey that they find there.
We know that some do, for we see them gathering it. We see the bees do
this. The busy little honey-bee goes from flower to flower, and gets
a little honey from each. When he has gathered as much as he well can
carry, off he flies to lay it up in the hive. A great many bees there
are in one hive; and each bringing continually his little load, they
after a while lay up a large amount of honey.

[Sidenote: Bumble-bees.]

The bumble-bee, too, is busy among the flowers. See how quickly he
flies from one flower to another, humming as he goes. Now he comes to
a little flower, sticks his head in, and in a moment is off--buzz,
buzz--for another. And now you see him come to a large, deep flower;
and in he goes, almost out of sight, and his buzzing is stopped for
some time. Soon he backs out to fly to another. And so he goes from
flower to flower to gather his load of honey.

[Sidenote: Curious facts about bumble-bees.]

I have been amused to see how the bumble-bee manages with some flowers.
The flower of the cypress-vine is very deep, but it is so small that he
can not get into it so as to reach the honey. He knows that there is
honey there, for he smells it. Now how do you think he gets at it? By
working away a little while he pushes himself into the flower so as to
split it open. And now he can come to the bottom of the flower where
the honey is. In this way he spoils a great many flowers in getting his
load of honey.

I have observed one thing about the bumble-bees that I do not
understand. Some of them go inside of flowers to get their honey, while
others go only on the outside, just at the bottom of the cup of the
flower. It is curious to see two bumble-bees on one stalk of flowers,
one going into all of them, and the other getting his honey from the
outside of them. I have often seen this, but never could find the
reason of it.

Another thing I have observed about the bumble-bees. Each one generally
goes only to flowers of one kind. If, for instance, he begins with
china-asters, he will go to no other flowers to gather his honey. He
will sometimes take a look at others as he goes buzzing along, but he
flies on till he finds some more china-asters. Soon off he starts for
his nest, and perhaps, when he comes again, he goes to some other kind
of flowers. If he begin now with morning-glories, you will see him
pushing himself into every one that he comes to, and he will not stop
at any other flower.

[Sidenote: Honey made from different things.]

We commonly speak of the bees as gathering honey. This is not exactly
correct. They _make_ honey out of what they get from the flowers.
And it is well known that the honey-bees, as they are called, can
manufacture better honey from what they gather from some flowers than
they can from what they gather from others. From the fragrant flowers
of the garden and the white clover of the fields is made the delicate
white honey that you often see on the tea-table. But the bee can not
always find such nice food; and then it flies off to the buckwheat
fields, or perhaps helps itself to the drainings of some molasses or
sugar cask in front of the grocer’s door. Honey made from these things
does very well for the bees’ winter store, but it does not suit our
taste.

[Illustration]

[Sidenote: Butterflies.]

Those beautiful insects, the butterflies, get their living among the
flowers. As they fly about, they now and then stop and rest upon some
flower, as you see this one doing. This is done not merely for the sake
of resting, but to take some food from the flower.

 _Questions._--What use have flowers besides being beautiful to look
 at? What is said of the honey-bee? What of the bumble-bee? Tell
 how he manages with the flowers of the cypress-vine. What is said
 about bumble-bees going some to the inside and some to the outside
 of flowers? What is said about the making of honey? Tell about the
 butterflies.




CHAPTER X.

MORE ABOUT WHAT LIVE ON FLOWERS.


The humming-bird also lives on the flowers. This little creature seems
always to be on the wing when he is not in his nest. He is seldom seen
sitting on a branch like other birds. As he puts his long bill into a
flower he does not stand on any thing. He is held up by his fluttering
wings. His wings never seem to be still, but are always quivering. And
then how very quickly he goes from one flower to another. He seems to
dart as if by a sudden spring, instead of flying like other birds.

[Illustration]

[Sidenote: The humming-bird and his nest.]

Here is a representation of a humming-bird, with his nest. It is the
smallest nest that is made by a bird. It is nicely made. It is very
soft inside with down and other things. The outside is generally
covered with moss gathered from trees or fences. Fastened to the branch
of a tree, as you see, it does not appear like a nest if you look at
it sideways. It is so nearly of the same color with the bark of the
branch, that you would not be apt to observe it unless you were looking
very sharply.

[Sidenote: Anecdote about a humming-bird.]

A lady once found a humming-bird that seemed almost dead. Its long
slender tongue lay out of its bill, and it was very dry. She pitied
the poor bird, and moistened its tongue with a little sugar and water.
It drew its tongue in, and then put it out again. As it seemed to like
the sugar and water, she gave it more. Soon the little creature was so
revived that it was on its fluttering wings again, and flew off to sip
something better than sugar and water from the beautiful flowers.

I have told you about the bees and butterflies. There are other insects
besides these that seem to get their living from flowers. There is a
great variety of them about flowers, if we look for them. St. Pierre,
a Frenchman in Paris, watched a strawberry-plant that he had in a
flower-pot. In three weeks he counted thirty-seven different kinds of
insects that visited it.

[Sidenote: Variety of insects about flowers.]

If you go out into the garden in the middle of the day, you will see
what a variety of insects there is. There are more about some flowers
than about others. About some of them there are so many that it makes a
very lively, busy scene. Besides the bees you will see flies of every
color and of every size. Some are flying from flower to flower. Some
seem to be on the wing all the time. These are all the while singing as
they hover over the flowers, as if they enjoyed themselves very much
in looking at such beautiful things. And others are resting themselves
here and there, or are walking leisurely about.

[Sidenote: Bugs on flowers.]

Besides the flies, there are bugs crawling about on the flowers. These
are of various sizes, and some of them are very small. Some of them
have brilliant and rich colors.

There is a great deal of hum and stir about a plant where there are so
many insects. It is just as it is where there are many people together.
And as some people make more noise than others, so it is with insects.
So, too, some insects are more bustling than others.

[Sidenote: Insects mostly gone from flowers at night.]

At night the scene is changed. The buzzing of the bees and the singing
of the flies are done. The insects have got through with their work
and their play, and have gone to the places where they sleep. If you
look just at dusk at a plant that you have seen all alive with insects
in the day, you will find all quiet. The insects are all gone, except,
perhaps, some little ones that have gone into the flowers to sleep on
the soft and elegant bed they find there.

[Sidenote: The chilled bumble-bee.]

Sometimes insects, like people, get into trouble by staying out late at
night. On a cool morning I found a bumble-bee clinging to a flower. He
was very torpid, and he could not fly when I poked him with a little
stick. He could only buzz and thrust out his sting. After the sun
warmed him he flew off. I suppose that he stayed out so late that he
got chilled, and could not make his way home to his nest.

 _Questions._--Tell about the humming-bird, and about his nest. Give
 the anecdote told about a humming-bird. Tell about the Frenchman and
 his strawberry-plant. What is said of the variety of flies that we see
 about flowers? And of the variety of bugs? What is said of the hum and
 stir about some plants? How is it at night? Tell about the bumble-bee.




CHAPTER XI.

WHAT THE BIBLE SAYS ABOUT FLOWERS.


[Sidenote: Why man is compared to a flower.]

Flowers are often mentioned in the Bible. Man is said to be like a
flower, because as he dies and is buried in the earth, so the flower
fades and withers, and falls to the ground. I might give you many texts
where this comparison is made. But I will mention only one, which you
will find in the first chapter of the First Epistle of Peter, in the
twenty-fourth verse. “For all flesh is as grass, and all the glory of
man as the flower of grass. The grass withereth, and the flower thereof
falleth away.”

Man is compared in the Bible to a flower for another reason. Flowers
live but a little while. This is true even of those that live the
longest. Some last but a few hours, as I told you about the flowers of
the morning-glory and the cypress-vine. So it is with mankind. Some
die very young. These are like the morning-glories. They are beautiful
while they live, and parents and friends like to look at them, just as
we like to look at the beautiful flowers. But their life is short, very
short, like a flower that blooms only for a day, and then withers and
falls. When such a child dies, how appropriate to put flowers into the
coffin! The dead child is beautiful and pleasant to look upon, like the
flower cut from its stalk, and both will decay together.

But perhaps you will say that old persons are not like flowers, for
they live a great while. It may seem a long time to you, but if you
ask them, they will tell you that life, as they look back upon it, is
very short. They are like the flowers that live the longest. While the
infant that dies is like the flower that lives but a few hours, those
that die old are like the flowers that last many days. That is all the
difference. All flowers die, and so do all people, and other flowers
and other people take their places.

[Sidenote: Why death is said to cut down people.]

In comparing people to flowers, the Bible speaks of them as being _cut
down_. And you have perhaps seen in an old primer Time represented as
an old man having a scythe, and underneath it reads:

    Time cuts down all,
    Both great and small.

It is because death is often so sudden both to young and old that
they are said to be cut down like the grass or the flower. You see a
beautiful flower standing among the grass, fresh and gay, in the bright
sun. But the mower’s scythe cuts it down, and it wilts and dies. So it
is when death comes, as it sometimes does, to the strong and beautiful.
So sudden is the change, that it seems as if they were really cut down
like the flower.

[Sidenote: The lilies of the field.]

[Sidenote: Flowers and cloth compared.]

There is one comparison about the beauty of flowers that you have often
read in the Bible. It is this: “Consider the lilies of the field, how
they grow; they toil not, neither do they spin; and yet I say unto you,
that even Solomon in all his glory was not arrayed like one of these.”
Now Solomon had very rich clothing, for he was a very rich king. But
take the richest clothing and look at it carefully, and then look at
even common flowers, and you will say that they are much more beautiful
than the clothing. And the difference is very great when you use a
microscope. The splendid cloth looks coarse and rough when magnified.
But it is not so with the flowers. The more they are magnified the more
beautiful they appear.

[Sidenote: Weedy-looking flowers.]

Even flowers that we commonly think of as weeds, are beautiful when
we come to examine them. The ox-eyed daisy is not considered at all
pretty. But pick it and look at it carefully, and you will see much
beauty in it. And if, with a microscope, you look at one of the
six hundred flowers in its yellow bosom, you will say that in this
weedy-looking flower there is a whole garden of beauties. Few people
think much about the tassels that hang on so many of the trees and
shrubs in the spring; but, as I have told you before, they are rich in
beauty when we examine them.

 _Questions._--Why does the Bible compare man to a flower? What other
 reason is there for this comparison? What flowers are they like that
 die young, and what are they like that die old? Why are people when
 they die said to be cut down like the grass or the flower? What does
 the Bible say of the lilies of the field? What is the difference
 between cloth and flowers when you look at them carefully? What is the
 difference when you look at them through a microscope? What is said of
 the beauty of common and weedy-looking flowers?




CHAPTER XII.

FRUITS.


When a flower wilts and falls, there is something left on the end of
the flower-stem. It is this that holds the seeds. You can see this in
the rose. When the beautiful leaves of the flower are all scattered by
the wind, there is a roundish thick part left on the end of the stem.
The seeds are in this. It grows larger, and becomes of a reddish color.
If you break it open you can see the seeds in it.

[Illustration]

[Sidenote: Seed-holders of the rose.]

Here is represented this seed-holder of the rose, in the first figure
as whole, and in the second as cut open to show the seeds. You see that
the seeds crowd it full. There is no room for any thing else.

Now this we do not call fruit; for there is very little of it, and
it does not taste good. But look at what is left when a pear-blossom
falls. It is shaped very much like what is left when the leaves of the
rose are scattered. But it grows more than that does. When it is fully
grown it is larger than it need to be to hold the seeds. The seeds are
but a small part of it. It is made to be eaten as well as to hold the
seeds. So we call it fruit.

[Sidenote: Pears.]

[Illustration]

Here is a small pear cut in such a way as to show the seeds. You see
that it is very different from the pear-shaped seed-holder of the rose.

[Sidenote: Oranges.]

When the blossom of the orange falls, you see a little round green ball
standing on the end of the stem. This grows very much, and when it is
ripe it is large and of a yellow color. Just as it is with the pear,
the orange is larger than it needs to be to hold the seeds. We call it
fruit, because it is made for us to eat.

[Sidenote: Berries.]

[Illustration]

The little yellow flower of the currant, when it falls, leaves a small,
round berry. This grows, and becomes red when it ripens. So it is with
the gooseberry. The whortleberry, you know, grows dark when it ripens.
These berries have the seeds inside of them. The strawberry has its
seeds on the outside, as you see here, and they give it a very pretty
appearance.

These berries are all larger than they need to be to hold the seeds.
The Creator intends them for fruit. But he never intended that what
holds the rose-seeds should be fruit, and so he made it only large
enough to hold the seeds.

[Sidenote: Grapes.]

The flowers on the grape-vine are very small and delicate. They are
much smaller than the fruit that forms after they fall. The delicious
grape is something more than a seed-holder. If it were meant only
to hold the seeds, it would not have all that juicy pulp that is so
pleasant to the taste.

[Sidenote: Different sizes of fruits.]

Fruits are of very different sizes. The fruits of some vines are
very large, as the pumpkin and the watermelon. The fruits of some
large trees are quite small. This is the case with the walnut and the
chestnut. The acorn is a very small nut, but every child has been
taught that

    “Tall oaks from little acorns grow.”

Some of the trees in warm climates bear very large fruit. Cocoa-nuts
are an example.

[Sidenote: Seeds that are fruits.]

The fruits of the earth that are most largely used by man are in the
form of seeds. This is the case with grain, corn, peas, beans, etc.
Most of what we raise of these is used for food, and we keep but a very
small part for seed for the next year. The different kinds of grain
and corn are used in making bread; and this, you know, is a part of
our food that we depend upon so much, that it is called the staff of
life. And this is the reason that in the Lord’s Prayer bread is used as
meaning food, when we say, Give us this day our daily bread.

The grains from which our bread is made are quite small. But there are
a great many of them. And they are freed from their chaffy coverings,
and are ground between mill-stones, so as to be changed into the fine
flour, from which we make bread.

 _Questions._--What is said of the seed-vessel of the rose? How is
 a pear different from this? What is said of the orange? What of
 currants, strawberries, etc.? What is said of grapes? What is said of
 the different sizes of fruits? In what shape are the fruits that are
 most used by man? Why is bread called the staff of life? How do we get
 the flour from which we make bread?




CHAPTER XIII.

MORE ABOUT FRUITS.


[Sidenote: Fruits made from the sap.]

You will want to know from what all the fruits are made. They are made
from the sap, just as the flower is. After the flower has fallen the
sap keeps coming along the pipes in the stem. And what is on the end of
the stem is made from the sap into fruit.

You remember that I told you that a flower is never like the sap from
which it is made. The same is true of the fruit. Bite the stem of a
cluster of grapes, and you will see that the sap in it has none of the
sweetness of the grapes; and yet they are made from it, just as the
flowers were before them.

How different the fruit often is from the flower that was before it,
though they are both made from the same sap! It may not, perhaps, seem
strange to you that the sweet orange and its fragrant blossom can be
made of the same sap; for, though they have different colors, they are
both sweet. But how different a sour apple is from the blossom that was
before it! And then, too, the orange was sour till it became ripe. But
the sap constantly came to it through the stem, and the juice after a
while became sweet. And see how different a thing the peel is from the
pulp of the orange. It tastes quite sharp, and is sometimes bitter. But
both peel and pulp are made from the same sap. So, too, the skin of
some grapes has a very different taste from the pulp.

[Sidenote: Variety in the taste and color of fruits.]

You see that there is a great variety in the fruits that God has given
to us. I have said something before of their variety of size. They
differ also in their taste, and color, and shape.

Some fruits are sour, and some are sweet. Many fruits have a taste
that is very different from the taste of any other fruit, and yet you
can not describe it. The chestnut does not taste like the walnut, but
you can not describe the difference to any one so that he would know
it. He must taste them himself to know the difference. Grapes and
whortleberries are both sweet, but they do not taste alike. There is a
great variety of sour apples, but you always readily see the difference
between them when you eat them.

There is a great variety in the _colors_ of fruits. But it is not as
great as the variety of color in flowers. The Creator made flowers
especially to please the eye. It is for this that he has given them
many different colors. He could have made fruits without having any
flowers. But he, in his kindness, wished to have us gratified by
looking at beautiful things.

[Sidenote: Beauty of some fruits.]

Flowers are for beauty, and fruits for use. But many of the fruits are
beautiful. Our heavenly Father likes to make beauty go along with what
is useful. The orange has a rich color, and looks beautiful among the
green leaves. We admire the clusters of grapes, as they hang by their
slender stems under the broad leaves of the vine. The colors of some of
the varieties of the peach and the apple are very rich. The strawberry
looks very beautiful, as the yellow seeds stand out on its red surface.

There is a great variety in the _forms_ of fruits. Look at the chestnut
burr, and see how different it is from a fair-skinned, round apple.
How different is the strawberry that melts in your mouth from any of
the hard nuts! How different is the cocoa-nut from a melon!

[Sidenote: God’s bounty in fruits.]

God smiles upon us in the flowers. But in the fruits we have something
more than his smiles. In them he blesses us with his bounty. The
flowers are a feast to our eyes; but the fruits are food to our bodies.

[Sidenote: Why fruits have a pleasant taste.]

But fruits are not made merely to nourish us. They are so made that
they gratify our taste while they nourish us and sustain our lives.
And in this we see the kindness of our heavenly Father, just as we do
in the beauty that he has given us to look upon in both flowers and
fruits. He could have made the fruits in such a way that they would be
without any pleasant taste. And they would have answered as well to
nourish us as they now do. But he wanted to gratify us in this as he
does in other things. For this purpose he has given to each kind of
fruit its own taste. All fruits are pleasant, but each is different
from the rest.

The variety of pleasant tastes in the fruits of the earth is very
great, as you will see if you will think of as many of them as you
can. What an evidence is this of God’s abundant goodness! He does not
gratify us merely in a few things, but in many things. The pleasant
things of this world are almost endless in their variety. How strange
it is that any one can know all this, and live on day after day without
any gratitude to his Maker!

 _Questions._--What are fruits made from? Is the fruit ever like the
 sap? What is said about the orange? What is said of the taste of
 fruits? What of their colors? What of their different forms? What is
 it said that God does in the flowers, and what in the fruits? Why is
 there such a variety of pleasant tastes in fruits?




CHAPTER XIV.

WHAT SEEDS ARE FOR.


[Sidenote: Growth from seeds wonderful.]

In telling you about fruits I told you also something about seeds. In
this chapter I shall tell you more about them. Plants commonly come up
from seeds. It is very curious to see how this is done. But most people
do not think much about it. Gardeners and farmers put seeds into the
ground. They see the plants come up from them. They see these plants
grow and blossom, and after a while they gather fruit from them. And
they do not seem to think that there is any thing wonderful in all
this. But when you have read what I shall tell you about it, I think
that you will say that it is very wonderful.

[Sidenote: Beans.]

You put a bean into the ground. A vine comes up from it. This runs up
a pole, winding round and round it as it goes up. It blossoms. Then
come the pods. In these are beans just like that which you put into
the ground. All this comes from that single little bean. And there is
nothing there like what you put into the ground but the beans. The
vine, the leaves, the flowers, are nothing like the bean from which
they grew.

[Sidenote: Corn.]

When you put a kernel of corn in the ground there comes up a stalk.
From this spread out broad, long leaves. At length large ears of corn
form. A great deal has come from that single kernel. And of all this
only the kernels of corn on the ear are like what you put into the
ground.

[Sidenote: Acorns.]

An acorn falls from an oak-tree. This is the seed. But nothing will
grow from it unless it gets into the ground. A cow perhaps treads on
it, and so presses it into the earth. A twig shoots up from it. This,
after many years, grows to be a large tree. Here a very great deal has
come from the seed in the ground. And the huge tree is not at all like
the little acorn from which it came.

You will want to know how it is that so much comes from a small seed. I
will now tell you as much about this as I can.

[Sidenote: How seeds begin to grow.]

[Illustration]

After a seed has been in the ground a little while it swells, because
the dampness of the earth gets into it. The covering of the seed
breaks, and out comes a little root. This root pushes down into the
ground. Pretty soon there comes out of the seed also a little stalk.
This shoots upward. Here is a representation of a seed which has burst.
And you see the root, with its fine fibres, going down while the stalk
goes up. Now what makes the root go down and the stalk go up we do not
know. Many very wise men have tried to find this out. But they can
not do it. They have guessed a good deal about it; but guessing is
not knowing, though people often think it is. The Creator knows, and
he makes the root of every seed go down and the stalk go up. There is
never any mistake about this. You never see a root pushing up through
the ground and a stalk growing down.

[Sidenote: Barley-seed.]

Here you see the way in which a barley-seed grows. Roots branch out
from one end of the seed down into the ground, and a stalk goes up from
the other end of it. It is so also with corn. No matter how the seed
lies in the ground, the roots will go down, even if they come out of
the upper end of the seed; and the stalk will go up to find the air,
though it must first come out of the lower end.

[Sidenote: A tree growing on a wall.]

[Illustration]

Roots sometimes seem to take a great deal of pains, as we may say, to
get down into the ground. A seed of a tree was seen to take root, in
Galloway in Scotland, on an old stone wall ten feet from the ground.
And a tree shot up from it. There was earth enough in the crevices of
the wall to make the little tree grow for a while. But after a time
it stopped growing. The reason was that the tree had become so large
that it could not get food enough out of the earth in the wall. The
little mouths in the root sucked up all they could find; but it was
not enough. The tree needed more food than when it was small, just as
a man needs more food than an infant. What was to be done? There was a
plenty of food in the ground below, but the trouble was to get at it.
If somebody would take the tree from the wall, and set it down into
the ground, it would do well enough. But no one did this. So the tree
managed the matter itself. It sent its roots down the wall the whole
ten feet into the ground. And then it grew finely, and would have done
well if the wind had not blown it over. It was so stilted up on the
wall that it could not stand against a strong wind as a tree could
whose roots spread right from the bottom of its trunk into the ground.

[Sidenote: Coverings of seeds.]

I have mentioned the covering of the seed. If you look at a bean you
will see that it has a firm skin. This bursts open for the root and the
stalk to come out. The place where it bursts is what is called the eye.
The potato, you know, has many eyes. When it is put into the ground a
root and a stalk will come out from each one of them. You sometimes see
potatoes sprout from the eye as they lie in the cellar.

[Sidenote: How they are opened to let the seed grow.]

There is great difference in the coverings of different seeds. The
covering of some nuts is very hard. You see this in the peach-stone,
the walnut, and the cocoa-nut. How do you think these are opened so
that the root and stalk may push out? I will tell you. The peach-stone
and the walnut, by being soaked in the ground, swell and crack open.
And as to the cocoa-nuts, it is said that the monkeys crack them open
by throwing them on the ground. So it is in various ways that the
prison-house of the seed, as we may call it, is opened.

 _Questions._--What come from seeds? Do most people think that there is
 any thing wonderful in this? Tell what comes from a single bean. What
 from a kernel of corn. What from an acorn. How does the seed begin to
 grow? What is said about the stalks shooting up and the roots going
 down? Tell about the barley-seed. What is told about a tree? What is
 the eye of a seed? What is said about the difference in the coverings
 of seeds? How are some hard seeds opened, so that the root and stalk
 may push out?




CHAPTER XV.

LIFE IN THE SEED.


A dry seed looks as if it were dead. But there is life there, shut up
in that prison-house. It is very quiet as long as it is shut up. But
once let it out, and it does great things. An apple-seed, with its
stout brown covering, is a very little thing. It does not look as if
any thing could ever come from it. But if it gets into the ground, the
moisture swells it, the covering bursts, and an apple-tree comes from
the seed. And you know the Bible tells us, a tree large enough for
the fowls of the air to lodge in its branches comes from the little
mustard-seed.

[Sidenote: Life asleep in seeds.]

[Sidenote: The city buried up with lava.]

The life in the dry seed is asleep. Put it into the moist ground, and
this life wakes up. This sleep of seeds sometimes lasts a great while.
Commonly we keep them only from one year to another. But sometimes
they are kept a long time in their state of sleep. I will tell you a
story about this: Many hundred years ago there came a great stream of
lava, as it is called, down from a mountain. It was all on fire, and
looked like a stream of melted iron. It rolled over a city and covered
it up. All the inhabitants were killed. When the lava cooled, people
came to look for the city, but could not find any of it. But lately,
people have dug down through the lava, and opened passages into this
covered-up city. They have gone into the houses, and have found many
things just as they were when the red-hot lava ran over the city. Some
seeds were found. These were planted; and they sprung up just as seeds
do that have been kept only from one year to another. The life in these
seeds, then, had been asleep for many hundred years.

[Sidenote: Many seeds from one.]

A great many seeds come from one seed put into the ground. From a
single kernel of corn come several ears full of kernels. The kernels
or seeds from one single ear are enough to plant quite a large piece
of ground. We use most of the corn for food, for we need to keep but
little of it for seed. So we eat most of the beans that we raise. We
keep only a little bag of them for planting the next year. As you look
at the little bag, you would hardly think that it holds what will cover
long rows of poles with vines. There is a great deal of life asleep for
the winter in that bag.

[Sidenote: Many destroyed.]

Most of the seeds that drop from trees and plants are killed, and they
decay on the ground with the leaves. It is only now and then that a
seed lives and takes root. If all seeds lived and sprung up we should
have too many things growing every where. If all the acorns lived,
and got into the ground, and took root, there would be too many oaks.
And so of other trees and plants. The seeds that are scattered on the
ground have to take their chance, as we say. Some out of the whole live
through the winter in some way, and come up in the spring.

 _Questions._--What is said of life in the seed? What wakes it up? Can
 the sleep of seeds sometimes last a great while? Tell about the seeds
 from a city that was covered up with lava. What is said of the number
 of seeds that come from one seed? What becomes of the seeds of plants
 and trees that fall to the ground?




CHAPTER XVI.

HOW SEEDS ARE SCATTERED.


Seeds are scattered in various ways. They do not all stay near the
place where they drop.

[Sidenote: Seeds scattered by man, by water, by wind, etc.]

There are many kinds of seeds that man scatters in raising his crops
from year to year.

Some seeds are carried away by water. Sometimes they sail a very great
distance in this way, and, like people, settle down far away from the
spot where they grew.

Seeds are sometimes carried about in the hair of animals, and are
dropped here and there. The sheep gets seeds into its wool, and then
shakes them out as it goes about the pasture, or rubs them off against
the trees and the fences. The little burrs with which you make baskets,
by sticking them together, are seed-holders. They often stick to your
clothes. When you pick them off and throw them away, you help to
scatter seeds just as the sheep does.

The wind is the great scatterer of seeds. It blows them about if they
are at all light. It sometimes takes them far away from where they
grew. Some seeds are made in such a way that the wind can blow them
about very easily. Look at the seed of the maple-tree. There is a sort
of wing on it, as if it were made to fly. So when it falls, it goes
whirling away in the air. It does not drop just by the tree if the air
is stirring.

[Sidenote: Seeds of the maple, the dandelion, and the salsify.]

Here is a representation of two seeds of the maple, with their wings.
They always grow in this way, in pairs.

[Illustration]

Look at the little feathery ball on the stalk of the dandelion after
the flower is gone. The seeds are in the middle of that ball. Pick it,
and then hold it up, and blow upon it as hard as you can. Away will fly
all the seeds. If the wind is blowing it will scatter them every where.
Now look at them to see what makes them fly so. You see that each seed
has a very little stem. This stem has on its end some very fine fibres
standing out all around. The wind blows the seed about by these fibres.
If the seed did not have this sort of balloon to fly with, it would
fall straight to the ground. But with this it may go a great distance.
Sometimes it travels over mountains and across rivers. Here is a
drawing of the dandelion-seed. But to see how delicate it is, and how
well fitted it is to fly, you must look at a real seed.

[Illustration]

[Illustration]

And here is the stem of the dandelion as it looks after the seeds are
scattered. You see that it has a cushion-shaped end. It is on this that
the seeds are fastened. It is curious to see how regularly they are
arranged so as to make that beautiful feathery ball.

[Illustration]

The seed of the salsify represented here, is very much like that of the
dandelion. But the fibres by which it is carried about by the wind
are, you see, very delicately feathered.

[Sidenote: Seeds of the clematis.]

[Illustration]

[Sidenote: Mosses and ferns.]

[Sidenote: Thistle-down.]

The seed of the clematis or virgin’s-bower is, as you see, rather
differently arranged. It has a very long stem, with little fibres
standing out from it all the way, something like a feather.

[Illustration]

The down of thistles and some other flowers is the wing of the seeds
by which they are scattered by the wind. Here is a representation of a
seed with its wing of down. This little seed has a very large wing to
fly with.

The seeds of mosses and ferns are scattered more widely than any others
because they are so small. You know the mosses well. You see them every
where on fences, rocks, and trunks of trees, as well as on the ground.
The wind carries their fine seeds about, and they lodge on every thing.
They go even to the tops of the mountains, and down into caverns in
the earth. There is great variety in the mosses, and some of them are
exceedingly beautiful, especially when examined with a microscope.

 _Questions._--In what different ways are seeds scattered about? What
 is the great scatterer of seeds? What is said of the seeds of the
 maple? What of the seeds of the dandelion? What of the seeds of the
 salsify--the clematis--the thistle? What of the seeds of mosses and
 ferns?




CHAPTER XVII.

LEAVES.


[Sidenote: Beauty of leaves.]

Most trees and bushes are stripped of all their leaves in the autumn,
and remain bare till the winter is passed. We should feel sad if they
were without leaves all the year round. One use of the leaves is to
gratify us by their beauty. When the winter is gone how delightful it
is to us to look out upon the trees and the plants as they put forth
their leaves! Their fresh green color is a feast to our eyes.

[Sidenote: Variety of their shapes.]

[Sidenote: Various shapes of leaves.]

You remember what I said about the flowers having so many different
shapes. The Creator has made the same variety in the shapes of leaves.
He likes to make beautiful things in great variety for us to look at.
Here I give you some figures of leaves, to show you how different their
shapes are.

[Illustration]

Here is a leaf which is shaped like the head of an arrow. There is a
plant called arrow-head, because its leaf has this shape.

[Illustration]

Here is one shaped very much like a lance, another is a good
representation of a mason’s trowel, and a third is very much like a
fiddle.

[Illustration]

This is like a shield. The nasturtium the leaves of this kind. The stem
is fastened to the leaf just where the hand holds on to a shield.

[Illustration]

This leaf has a tendril on the end of it. This clasps around whatever
it happens to touch. Some plants are held up in this way by their
leaves.

[Illustration]

This leaf is notched all around its edge, like a saw. The leaves of a
great many plants are notched in this way, as those of the rose, the
peach, and the nettle.

[Illustration]

Here is one that is notched differently. The teeth are rounded, and not
sharp. It may be said to be scalloped rather than toothed. The ground
ivy has a leaf of this kind.

Below are two leaves, one of which is spread out like a hand, and
the other is very much like the claws of the feet of some birds. The
passion-flower is of the shape of the hand. So, also, is that of the
castor-oil plant.

[Illustration]

[Sidenote: Variety in the arrangement of leaves.]

I have thus given only a few of the shapes of leaves. Their variety is
very great. They vary not only in shape, but in color. They vary also
in other things. Some have down on them, and some hairs, and some have
neither. It will be well for you to see how many different kinds of
leaves you can bring to the teacher, and she will tell you about them.

[Illustration]

Leaves are arranged in a great many different ways on their stems. Here
are three leaves together on a stem. The leaves of the clover and the
wood-sorrel are arranged in this way.

[Illustration]

Here the leaf-stem has three little branches, and each branch has three
leaves.

[Illustration]

On this leaf-stem are a great many leaves. I have thus shown you three
ways in which leaves are arranged. But there are many other ways in
which they are arranged, making a great variety in the appearance of
leaves. The only way to know how very great this variety of arrangement
is, is to look for yourselves at plants, and trees, and shrubs, as you
walk in the garden or in the fields.

Leaves are of all sizes. Some are very small, and some are very
large. Look at the little delicate leaves of the chick-weed and
the cypress-vine, and then at the large spreading leaves of the
rhubarb-plant and the pumpkin-vine, and the very long ones of the
corn. The common palm-leaf fans so much in use are made from the large
leaves of the palm-tree.

[Sidenote: Forms of leaves not commonly observed.]

I think that you will be quite interested in observing the various
forms of leaves, though most people do not observe them much. A friend
once told me that a number of leaves from our common trees were brought
to some ladies, and that not one of them could tell from what kind of
tree each leaf came. It seems to me that they could have used their
eyes to little purpose, as they walked about among the trees of the
field and the garden. They probably looked at leaves merely as making
a pleasant green to the eye, and never examined them, as they perhaps
would flowers, to see what a difference there is between them. You had
better gather some leaves of various kinds, and see if your schoolmates
can tell from what trees they came. Take the star-shaped leaf of the
maple, the birch-leaf with its nicely notched edges, the bright, firm
leaf of the oak with its wavy edge, and the wrinkled leaf of the elm.
Show them a willow-leaf beside a peach-leaf, which is very much like
it. An apple-leaf and a pear-leaf together might puzzle them, though I
think that some wide-awake child would see the difference between them.

 _Questions._--What is said of one of the uses of leaves? What of the
 variety in their shapes? Mention some of these shapes. In what other
 things do leaves vary besides shape? What is said of the arrangement
 of leaves on their stems? What is said of their different sizes? What
 is said about observing the shapes of leaves?




CHAPTER XVIII.

MORE ABOUT LEAVES.


[Sidenote: Beauty of common leaves.]

Leaves are such common things that we do not think how beautiful they
are. But take any common leaf into your hand and look at it. Take the
leaf of the strawberry. See how prettily it is notched. Hold it up
to the light and see the lines that run from the middle line to the
edge. Then see the fine net-work between these lines. How delicate and
beautiful! The leaf of the raspberry is even more beautiful than the
strawberry leaf, if you pick it from a new shoot. See the fine points
on its edge, and see how delicate are its lines and net-work as you
hold it up to the light.

[Sidenote: Ribs in leaves.]

Observe the back of a leaf, and you will see ribs that spread out from
the main rib in the middle to the edges. These are the frame of the
leaf, just as timbers are the frame of a house. They are to the leaf
what whalebones are to an umbrella. They give strength to it. Without
them it would droop like a wilted leaf. It would not stand out straight
and firm. The wind would blow it every way, like a rag tied to a stick.

You see these ribs very large in broad spreading leaves. They are large
in grape-leaves, and in the leaves of the rhubarb-plant, or pie-plant,
as it is often called.

In leaves that are very stiff and firm these ribs are so small, that at
first you would say there were none. This is the case with the leaf
of the pear and the orange. There is one strong rib running through in
the middle of the leaf. But there are no strong ribs branching out from
this. The leaf is so firm that it does not need them.

[Sidenote: The upper and under side of leaves.]

See the difference there is between the upper and the under side of a
leaf. The upper is greener than the under side. In the grape-leaf the
under side is covered with a very fine white fuzz. If you tear the leaf
gently, you can see the delicate white fibres of this furze across the
rent. In the silver-leaf poplar there is a silvery whiteness on the
under side of the leaf. This makes the tree look very pretty as its
branches are moved back and forth by the wind.

I have thus told you a few things about leaves. By looking at them
yourselves you will see a great many things in them that will interest
you. Look at them as you walk in the garden or roam in the field, and
you will see that there is no end to the variety. And among them all
you can not find one that is not beautiful when you examine it.

[Sidenote: Leaves seen through the microscope.]

Leaves are very beautiful if you look at them through a microscope.
Take the most common leaf and look at it in this way, and you will be
delighted. You will be surprised to find how much beauty there is in
leaves that you knew nothing about before.

And now I will tell you about some leaves of a very singular character.

There are some leaves that are of very singular shape. I will mention
only a few.

[Sidenote: Leaf of the side-saddle flower.]

[Illustration]

Here is the leaf of the side-saddle flower, as it is called. It is
shaped somewhat like a butter-boat. You see that it is open. It can
hold considerable water. It has a kind of lip, which looks as if it
were made in order that water might be poured out of it easily. This
plant grows in some parts of this country. The flower is purple, and
has a curious shape. It is on a stalk that stands up in the midst of
about half-a-dozen of these leaves.

[Sidenote: Chinese pitcher-plant.]

[Illustration]

One of the most singular leaves is that of the Chinese pitcher-plant.
At the end of the leaf the main rib extends out like a tendril, and
this ends in the appendage which is represented here. It is in the
shape of a pitcher, and has, as you see, a regular lid. This is
generally shut down, though, as you see it here, it is raised up. The
rain can not, therefore, get in, and yet the pitcher is always full of
water. It holds about a tumblerful. Now how do you think this water
comes there? It is a part of the sap that comes to the leaf. The watery
part of the sap is poured from thousands and thousands of little mouths
on the inside of the pitcher; and so it is kept filled with water.
This plant is quite common in the island of Ceylon. There it is called
monkey-cup, because the monkeys sometimes open the lid and drink the
water. And men sometimes drink from these leaves when there is no
spring of water where they can quench their thirst.

[Sidenote: Venus’s fly-trap.]

[Illustration]

The leaf of the Venus’s fly-trap, which grows in North Carolina, is a
real trap for flies and other insects. Here you see the leaf as it is
spread out, wide open. It looks as if there was no danger there. But
let an insect alight on the leaf, and he is made a prisoner at once.
The two parts of the leaf close together, as you see, and the points on
the edges are locked together, so as to furnish bars to the prison. You
see a little insect caught in this leaf that had lighted only on its
very edge. He can not get away, and there, poor fellow! he must die a
slow death. Of what use it is to have such traps for insects we do not
understand.

[Illustration]

[Illustration]

[Sidenote: Leaves of the fern.]

This is the leaf of the common fern or brake. It is beautiful if you
examine it, for it is very delicate. And it has one great peculiarity.
The flowers of the plant are on the under side of the leaf. They are
where you see the little round spots. If you look at the leaf with a
microscope you can see the different parts of the flowers.

[Sidenote: Thick leaves.]

Most leaves are thin, but some are quite thick. This is the case with
the leaves of the India-rubber tree. The wax-plant has thick leaves,
which, with the flowers, look so waxy as to give the name to the plant.
The flowers of the cactuses grow right out from the thick fleshy
leaves, making these plants look very awkward, although the flowers are
so beautiful. And it is a singular fact, that if one of the leaves is
broken off and put into the ground it will take root and grow.

[Sidenote: Live-forever.]

Did you ever make a blow-bag, as it is called, of the leaf of the
live-forever, as children very often do? If you have not, I will tell
you how it is done. The leaf is rather thick, and is made of two
layers. These you can separate at the stem-end of the leaf, and then
by pinching the leaf and blowing into it you can make it puff out like
a bag. You must do this very carefully, or you will break the layer on
the under side of the leaf, which is very thin, while the upper layer
is thick.

[Sidenote: Ribbon-grass.]

The leaf of the ribbon-grass, as it is called, is very singular in one
respect. It is very prettily striped, but you can not find any two
leaves that are striped exactly alike, any more than you can find two
faces exactly alike among all the people on the earth.

 _Questions._--What is said of the beauty of common leaves? Tell about
 the ribs of leaves. What leaves have large ribs? How is it with the
 leaf of the pear and the orange? What is the difference between the
 upper and the under side of leaves? Tell about the grape-leaf. And
 about the leaf of the silver-poplar. What is said of the beauty of
 leaves as seen through the microscope? Tell about the leaf of the
 side-saddle flower. And about the Chinese pitcher-plant. Also about
 the Venus’s fly-trap. What is said of the leaf of the common fern?
 What of thick leaves? What of the leaf of live-forever? What of
 ribbon-grass?




CHAPTER XIX.

THE SAP IN LEAVES.


I have told you about the ribs of leaves. Let us see what makes them
so firm and strong. Look at a large grape-leaf on the vine. It spreads
out very firmly. If the wind blows it very hard it bends, but it stands
out again as firmly as ever. But break the leaf off, and see what
happens. In a little time it wilts. If you hold it up by the stem its
edges droop down all around. The leaf does not stand out as it did when
it was on the vine. The ribs are all there, but they have lost their
strength. How do you think they lost it? I will tell you.

[Sidenote: Wilting of leaves explained.]

When you broke off the stem, the sap could no longer get to the leaf.
It is just as no water can get into a house when the water-pipe is
cut off outside. The sap goes to all parts of the leaf from the stem
through the ribs. The ribs, like the stem, have little fine pipes
in them for the sap to run in. Now, if the ribs are not full of the
sap they are not firm, and they bend easily. When these ribs and the
net-work between them are not full of sap the leaf is _wilted_, as we
say.

But when the leaf is picked it is full of sap. How does any of the sap
then get out of it so as to make it wilt? It does not leak out of the
stem. If it did, you could see it drop as you hold the leaf up. Where,
then, does it get out? This I will explain to you. There are little
holes, or pores, as they are called, all over the leaf. They are so
small that you can not see them without a strong microscope. The watery
part of the sap escapes into the air through these pores.

[Sidenote: The quantity of moisture that comes from leaves.]

There is a great deal of moisture that comes from leaves. You can see
that this is so if you put a cluster of leaves under a glass vessel.
A large tumbler will answer. You will, after a little time, see the
moisture in drops on the inside of the glass. This moisture is the
water that comes from the pores of the leaves.

You remember what I told you in the last chapter about the leaf of
the pitcher-plant. The water in that leaf comes from its pores on the
inside. If, instead of its having a pitcher-shape, the leaf was laid
open and spread out like common leaves, the moisture would all go off
in the air. But as it is a pitcher with a lid, the moisture that comes
from all the pores is shut in. It can not fly off in the air. And after
a while enough moisture collects to fill the pitcher. This shows how
much water commonly goes from leaves into the air. If any leaf that
you see spread out could be changed into a pitcher or cup shape with a
lid, it would in a little time be full of the water that comes from its
pores.

Now you can understand why a leaf wilts after it is picked. It does not
wilt as soon as you pick it, for the sap is all in it then. But let it
be a little while. The watery part of the sap is going out of the pores
of the leaf all the time, and there is no sap coming to it through the
stem. So the leaf wilts.

[Sidenote: Keeping flowers from wilting.]

You can keep a leaf from wilting for a long time by placing the stem in
water. When you do this the water goes up through the little pipes in
the stem. This takes the place of the water that goes out of the pores
of the leaf.

When you put flowers in water, you know that the water is less the next
day. This is because so much of the water goes up in the stems to the
leaves and blossoms.

You know that if you have a plant in a flower-pot, the earth gets dry
in a day or two. This is chiefly because the water in the earth is
sucked up by the roots, and runs up all through the plant, and goes
out of the pores of the leaves and blossoms. Some of the water goes up
directly from the earth into the air, but most of it goes through the
plant.

[Sidenote: Much water in the air, but not seen.]

You can not see the water that comes out of the leaves and blossoms
into the air. There is a great deal of water in the air that you can
not see. You have often seen in a hot day the water stand in drops on
the outside of your tumbler. Just think how these drops come there.
People sometimes say that the tumbler sweats, just as if the water came
through the glass. But this, you know, can not be. Water can not get
through glass. The drops come there in this way. The cold water in the
tumbler makes the glass very cold. And the water in the warm air around
the tumbler, therefore, gathers upon it. Sometimes there is much more
water in the air than there is at other times. Then the tumbler is very
wet. Now a great deal of the water in the air comes from the leaves of
the trees and the plants all about us. The leaves may be said to be
breathing moisture into the air all the time. I shall tell you more
about the water that is in the air in Part Third.

This moisture that is breathed out from the leaves makes the air soft,
while the fragrance of the flowers makes it balmy. Each leaf yields but
a little water, and so does but little good in this way. But there are
so many leaves that a great deal of water comes from all of them. It
puts me in mind of the Scotch proverb, “Many a little makes a mickle.”

[Sidenote: Lesson that can be learned from the leaves.]

Those who want to do good in the world may learn a lesson from the
leaves. A large amount of good may be done when a great many do each
a little. Let those who can do but little think of this. Let them do
every day what they can, just as each leaf does. Great men, that excite
the wonder of the world, can do a great deal of good; but they can not
do any thing like as much as is done by a great many people together
that do each a little in a noiseless way. Every child, in doing little
kind things, may, like the small leaf, do his part of the good that is
to be done in the world. And if much of the good that he does is not
noticed by others, God sees it all, just as he sees all the moisture
that is breathed out by each little leaf.

 _Questions._--What makes the ribs of leaves firm? What happens to
 these ribs when a leaf wilts? How does the watery part of the sap get
 out of a picked leaf? What is said of the quantity of water that comes
 from leaves? Tell about the water in the leaf of the pitcher-plant.
 How does a picked leaf wilt? How does putting a leaf in water keep it
 from wilting? What makes the earth in a flower-pot become dry? Can you
 see the water that goes into the air from the leaves and other things?
 Tell about water settling on tumblers in hot weather. What lesson can
 we learn from the leaves?




CHAPTER XX.

THE USES OF LEAVES.


[Sidenote: Refreshing moisture from leaves.]

One use of leaves, as I told you in the last chapter, is to supply
the air with water. In the hot weather the air would be very dry and
uncomfortable to us if the leaves did not breathe out moisture from
their pores. You can see how this is if in a hot day you walk across a
sandy plain where there are no leaves except those of the scanty grass
and weeds. Here no moisture is breathed out upon you, to lessen the
heat that you suffer from the burning sun.

Another use of the leaves is this. They are pleasant and beautiful to
the sight. I have told you about this use of them in the beginning of
the seventeenth chapter.

[Sidenote: Their shade.]

Another use of leaves is to give shade. We know how refreshing this is
to us in a hot day. When in a city we walk through streets where there
are no trees, how delightful it is to come out of the blazing sun into
a square that is full of trees! How comfortable are the cows in the
pasture lying under the trees at mid-day, chewing the cud!

But the shade given by leaves does good not merely to man and animals.
It does good to fruits, if there is not too much of it. The sun would
very often be too hot for the fruits, if it shone full on them all the
time. So the leaves partly shade them.

[Sidenote: The grape-vine stripped of its leaves.]

The chief use of leaves is to keep plants and trees alive and make
them grow. If you should strip off the leaves from a plant as fast as
they came out, you would, after a while, kill it. Sometimes worms eat
up the leaves on trees. If this is done year after year to a tree it
dies. I knew a man to strip off all the leaves from a grape-vine. He
thought that it would make the grapes grow finely. He had seen people
take off some of the branches from grape-vines, to make the grapes
grow large and full. So he thought that if he took _all_ the leaves
off, the sap would all go into the grapes and make them very large. He
thought, too, that the sun would make them ripen fast. But he found
that the grapes stopped growing, and wilted, and dropped off. There are
two reasons for this. The sun was too hot for the grapes when all the
leaves were gone. And besides, there were some leaves needed to keep
the grapes alive.

[Sidenote: Leaves are lungs to plants.]

Leaves are the same thing to plants that lungs are to an animal. The
air that goes into our lungs helps to keep us alive and make us grow.
So the air that is all about the leaves of a plant or tree helps
to keep it alive and to make it grow. How this is done you can not
understand now. I explain it in another book, which you will be able to
understand when you are a little older.

[Sidenote: The barter between lungs and leaves.]

There is one thing about this that you can understand, which is very
curious. The air does not keep the plants alive in just the same way
that it does animals. You know that by breathing air we make it bad;
and so we must have all the time a supply of fresh air. Now what do
you think becomes of the bad part of the air that we breathe out from
the lungs? The leaves all around us take it in. It is good for them.
It makes them and the plants that they are on grow. They then, like
our lungs, are all the time taking in air and giving out air. And
leaves take what lungs give, and lungs take what leaves give. So lungs
and leaves have a sort of trade together. They are always making this
exchange with each other. And it is a good bargain for both. Both get
what they want, and barter away what they do not want.

[Sidenote: How it is carried on in winter.]

But in winter, when the leaves are all gone except those on the
evergreens, how is it with this trade between lungs and leaves? Lungs
are all the time giving out bad air; but there are not leaves enough on
the evergreens to take it all, and give back the good air. Well, what
is to be done? A barter is carried on with the leaves a great way off
in the southern countries. The air moves about so freely that this is
easily done. The bad air goes there, and the leaves that take it into
their pores give out the good air, which immediately spreads every
where, even to us at the north. It is a free trade--as free as air, as
we may say. There is not as much bad air made by lungs in winter as in
summer, because many animals are either dead or torpid. But what is
made is disposed of mostly in this way.

 _Questions._--How are leaves useful to us in giving out moisture to
 the air? What use of them is next mentioned? What is said of the
 shade made by leaves? Is this shade useful to fruits? What is the
 chief use of leaves? Tell about the man who stripped the leaves from
 his grape-vine. How are leaves like our lungs? What kind of barter
 is there between leaves and the lungs of animals? How is this barter
 carried on in winter?




CHAPTER XXI.

LEAVES IN THE AUTUMN.


[Sidenote: The fall of leaves.]

In the autumn in cold climates the leaves fall. This is the reason that
the autumn is called the fall of the year. There are some trees that
have leaves on them all the time. These are called evergreens. In very
hot climates the leaves of trees and bushes are out all the year round.
They have no particular time to fall. And some leaves stay on for many
years. Those that stay on so long grow to be very large.

[Sidenote: Evergreens.]

If a tree or a bush that has its leaves fall in the autumn in a cold
climate be raised in a warm climate, it will there keep its leaves
on all the year. In the southern parts of Europe quince-trees are
evergreen. The currant-bush, which, you know, with us is bare through
the winter, in a hot country has leaves on it all the year.

[Sidenote: Change of color in leaves in autumn.]

Before the leaves fall, many of them, you know, become very beautifully
colored. The variety of colors that you see in different trees is
very pleasing to the eye. The maple-leaf is colored bright red, the
oak a deep red, the walnut yellow, and other trees have their leaves
variously colored.

Some trees change their leaves earlier than others, and some at first
are only partly changed. So you see the green mingled beautifully
with the bright red, yellow, and other colors. I have often admired a
single tree standing by itself when it is partly changed. The maple is
particularly beautiful. The top generally changes first. You often see
the top bright red, and then the red is mixed with the green here and
there in other parts of the tree. A little way off it looks as if the
top were a cluster of red flowers. And the other parts of the tree look
as if the flowers were coming out among the green leaves.

[Sidenote: Brilliant and varied beauty of the forests in autumn.]

When the sun shines brightly all the different colors of the leaves
make the woods look at a little distance as if they were all covered
with blossoms. It is a very splendid sight that you see when you look
off from a high hill over the woods on the hills and valleys. It looks
as if monstrous bouquets of flowers had been stuck down thick together
in the ground.

Such a sight is especially splendid when the sun is nearly down. Then
the light and shade vary the scene. Here you see the top of a tall
tree standing bright in the sun, while the other trees around are in
the shade. There you see a whole cluster of tall trees lighted up on
one side. Here is a shaded spot, and there, close by, is a very bright
spot, the sun shining upon it through some break in a hill. The colors
in the lighted spots look the brighter for the shaded spots near by.

So, too, it is very beautiful when, with the sun overhead, broken
clouds are passing quickly in the sky. The swift shadows of the clouds
give constant changes to the scene. One shadow seems to be chasing
another over a bed of flowers.

When the leaves put on these bright colors it is the beginning of their
death. They soon fall to the ground, and decay, and become a part of
the earth. Some one has said that flowers are God’s smiles. So we may
say that God smiles upon us in the dying leaf, when he makes it so much
like a flower.

[Sidenote: What makes the colors of the leaves in autumn.]

How it is that all these different colors are made in the leaves in
the autumn we know not. It is said that the frost makes them, but no
one can tell how it does it. And, indeed, it is probably not the frost
alone that thus paints the leaves, for the change sometimes begins
before any frost is perceived. We do not understand how this effect is
produced any better than we do how the various colors of the flowers
are made.

[Sidenote: Forests in England.]

It is singular that in England the leaves do not appear in these very
bright colors in autumn, so that an Englishman is astonished at the
beauty of our forests in that season of the year. Now why it is that
the leaves are not affected there, in the same way that they are
here, we do not know. It is supposed that it is because there is more
dampness there than there is with us. Whatever may be the cause, it
makes a great difference with the beauty of autumnal scenery. We should
hardly be willing to exchange the brilliancy of an American October day
for the dull colors presented by the forests in England.

 _Questions._--Why is autumn called the fall of the year? What are
 evergreens? What is told about quince-trees and currant-bushes? What
 is said of the colors of leaves just before they fall? Tell about
 the maple as its leaves are changing. How do the forests look in the
 bright sun when the leaves are changed? How do they look just before
 sundown? How when shadows of clouds are passing over them? What is
 said about God’s making the dying leaves so much like flowers? Do we
 know how the colors are made in the leaves in autumn? What is said
 about the leaves in England?




CHAPTER XXII.

LEAF-BUDS.


Leaves come from buds just as flowers do. If you look at the buds in
the spring on a tree you see that they are beginning to swell. They
grow larger and larger, like the buds that turn into blossoms. After a
while they unfold, and the green leaves are spread out.

How is it, you will want to know, that these leaves are made? They are
very different from the leaves of the blossoms; but, like them, they
are made out of the sap. The sap comes constantly to the leaf-bud, just
as it does to the flower-bud, through the fine pipes in the stem. And
so this sap is made into leaves.

[Sidenote: Difference between leaf-buds and flower-buds.]

There are, then, leaf-buds and flower-buds. You can tell them apart
by their shapes. The flower-buds are round and short; the leaf-buds
are long and pointed. You can see this difference very plainly on a
peach-tree in the spring.

On some trees the flower-buds open before the leaf-buds. This is the
case with some of the maples. The red color that makes them look so
beautiful in the spring, before they have put out their leaves, is
owing to the blossoms with which they are covered. These are quite
small, and they are very rich, if you examine them with a microscope.
The flower-buds of the peach-trees also open before the leaf-buds, and
some of them are very splendid with their multitudes of pink blossoms.

[Sidenote: Leaves and flowers from the same buds.]

There is sometimes another kind of buds. There are buds from which
both leaves and flowers are formed. You see this in the lilac. The
leaves first spread out from the bud, and then in the midst of the
leaves comes out a cluster of flowers. When we see all these leaves and
blossoms, and remember the bud, we wonder that so much can come out of
so little a bud as this was.

[Sidenote: Buds of the horse-chestnut and grape-vine.]

[Illustration]

This seems very wonderful when we see it in the horse-chestnut. I
have often watched from day to day the buds of this tree as they were
opening. You see at first a small bud covered with brown scales. It
grows larger and larger day after day, and after a while appears as you
see it here. Soon you see it open and the leaves push out. But they are
all folded up. You see them unfold more and more every day. After a
while there is a tall stalk with leaves having long stems. Then comes a
large cluster of blossoms at the top of this stalk.

You can see the same thing in the grape-vine. The grape-stalk looks in
winter as if it were a dead stick. It does not look as if any thing
living could come out from it. But in the spring you see little buds
starting out here and there. Watch one of these buds. You will see
it swell, and after a while leaves will unfold from it. And you will
see that what comes from the bud is not leaves alone. It is a branch
with leaves on it. After a while clusters of blossoms appear among the
leaves, filling the air with their fragrance. Then grapes form. The
branch goes on to grow, and gets to be many feet long by the time the
grapes are ripe. All this comes from the little bud, and is made out of
the sap.

[Sidenote: The unfolding of plants from buds.]

[Illustration]

Now suppose you could see all this happen while you stand looking at
the vine. Suppose you could see the bud swell, then the leaves push
out, then the flowers form, then the grapes, and then see the whole
grow while the grapes are growing and ripening. You would think this
very wonderful. But it is just as wonderful to have all this done
slowly. The great wonder is that it is done at all. No one but God
could make all this come from a bud. And he could do it in an hour as
well as in several weeks if he thought it was best.

[Sidenote: Rock-saxifrage.]

This unfolding of plants is very beautiful and interesting. I have
often watched it in the rock-saxifrage, one of the wild flowers of
spring. I have, for this purpose, taken it up with a little earth
around it, when it was nothing but a small bud peeping up out of the
ground, and have put it into a saucer. As I watched it from day to day
the bud spread out into leaves. Then came up a little stalk out of the
midst of the cluster of leaves, and on the end of the stalk appeared a
great many little white flowers.

[Sidenote: English cowslip.]

[Sidenote: The crown of the crown-imperial.]

You see the same thing in the English cowslip, which is represented at
the bottom of the opposite page. All this came from a little bud, just
as it is with the rock-saxifrage. That curious but elegant plant, the
crown-imperial, unfolds in a little different way. A stalk comes up in
the midst of the leaves; but as it grows up leaves come out from the
stalk. When it is fully grown, and in blossom, the whole plant presents
a singular but splendid appearance. The long pointed leaves stand out
around the tall, straight stalk for some way up. Then the stalk is
naked for as much as the length of two fingers, and on the top is a
crown of leaves and flowers, the flowers hanging down. It is very well
named the crown-imperial.

But there are jewels in this crown that most people do not see. They
are to be seen only by looking up into the flower. In each leaf of
the flower where it joins on to the stem there is a beautiful little
shallow cup which is very white. From this cup hangs a shining drop,
like a tear. The whiteness of the cup gives the drop a rich pearly
color. It seems, as you look up into the flower, as if there were six
splendid pearls fastened there.

Each cup always has this drop hanging from it. If you put up something
which will soak it up, there will soon be another one formed there.
These drops are the honey of the flower.

 _Questions._--What do leaves come from? What are they made of? How
 can you tell the difference between flower-buds and leaf-buds?
 Mention some trees on which the flower-buds open before the
 leaf-buds. What is said about another kind of buds? Tell about
 the lilac--the horse-chestnut--the grape-vine. Would it be any
 more wonderful if the unfolding of the buds of the grape-vine were
 done in a shorter time? Tell about the rock-saxifrage--the English
 cowslip--the crown-imperial. What is very curious and beautiful in the
 crown-imperial?




CHAPTER XXIII.

THE COVERINGS OF THE BUDS.


[Sidenote: Scales of the horse-chestnut bud.]

You remember that I mentioned to you the brown scales on the buds of
the horse-chestnut. I will tell you what these scales are for: they
cover up the tender bud from the cold of winter and early spring. These
scales are quite thick, as you can see. They are glued together, too,
quite tightly by a sticky substance. They make in this way a close
little case for the bud, to keep it snug from the cold air. When the
weather gets warm enough the swelling bud pushes the scales apart. And
when the leaves are out these scales drop off, because there is no more
use for them.

In cold climates the buds are always protected in this way by a
covering. The buds that you see in the spring do not begin in the
spring. They are formed the year before, a little while before the
leaves begin to fall. And as they form they loosen the leaves, and soon
push them off.

[Sidenote: Treasures in the buds in winter.]

Now in these little buds are locked up all the leaves and flowers that
are to come out the next spring. The precious treasures of another
year are in these buds. They must be kept safe, then, through the cold
winter. And so they have tight coverings to guard them from the cold.
They are all this time quite small, but they are ready to grow whenever
the warm weather comes. If you should pick off the covering of one of
these buds in the winter the cold air would freeze it, and it would
die.

These coverings have been called by some one the “winter-cradles” of
the buds. It is a very good name for them. The little buds in these
cradles rock back and forth in the cold winds of winter, and are as
secure from harm as the little baby in its cradle in its nice warm
home, shut in from the wintry blasts.

And notice another thing. The inside of these cradles is lined with
a soft down. This is the bud’s little blanket to keep it warm in its
cradle.

In warm climates the buds do not have these “winter-cradles,” for there
is no need of them. The buds of the orange-tree and lemon-tree have no
coverings.

[Sidenote: The care which the Creator takes of buds in the winter.]

It is thus that God takes care of the tender bud. He always gives it a
covering when it needs one to keep it from the cold. But in the sunny
south he leaves the bud naked to the pleasant warm air. To put a thick
covering over it there would do it harm. It would be like a man’s
putting on a heavy overcoat in mid-summer.

 _Questions._--What is said of the scales of the horse-chestnut bud?
 What is said of the buds in cold climates? Why is it very necessary to
 have the buds kept safe through the winter? What very good name has
 been given to the coverings of buds? How is it with the buds in warm
 climates? What is said of the care which God takes of buds?




CHAPTER XXIV.

WHAT ROOTS ARE FOR.


[Sidenote: The business of roots.]

When a seed sprouts, the root, I have told you, goes down into the
ground, while the stalk goes upward into the air. The root goes down
because the food of the plant is in the ground. It is the business of
the root to suck up this food, so that the plant may be nourished and
grow. The root is, then, a sort of stomach to the plant. If it had no
root it would not grow, any more than you would if you had no stomach
to put your food in.

[Sidenote: Mouths in their fibres.]

The root has little mouths in its branches every where. It is by these
that the food of the plant is sucked up. They are so small that you can
not see them without a powerful microscope. They are in the fine parts
or fibres of the root that you see hanging to the main branches of it
when you take up a root. We are very careful not to break off these
fibres when we take up a plant or tree to set it out again in another
place; for the more of these little mouths there are, the more likely
will it be to live. If all the fibres be broken off from the root the
plant can not live, because there are no mouths to suck up the food. It
will die just as you would if you should stop eating.

As there are little mouths all over the fibres of a root, there must be
a multitude of them. You can not count them any more than you can count
the sands on the sea-shore. These mouths drink up a fluid from the
ground. This fluid is the sap that goes up in the stalk to nourish the
plant. Every thing in the plant--the leaves, the flowers, the fruit--is
made, as I have told you before, from the sap that the root sucks up.

[Sidenote: Mouths in roots choose what they will suck up.]

These mouths do not suck up exactly the same thing in all roots. The
sap of one plant differs somewhat from that of another plant. What the
root of a pepper-plant sucks up is not the same that is sucked up by
the root of a strawberry-plant. The root of the pepper-plant sucks up
such sap that the biting peppers can be made out of it. And the root of
the strawberry-plant sucks up sap that is fitted to make its pleasant
fruit.

The pepper-plant and the strawberry-plant are so different from each
other, that we should hardly suppose that they could grow out of the
same earth side by side. But they can. How is this? Do the little
mouths in the roots choose their food? They do. The strawberry mouths
choose what will make strawberries, and the pepper mouths choose what
will make peppers. But they do not choose in the same way that we
choose. They do not think about it as we do. But they choose just as
well as if they did think. Perhaps they choose better than we do. We
sometimes make mistakes about our food. But they always choose just
right. How this is we do not know. God has made them in such a way that
they suck up the right kind of food from the earth. This is all that we
know about it.

Very commonly different kinds of plants will grow in the same kind
of earth. What a variety of plants and trees you often see in the
same garden! But sometimes one plant requires a different soil from
other plants. You see this in the asparagus. This vegetable does
best in a soil that has considerable salt in it; that is, it thrives
on salt food, as we may say. For this reason we sprinkle salt over an
asparagus-bed in the spring.

[Sidenote: Asparagus roots like salted food.]

But while salt makes the asparagus grow so well, it will kill other
plants. It will kill all the weeds and grass that happen to be in the
asparagus-bed. If you put on a good deal of salt no weeds will come up
till after all the salt is sucked up by the asparagus. I had a chance
last spring to see how bad salt is for grass. The man who put the salt
on my asparagus-bed spilled some of it on a grassplot close by. In
every spot where it fell it killed the grass. So you see that what is
poison to grass is food to asparagus.

[Sidenote: Flowers in swamps.]

We find some kinds of flowers only in swamps. These will not grow well
in the high grounds where the soil is different. The reason is, that
the little mouths in the roots do not find the right kind of food there.

 _Questions._--How is the root a sort of stomach to a plant? Where
 are the little mouths of the root? What is said about care in
 moving plants or trees? What is said of the number of mouths in a
 root, and of their size? Do the roots of the pepper-plant and the
 strawberry-plant suck up the same kind of food? What is said of the
 mouths of roots choosing their food from the ground? Tell about the
 asparagus. What is said of plants growing in swamps?




CHAPTER XXV.

MORE ABOUT ROOTS.


[Sidenote: Branching roots.]

[Sidenote: Fibrous roots.]

[Illustration]

The root, besides being a sort of stomach to the plant, is its support.
The plant is fastened by it firmly in the ground. For this reason a
large tree has a large and deep root. Its root branches out very much
as the tree does above. It is shaped as you see here. But when the
plant is quite small, and there is not much to be supported, the root
is different. It is perhaps made up of fibres as seen in this figure.
This is the case with the roots of grass, as you can see by pulling up
some of it. In a piece of turf there are a great many spears of grass,
and so it is full of these fibrous roots mingled together.

[Illustration]

Some roots are made for still another purpose. Besides nourishing the
plant and supporting it, the root sometimes answers for food. When a
root is intended for this use it is large. Look at the root of the
beet. Here is a figure of it. The plant does not need so large a root
as this to nourish and support it. The plant is nothing but a bunch of
leaves, and with a very small root it would stand up in the ground. A
small root, too, would answer to suck up all the sap that it needs. So
small a plant could get along with a very small stomach.

[Illustration]

You remember that in the chapter on seeds I told you that the
seed-holder is sometimes larger than it need be to hold the seeds. The
pear is a seed-holder, but it is larger than it need be if it were
meant to be only a seed-holder. It is meant to be something else. It is
fruit to be eaten as well as a seed-holder. It answers two purposes.
So, too, when a root is larger than it need be to nourish the plant, it
answers two purposes. Besides sucking up food for the plant, it answers
as food for animals.

[Sidenote: Beets and turnips.]

[Illustration]

In these large roots the mouths that suck up the sap are not in the
body of the root. They are in the little fibres that are joined on to
the main root, as you see in the beet. In the root of the turnip, as
seen in this figure, there is a sort of tail going down into the ground
from the bottom of it. The fibres, where the mouths are, make a part of
this tail.

[Sidenote: Runners.]

[Illustration]

In some plants roots are formed very curiously. Shoots start out and
run along on the ground. After a little while these runners, as they
are called, send down roots into the ground, as is here represented.
The strawberry, you know, spreads in this way. So do the verbenas.
When a runner gets fairly rooted it can live by itself, for it has a
root, that is, a stomach of its own. You can separate it now from the
main plant if you choose, and set it out somewhere else. This is done
whenever we plant a new strawberry-bed.

[Sidenote: Roots of dahlias.]

[Illustration]

This is a singular kind of root. It is spread out like a hand. Each of
these fingers can be separated from the rest, and will grow by itself.
The roots of the dahlias are of this kind.

[Sidenote: Bulbs.]

[Illustration]

Some roots are bulbs, as they are called. The onion is a bulbous root.
Below is one cut open. You see that it is all made up of coats, one
inside of another, which you can peel off. The roots of hyacinths,
lilies, blue-bells, and crocuses, are bulbs. These lie in the earth
very still through all the winter. The life in them is asleep, just as
it is in the buds. But it wakes up in the spring, and down go the roots
from the bottom of the bulbs, and up come the plants from their tops.
It is sometimes said that a bulb is really a bud, only it is in the
ground, instead of being in the air as most buds are. Thus the onion is
a bud, and the real roots of the plant are what you see branching down
from the bottom of the bulb.

[Sidenote: Slips of plants.]

You have heard people talk about setting out slips. A slip is a branch
of a plant. Some plants will grow from slips. Geraniums will. If you
put a slip of geranium into the ground and keep it well watered, a root
will shoot down into the earth from the end of the stem. And so the
branch cut off becomes a growing plant. Before it was cut off it got
its food with the other branches from the root of the plant to which it
belonged. After it was cut off it could not live unless it could get a
root of its own to suck up its food from the ground.

[Sidenote: Duck-meat.]

[Illustration]

Most plants get their food from the ground. But some do not. Some get
their food from water. This is the case with a plant called duck-meat,
that is found in ponds and ditches where the water is still. You see
little leaves on the surface of the water, and the roots hang like
threads from the leaves. This is represented in this figure. Now there
is something in the water in these places which is sucked up by these
roots and makes the leaves grow. Sea-weed has no roots extending down
into the ground, but it gets its nourishment from the water.

[Sidenote: Hanging moss.]

There are some plants that live on other plants. The mosses that you
see on trees are plants of this kind. At the South there is a kind of
gray moss that hangs down from the branches of trees, sometimes to a
great length. It makes the land look as if it were hung in mourning.
The sap that nourishes this plant it gets from the bark of the trees.
There are mouths in the moss where it hangs from the tree that suck in
the sap which they find there.

[Sidenote: Dodder, or love-vine.]

The dodder, or love-vine, is a curious plant. It lives on other plants.
It comes up out of the ground and clings to any plant that happens to
be near it. After it is well fastened, and has grown considerably, its
root in the ground dies. The little vine does not need it any longer,
for it clings by real roots to the plant up which it runs. This is the
reason that it is called love-vine; for, like love, it lives on that to
which it clings. This vine has no leaves, and it is of a bright-yellow
color. So it is sometimes called gold-thread vine.

 _Questions._--What is said about the root as a support for a tree?
 How is it with the roots of grass? What is said about roots that
 are for food? Tell about the root of the beet. Give the comparison
 made between roots and seed-holders. What is said of the root of the
 turnip? What of the roots of strawberries and verbenas? What of the
 roots of dahlias? What is said of bulbs? How do plants grow from
 slips? What is said about the duck-meat? What is said of mosses? Tell
 about the dodder.




CHAPTER XXVI.

STALKS AND TRUNKS.


[Sidenote: Trunks of trees.]

We speak of plants as having stalks, and of trees as having trunks. A
tree has a stout firm trunk, because its top is so large and heavy. Its
branches spread out so much, that the tree would be broken down by the
wind if it did not have a strong trunk.

It is the woody part of the trunk that is so strong. The stalks of
plants have no wood in them, because they do not need it. They are
strong enough to support the branches without having any wood in them.

[Sidenote: Stalks of grain and grass have flint in them.]

Some plants have their stalks made strong in a singular way. There is
a flinty earth in them. This is the case with wheat, and rye, and most
kinds of grass. See how tall the stalk of rye or wheat is. And it is
very slender. But as the wind bends it over it does not break, because
the flint in it makes it so strong.

It is this flint in different kinds of straws that fits them to be used
in making hats and bonnets. They would not be firm enough for this use
if there was no flint in them.

You can not see or feel the flint in the straw. The reason is, that the
particles of the flint are so fine, and are so well mixed up with the
fibres or threads of the straw. It is this fine flint in straw that
makes its ashes so useful in polishing marble. In some plants you can
feel the roughness that is made by the flint. You can feel it in the
scouring-rush, which is sometimes used by house-keepers in scouring.
In this there is more of the stony substance than there is in the straw
of your hat, and it is not as fine.

[Sidenote: How flint gets into stalks.]

But you will ask how stone or flint gets into these plants. It is
sucked up from the ground by the mouths in the roots, and it goes up in
the sap to where it is wanted. It is wanted in the stalk of the grain,
and so it stops there. It never makes a mistake by going into the
kernels of the grain. If it did, the flour that is made from them would
be gritty, as we should find out when we came to eat the bread.

[Sidenote: Shrubs.]

All plants that have no wood in their stalks die down to the ground in
the autumn, though the roots of some of them live through the winter.
But trees, you know, remain from year to year. So do shrubs and bushes.
These may be considered as little trees. Some shrubs are so small that
they do not need to have their stalks woody merely to support the
branches. Thus the currant-bush could have its branches well supported
if the stalks were not woody. In such cases the stalks are made woody
so that they may last over the winter.

[Sidenote: Vines.]

Stalks and trunks commonly stand up of themselves. But there are some
that can not. When this is so we call the plant a vine. Vines are
supported in various ways. Some are held up by merely winding around
something. This is true of the bean-vine. It winds itself, as it grows,
around the pole that is put up for it. The hop-vine is supported in the
same way. It is, you know, quite rough, and so it can cling firmly even
to quite a smooth pole.

[Sidenote: Tendrils.]

Pea-vines are held up in a different way. Little tendrils are put
forth which wind around the branches of the bushes that are set for the
vines to run up on. These tendrils clasp very tightly. You see them on
many kinds of vines. You see them on grape-vines, and on the vine of
the passion-flower. Sometimes the tendrils go out from the ends of the
leaves. You see a leaf of this kind on page 68.

[Sidenote: Thunbergia.]

A vine called thunbergia is held up in a very queer manner. If a leaf
happens to come near a twig or a string it twists its stem around it.
So the stems of the leaves act as tendrils to support the vine.

[Sidenote: Trumpet-creeper.]

The vine of the trumpet-creeper is supported in a singular way.
Whenever it touches any thing there come out at the joints of the
stalks some sprawling things like the feet of a spider. These feet
fasten themselves very strongly to whatever the vine is running on. If
it runs up the side of a board fence, these feet mix up their fibres
very tightly with the fibres of the wood. It is curious to observe that
where any part of the vine is not against any thing these feet do not
appear. They are made only where they can be used. The plant acts just
as if it knew where it could use them.

 _Questions._--What is the difference between stalks and trunks? Why
 does a tree need so strong a trunk? Why do the stalks of plants have
 no wood in them? What is said of the flinty earth that is in some of
 them? In what ways is the flint in straws of use? What is said of the
 scouring-rush? How does flint get into any plant? Why does it not go
 into the kernels of grain as well as into the stalks? What becomes of
 stalks that are not woody in the winter? What is said of the woody
 stalks of shrubs? What are vines? How is the bean-vine supported? Tell
 about tendrils. What is said of the thunbergia? Describe the way in
 which the trumpet-creeper is supported.




CHAPTER XXVII.

THE BARK OF TREES AND SHRUBS.


In the trunk of a tree or the stalk of a shrub there are three parts.
They are the bark, the wood, and the pith.

[Sidenote: The outer bark of a tree its coat.]

The bark is not all one thing. It is made up of two parts; or rather,
we should say, there are two barks. There is an outer bark and an inner
one. The outer bark has no life in it. It is this outer bark that gives
such a roughness to the trunks of some trees, as the elm and the oak.
In the birch, you can peel off this bark in strips right around the
trunk of the tree. Indians make very pretty boxes of these strips of
birch-bark.

The outer bark is a _coat_ for the tree. It covers up the living parts
so that they shall not be injured. It does for the tree what our
clothes do for our bodies. It is not a perfectly tight coat. It has
little openings every where in it. It would be bad for the tree to have
this coat on it tight, just as it would be bad for our bodies to have
an India-rubber covering close to the skin.

This outer bark is a great protection to the tree through the cold
winter. It keeps the cold from killing the trunk and the branches. This
coat of the tree covers it all, even out to the end of the smallest
twig. The tree looks as if it was dead in winter without its green
leaves. But there is life locked up there, just as I told you there is
in the seed that is kept through the winter. The life in the tree is
asleep as it is in the seed. It is ready to be waked up when the warm
weather of the spring shall come. During this winter’s sleep of the
tree, the living inner bark and wood are safe, covered up by the tree’s
rough coat.

[Sidenote: The inner bark.]

If you peel off the outer bark, as you can very easily in the birch,
you come to the fresh and juicy inner bark. This I have told you is
alive. It is full of sap. It has a great deal to do with the growth of
the tree. It is by this bark that the wood inside of it is made.

[Sidenote: Trees sometimes covered with straw in winter.]

You have sometimes seen small trees covered in the winter with straw
tied nicely all around them. This is because they are tender trees that
are not used to our cold weather. They belong to a warmer climate,
and God gave them just such a coat as they needed there. And when we
undertake to have such trees here at the north, the coat that God has
given them is not enough to keep them from freezing in our long, cold
winters. So we have to put another coat over it.

 _Questions._--What are the parts of the trunk of a tree? Tell about
 the bark. What is the outside bark for? How much of the tree does it
 cover and protect? What is said of the life asleep in the trees in the
 winter? What is said of the inner bark? Why is straw tied around some
 trees in winter?




CHAPTER XXVIII.

THE WOOD IN TREES AND SHRUBS.


[Sidenote: How wood is made.]

Perhaps it seemed strange to you when I said in the last chapter that
bark makes wood. But so it is. Every year the living inner bark goes to
work and makes a layer of wood out of the sap that is in it. This work
is done in the warm weather. In the winter there is no wood made. The
tree is asleep then.

It is what the bark does that makes the tree larger every year. A new
layer of wood is formed by it all up the trunk, and along out to the
end of all the branches.

[Sidenote: Its layers.]

[Illustration]

The different layers of wood made in the different years are often
very distinct from each other. You can see them in a log that has
been cut or sawn across. Sometimes they are so distinct that you can
count them, and so tell just how many years old the tree is. Here is a
representation of the sawn end of the trunk of a tree. You see that the
rings of the wood are very plain.

[Sidenote: Pipes in the wood for the sap.]

The wood part of the trunk and branches is full of small pipes. It is
through these pipes that the sap goes up from the roots and gets to the
leaves. It is in this way that it goes to the very ends of the topmost
boughs of the tallest trees. This is very wonderful. How the sap is
made to go up such a great distance through these pipes in the wood we
do not know. There is only one way that man can make water go so high
through pipes. He can do it by a forcing-pump. But we can see nothing
like forcing-pumps in the trees. We find nothing but these pipes going
from the roots up to the leaves. And the sap is flowing up through them
very quietly all the time.

[Sidenote: Sap-pipes numerous.]

In a large tree there is a multitude of these pipes in the wood. And
when you look at the huge trunk, think what a quantity of sap there is
going up through it all the time to keep all those leaves fresh and
green. If you could see it all in one pipe it would be quite a stream.

[Sidenote: Heart-wood.]

If you look at the end of a log you will see that there are two kinds
of wood. The wood in the centre is different from that which is around
it. It is called the heart-wood. The pipes in it are stopped up, and no
sap can go up through it. The pipes for the sap are clear only in the
newest part of the wood.

[Sidenote: Pith.]

The use of the pith of trees and plants we do not understand. The
pith is very small in trees, but it is quite large in some plants and
shrubs. All boys know that it is very large in the elder. It is also
large in the stalks of corn, and of the sugar-cane.

 _Questions._--How is the wood in a tree made? What is said of the
 different layers of wood? What is said of the small pipes in the wood?
 Do we know how the sap is made to go up in them? What is said of the
 quantity of sap that goes up in the trunk of a large tree? What is
 said of the two kinds of wood that you see in looking at the end of a
 log? What do we know about the pith of trees and plants?




CHAPTER XXIX.

WHAT IS MADE FROM SAP.


Every thing that you see in a tree or a plant is made from the sap. The
bark, the wood, the leaves, the flowers, the fruit, are all made from
it. Even the root that sucks up the sap from the ground is made from
the sap itself.

[Sidenote: The great difference in things made from sap.]

It is strange that so many different things can be made out of the same
thing. It is strange that a rough bark and hard wood can be made from
the same thing as the beautiful flower and the delicious fruit. Look at
an apple-blossom, and then look at the bark of the tree, and think of
them as being made from the same sap. You can hardly believe that it
is so. How strange it is to think of the sharp thorns on a rose-bush
as being made from the same sap that makes the soft, and smooth, and
beautiful leaves of the roses!

If any man should tell you that he could make a brick and a piece of
cloth, with beautifully colored figures on it, from the same thing, you
would say he was crazy. But there is not as much difference between the
brick and the cloth as there is between rude bark and a flower made
from the same sap. The Creator does, in the most common plants and
trees, what man can not equal in any way.

There are some things made from sap that I have said nothing about as
yet. There are many bitter, and sweet, and sour things made from sap.
Sometimes sweet and bitter things are made at the same time from the
same sap. You see this in the orange. From the same sap that comes to
the orange through the stem are made the sweet juice and the sharp and
bitter peel.

[Sidenote: The sugar-cane.]

Almost all our sugar comes from the sugar-cane. This is shaped like
the stalks of corn. The sugar is made from the sap that comes up in
the pipes of the cane from the ground. The cane, then, is really a
sugar-factory. Man does not make the sugar, but it is made for him in
the cane. It is in the juice of the cane. This juice is mostly sugar
and water. In making sugar, as it is called, the sugar is not made.
It is only separated from the water and other things with which it is
mixed in the cane.

[Sidenote: How the sugar is obtained from it.]

The sugar is made from the cane in this way. The cane is cut into
pieces, and these are put into a mill where they are pressed between
iron rollers. The juice squeezed out in the mill runs off into a large
reservoir or tub in the boiling-house. It is now put into boilers and
boiled down. In this boiling the water goes off in steam, but the sugar
remains. When it is boiled down to a sirup it is put into very large
wooden trays called coolers. Here the sirup becomes sugar, because the
rest of the water goes off in the air.

The way in which sugar is made perfectly white, it is said, was
discovered in a curious way. A hen that had gone through a clay
mud-puddle went with her muddy feet into a sugar-house. She left her
tracks on a pile of sugar. It was observed by some one that wherever
her tracks were the sugar was whitened. This led to some experiments.
The result was, that wet clay came to be used in refining sugar. It is
used in this way. The sugar is put into earthen jars shaped as you see
the sugar-loaves are. The large ends are upward. The small ends have a
hole in them. Here is a picture of one of these jars. The clay is put
on the top of the sugar in the large end of the jar, and it is kept
wet. The moisture goes down through the sugar, and drops from the hole
in the small end of the jar. This makes the sugar perfectly white.

[Illustration]

[Sidenote: How a discovery was made about whitening sugar.]

This discovery shows how much a little looking and thinking will
together do. What the hen did was a small thing. One would hardly
suppose that any thing could be learned from a hen’s tracks. Most
people would have scraped off the mud from the pile of sugar, and
thought nothing more of it. But the man who saw the tracks was in the
habit of thinking about what he saw. And so he discovered in that hen’s
tracks a very useful fact. If you always think about what you see you
may some time be a discoverer too. At any rate, that is the way to
learn. And it is to help you in learning to think about what you see
that I have written this book.

 _Questions._--What things are made from sap? Mention some things
 very different from each other that are made from the same sap. Give
 the comparison about brick and cloth. What is said about the orange?
 What about the sugar-cane? How is sugar made from the sugar-cane?
 Of what use is the boiling? Tell how one way of purifying sugar was
 discovered. What does this discovery show?




CHAPTER XXX.

MORE ABOUT WHAT IS MADE FROM SAP.


[Sidenote: Maple-sugar.]

You have eaten maple-sugar. This comes from a tree called the
sugar-maple. The sugar is in the sap, just as it is in the case of the
sugar-cane. The sap is obtained early in the spring by tapping the
trees, and then it is boiled down, as it is called. In this boiling the
water goes off in steam and the sugar remains. The sugar-maple, then,
is a sugar-factory as well as the sugar-cane.

There are many roots in which there is sugar. Sugar has often been
obtained from a kind of beet called the sugar-beet. There is sugar in
many fruits, making them sweet to the taste.

[Sidenote: The sugar-cane.]

Now where does the sugar in the sugar-cane, the maple, the beet, etc.,
come from? The sap in which the sugar is comes up from the roots. You
will say, then, that the little mouths in the roots suck up sugar from
the ground. But there is no sugar in the ground. No one ever found any
there. Take up a handful of earth, smell of it, and taste of it. There
is no sweetness in it.

[Sidenote: Some plants sugar-factories.]

Though there is no sugar in the ground, what the sugar is made from is
there. This the little mouths in the root drink up, and it is made into
sugar in the plant. You see, then, how true it is that the plant is a
sugar-factory.

Now do you think that any man could in any way make sugar from the
earth under his feet? He can no more do it than he can make a flower or
a leaf.

There are a great many other things made by plants from what they suck
up from the earth. I will mention some of them.

[Sidenote: Plants make starch, medicines, gums, and perfumes.]

Some plants are starch-factories. They make the starch from the sap
that comes up from the root, just as the sugar is made. There is starch
in every kind of grain, in potatoes, and in many other roots.

Some plants are medicine-factories. Camphor is obtained from the bark
and wood of a tree. Opium is found in the different kinds of poppies.
There are various bitter medicines that are found in different plants.
Castor-oil is obtained from the seeds of a large plant. These, and
various other medicines, are made from sap.

Some plants are gum-factories. You have sometimes seen gum on the bark
of peach-trees and cherry-trees, when the bark has been wounded in some
way. Now there are some kinds of trees in which there is a great deal
of gum. The India rubber is a gum that is obtained from some kinds of
trees in warm climates. When the bark of these trees is wounded this
gum oozes out. It is collected as it flows. It is dried in smoke, and
this gives it its dark appearance.

Many plants are perfume-factories, as I told you in Chapter V. The
perfumes are made most often in the flowers, but they are sometimes
made in the leaves and other parts. You know how fragrant the leaves of
the geranium are. Even wood is sometimes fragrant. The sandal-wood is
very much so.

Some plants are color-makers. They not only make colors for their own
use--that is, to color their flowers--but they make them for us to use.
Many of our dyes with which we color cloths come from plants. They are
made in the plants from the sap that comes up from the ground. It seems
strange that the blue indigo should be made out of what a plant drinks
up from the brown, dull earth. But so it is.

[Sidenote: The great variety of things made from sap.]

Now just think over the various things that are made from the sap
in plants. There are wood, bark, leaves, flowers, fruits, thorns,
perfumes, colorings, sugar, starch, gum, various medicines, etc. And
then there are many other things that I have not mentioned. How strange
it is that so many and such different things can be made from what the
plants suck up out of the earth! As you look at the ground under your
feet, you can hardly believe that so much can be got out of it. It is
the busy little mouths in the roots that get from it what is needed to
make all these different things.

 _Questions._--What is said of the sugar-maple? What is said of sugar
 in some roots and fruits? As there is no sugar in the ground, how does
 it get into plants? Can any body make sugar from earth? What plants
 are starch-factories? Mention some medicines made in plants. What is
 said about plants that are gum-makers? What is said about perfumes
 being made in plants? What about colors? What is said about indigo?
 Mention now all the things that you can think of that are made from
 the sap in plants.




CHAPTER XXXI.

CIRCULATION OF THE SAP.


I have told you that the sap goes up in a plant or a tree in certain
pipes. Now when it gets to the leaves it turns about and goes back
again down toward the ground by some other pipes.

[Sidenote: The difference between the sap that goes up and that which
comes down.]

So there is a set of pipes for the sap to go up, and a set of pipes for
it to go down. In a tree, the pipes for it to go up are in the wood.
Now where do you think the pipes are for it to go down? They are in the
live part of the bark. The sap is all the time going up to the leaves
in the one set of pipes, and coming down in the other set. And this is
what we call the circulation of the sap.

The sap that goes up has a great deal of water in it. Much of this
water is got rid of when the sap comes to the leaves. You remember that
I told you, in the chapter on leaves, that water is let off into the
air from their pores. For this reason the sap that comes down from the
leaves has much less water in it than the sap that goes up.

The sap that goes up is not perfect sap. It has to make a visit to the
leaves and get an airing there before it can be of much use. After it
is aired it goes to all parts of the plant, down to the very roots.

It is this aired sap from which generally every part of the plant
grows, or is made. You remember that I told you in the last chapter
that in trees the inner bark makes a new layer of wood every year. Now
the bark makes the wood from some of this aired sap as it goes down in
the pipes of the bark.

[Sidenote: The airing of the sap.]

You remember that I told you in the chapter on leaves, that they have
much to do with the growth of a plant. You can now see why this is so.
The sap has to go up to the leaves to be made good sap. Just what the
air does to it there you are not yet old enough to understand. But
after a little time you will be able to understand this, and then you
will see that leaves are very properly called the lungs of plants,
and that they breathe with them as we do with our lungs, though in a
different manner.

[Sidenote: The sugar made from the sugar-maple.]

I have said that the sap that goes up is not of much use, and that
every thing in the plant is made from the sap that goes down. This is
not always so. In the sugar-maple it is the sap that goes up in the
early spring that has the sugar in it. The sugar-gatherers tap the
trees before the leaves are put forth. The leaves, then, have nothing
to do with making the sugar. How it is made we can not understand. We
suppose that it is done in the root, where the mouths are that drink up
the sap from the earth. But though we do not know how it is, in some
way every sugar-maple as soon as it begins to be warmed by the air of
spring becomes at once a sugar-factory.

Though most of our sugar comes from the sugar-cane of southern
climates, a great deal is made from the sap of the sugar-maple in some
parts of the northern and western states in this country. A very busy
time they have in some places in the early spring in collecting the
sap and in boiling it down. The sirup is often sold as maple-sugar
molasses. But more often it is made into sugar; and great quantities
of it are sold every year. In some places where it is made many of the
people use no other sugar.

[Sidenote: The sap always in motion except in winter.]

The sap is all the time in motion in the trees and plants in all the
warmer months of the year. It is always going up and coming down. It
does so till the leaves fall and the cold of winter comes. Then all
this motion stops. And through the winter the sap is almost as still
as if the trees and shrubs were dead. Then when the spring comes, the
mouths in the roots begin again to suck up sap from the ground, and it
runs up and down in the little pipes as it did the year before.

As you look at all the trees and plants about you, think how much sap
there is running up and down in their pipes. Look at a very large tree,
and think of this. In multitudes of pipes in that huge trunk the sap
goes up to the very end of all the branches to the leaves, and then it
comes down in other pipes. How wonderful this is, and yet how few there
are that ever think about it!

 _Questions._--Where are the pipes in which the sap goes up in a tree?
 Where are the pipes in which it comes down? What is said about the
 water in the sap? What becomes of a part of this water? Why is it
 necessary for the sap to go up to the leaves? Are things made from the
 sap that goes up, or that which comes down? How is it with the sugar
 in the maple? Where is its sugar made? Is the sap always in motion?




CHAPTER XXXII.

THE SLEEP AND THE DEATH OF PLANTS.


When the cold weather comes some plants die, and some go to sleep for
the winter.

[Sidenote: Most plants die in the fall.]

Some plants always die in the fall. Corn dies; so does the bean-vine.
And so do many other plants. In order to have such plants another year,
we keep some of their seeds to put into the ground in the spring.

[Sidenote: How trees sleep in the winter.]

But some plants sleep in the winter. Look at a tree. Its branches are
all bare. It seems as if it had no life in it. But there is life there,
and it will show itself next spring. Its life is asleep, just as I told
you it is in the seed before it is put into the ground. Its sap is all
quiet in the pipes. The mouths in the roots have stopped their busy
work. The buds all over the tree are asleep in their “winter-cradles.”
The wind rocks them back and forth, but never wakes them up.

How much life there is asleep in that tree! The buds are all there
which are to make all that you will see on it the next summer. They
are covered up snugly from the cold in their winter coats. The little
things are very still, but they are alive. They only want a warm sun
to make them show it. As soon in the spring as they feel the warmth
through their coats, they begin to swell, as I have told you in another
chapter, and soon open their coats and go to work to make leaves, and
flowers, and fruits. A great work they do after their long winter
sleep. Look up into a tree in summer and see how these leaf-buds have
filled every branch with leaves. You can hardly believe that it is the
same tree that you saw so bare in the winter.

[Sidenote: Life asleep in roots.]

Some plants die down to the ground, and their roots live through the
winter. You know that this is the way with tulips and daffodils. They
come up in the spring from the roots that have been in the ground all
the winter. So, too, do the beautiful crocuses, that peep up so early
in spring that they often get covered with snow. The roots of grass,
too, live in the earth through the winter.

The life in these roots is asleep through the winter, just as it is in
the trees and bushes. Their little mouths do not drink up any sap. How
much life there is asleep in the winter covered up in the earth!

[Sidenote: Decay of leaves and plants.]

What do you think becomes of all the leaves that fall, and of all the
plants that die in the autumn? They are not lost. They decay and become
a part of the earth. A great deal of the ground under your feet was
once in the shape of stalks, and leaves, and flowers. And now the roots
suck up from it sap to be made into the same shapes again. So you see
that the dead plants and leaves of one year are used in making the
plants and leaves of the years that come after.

 _Questions._--What is said of plants that die in the fall? Tell how
 it is with a tree in the winter. What does the warm weather do to its
 buds in the spring? Mention some plants that die down to the ground in
 the fall, but whose roots live through the winter. What is said of the
 life in these roots? What effect does the spring have on them? What
 becomes of all the leaves and plants that die in the fall?




CHAPTER XXXIII.

CONCLUSION.


[Sidenote: Knowledge of nature increases our enjoyment of it.]

So I have told you in this book many things about trees and plants.
And I suppose that you will look at them with more pleasure now than
you did before you knew so much about them. Almost every body says
when looking at a handsome plant or tree, how beautiful it is! But you
will say something more than this. You will say how beautiful and how
_wonderful_ too! You think of the sap going up and down in the pipes,
of the busy mouths in the roots drinking it up from the ground, of the
many different things that are made from the sap, of the beautiful
leaves acting as the lungs of the plant, and of the leaf-buds from
which the leaves are made. And because you know something about all
these things, plants and trees look more beautiful to you than they
ever did before.

You have always admired the weeping-willow with its long branches
hanging almost to the ground. But you admire it much more now, because
you think how wonderful it is that the sap circulates back and forth in
the trailing branches. Follow it as I have told you that it goes, and
see how wonderful the circulation of the sap is in this tree. It goes
from the roots up through the trunk, and down the trailing branches to
the very tips of the leaves; and then it mounts up again through other
pipes in the branches to the trunk, that it may go down again to the
roots. As you think of all this, do not the beautiful branches, as
they swing back and forth in the wind, look more beautiful than ever?

[Sidenote: Flowers and leaves.]

You have always loved to look at flowers with their various colors. But
now you love them more than ever, because you know something about how
they grow, and what their colors and perfumes are made from, and many
other interesting facts about them. Even fruits will, I think, taste
better to you, for what you have learned about them in this book.

Leaves are such common things that most people do not know how
beautiful they are. From what I have told you about them, I think you
will always be ready to examine them, and see what a variety of beauty
there is in the leaves of different trees and plants. And when you
think what is done in the leaves, and how the sap comes continually to
them to be aired, you admire them more than they do who think of them
merely as pretty green things.

Think of a leaf as _made_, for growing is making. No one can make
leaves but God. But suppose that a man could make leaves and put them
on a tree. It would take him his whole life to cover a tree of any
size with leaves. But God, as I have told you, makes the leaves out of
sap on all the plants and trees. He sends to them the warm breezes of
spring, and sets the sap running in the pipes, and then the buds come
out, and from them are formed the leaves. What a busy workshop, as you
may say, is every plant and tree in the spring when all the leaves are
making!

I have told you about the wonderful change that we see in plants and
trees year by year. What multitudes of leaves and flowers fall to the
ground every year and decay! What a waste, as it seems, of beautiful
things! But are they really wasted? Oh no! God, as I have told you,
can make again from these decayed leaves and flowers other leaves and
flowers just as beautiful as these once were.

[Sidenote: Changes in winter and spring.]

How wonderful this is! Look out in summer, and see on trees, and
shrubs, and plants, flowers of every color mingled with the green
leaves. What a world of varied beauty you behold! You can not believe
that all this will be soon gone. But wait a little and there are no
leaves nor flowers. All is bare and dreary. The leaves and flowers
have fallen in all their beauty, and the snow covers them as with a
winding-sheet.

[Sidenote: “Seed-time and harvest shall not cease.”]

Is it possible that all this beauty that we have seen thus buried can
be revived again? Will the green grass again appear? Will these bare
trees and shrubs again be covered with leaves and blossoms, and will
the flowers again spring up? Oh yes! We have seen God do all this year
after year, with the sunshine, and the rain, and the dew of spring; and
he will do it again, for he has said that “seed-time and harvest shall
not cease.”

 _Questions._--With what thoughts and feelings will what you have
 learned in this book make you look at plants and trees? What is said
 about the weeping-willow? What about flowers and fruits? What about
 leaves? What is said about leaves being _made_? What is said of the
 change that you see every year in plants and trees? Tell about the
 change from summer to winter, and then from winter to summer.


THE END.




    THE CHILD’S BOOK OF NATURE.

    FOR THE USE OF

    FAMILIES AND SCHOOLS.

    INTENDED TO AID MOTHERS AND TEACHERS IN TRAINING CHILDREN
    IN THE OBSERVATION OF NATURE.

    IN THREE PARTS.

    PART II.--ANIMALS.

    BY WORTHINGTON HOOKER, M.D.,

    AUTHOR OF “FIRST BOOK IN CHEMISTRY,” “CHEMISTRY,” “NATURAL
    PHILOSOPHY,” “NATURAL HISTORY,” ETC.

    With Illustrations.

    NEW YORK:

    HARPER & BROTHERS, PUBLISHERS,
    FRANKLIN SQUARE.

    1882.




By Dr. WORTHINGTON HOOKER.


 THE CHILD’S BOOK OF NATURE. For the Use of Families and Schools;
 intended to aid Mothers and Teachers in training Children in the
 Observation of Nature. In three Parts. Illustrations. The Three Parts
 complete in one vol., Small 4to, Cloth, $1 00; Separately, Cloth, Part
 I., 40 cents; Parts II. and III., 44 cents each.

 PART I. PLANTS.--PART II. ANIMALS--PART III. AIR, WATER, HEAT, LIGHT,
 &c.


 FIRST BOOK IN CHEMISTRY. For the Use of Schools and Families. Revised
 Edition. Illustrations. Square 4to, Cloth, 44 cents.


 NATURAL HISTORY. For the Use of Schools and Families. Illustrated by
 nearly 300 Engravings. 12mo, Cloth, 90 cents.


 SCIENCE FOR THE SCHOOL AND FAMILY.

 PART I. NATURAL PHILOSOPHY. Illustrated by nearly 300 Engravings.
 12mo, Cloth, 90 cents.

 PART II. CHEMISTRY. Revised Edition. Illustrations. 12mo, Cloth, 90
 cents.

 PART III. MINERALOGY AND GEOLOGY. Illustrations. 12mo, Cloth, 90
 cents.


Published by HARPER & BROTHERS, Franklin Square, N. Y.

☞ _Either of the above volumes will
be sent by mail, postage prepaid, to any part of the United States or
Canada, on receipt of the price._


Entered, according to Act of Congress, in the year one thousand eight
hundred and fifty-seven, by HARPER & BROTHERS, in the Clerk’s Office of
the District Court of the Southern District Court of New York.




PREFACE.


Having presented in Part First such facts or phenomena of Vegetable
Physiology as would be interesting to a child, I proceed in this Part
to do the same with Animal Physiology.

The teacher and parent will observe, that in doing this I bring out
quite prominently the analogies that exist between the animal and the
vegetable world in the operations of life. Such analogies are always
interesting to the child as well as to the adult, and the consideration
of them adds much to the enjoyment of the observer of nature, for it
opens to him the simple plans and principles upon which the Creator
works out the almost endlessly varied results that life, both animal
and vegetable, presents to our view.

What is true of the analogies that exist between the two kingdoms of
life is also true of those that we find in each kingdom by itself.
I have therefore, in this Part, traced the resemblances which the
contrivances in the human system bear to those which we see in animals
of different kinds, and also the differences, giving to some extent
the reasons for them--that is, I have made it in some measure a book
of comparative physiology. The effect of this mode of treating the
subject will be to interest the child’s mind in the observation of the
various animals, great and small, that he sees from day to day. Natural
History, which is otherwise rather a dull study, will thus become very
attractive to him. And, to further this object, which I deem to be of
great importance, I have noticed the habits of some animals in such
a manner as to connect distinctly Physiology with Natural History,
a relation which, though an obvious one, has very generally been
disregarded.

While I have aimed in this Part at the same kind of simplicity as in
the First, there are some points in it which require a greater compass
of mind to understand. This is as it should be; for in going through
the First Part there will, of course, be acquired by the learner some
amount of skill in observation and reasoning. I have taken special
care, however, not to presume too much upon the mental advance thus
made.

  WORTHINGTON HOOKER.




CONTENTS.


  CHAPTER                                                     PAGE

         I. WHAT IS MADE FROM THE BLOOD                          7

        II. MORE ABOUT WHAT IS MADE FROM THE BLOOD              10

       III. HOW THE BLOOD IS MADE                               13

        IV. MOTHER EARTH                                        15

         V. THE STOMACH AND THE TEETH                           19

        VI. MORE ABOUT THE TEETH                                22

       VII. THE CIRCULATION OF THE BLOOD                        26

      VIII. BREATHING                                           30

        IX. BRAIN AND NERVES                                    34

         X. HOW THE MIND GETS KNOWLEDGE                         40

        XI. SEEING                                              47

       XII. HOW THE EYE IS GUARDED                              52

      XIII. HEARING                                             57

       XIV. THE SMELL, THE TASTE, AND THE TOUCH                 63

        XV. THE BONES                                           68

       XVI. MORE ABOUT THE BONES                                72

      XVII. THE MUSCLES                                         77

     XVIII. MORE ABOUT THE MUSCLES                              82

       XIX. THE BRAIN AND NERVES IN ANIMALS                     87

        XX. THE VARIETY OF MACHINERY IN ANIMALS                 91

       XXI. THE HAND                                            96

      XXII. WHAT ANIMALS USE FOR HANDS                         102

     XXIII. THE TOOLS OF ANIMALS                               109

      XXIV. MORE ABOUT THE TOOLS OF ANIMALS                    115

       XXV. INSTRUMENTS OF DEFENSE AND ATTACK                  122

      XXVI. WINGS                                              131

     XXVII. COVERINGS OF ANIMALS                               138

    XXVIII. BEAUTY OF THE COVERINGS OF ANIMALS                 142

      XXIX. HOW MAN IS SUPERIOR TO ANIMALS                     148

       XXX. THE THINKING OF ANIMALS                            153

      XXXI. MORE ABOUT THE THINKING OF ANIMALS                 157

     XXXII. WHAT SLEEP IS FOR                                  162




THE

CHILD’S BOOK OF NATURE.




PART II.--ANIMALS.




CHAPTER I.

WHAT IS MADE FROM THE BLOOD.


[Sidenote: The blood the building material of the body.]

I have told you, in Part First, how every thing in a plant or tree is
made from the sap. This is, then, the building material, as we may say,
of the plant. Now every thing in your body is made from the blood. The
blood, then, is to your body what sap is to a plant. It is the common
building material of the body.

You remember what I told you in Part First about the full-blown rose.
This is made from the sap that comes to the bud through the pipes in
the stem. Just so the little finger of the child becomes the large
finger of the man, from the blood that comes to it through the pipes
in the arm. And as the stem of the plant grows larger all the time, so
does the arm of a child. The sap makes the stem grow, and the blood
makes the arm grow.

If you cut off a branch of a plant it stops growing, because the sap
does not come to it any longer. It soon dies and decays. So, if the arm
of a child be cut off, it can not grow, because no more blood can come
to it. Like the cut-off branch, it dies and decays.

[Sidenote: The twig and the infant.]

You see a twig come up out of the ground. It grows larger and larger
every year. Soon it is a small tree. After many years it becomes
very large, and spreads out its long branches over a great space. As
you look up into it, you think of all that you see, its branches and
leaves, as having been made from the sap that is continually running
in its pipes. Now, as the little twig becomes a tree, so the infant in
the cradle becomes the large man. And when you look up at a man, you
can think of all his body as having been made from the blood that runs
every where in its pipes, just as you think of a tree as made from the
sap.

It is wonderful, as you have seen in Part First, how many and how
different things are sometimes made from the same sap. Look at an
apple-tree. There are the hard wood, the rough bark, the tender leaves,
the beautiful blossoms, and the pleasant fruit, all made from the
same sap. But the variety of things made from your blood is much more
wonderful.

[Sidenote: Variety of the things made from the blood.]

Look at some of the things that are made from the blood. See the skin,
the hair, the nails. Look at the soft red gums and the hard white teeth
in the mouth. Then look at the eye. See the eyelids, the eyelashes, the
firm, pearly-white coat of the eyeball, and the clear window in the
front part of the eye. See, too, inside of this window, that round,
colored curtain, with an opening in the middle that we call the pupil.

[Sidenote: Bones, muscles, lungs, brain, nerves, bile, tears, etc.,
made from the blood.]

All these different things that you see are made from the same blood.
Then there are many other things inside of the body that you can not
see. These are the hard bones, the red muscles, the white, shining
cords by which the muscles pull the bones, the light, spongy lungs, the
thick and firm liver, the soft brain, the white nerves, etc., etc.

How strange it is that all these parts of the body, so different from
each other, are made from the same building material, the blood. But
this is not all. The wax in your ears is made from the blood. So is the
bile, that bitter stuff that is manufactured in the liver. The tears,
too, are made from the blood. There are many other liquids in the body
that are made from this common material. When you look into a person’s
eye you look into a watery fluid, and the back part of the ball of the
eye is filled with a sort of jelly; both of these are made from the
blood.

But even this is not all. The arteries and veins in which the blood
runs are made from the blood. Even the heart that pumps the blood is
made from the blood that it pumps. This is as strange as it would be to
have the walls of a canal made from the water that runs in it, or to
have a pump made from the water that it pumps out.

 _Questions._--What is every thing in a plant made from? What is every
 thing in your body made from? Tell what is said about the bud and the
 finger, and about the stem and the arm. What is said about cutting
 off a branch and an arm? How is a child compared to a twig? Mention
 the different things in an apple-tree that are made from the sap. Are
 there more things made from your blood? Mention some of them that you
 can see. Mention some that are inside of the body that you can not
 see. What is said about the ear-wax, the bile, the tears, etc.? What
 about the arteries and veins, and the heart?




CHAPTER II.

MORE ABOUT WHAT IS MADE FROM THE BLOOD.


[Sidenote: How wonderful it is that so many things are made from the
blood.]

How different from each other are some of the things that are made from
the blood! You could hardly believe that the white, hard teeth are made
from the same blood that the red, soft gums are. Suppose that while you
are in a China-ware factory a man should tell you that even the whitest
China is made from a red liquid, and that they also make in this
factory fine red cloth from this liquid. You would not believe him. But
white China-ware and the fine red cloth are not any more unlike than
the teeth and the gums.

Suppose, now, that he should show you a yellow, bitter fluid, and then
a clear, soft eye-water, and tell you that these he makes from the
same red liquid from which the China and the red cloth are made. This
certainly you would not believe. And yet, in our bodies, the bile and
the tears are made from the same blood with the teeth and the gums.

But not only are a few things very much unlike made from the blood, but
many things that differ from each other, some of them much and some but
little. Suppose that the China-ware maker should tell you that besides
making white China and red cloth from his red liquid, he made also a
variety of both hard and soft things, such as velvet, and various kinds
of cloth, nails, glass, etc. Impossible! you would say. But this is no
more wonderful than that hair, teeth, gums, nails, bones, and all the
different parts of the body should be made from that red fluid--the
blood.

[Sidenote: The China-ware factory.]

But suppose, again, that the China-ware man should tell you that his
factory was made from the same red fluid from which he manufactures
so many things in it--that the very pipes that carry the fluid around
the building were made from it, and so also was the pump that sends
it through these pipes. This would seem to you strangest of all. And
yet all the various machinery of the body is made from the blood. The
liver, that manufactures bile from blood, is itself made from blood;
and so of other things; even the pipes in which the blood runs all over
your body, and the heart that pumps it into them, are made, as I have
before told you, from the blood.

[Sidenote: The body the house of the soul.]

The body is the house or habitation of the soul. It is a well-built
and a well-finished house. The bones are its timbers. The skin is its
covering. The hair is its thatched roof. The eyes are its windows. It
is a house that can be easily moved about, just as the soul wishes.
There is for this a great deal of machinery in it. And the soul has
little cords, called nerves, running to all parts of this machinery,
like telegraphic wires. There are also other kinds of machinery, as the
breathing machinery, the machinery for taking care of the food, and the
machinery for circulating the blood. The soul resides in the top of
this house, the brain. Here it sends out messages every where by the
little cords, and receives messages by them. Here it thinks and acts,
and some of the time sleeps. This part of the house is very curiously
and beautifully fitted up.

[Sidenote: All the parts and the furniture of the soul’s house made
from blood.]

Now all the various parts of this house are made, as I have told you,
from the blood, and yet there is more variety in them than there is in
the parts and furniture of the houses that man builds. Suppose that a
man should show you a great quantity of a red liquid, and tell you that
with that he intended to build a house and furnish it--that he should
make from it all his stones, and bricks, and timbers, and glass, and
nails, and plaster, and papers for his walls, and paints of different
colors, and then his carpets, and mirrors, and chairs, and curtains,
etc., etc. You would say that the man is crazy. But God makes from that
red fluid, the blood, all the parts of the house of the soul.

Exactly in what way all the different parts of the body are made from
the blood we do not know. Wise men have studied this a great deal, and
they have found out some things about it. What they have found out
you are not yet old enough to understand. After all, the wisest men
know but little about it, and, with all their wisdom, they do not know
enough to make skin, or hair, or any thing else that you see in your
body from the blood any more than, as I told you in Part First, they
can make even a simple leaf from the sap.

 _Questions._--What is said about the teeth and the gums? Give the
 comparison about China and cloth. What is said about the tears and the
 bile? What is said about the variety of things made from the blood?
 Give the comparison about the China-ware factory and the machinery of
 the body. What is said about the different parts of the habitation of
 the soul? In what part of this house does the soul reside? Give the
 comparison about a house and its furniture. What is said about wise
 men?




CHAPTER III.

HOW THE BLOOD IS MADE.


I have told you what is made from the blood, and now you will want to
know how the blood itself is made.

[Sidenote: Blood made from food.]

The blood in your body is made from the food that you eat. It is made
very much in the same way that the sap in the plant is made. This
sounds strange to you, but it is true. You remember that I told you in
Part First that the plant’s food is in the ground, and that the root
is its stomach. You remember what I told you about the little mouths
in the root that suck up the plant’s food out of the ground. There are
little mouths in your stomach that suck in the nourishing part of the
food that you eat, as the mouths in the root suck up the nourishing
part of the earth. And the stomachs of all animals have these little
mouths.

[Sidenote: The mouths in the stomach.]

The mouths in the root of a plant do not, you know, suck up all the
soil. They drink in only what is good to make the plant grow. So the
mouths in the stomach of an animal do not suck up all the food; they
suck up only that part of the food that will make the animal grow--that
is, what will make good blood. There is, you know, no sap in the
ground, but there is what can be made into sap. So there is no blood in
your food, but there is in it what can be made into blood. It is the
business of the mouths in the root to take in what will make sap, and
so it is the business of the mouths in the stomach to take in what will
make blood. And they generally do this business very faithfully. It is
very seldom that they take in what they ought not to.

[Sidenote: Variety of our food.]

You have seen how many different things are made from the blood. This
is very wonderful. But it is quite as wonderful that the blood can be
made from so many different kinds of food as you sometimes take into
your stomach. Just think of all the various things that you sometimes
eat at dinner--meat, potato, turnip, squash, apple-sauce, cranberry,
celery, pie, filberts, raisins, etc. It seems strange that red blood
can be made from such a mixture as this. But so it is. There is
something in all these different things that helps to make the blood.

[Sidenote: Stomachs of animals suited to their food.]

The blood is made from different things in different animals. The cow,
you know, never eats meat. It would be of no use in its stomach. The
mouths there would not suck up any thing from it. This is not their
business. Their business is to suck up something from grass, and meal,
and potatoes, etc., but not from meat. So grass would be of no use to a
dog. The Creator has made the stomach of the cow in such a way that it
can get from grass what is needed to make blood; and he has given such
a stomach to a dog that blood can be made from the meat that he eats.
Our stomachs are made in such a way that our blood can be made from a
great many different things; and so the variety of our food is much
greater than that of such animals as the cow and the dog.

 _Questions._--From what is the blood made? How is an animal’s stomach
 like the root of a plant? What part of the food do the mouths in
 stomachs and in roots suck up? What is said about the different kinds
 of food that blood is made from? Tell about the food of the cow and
 the dog. What is said about our stomachs?




CHAPTER IV.

MOTHER EARTH.


[Sidenote: Our food in the ground.]

The food of plants is in the ground, and the roots take it up; but so,
too, is the food of animals in the ground. And yet, if we should fill
our stomachs ever so full of earth, we should not be nourished. How is
this? It is because the food is not in the right condition for us while
it is in the earth. It must be _changed_ before our stomachs can do any
thing with it.

[Sidenote: The plants gather it and fit it for our use.]

Now this is just what the plants do for us. They get this food out of
the earth for us, and put it into such a condition that our stomachs
can use it. I will make this plain to you. We eat bread made from
wheat. It nourishes us--that is, blood is made from it. But what is
the wheat? It is grain that is made from the sap that comes up in the
pipes of the stalk, and this sap is made from what the root sucks up
out of the ground. You see, then, that what the wheat is made from is
in the ground; and all that the plant does is to take this up out of
the ground and make it into wheat, so that our stomachs can use it for
food. The plant’s stomach, then, we may say, gathers food out of the
ground for our stomachs.

One of the things that we eat is sugar. Where does it come from? It is
made from the earth. But if you should put earth into your stomach, no
sugar could be made from it in your body. There are some plants that
have to do this for us. They make sugar from the earth for us to eat.
This part of our food then, may be said to be really in the ground, for
what it is made from is there.

The same thing is true when you eat meat. This meat was once a part of
the ground. See how this is. Suppose it is a piece of beef from an ox:
the grass that the ox ate was made from sap sucked up from the ground;
then from this grass blood was made in the ox; from this blood the meat
was made; and now from the meat blood is made to nourish you.

[Sidenote: Changes in the food while it is becoming fitted for us.]

See, now, how many changes the food in the ground goes through in this
case before it becomes a part of your body. First it becomes sap; then
it becomes a part of the grass; then in the stomach of the ox it is
sucked up, and is changed into blood; then it becomes a part of the ox;
then it is sucked up in your stomach, and is changed into blood; and
now it is ready to be used in your body to make nerve, or bone, or eye,
or tooth, or any part of the house of your soul.

You sometimes drink the milk of the cow. This also comes from the
ground. See how this is. The cow goes to pasture, and eats the grass
that is made from the ground. The cow’s blood is made from this, then
milk is made in her bag from the blood, and in you this milk is changed
back to blood.

So you see that all our food really comes from the earth. There is in
the earth under our feet just what makes and nourishes our bodies. We
can not get at it ourselves, mixed up as it is with the earth, but the
plants suck it up and prepare it for us; and in this you see the reason
for the expression “Mother Earth.” The earth is our mother. We get all
our food from the earth as really as the infant gets its food from its
mother’s breast.

You can also see, from what I have told you in this chapter, the
meaning of the text, “Dust thou art, and unto dust shalt thou return.”
We are dust, that is, earth; for we are made from it, and are nourished
by what comes from it, and when we die our bodies will become a part of
the earth again.

[Sidenote: Reasons why animals have a stomach.]

You see that there are two reasons why animals have a stomach to put
their food in. One is that they want to move about. They could not have
a root for a stomach as plants do. They must have a stomach that they
can carry about with them. We can suppose an animal made like a plant.
It might have feet with roots sprouted out from them, and these roots
might have little mouths which would suck up food as soon as they were
put into the ground. But how very awkward and inconvenient this would
be! The animal would be obliged every now and then to bury up its feet
with their roots in loose moist earth, and stay still in one spot till
enough was sucked up from the earth for its nourishment. And, besides,
the roots would be dangling around, and catching in every thing as
the animal moved about. Your little feet could not carry you about as
nimbly as they now do if you had such roots fastened to them.

Another reason is, that the food in the ground is not fitted to nourish
an animal. It must be gathered up in plants, and be changed in them,
as I have shown you in this chapter, before it can be of any use to
animals.

[Sidenote: Why the stomach of a plant is so much larger than the
stomach of an animal.]

The stomach of a plant is much larger than that of an animal. The
stomach of an animal, you know, is but a small part of its body; while
the root of the plant--that is, its stomach--is nearly as large as
the plant itself. What do you think is the reason of this? The little
mouths in the root of the plant suck up only a small part of the earth,
the plant’s food, and so it takes a great deal of earth to give the
plant all the sap that it needs. It is for this reason that the root
spreads out so far on every side. Now in the animal the mouths in
the stomach suck up a great part of the food. It does not require,
therefore, a large stomach, for it needs to put but a small amount of
food into it. You see, then, that the food of the plant is bulky, as we
say, and therefore it must have a large stomach, while the animal can
manage its food with a small one.

 _Questions._--Where is the food of animals? What must be done to it
 before they can use it? What do the plants do for us? Tell about the
 wheat. What is said about sugar? What about meat? Mention the changes
 that food goes through in this case before it becomes a part of your
 body. What is said of milk? What is the reason of the expression
 Mother Earth? Explain the text, “Dust thou art, and unto dust shalt
 thou return.” What is the first reason given why an animal has a
 stomach to put his food in? What is the second reason? Why is the
 stomach of a plant so much larger than the stomach of an animal?




CHAPTER V.

THE STOMACH AND THE TEETH.


The little mouths in the stomach, as I have told you, suck up from the
food what is made into blood, but they do not do this as soon as the
food is put into the stomach. The food must be digested first. You have
heard people talk about digestion, and now I will explain it to you.

[Sidenote: What is done to the food in the stomach.]

When you swallow your food, there is a liquid formed in the stomach
that mixes up with it. This liquid, after a little time, changes all
the different kinds of food in such a way that the whole looks as if it
was all one thing. The meat, and potato, and pie, etc., are not only
well mixed, but they are so changed that you could not tell one from
the other.

When the food becomes changed in this way, the little mouths begin
their work upon it. They suck up from it a white fluid very much like
milk; and it is from this fluid that all the blood in our bodies is
made.

[Sidenote: The grinding of the food.]

Now observe what is done to the food before it goes into the stomach.
There is a mill in your mouth for grinding it up, and a very good mill
it is. There are twenty teeth there for the purpose of dividing up your
food very finely. You can see what the use of this is. The finer the
food is, the more easily will the digesting fluid in the stomach change
it. It takes some time for this fluid to soak through a solid piece of
meat or potato. So you see that you must not swallow your food too
fast, but must let the mill in your mouth grind it up thoroughly.

[Sidenote: Breaking up the food of plants.]

Something like this grinding we do sometimes for the food of plants,
You know that in the spring the gardener digs up his garden, and the
farmer plows his fields. What is this for? It is to loosen up the
ground; that is, it is to break up the food of the plants, so that they
can use it well. If this was not done, the hard earth would be to the
plants just as your food would be to your stomach if you swallow it
without chewing it well. So your teeth do to your food what the spade
and the plow do to the food of plants.

[Sidenote: The saliva factories.]

While the mill is grinding the food, there are some factories about
the mouth, making and pouring forth a fluid to moisten it. This fluid,
called the saliva, is what you feel in the mouth when the mouth waters,
as we say. The two largest of these factories are just below your ears.
It is these that swell up so much when one has the mumps. These saliva
factories do a moderate business generally. Most of the time they only
make enough liquid to keep the mouth moist. Sometimes they do not make
enough even for this. This is the case when your mouth gets dry, as
it is apt to do in fever. When you eat, these factories do a brisk
business, for they then have to make a good deal of fluid to mix with
the food. It seems as if they knew when it was necessary for them to go
to work and make more saliva than usual. This, of course, is not so;
but how it is that they are made to work so hard while we are eating we
do not know.

The food of plants needs moistening just as our food does. The rain
moistens it for the root, the stomach of the plant, so that it may get
nourishment from it. When you water the dry earth in a flower-pot, you
do for the food of the plant what the saliva factories do for your food.

[Sidenote: Parched plants and the parched mouth in fever compared.]

Sometimes in fever, as I have just told you, the mouth is very dry.
This is partly because the saliva factories have almost stopped work;
hardly any saliva comes through their canals into the mouth. It would
be hard work then to eat dry food. The dry cracker must be moistened
before it can be eaten. This is very much like what sometimes happens
to plants when there has been no rain for a long time. There they are,
with their roots in the ground, just as they have been all along. The
food is close to their little mouths, but it is so dry that they can
not well manage it. They languish, therefore, and perhaps wilt. The dry
earth is to them like the dry cracker to the fevered mouth.

 _Questions._--What is done to the food in the stomach? What do the
 months in the stomach suck up? What is done to the food before it goes
 into the stomach? What is the use of grinding the food? What harm does
 it do to eat fast? What is said about the food of plants? What else
 is done to our food while the teeth are grinding it? Tell about the
 working of the saliva factories. What is said about moistening the
 food of plants? How are plants sometimes like persons in a fever?




CHAPTER VI.

MORE ABOUT THE TEETH.


[Sidenote: The different kinds of teeth for cutting, and tearing, and
grinding.]

Notice that in the mill in your mouth there are different kinds of
teeth. They are for different purposes. The front teeth are for cutting
the food; the large back teeth are for grinding it up fine; the pointed
teeth, called the stomach and eye teeth, are for tearing the food.

You can see these different kinds of teeth in different animals. Every
animal has such teeth as it needs to divide its food. The dog and the
cat eat meat, and they want to tear this to pieces; they therefore
have long, sharp, tearing teeth; so, too, have the lion and the tiger,
for the same reason. Now look at the cow’s mouth: she has no tearing
teeth. The grass that she eats does not need to be torn; it needs to
be bruised and ground up, and for this purpose she has large, broad,
grinding teeth. These are her back teeth.

But you notice that the cow has a few different teeth in front; they
are made to cut. Now watch a cow as she eats grass, and see how she
uses these two kinds of teeth. With the front teeth she bites the
grass--that is, she cuts it; then with the end of her tongue she puts
it back where the grinding teeth are, to be ground before it goes into
the stomach. So the cow has in her mouth both a cutting machine and a
mill.

The horse has these two kinds of teeth, as you see represented in this
figure, which is the skull of a horse.

[Illustration]

[Sidenote: The teeth of the horse, the cow, and the giraffe.]

Now when you eat an apple you do very much as the cow or the horse does
with the grass; with your front cutting teeth you bite off a piece;
then it is pushed back where the grinders are, and they grind it up
into a soft pulp before you swallow it.

The cow does not always use her cutting teeth in the way that I have
mentioned. See her as she eats hay; she does not cut this as she does
the grass. With those front cutting teeth she merely takes up the hay,
and it is gradually drawn back into the mouth, the grinders all the
while keeping at work on it. If the hay is in a rack, she pulls it out
with her cutting teeth. It is the same with the horse.

[Illustration]

That beautiful and singular animal, the giraffe, which you see here,
has these two kinds of teeth. This animal, when of full size, is three
times the height of a tall man; it lives on the leaves of trees, which
it crops with its front teeth, grinding them up with its large back
teeth, as the cow and horse do their hay and grass.

[Sidenote: Tearing teeth.]

You notice that your tearing teeth are not nearly as long and powerful
as these teeth are in dogs, cats, tigers, etc. What is the reason of
this? It is because, although you eat meat as they do, you can, with
your knife and fork, cut up your food. They do not know enough to use
such things, and so God has given them long, sharp teeth to tear their
food to pieces.

[Sidenote: Stomachs of the cow.]

The cow grinds the grass and hay twice. So do the sheep, the deer, the
camel, the giraffe, and many other animals. See the cow cropping grass
in the pasture; she grinds it partly in her mouth as she crops it,
and then stows it away in a very large stomach that she has for the
purpose; after a while she stops eating, and you see her standing or
lying in the cool shade chewing her cud, as we say. That large stomach
is very full of grass now, and this is all to be chewed over again. How
do you think this is done? I will tell you.

[Sidenote: Chewing the cud.]

After the grass is well soaked in this large stomach, it passes into
another, for the cow has more than one stomach--she has four. In this
second stomach the grass is all rolled into balls. This is a very
curious operation. Now each one of these balls goes up into the mouth
to be chewed over again. After it is well chewed, down it goes again,
but it goes into still another stomach, and then up comes another
ball to take its place; and so the cow goes on till all the balls are
chewed. If you look at the cow’s neck while she is doing this, you can
see when the ball goes up and when it goes down. She seems to have the
same quiet enjoyment while thus chewing her cud that the cat has when,
with her eyes half open, she lies purring and wagging her tail after a
full meal.

[Sidenote: Gizzards of birds.]

Birds, you know, have no teeth. Their mill for grinding food is not
in the mouth, it is in the stomach. What we call the gizzard is this
mill. See a hen pick up the corn that you throw to her. She swallows it
very fast. Where do you think it goes to? It goes into a bag called the
crop. Here it is soaked, just as the grass is in the large stomach of
the cow. When it becomes soft enough it goes into the gizzard. Here it
is crushed so as to make a soft pulp by being rubbed between two hard
surfaces, as corn in a mill is ground between two mill-stones. If you
cut open the gizzard of a fowl, you can see how well these surfaces are
fitted to grind up the corn. They do it quite as well as teeth would.
Birds that live on food that does not need grinding do not have a
gizzard, but a common stomach.

 _Questions._--What are the different kinds of teeth that you have in
 your mouth, and what are they for? What is said about the teeth of the
 dog, cat, etc.? What is said about the cow’s back teeth? What of her
 front ones? Tell how the cow uses these two kinds of teeth in eating
 grass, and how in eating hay. How do you eat an apple? Tell about the
 giraffe. Tell about the cow’s chewing her cud. What is the crop of a
 bird for? What is the gizzard for? Do all birds have gizzards?




CHAPTER VII.

THE CIRCULATION OF THE BLOOD.


[Sidenote: Arteries and veins.]

You remember that I told you in Part First how the sap circulates in
a plant or a tree. It goes up in one set of pipes, and goes down in
another set. Just so it is with the blood in your body; it is always
in motion. There are two different sets of pipes for it to go back and
forth, as there are in the plant for the sap; these two sets of pipes
are called arteries and veins.

[Sidenote: The heart.]

The blood in your body is kept in motion by a pump that works all the
time, night and day. This pump is in your chest. It is the heart. Put
your ear to the chest of some one, and you can hear its working as it
pumps out the blood. You can hear it in your own chest sometimes when
it works very hard. When you have been running very fast you can hear
it.

The heart pumps the blood out at every beat into a large artery. From
this great main pipe other pipes or arteries branch out every where,
and from these branches other branches go out; dividing in this way,
like the branches of a tree, the arteries at last are very small.

[Sidenote: The capillaries.]

At the ends of the arteries there are exceedingly small vessels. They
are called capillaries, from the Latin word capilla, which means a
hair. They are really smaller than the finest hairs, for you can not
see them. When you cut your finger you divide a great many of these
vessels, and the blood oozes out from them. When any one blushes,
these capillaries in the skin of the face are very full of blood, and
this causes the redness. It is the blood in these little vessels that
makes the lips red. These capillaries are every where, so that wherever
you prick with a pin the blood will ooze out.

The blood goes out from the heart by one set of pipes, and comes
back to the heart by another set. It goes out from the heart by the
arteries, as I have just told you; it comes back to the heart by the
veins.

[Sidenote: How arteries are guarded more than veins, and why.]

The veins lie, some of them, very deep, and some just under the skin.
You see some of them under the skin in your arm and hand. But you can
not see the arteries; they nearly all lie deep. Think of the reason of
this. If an artery of any size is wounded, it is not easy to stop its
bleeding, for the heart is pumping blood right through it; but it is
easy to stop the bleeding of a wounded vein, because the blood is going
in it quietly back to the heart. Now it is because it is so dangerous
to wound arteries that God has placed them so deep that they can not
easily be wounded.

The maker of our bodies has guarded the arteries in another way. He
has made them much stronger than the veins. If they were not made very
strong they would now and then burst. You sometimes see the hose of
a fire-engine burst when they are working the engine very hard; but,
though your heart pumps away sometimes so fast and hard, as when you
have been running, not one of all the arteries gives way; but they
would often burst if they were not made stronger than the veins are.

The blood in the arteries is red; but the blood that comes back to the
heart in the veins is dark. This is the reason that the veins which you
see under the skin look dark. I will tell you more about the dark and
the red blood in the next chapter.

[Sidenote: Circulation of the sap.]

You see that the blood is kept in motion in a different way from what
the sap is. In a large tree there is a great deal of sap going up in
its trunk all the time, but there are no large pipes there like our
arteries and veins. The sap goes up and down in a multitude of very
small pipes, and there is no pump in the tree, as there is in our
bodies, and in the bodies of other animals. How the sap goes up to the
top of the tallest tree without being pumped up we do not know.

[Sidenote: Pumping of the heart.]

The heart is at work, as I have told you, all the time, while you are
asleep as well as when you are awake. If it should stop pumping the
blood, you would die. How steadily it works, going tick-tack all the
while! How much work it does in a lifetime! It takes but a few days for
it to beat a million of times; and here I will give you something about
this work of the heart that I wrote in another book.[A1]

If the heart could think, and know, and speak, suppose it should count
up how many times it has to beat before the days of seventy years are
numbered and finished. I think it would feel a little discouraged at
the great, long work that was before it, just as some people do when
they look forward and think how much they have to do; but remember that
the heart has a moment in which it can make every beat. There is time
enough to do the work; it is not expected to make two or more beats at
once, but only one.

[Footnote A1: Every-day Wonders; or, Facts in Physiology. American
Sunday-school Union.]

[Sidenote: Cheerful working.]

As the heart can not think, it does not faint with discouragement, but
goes right on with its work, doing in each moment the duty of that
moment; and it would be well if people that can think, whether children
or adults, would take a lesson from this little busy worker in their
bosoms. If one goes right on, performing cheerfully every duty as it
comes along, he will do a great deal in a lifetime, and he will do it
easily and pleasantly, if he does not keep looking ahead and thinking
how much he has to do.

[Sidenote: The discontented pendulum.]

There is a pretty story, by Miss Jane Taylor, about a discontented
pendulum. The pendulum of a clock in a farmer’s kitchen, in thinking
over the ticking that it had got to do, became discouraged, and
concluded to stop. The hands on the clock-face did not like this, and
had a talk with the pendulum about it. The pendulum was, after a while,
persuaded to begin its work again, because it saw, as the hands said,
that it always had a moment to do every tick in. The pendulum’s foolish
waste of time in complaining made the farmer’s clock an hour too slow
in the morning.

 _Questions._--What is said about the circulation of the sap and the
 blood? What is said about the heart? What about the arteries? What are
 the capillaries? By what pipes does the blood come back to the heart?
 Where can you see some of the veins? Why are the arteries laid deeper
 than these veins? Why are they made stronger than veins? What is the
 color of the blood in the arteries? What is its color in the veins? Is
 the sap kept in motion in the same way that the blood is? What is said
 about the work that the heart does? Tell about the pendulum.




CHAPTER VIII.

BREATHING.


What do you breathe for? That is plain enough, you will say: I can not
live without breathing. But why is it that your life depends on your
breathing? This I will explain to you.

[Sidenote: The blood changed from dark to red in the lungs.]

You remember that I told you that the blood that comes back to the
heart in the veins is dark; it is not good blood. It has been used
while it was in the capillaries in building and repairing bone, and
skin, and muscle, and nerve, etc. It is not fit to be used again so
long as it is dark blood. What shall be done with it? It must be made
in some way into good red blood again. Now the factory where this is
done is the lungs.

Just as fast as the dark blood comes to the heart, it sends it to the
lungs to be made into red blood, then it goes back to the heart to
be sent all over the body. But how, you will ask, is the dark blood
changed into good red blood in the lungs? It is done by the air that
you breathe in; every time that you draw a breath, air goes down into
the lungs and changes the blood that it finds there.

And now you see why it is that you have to breathe to keep alive. If
the air does not go down into the lungs, the dark blood that is there
is not changed into red blood: it goes back to the heart dark blood,
and is sent all over the body; but this dark blood can not keep you
alive: it is the red blood that does this.

[Sidenote: Drowning.]

You see, then, how death is caused in drowning; the air is shut out by
the water, and the blood is not changed in the lungs; so the blood goes
back to the heart dark instead of red, and is sent all over the body.

[Illustration]

The heart and the lungs fill up your chest. The lungs cover up the
heart, except a little part of it on the left side: this is where you
can feel its beating so plainly. Here is a figure of the heart and
lungs; the lungs are drawn apart, so that you can see the heart, and
its large arteries and veins. You see, marked _a_, the windpipe by
which the air goes down into the lungs. The lungs are light, spongy
bodies. They are light because they are full of little cells for the
air to go into. It is in these cells that the blood is changed by the
air.

[Sidenote: Situation of the heart and lungs of fishes.]

[Sidenote: Gills of fishes.]

[Sidenote: How fishes breathe.]

And now I will tell you about the lungs of fishes. But perhaps you will
say that fishes do not breathe, and it can not be that they have lungs,
for they would be of no use to them. It is true that they do not have
such lungs as we have; but they have lungs, and they really do breathe
air. How is this, you will ask, when they live in the water? There is
a good deal of air always mixed up with water, and the lungs of a fish
are so made that the air in the water can change the blood in them. The
gills of a fish are its lungs, and the way that they are used is this.
The fish takes water into its mouth, and lets it run out through the
gills, and so the air that is mixed with the water changes the blood
in them. Our lungs are fitted to breathe air alone, but the fish may
be said to breathe air and water together. Air alone does the fish no
good; he can not live in it; he must have his air mixed with water, or
it is of no use to him.

[Sidenote: Breathing of the lamprey eel.]

[Illustration]

Here is a picture of the lamprey eel. You see that it has a row
of holes on its neck: these are openings that lead to its lungs;
there are seven on each side. It is from this that it is sometimes
called seven-eyes. Insects have such openings into their lungs. The
grasshopper has twenty-four of them, in four rows. So you see that
there are different ways of breathing in different animals. They do not
all breathe through their mouths and noses, as we do.

[Sidenote: The voice.]

You see that the chief use of breathing is to air the blood; but it is
of use to us in another way. It makes the voice. We could not speak
if we did not breathe. The sound of the voice is made in the top of
the neck, in what we call Adam’s apple. This is a sort of musical
box at the top of the windpipe: in this box there are two flat cords
stretching right across it. Now when we speak or sing, the sound
is made in this way: the air, coming up out of the lungs, strikes
on these cords, and makes them shake or vibrate. It is just as the
vibration of the fiddle-string makes a sound when the bow is drawn over
it. If you look at an Æolian harp fixed in a window, you can see that
the strings are made to quiver by the wind, and this causes the sound.
In the same way, the wind that is blown up from your lungs makes the
cords in the Adam’s apple vibrate; and the chest may be said to be the
bellows of that little musical box or organ that you have in the throat.

[Sidenote: The voices of animals.]

[Sidenote: The purring of the cat.]

Many animals have a musical box in the throat similar to ours. The
lowing of the cow, the barking of the dog, and the mewing and squalling
of the cat are all done in such a box. You perhaps have wondered how
the cat purrs. This noise is made in the same box where she does her
mewing and squalling; for if you put your finger on her Adam’s apple
while she is so quietly purring, you can feel a quivering motion there.

[Sidenote: The croaking of the frog.]

Fishes, you know, have no voice. They have no musical box. If they had
they could not use it, for the only way in which it can be used is to
blow air through it. The frog can not use his so long as he is under
water; he has to stick his head up out of water when he wants to croak.

 _Questions._--What do you breathe for? How is the blood in the lungs
 changed? What would it do if it were not changed? How is death, caused
 in drowning? How are the heart and lungs situated? Why are the lungs
 so light? What is said about the lungs of fishes? What is said about
 the breathing of the lamprey eel? What about the breathing of the
 grasshopper? How is the breathing of use besides changing the blood?
 Tell how the voice is made. What is said about the voices of animals?
 Where is the cat’s purring done? Why do fishes have no musical box?
 What is said about the croaking of frogs?




CHAPTER IX.

BRAIN AND NERVES.


[Sidenote: The body the soul’s house, with a great deal of machinery in
it.]

I have told you some things in the previous chapters about how the body
is built and kept in repair. I have told you that the blood is the
building material from which all the parts of the body are made. The
use of food, you have seen, is to make the blood, and the chief use
of the breathing is to keep the blood in good order. The heart, with
its arteries and veins, keeps the blood moving all about the body, so
that it may be used in building and repairing. But what is the body
built and kept in repair for? It is a house for the mind or soul. The
soul--the thinking part of you--so long as it remains in this world,
dwells in the body.

The body is something more than a house for the soul. The head, where
the soul dwells, is but a small part of the body. But it uses all parts
of it. When the hand is moved, the soul uses the hand; when you walk,
it uses the legs and the feet; when you see, it uses the eyes; it uses
the ears as its instruments to hear with, and the nose is its smelling
instrument; and so of other parts.

You can think, then, of the body as having in it many different kinds
of machinery that the mind or soul uses. And the object of eating, and
drinking, and breathing, and having the blood circulate, is to make all
this machinery for the mind to use.

[Sidenote: How the mind uses its machinery.]

Let us see, now, how it is that the mind uses the machinery of the
body. Raise your hand. What makes it go up? It is what we call the
muscles. They pull upon it and raise it. But what makes them do it?
They do it because you think to have them do it. It is your thinking
mind, then, that makes them raise the arm.

But the mind is not there among the muscles; it is in your head. Now
how does the mind get at the muscles to make them work? It does not go
out of the brain to them, just as a man goes out of his house among his
workmen to tell them what to do. The mind stays in the brain all the
time; but there are white cords, called nerves, that go from the brain
to all parts of the body, and the mind sends messages by these to the
muscles, and they do what the mind tells them to do.

[Sidenote: Nerves like telegraphic wires.]

These nerves act like the wires of a telegraph. The brain is the mind’s
office, as we may call it; here the mind is, and it sends out messages
by the nerves as messages are sent from a telegraphic office by its
wires. This is done by electricity in the telegraphic office, but how
the mind does it we do not know. When you move your arm, something goes
from the brain along the nerves to the muscles, and makes them act, but
what that something is we do not know.

If the wires that go out from a telegraphic office are broken off in
any way, the man in the office may send out messages, but they will
not go to the place he wishes. He may work his machine, and send the
electricity along the wire, but it will stop where the break is.
Just so, if the nerves that go to the muscles of your arm were cut,
the muscles could not receive any message from the mind. You might
think very hard about raising the arm, but the message that your mind
sends to the muscles is stopped where the nerves are cut, just as the
electricity stops where the break is in the wire.

[Sidenote: The two sets of nerves.]

[Sidenote: The brain.]

While the mind sends out messages by one set of nerves, it receives
messages by another set; it receives them from the senses. Just see how
this is. If you put your finger upon any thing, how does the mind in
your brain know how it feels? How does it know whether it is hard or
soft, rough or smooth? The mind does not go from the head down into the
finger to find out this; it knows it by the nervous cords that stretch
from the brain to the finger. When you touch any thing, something goes,
as quick as a flash, from the finger along these nerves to the brain
where the mind lives, and lets it know what kind of a thing it is that
your finger has touched. So, when you smell any thing, it is the nerves
which connect your nose with the brain that tell the mind what kind of
a smell it is. And when you taste any thing, it is the nerves of the
mouth that tell the mind in the brain whether it is bitter, or sweet,
or sour, etc. So, too, when you see any thing, it is the nerve which
connects the eye with the brain that tells the mind what it is that you
see.

[Sidenote: The nerves of the face and head.]

The brain, in which the mind lives and with which it thinks, is the
softest part of the body. You can see what sort of a thing your own
brain is by looking at the brain of some animal at the meat-market.
You can see it very well in the calf’s head when it is prepared for
cooking by being sawed in two. I have compared the nerves to the wires
that stretch out from the telegraphic office; but there are only a
few wires, while the nerves that branch out from the brain, all over
your body, can not be counted. Here is a figure showing how the nerves
branch out over the face and head; there are a great many of them, and
so there are in all other parts of the body.

[Illustration]

The nerves, by dividing, spread out, so that there are little nerves
every where. If you prick yourself with a pin any where, there is a
little nerve there that connects that spot with the brain, and that
tells the mind about it. Now all the nerves in all parts of the body
have their beginnings in the brain. In this soft organ are bundled
together, as we may say, all the ends of the nerves, so that the mind
can use them. There the mind is at its post, just like the man in the
telegraph office; and from that great bundle of the ends of nerves it
is constantly learning what is going on at the other ends of them in
all parts of the body.

[Sidenote: The mind very busy in attending to all its nerves.]

A great business the mind has to do in attending to all these ends
of nerves in the brain; and how strange it is that it does not get
confused, when so many messages are coming to it over its wires from
every quarter! It always knows where a message comes from. It never
mistakes a message from a finger for one from a toe, nor even a message
from one finger for one from another.

And so, too, in sending out messages to the muscles, there is no
confusion. When you want to move a finger, your mind sends messages
by the nerves to the muscles that do it. The message always goes to
the right muscles. It does not go sometimes to the muscles of another
finger by mistake, but you always move the finger which you wish to
move. And so of all other parts. Messages go from your busy mind in the
brain to any part that you move. You can see how wonderful this is,
if you watch any one that is dancing or playing on an instrument, and
think how the messages are all the time going by the nerves so quickly
from the brain to the different parts of the body. I shall tell you
more about this in another chapter.

[Sidenote: Messages go from the brain by some nerves, and come to it by
others.]

The man in the telegraph office receives messages by the same wires
by which he sends them out. It is not so, as I have told you before,
with the mind’s wires, the nerves; the mind receives messages from
the senses by one set of nerves, and sends messages to the muscles by
another set. If you burn your finger, you pull it away from the fire.
Now in this case the mind gets a message from the finger by the nerves,
and so knows of the hurt. The message goes from the finger along some
nerves to their ends in that bundle of them in the brain; and the mind,
being there on the watch, receives it. Now what does the mind do? Does
it leave the finger to burn? No; it sends a message at once along some
other nerves to the muscles that can pull the finger out of harm’s way.

 _Questions._--What are some of the things that I have told you in
 the chapters before this? What is the body built and kept in repair
 for? In what part of the body does the soul live? Tell how it uses
 different parts of the body. When your arm is raised, how is it done?
 In what way does the mind make the muscles act? What are the nerves?
 How are they like telegraph wires? What is it that goes along the
 wires? Do we know what it is that goes along the nerves? Give the
 comparison between cut nerves and broken wires. From what does the
 mind receive messages? Tell about touching, smelling, tasting, and
 seeing. What is said about the brain? What is said about the number
 of nerves? What is said about the mind’s attending to all its nerves?
 What is said about its making no mistakes in its messages? Give what
 is said about the burning of a finger.




CHAPTER X.

HOW THE MIND GETS KNOWLEDGE.


[Sidenote: Knowledge enters the mind by the senses.]

The mind, as you learned in the last chapter, has a sort of telegraphic
communication with all parts of the body by means of the nerves, and
it is all the time receiving messages from the fingers, the eyes, the
nose, the ears, the mouth, and other parts. These are instruments
which the mind uses to get a knowledge of what is around us. It gets
different kinds of knowledge by the different instruments. For example,
it learns whether a thing is hard or soft by the touch of the fingers,
and it learns how it smells by the nose, how it tastes by the mouth,
and how it looks by the eyes.

There is knowledge, then, going all the time to the mind by the nerves
from these instruments. It can not get there in any other way. Suppose
the mind was locked up in the brain, and had no nerves going out from
it. It could not learn any thing about what is around it; there might
be eyes, and fingers, and ears, and a nose, and a mouth, but these
would be of no use to the mind if there were no nerves.

[Sidenote: How the mind learns about things.]

See how the child learns about the world of things all around him.
When he is first born he does not know any thing. He does not know how
any thing feels, or looks, or tastes, or smells. But with his little
nerves his mind gets messages from the senses, and so he learns every
day about the things that are around him. Eyes, ears, nose, mouth,
and fingers are all the time telling his mind something through the
nerves. They tell him first about those things that are in the room
where he is, and then, after a while, when he is carried out, they tell
him about things that are out of doors, and thus he knows more and more
every day.

And then, too, the mind thinks about what the senses tell it. It lays
up what comes to it by the nerves, and looks it over, as we may say,
and in this way it learns a great deal. There is great difference in
people in this thinking about what the mind knows by the senses. Some
that see and hear a great many things do not know as much as some that
see and hear few things. It is because they do not think much about
what the senses tell the mind.

You see, then, that all that we learn in this world really comes
into the mind by the way of the nerves from the senses--the sight,
the hearing, the touch, the smell, and the taste. The senses are the
_inlets_ or openings by which knowledge enters, and the nerves are the
passages by which it gets to the mind in the brain; and after it gets
there the mind thinks about it and uses it in various ways.

[Sidenote: The deaf and the blind.]

[Sidenote: Deaf and dumb.]

[Sidenote: How the blind read.]

Some persons, you know, do not have all these inlets for knowledge
open. For example, some are deaf; in them no knowledge can get into the
mind by the ears. Some are blind, and no knowledge can get into their
minds by the eyes. More knowledge comes into the mind by the sight than
by the hearing; it is therefore a greater misfortune to be blind than
it is to be deaf.

It is astonishing to see how much the deaf and the blind can learn if
they try. If the mind is wide awake and ready to learn, it can get a
great deal of knowledge even when one of the openings for it is shut
up. It can use the knowledge gained by the other senses in such a way
as to make up very much for the loss. A lazy mind, with all the senses
letting in knowledge, will not know as much as a busy mind will with
one of the senses shut up. In the deaf and dumb the eyes have to answer
for both eyes and ears in getting knowledge. They have to do double
duty; and they do it very well if the mind is only wide awake and
attentive to all that it can learn by the eyes. In the blind the ears
have to do a great deal more than in those that can see. The fingers
also of the blind are very busy, for they learn very much about what is
around them by the sense of feeling. There are books now made for their
use with raised letters. By passing their fingers over them, they read
just as you do by looking at printed letters.

[Sidenote: Story of Laura Bridgman.]

And now I will tell you about a girl that has had to get all her
knowledge with only one of the senses, the sense of feeling. Her name
is Laura Bridgman. When she was in her second year she became very
sick. Her sickness lasted a very long time. After she got well it was
found that she was blind and deaf, and that she had no taste nor smell;
only one of the five inlets for knowledge was open. All that could come
into her mind was what could be learned by the touch alone. But she had
an active mind, and so she went round feeling of every thing, to find
out all she could about things.

The only way that she could know people was by feeling them. Her
mother was very kind to her, and the little helpless girl liked to be
with her all the time. She followed her about the house, and tried to
do things just as her mother did them. She would feel of her mother’s
arms and hands while she was doing things, that she might find out
how she did them. In this way she learned to knit, which was a great
comfort to her, for she did not like to be idle.

[Sidenote: Laura in the asylum.]

A kind physician, who had charge of an asylum for the blind in Boston,
heard about Laura. He was much interested for the helpless child, and
went to see her. He persuaded her mother to let her come to the asylum.
Laura did not feel at home at first, but, as they were all kind to her
in the asylum, she soon liked it very much.

She now began to learn many things, and I will tell you a little
how the teacher managed with her. He put into her hands different
things--spoons, keys, books, etc. Each article had a label on it. The
letters on the labels were raised letters, such as are used in teaching
the blind. She would feel them all over with the tips of her little
fingers, her busy mind all the time thinking about how they felt. Then
the labels and the things were put before her, but separated from each
other. After a little trying, she learned to put the labels on the
things right.

All this time she did not know that these labels had the names of the
articles on them. If she were blind only, she would have known this
at once, for she could have been told of it; but after a while she in
some way got this idea into her mind. She was delighted, for she had
now found a new way of learning things, and of telling about things to
others.

[Sidenote: How Laura learned to read and to converse.]

And now Laura went on fast with her learning. The letters were
separated, and she would put them together so as to spell spoon, key,
etc. This was a great amusement to her. Sometimes, when she carelessly
placed the letters wrong, she would playfully strike her right hand
with her left one, and then, when the letters were placed right, she
would pat her head, as the teacher was apt to do when he was pleased
with any thing that she had done.

After a while the teacher taught Laura to use her fingers in talking,
as you, perhaps, have seen the deaf and dumb do. She soon learned to
make all the letters in this finger-alphabet, which you can see on page
98; and now she could talk with people quite easily, if they happened
to know this alphabet. When she had any thing to say, she would make
the letters with the fingers, while the person to whom she was talking
would look at her. But how do you think that she managed when this
person said any thing to her with his fingers? She could not see his
fingers, but she could feel them, and this was the way in which she
knew what was said to her; she would carefully, but rapidly, pass her
fingers over his as fast as he made the letters. It was surprising to
see how quickly the touch of her nimble fingers would tell her mind
what letter was made, and how fast she could converse with persons in
this way.

[Sidenote: Laura’s industry.]

Laura learned much more at the asylum than we should suppose she could
with only her one sense of touch. Some persons with the whole five
senses do not know as much as she does. She even learned to write; and
writing and knitting were very pleasant employments to her. By writing
she could put the thoughts of her busy mind on paper, so that others
might read them; and while she was sitting alone thinking, she liked to
make her nimble fingers useful in knitting. It was a great satisfaction
to her that, though she had but one sense, she could do something
useful. What a pity it is that many children, and many adults too, do
not have more of this feeling than they seem to have! The example of
Laura teaches a good lesson to all idlers.

[Sidenote: Her fun.]

Though Laura could never see beautiful things, nor hear pleasant
sounds, as you do all the time, she was very cheerful, and sometimes
she was very funny. She liked to play with her doll; and as the blind
children in the asylum had ribbons tied over their sightless eyes, she
tied one over her doll’s eyes. One day she was in her play taking care
of her doll as one would of a sick child. She made believe give it
medicine, and put a hot bottle to its feet; and when some one proposed
to her to put a blister on its back, she was so much amused that she
laughed and clapped her hands.

[Sidenote: A visit from her mother.]

[Sidenote: How Laura knew her mother.]

After Laura had been some time at the asylum her mother came to see
her. She did not know her mother at first, but thought that she was
some stranger. She held back and would not come near. Her mother
handed her a string of beads which she used to wear when at home.
She took them, and as soon as she felt them she knew what beads they
were. She put them on her neck, and, showing great joy, said with her
finger-language that she knew these came from home. Something else from
home was given her. She now drew near, and her mother kissed her. The
moment that her mother’s lips touched her she knew who it was, for
that kiss was just like the many kisses her loving mother used to give
her. She remembered how those lips used to feel, and they had the same
feeling now; and now she clung to her mother, and put her head into her
bosom. They were both very happy. When her mother left her Laura felt
sad indeed. She wanted to go with her, but she knew that it was best
for her to stay in the asylum, where she could learn so much.

 _Questions._--What are the instruments by which the mind gets its
 knowledge? How does the knowledge get to the mind? What good would the
 instruments do if there were no nerves? Tell how the child, when first
 born, learns about things around him. What is said about thinking of
 what is learned by the senses? Why may the senses be called the inlets
 of knowledge? Tell about the deaf and the blind. Why is it worse to
 be blind than it is to be deaf? What is said about the amount of
 knowledge that the blind and the deaf can obtain? What is said about
 the sense of sight in the deaf and dumb? What senses do the blind
 chiefly use in getting knowledge? How do they read? How many of the
 senses did Laura Bridgman lose? How did she learn about things before
 she went to the asylum? Tell how she learned after she went there. How
 did she talk with people? Tell about her industry. What is said of her
 cheerfulness? What of her fun? Tell About her mother’s visit.




CHAPTER XI.

SEEING.


The senses by which the mind obtains most of its knowledge are the
sight and the hearing. In this chapter we will look at the organ or
instrument of sight.

[Sidenote: The eye a beautiful instrument.]

The eye is a very beautiful instrument. It is very nicely made, and
it has a great many different parts. You are not old enough yet to
understand all about these parts, but there are some things about them
that I can explain to you.

What we call the white of the eye is a strong, firm sort of bag. It is
filled mostly with a jelly-like substance. It is this that makes it a
firm ball. If it were empty it would be like a bag. Into the open part
of this, in front, is fitted a clear window. The light goes in here. It
can not get in at the sides of the eyeball, through the thick white of
the eye.

[Sidenote: Its window and dark chamber.]

Through this very clear window you can look into the bag or ball of the
eye. You can not look through the jelly-like substance that is there,
and see the very back of the inside of the eyeball; but it is like
looking into a dark chamber. The reason that it is so dark is, that it
is lined with something almost black. If this were not so, the eyes
would be dazzled with the light that commonly goes into them, just as
they now are when the light is very bright indeed.

Inside of the front window of the eye that I have told you about there
is a fluid as clear as water. In this fluid you see a sort of curtain
with a round opening in it. This opening is called the pupil of the
eye. It is not always of the same size. When there is a very bright
light, it is small; but when the light is dim, it is large, for then
you want all the light that you can get in that dark chamber where the
jelly is. You can see the pupil change in its size if you look into the
eye of any one while you bring a light very near, and then move it off
quickly.

[Sidenote: The iris the curtain in the eye.]

The curtain in which this opening is we call the iris. It is circular.
Its outer edge is fastened all round to the inside of the eyeball. The
watery fluid, that I told you is inside of the window of the eye, is on
both sides of this curtain. It would not do to have the jelly here, for
the curtain would not move easily in that in changing the size of its
opening.

[Sidenote: The pupil a round opening in it.]

The iris is, you know, of different colors in different persons. When
it is blue, we say that the person has a blue eye; and if it is quite
dark, we say that he has a black eye; and so of other colors. This
curtain makes the eye very beautiful; but its chief use is, as you see,
to regulate the quantity of light that goes into the eye. When there is
a great deal of light, the curtain is drawn in such a way as to have
the round opening very small; but when there is little light, it is
drawn so as to make this opening large. This curtain must be made very
nicely, or it would be puckered when the opening in it is changed in
this way. No man could make a curtain of this shape, and have it work
like this: it would be a very awkward thing if he should undertake it.
He could not possibly make it so that the round opening in it could be
made smaller and larger without wrinkling. But look at this beautiful
curtain in the eye, and see how smooth it is, and how perfectly round
its edge keeps, as the size of the pupil is changed. Did you ever see
any thing work more prettily and easily than this does?

[Sidenote: The pupil in the eye of the cat and the horse.]

The opening in the curtain is different in different animals. In
                             /\
the cat it is of this shape (  ); in the horse it is shaped in this
                            (  )
                            (  )
                             \/
      ____________
way  /            \
    (              ). You can see the difference in the size
     \____________/

of the cat’s pupil in different lights: if you look at her eyes in a
bright sunlight, and then again in the evening, you will see that
it is very much larger in the evening than it is in the day. When

                                                             ()
the sun is very bright, her pupil is a mere chink, like this (); but
                                                             ()
                                                             ()
                                                             ()

                                                          /\
                                                         /  \
in the evening it is very wide open, shaped in this way (    ).
                                                        (    )
                                                         \  /
                                                          \/

[Sidenote: The images in the eye’s dark chamber.]

But I have not yet told you how you see. It is done in this way. The
light that goes in through the pupil makes an image or picture there of
every thing that is before the eye. It makes the image on a very thin
sheet spread out on the back part of the dark chamber where the jelly
is; it is just as light makes images of things in a looking-glass, or
in the smooth, still water; the only difference is, that the image
or picture in the eye is very small. When you see a tree pictured in
the still water, the picture is as large as the tree itself; but the
picture that the light makes of the tree in that dark chamber of your
eye is very small. The picture in your eye of a whole landscape, with
all its trees, houses, hills, etc., does not cover over a space larger
than a ten cent piece.

But how does the mind in the brain know any thing about these pictures?
It knows about them by means of a nerve, that goes from the brain to
the eye, and is spread out where the pictures or images are made. It
would do no good to have the pictures made in the eye, if the nerve
could not tell the mind about them. The eye might be perfect, and yet
there might not be any seeing. It is as necessary to have the nerve in
good order as it is the eye itself. It is not your eye that sees; it is
your mind, and in seeing it uses both the nerve and the eye.

[Sidenote: Why we have two eyes.]

You have two eyes. When you look at one thing, say a house, there is
a picture of the house in both eyes. The two nerves tell the mind in
the brain about the two pictures. How is this? Why does not the mind
see two houses? It is because the pictures in the two eyes are exactly
alike, and both nerves, therefore, tell exactly the same story; if
they did not, then the mind would see two houses; that is, it would
see double, as it is called. You can see double by pressing one eye
sidewise while you let the other go free.

[Sidenote: The eyes of insects.]

The eyes of insects are very curious. You remember what I told you
about compound flowers. Now, as in a compound flower there are a great
many flowers together, so it is with the eyes of insects. The eye of a
common fly is made up of thousands of eyes; so, when he looks at any
thing, there are thousands of very little images of it made by the
light in these eyes, and the nerves tell the fly’s mind, in his little
brain, about them. These eyes are so exceedingly small that you can
not see them without a microscope. How fine, then, must be the nerves
that go from them to the fly’s brain! Your eye is a very wonderful
instrument, but God has put thousands of them just as wonderful into
the head of the fly that buzzes about you. It is as easy for him to
make little eyes as large ones, and he can make a multitude as easily
as one.

 _Questions._--By what senses does the mind learn the most? What is
 the white of the eye? What is it filled with? What is there in the
 front part of the eye? What is said about the dark chamber of the
 eyeball? What is just inside of the front window of the eye? What is
 the pupil of the eye? What is the iris? How is it arranged? What is
 said of its color? What is its chief use? Tell about this. What is
 said about its being made nicely? What is said about the shape of its
 opening in different animals? What is said about the cat’s pupil in
 different lights? Tell about the images made in the eye. What is said
 about the nerve of the eye? How is it that, with two eyes, you do not
 see double? Why do you have two eyes? What is said about the eyes of
 insects?




CHAPTER XII.

HOW THE EYE IS GUARDED.


[Sidenote: The eye seldom hurt.]

The eye, you know, is a very tender organ. It is therefore guarded
thoroughly, and it is really very seldom hurt. But notice that it is
just where it would be likely to be hurt if it were not thus guarded.
It is right in the front part of the head. It must be there for the
mind to use it in seeing. And it is much of the time open. You would
suppose, then, that it must very often be struck and hit by things that
are thrown about; but it is really very seldom hit so as to be hurt
much.

The parts about the eye are often injured, but the eye itself generally
escapes. We often see the eyelids and the cheek black and blue from a
blow, and yet the tender and delicate eye is as sound as ever. People
say, in such cases, that the eye is black and blue, but this is not so;
the injury is all on the outside, and does not go into the eye.

[Sidenote: How it is guarded with the bones around it.]

Now let us see in what ways the eye is guarded. It is in a deep bony
socket. There is bone all around it except in front. Then, too, see how
the bones stand out all around it. The bone of the forehead juts over
it. Below and to the outside stands out the cheek bone, and the nose
is its wall on the inside. Now you can see that a blow with a stick
would be very likely to strike upon some of these walls of bone, and
the eye would then escape. They are real walls of defense to the eye. A
stick can not hit the eye itself unless it goes with its end pointed
to the eye. It must go in this way to avoid striking on these walls, or
parapets of bone, by which the eye is surrounded.

But if the stick gets by these bony walls, it may not hurt the eye,
after all. Perhaps you never thought what use there is in being able
to wink so quickly. See what winking does. It shuts the eyelids over
the eye, so that nothing can get into it unless it is something sharp
enough to pierce through the lids. And a blow will not hurt the eye, if
the lids are closed, unless it is hard enough to bruise it through the
lids.

[Sidenote: The winking muscle.]

How quick is the working of that winking muscle! The moment that the
eye sees any thing coming toward it that may injure it, this muscle
shuts up the eye out of sight as quick as a flash. It hardly seems as
if there was time for a message to go from the eye to the brain, and
then another back from the brain to that muscle in the lids. But all
this happens. The nerve of the eye tells the mind of the danger, and
the mind sends a message to the winking muscle. This is done so quickly
that whenever people speak of any thing as being done very quickly,
they are very apt to say that it was done in the twinkling of an eye.
This expression is used in the Bible in this way.

[Sidenote: The eye’s cushion of fat.]

But I have not told you all that this winking muscle does. It does
something more than shut the eye in. It pushes it back in its socket,
so that it is a little farther out of the way of a blow. And it does
not push it right against the hard bone of the socket: there is a soft
cushion of fat for it to press the eye against.

And this is not all. When the eye sees a blow coming, this muscle acts
so strongly that it wrinkles the skin of the eyelids, and pulls down
the eyebrow, and draws up the cheek, as you see here. Now see how this
guards the eye. The cheek and the eyebrow are brought so near together
that there is but little room for the blow to get at the eye; and even
if it does, the wrinkled skin of the lids makes a cushion over it that
breaks the force of the blow. You can see that the blow would be much
more apt to do harm if the winking muscle merely brought the lids
together. As it is, a blow commonly hits on the eyebrow or cheek, or
both, while the eye is safe, shut up and pushed back in its cavern upon
its cushion of fat. To see how much the bringing together of the cheek
and eyebrow defends the eye, you must look at some one as he forcibly
closes the eye, as represented in the figure. And if, at the same time,
you put your finger on the parts, you will see how the cushions which
all this wrinkling makes over the eye and about its socket defend it
from harm.

[Illustration]

[Sidenote: The winking muscles raise cushions over the eye to defend
it.]

So you see that not only is the eye guarded by parapets of bone, but
the busy winking muscle raises up cushions on them whenever the eye
sees a blow coming. These cushions often save the bone from being
cracked, and in this way also keep the eye from being hurt.

[Sidenote: The eyebrows.]

Of what use do you think the hairs on the eyebrows are? They are for
good looks, you will say. But they are for something more than this;
they are a defense to the eye. How this is I will explain to you. You
know what the eaves of a house are for when there is no trough to the
roof; they keep the rain from running down from the roof on the sides
of the house. They make it drop off to the ground a little way from the
house. Just so the hairy eyebrows make the sweat of the forehead drop
off upon the cheek, instead of running down into the eye. The eyebrows,
then, are the eaves of the roof of the eye’s house.

Perhaps you will ask what hurt the sweat would do if it should run down
into the eye. It would be very disagreeable; and, besides this, it
would irritate the eye and make it red. The eye would become inflamed.

[Sidenote: The eyelashes.]

The eyelashes, too, besides making the eye look well, are a defense
to it. You know that there are often small things flying about in the
air which we are not apt to see. If these fly against the eye, they
generally hit against the eyelashes, and so are prevented from going
into the eye.

[Sidenote: How the tears defend the eye.]

The tears, also, are a defense to the eye. If any thing happens to get
by the eyelashes into the eye, how quick the tears flow to wash it out!
Commonly the gland, or tear factory, only makes enough tears to keep
the eye a little moist; but as soon as any thing gets into the eye and
irritates it, the tear factory sets to work briskly, and sends down the
tears abundantly. At the same time, the winking muscle keeps moving the
lids, and generally what is in the eye is soon washed out.

Tears are flowing into the eye all the time. If they did not, the
eyeball and the inside of the lids would become dry, and they would
not move easily on each other. You would have to keep wetting them
with water to prevent them from rubbing. The tear factory, which is
just above the eye, continually sends down, through some little tubes
or ducts, just enough tears to make the motion of the eye and the lids
easy.

[Sidenote: The sink-drain of the eye.]

[Sidenote: In weeping the tears overflow their banks.]

But you will ask where the tears that are made go. They do not commonly
run out over the lids, and they must go somewhere. I will tell you
about this. If you look at the eyelids of any one, you can see in each
lid a little hole at the end of the edge toward the nose. The tears go
into these holes, and down through a duct that ends in the nose. This
duct may be called the sink-drain of the eye, for the tears, after
washing the eye, run off through it. The two little holes or mouths
in the lids commonly take in all the tears as fast as they come to
them; but when we cry, the tear factory makes tears so fast that these
mouths can not take them all in. The tears, therefore, overflow their
banks--the lids--and run down on the cheek.

 _Questions._--Is the eye in a very exposed situation? Why is it seldom
 much hurt? Are the parts about it often hurt? Tell how the bones about
 the eye defend it. Of what use is winking? What is said about the
 quickness with which it is done? What else does the winking muscle do
 besides shutting the eye? What does it push the eye back upon? What
 else does this muscle do besides what has been mentioned? How does
 this defend the eye? On what does a blow aimed at the eye commonly
 hit? Of what use are the hairs on the eyebrows? What harm would the
 sweat do if it ran down into the eye? Of what use are the eyelashes?
 In what ways do the tears prevent the eyes from being injured? Where
 do the tears go to from the eye? What happens when one cries?




CHAPTER XIII.

HEARING.


[Sidenote: What sound is.]

What is sound? If you look at a large bell when it is struck, you can
see a quivering or shaking in it. If you put your hand on it, you can
feel the quivering. It is this that makes the sound that we hear. You
can see the same thing in the strings of a piano when they are struck,
and in the strings of a violin as the bow is drawn over them. The
wind makes the music on the Æolian harp in the window by shaking its
strings. And when you speak or sing, the sound is made, as I have told
you before, by the quivering of two flat cords in your throat.

But when a bell is struck, how does the sound get to our ears? The
quivering or vibration, as it is called, of the bell makes a vibration
in the air, and this vibration is continued along through the air to
our ears.

[Sidenote: The experiment of scratching on a log with a pin.]

The vibration can go through other things besides the air. It will go
through something solid better than it will through air. Put your ear
at the end of a long log, and let some one scratch with a pin on the
other end, you can hear it very plainly. The vibration made by the pin
travels through the whole length of the log to your ear; but if you
take away your ear from the log you can not hear it, for the vibration
or sound can not come to you so far through the air.

[Sidenote: Dying away of sound.]

The nearer you are to where the sound is made, the louder it is; and
the farther sound goes, the fainter it is. It is said to die away as
it goes; that is, the vibration becomes less and less, till, after a
while, it is all lost. It is like this: if you drop a stone into water,
it makes little waves or ripples in all directions. These become less
and less the farther they go from where the stone was dropped. It is
just so with the waves or vibrations of sound in the air.

What is an echo? It is when a sound that you make comes back to you
again. It is done in this way. The vibration strikes against some rock,
or house, or something else, and then bounds back to you, just as a
wave striking against a rock bounds back.

[Sidenote: Speaking tubes.]

Why is it that a person speaking in a building can be heard more easily
than one speaking in the open air? It is because the vibrations are
shut in by the walls. It is for the same reason that you can hear a
whisper so far through a speaking tube extending from one part of a
building to another. The vibrations are shut in within the tube. They
have no chance to spread out in all directions, and they go right
straight on through the tube.

I have thus told you how sound is made, and how it goes through the
air and through other things; but how is it that we hear sound when it
comes to our ears? How does the mind know any thing about the vibration
of the air? This vibration does not go into the brain, where the mind
is; it only goes a little way into the ear, and there it stops. It
comes against the drum of the ear, and can go no farther. How, then,
can the mind know any thing about it? This I will tell you.

The vibration of the air goes into the ear to a membrane fastened to
a rim of bone, and called the drum, and shakes it, and this shakes a
chain of little bones that are the other side of this drum-head. The
last of these bones is fastened to another little drum, and, of course,
this is shaken. This drum covers an opening to some winding passages in
bone. These passages are filled with a watery fluid. Now the shaking
of the second little drum makes this fluid shake. The nerve of hearing
feels this shaking of the fluid, and tells the mind in the brain.

[Sidenote: The bones of the ear.]

Here are the four little bones that make the chain of bones in the ear.
They are curiously shaped. The one marked _a_ is called the hammer, and
_b_ is called the anvil. The little bone marked _c_ is the smallest
bone in the body. That marked _d_ is called the stirrup. This is the
bone that is fastened to the second drum--the one that covers the
opening into the winding passages. The vibration that comes to the
first drum is passed on by this chain of bones to the second drum.

[Illustration]

[Sidenote: The different vibrations in hearing.]

See, now, how many different shakings there are for every sound that
you hear. First, the bell, or whatever it is that makes the sound,
shakes. Then there is a shaking of the air. This shakes the drum of the
ear. Then the chain of bones is shaken. The farthest one of them shakes
another drum, and this shakes the fluid in the bony passages. All
this happens every time that you hear a sound; and when you hear one
sound after another coming very quickly, how the vibrations chase each
other, as we may say, as they go into the ear! But they are not jumbled
together. They do not overtake one another. Every vibration goes by
itself, and so each sound is heard distinct from the others, unless the
vibrations come very fast indeed. Then they make one continued sound.
Each puff of a locomotive, when it starts, is heard by itself. The
vibration of one puff gets into the fluid in the bony passages before
the one that follows it; but as the locomotive goes on, the puffs get
nearer and nearer together, and when it goes very fast, they are so
near together that the vibrations do not go separate into the ear, and
they make a continued sound.

[Illustration]

[Sidenote: Different sizes of ears in animals.]

[Sidenote: Ear-trumpet.]

Sound, I have told you, spreads in all directions in vibrations or
waves. Now the more of these waves the ear can catch, the more distinct
is the hearing. Some animals that need to hear very well have very
large ears. Here is one, the long-eared bat. He must hear very well
indeed, for his monstrous ears must catch a great many of the waves of
sound. We could hear better if our ears were larger; but large ears
would not look well on our heads; and we hear well enough commonly.
Sometimes, when we do not hear as distinctly as we wish to, we put up
the hand to the ear, as you see represented on the opposite page. This
helps the hearing by stopping the waves of sound, and turning them into
the ear. Those who are very deaf sometimes have an ear-trumpet, as it
is called. In using it, the large trumpet end is turned toward the
person speaking, so as to catch the vibrations, while the tube part of
it is in the ear.

[Illustration]

[Sidenote: Ears of rabbits, deers, etc.]

Some animals can turn their ears so as to hear well from different
directions. How quickly the horse pricks up his ears when he sees or
hears something that he wants to know more about; and then he can
turn his ears backward when he wants to do so. It is in such timorous
animals as the hare, the rabbit, and the deer, that we see the ears
most movable. They are on the watch all the time for danger, and the
least sound that they hear they turn their ears in the direction of it.
Their ears, too, are large, so that they hear very easily.

[Sidenote: How the ear is guarded.]

I have told you how the eye is guarded. The ear is well guarded also.
I do not mean its outer part: it is the inner parts, where the hearing
is really done, that are so well guarded. You remember that I told you
that there are passages filled with a fluid. The nerve of hearing has
its fine, delicate fibres in these passages. They feel the shaking of
the fluid, and tell the mind of it. Now it is necessary that this part
of the hearing apparatus should be well guarded; for this reason, these
passages are inclosed in the very hardest bone in the body.

[Sidenote: How the ear-wax guards the ear.]

Then, too, the very entrance into the ear is well guarded, and in a
curious way. The pipe that leads into the drum of the ear is always
open, and you know bugs are very apt to crawl into such holes. What do
you suppose is the reason that they do not often crawl into the ear?
There is something there to prevent them. It is the wax. They probably
do not like the smell of it, and so, if they come to the entrance, they
turn about. Once in a while one goes in, and then he is prevented from
doing much harm by the wax. He is soon covered with this, and it is so
sticky that it keeps him from kicking very hard. And, after all, though
he may cause some pain, he can not get at the delicate part of the
machinery of the ear. He dies after a while, if he is not got out, and
perhaps the bitterness of the wax has something to do with killing him.

 _Questions._--How is sound made? How does it get to our ears? Tell
 about the vibration of sound in a log. What is said about the dying
 away of sound? What is this like? What is an echo? What is said about
 speaking in a building? What about speaking through a tube? Tell how
 we hear sound. Tell about the little bones in the ear. What do these
 bones do? Tell what the different vibrations are in hearing. What is
 said about the puffing of a locomotive? Why do some animals have large
 ears? Why are our ears so small? What animals can turn their ears
 different ways, and why? How is the inner part of the ear guarded?
 Tell what is said about the wax.




CHAPTER XIV.

THE SMELL, THE TASTE, AND THE TOUCH.


I have told you that most of what the mind knows about the world around
it comes to it by the sight and the hearing. But it learns a great deal
by the other senses, and these I will tell you about in this chapter.

[Sidenote: How we smell things.]

Did you ever think how it is that you smell any thing? You put a rose
up to your nose, and the fragrance is pleasant to you. Now what is this
fragrance? Is it something that goes up into your nose? You can not see
any thing come from the rose. But in reality very fine particles come
from it. They are finer than the finest powder. They float every where
about in the air, and, as you breathe, they go with the air into your
nostrils. Every perfume that you smell is made of such particles.

But how do you think the mind knows any thing about these particles
when they come into the nose? It is in this way. In the lining of
the nose are the fine ends of the nerve of smell. These ends of the
branches of this nerve are so small that you can not see them. Now
the fine particles that I have told you about touch these ends of the
nerve, and the nerve tells the mind about them; and this is smelling.

The nose is a more extensive organ than most people think it is. There
are divisions in it. These fold on each other in such a way that there
is a great deal of surface in the nose, and the ends of the nerve of
smell are all on this surface.

[Sidenote: The smell of some animals.]

Some animals have a very sharp smell. In them the divisions in the
nose are very great in extent, and so the nerve spreads over a large
surface. The dog, you know, is able to track his master by scenting his
footsteps. The cat, too, has a very quick smell for rats and mice.

Some persons have a sharp smell for some things. I have heard of a
blind gentleman who could always tell when there was a cat any where
near him by his sense of smell. Once he was very sure that there was
one near by, though no one could see her; he insisted upon it that he
was right, and after a while pussy was found in a closet of the room.
There was also a blind and deaf person who could distinguish between
different people that he knew by the sense of smell.

[Sidenote: The enjoyment afforded by the sense of smell.]

The sense of smell affords us great enjoyment. The Creator has, for the
purpose of gratifying us, scattered sweet-smelling flowers all over the
earth. These are all perfume factories, as I told you in Part First,
made by him to give us pleasure. He could have made the flowers and
fruits in such a way that they would have no smell; but, in his desire
to please us and make us happy, he has given to them a great variety of
pleasant odors. There are, it is true, some unpleasant smells in the
world, but these are not any thing like as common as the pleasant ones;
and many of them are manifestly very useful in warning us of danger.
For example, the unpleasant odor caused by filth and decay tells,
people where these causes of disease are, so that they may get rid of
them. And plants that are poisonous generally have a disagreeable odor,
which leads us to avoid them.

[Sidenote: How we taste and how we feel.]

The sense of taste is another source of gratification to us. The nerve
of this sense has its fine ends mostly in the tongue. What we take into
the mouth touches these ends of the nerve, and the nerve tells the mind
about it; and this is tasting.

Besides the pleasure which we have from the taste, the great use of
this sense is to guide us in the choice of food. Animals choose the
kinds of food that are proper for them, and they do it by their taste.
They very seldom make a mistake in this. The sense of taste, like that
of smell, sometimes warns us of danger. If out food tastes bad, we
know that there is something wrong about it and do not eat it, and so,
perhaps, avoid being made sick.

The sense of touch gives a great deal of knowledge to the mind. This
sense has a large number of nerves in all parts of the body, and they
are making reports continually to the mind. Especially busy in this
way are the nerves of the tips of the fingers. It is by the fine ends
of these nerves that the mind finds out how different things feel. It
finds out whether they are soft or hard, smooth or rough, etc.

These nerves in the tips of the fingers are of great service to the
mind in guiding it in using the muscles. In playing with the fingers
on an instrument, the feeling in the ends of them is a guide to the
mind in working them. So it is with any thing that we do with them. You
could not do some of the simplest things if there was no feeling in
your fingers. You could not even button and unbutton your coat. I shall
have more to say about this when I tell you particularly about the hand.

[Sidenote: The nerves of touch in the skin.]

The nerves of touch are not placed on the surface of the skin. We have
really two skins, an outer and an inner one. The nerves are in the
inner skin, and are covered by the outer skin. This outer skin is very
thin except on the sole of the foot and the palm of the hand; from its
thinness it is called the scarf-skin. It is this which is raised when a
blister is drawn; and perhaps you know that it does not hurt to prick
this when we want to let the water out; but if the needle touches the
inner skin, where the nerves are, you feel it very quickly.

Now, when you touch any thing, the nerves in the inner skin feel it
through this scarf-skin. This is so thin and soft that the nerves can
feel through it; and, at the same time, it is a good protection to
them. If it were not for this, the nerves would be affected too much by
the rubbing of things against them. They could not even bear the air.
If you had no scarf-skin you would be in great distress all the time.
You know how much pain you suffer if you rub off the skin, as it is
called, any where. It is the scarf-skin only that is rubbed off, and
this exposes to the air the fine ends of the nerves in the inner skin.

The ends of the nerves of touch are in rows on the tips of the fingers.
It is these rows that make the curved lines that you can see so plainly.

[Sidenote: How some animals feel.]

[Sidenote: Whiskers of the cat.]

There are no animals that have such perfect instruments of touch as our
fingers are. Animals that have hoofs, as the horse and the cow, can not
feel much with their fore feet. They have their sense of touch mostly
in their lips and tongues. The elephant has this sense chiefly in the
finger-shaped thing at the end of his trunk. There is not much feeling
in the paws of dogs, cats, etc. The whiskers of the cat are feelers.
There are nerves at the root of each of those long hairs, so that when
any thing touches the whiskers the cat’s mind knows it at once.

[Illustration]

[Sidenote: Feelers of insects.]

Insects have feelers extending out from their heads. Sometimes they are
very long, as you see in this insect, called the ichneumon fly. We see
insects, as they are going about, touch things with these feelers as we
do with our hands. Bees can work in the dark, in their hives, guided
by their feelers; indeed, the bee will not work at all if his feelers
are cut off: he does not seem to know what to do with himself. Insects
sometimes appear to tell each other things by their feelers. In every
hive of bees there is a queen. If she dies, those that know about it go
around very quickly, telling the other bees by striking their feelers
with their own; and those that are told tell others, and thus the sad
event is soon known all over the hive.

 _Questions._--By which senses does the mind get most of its knowledge?
 What is fragrance? How does the mind know any thing about it? What is
 said of the extent of the organ of smell? What is said of the smell
 of some animals? Of the acute smell of some persons? What is said of
 the enjoyment afforded by the sense of smell? How are offensive odors
 sometimes useful? What is said of the sense of taste? What are its
 uses? Where is the sense of touch? Where is it especially active? What
 do the nerves of touch in the fingers tell the mind? In what way do
 they help us in using the muscles? Tell about the two skins of our
 bodies. Why is the outer skin needed? What makes the curved lines on
 the tips of the fingers? What is said of touch in animals that have
 hoofs? What are the whiskers of the cat for? What is said of the
 feelers of insects? What is told about the bees?




CHAPTER XV.

THE BONES.


I have told you, in the last few chapters, how it is that the mind
learns about the world around it by the senses. But the mind does
something besides learn. It tells others about what it learns. It
does this by the muscles in various ways. When you tell any thing by
speaking, it is the muscles of the throat, and mouth, and chest that
do it. When you write, the muscles of your hand are telling what the
mind directs them to tell. When your face expresses your thoughts and
feelings, it is the muscles of the face that tell what the mind thinks
and feels.

[Sidenote: How the mind uses what it learns.]

The mind not only tells things, but it does things also, and it does
them by the muscles. You see a man busily at work making something:
his muscles are doing the work. The mind is directing them how to do
it by the nerves that spread to them from the brain. How does his mind
know in what way to direct them? It is by knowledge gained through the
senses--by his eyes and ears. He has seen people do the same kind of
work and they have told him about it. His mind uses with the muscles
what it has learned by the senses.

You see, then, that the mind makes use of what it learns by the senses
in two ways: it tells about it, and it uses it in doing things; and in
both telling and doing it uses the muscles. Our knowledge, then, goes
into the mind by the senses--they are its _inlets_; but it comes out
by the muscles--they are its _outlets_. If a mind were in a body that
had the senses, but had no muscles, it might know a great deal, but it
could never let any body know what it knew, and it could not do any
thing.

The chief things that are moved in the body by the muscles are the
bones, and I shall tell you about these before I tell you about the
muscles.

[Sidenote: The joints of the bones.]

When you bend your arm, the muscles make the bones in the lower part
of the arm bend on the bone in the upper part. There is a joint at the
elbow for this purpose; and there are joints in many other parts of the
body, so that the muscles can move one bone upon another.

These joints of the bones are so contrived that they do not wear out.
They work nicely through a long life. Now it would be very strange if
a joint in a machine should work all the time for seventy or eighty
years, and still be almost as good as new. No man ever made such a
joint.

[Sidenote: The oiling of them.]

You know that men keep oiling the joints in machinery. If they did
not, the joints would soon wear out. When the cars stop at a station,
you see men with tin vessels oiling the boxes of the wheels of the
locomotive and the cars, and other parts that rub on each other. The
joints of our bones need no such care from us. We never need to oil
them as men oil machinery. They are very nicely made. The ends of the
bones are tipped with a very smooth substance, and this is always kept
in good order; and then, too, the joints always keep themselves oiled.
How this is done I explain in a book for older scholars.

The bones are the frame-work of the body. They are to the body what
whalebones are to an umbrella, what timbers are to a house, or what the
ribs of leaves are, as I told you in Part First, to the leaves. The
bones make the body firm. You could not stand up if you had no bones;
you would have to crawl like the worm. See one bracing himself to pull
or push. The bones are all pressed tightly against each other by the
strong muscles.

The bones of the body have very different shapes and sizes. Let us look
at some of them.

[Illustration]

[Sidenote: Bones of the head.]

The bones of the head, represented here, make a roundish box. This is
to hold the brain. Here the mind, the governor of all the machinery of
the body, resides. Great care is therefore taken to guard well this
upper room of the body. Its bony walls are made very strong.

[Illustration]

[Sidenote: Bones of the chest.]

Look at this barrel-shaped set of bones that make the chest. The ribs
go round it as hoops do round a barrel. They are joined to the back
bone behind and to the breast bone in front. They are joined to the
back bone in such a way that they move up and down as you breathe. You
can feel them move upward if you put your hand on your chest as you
take a full breath. Inside of this barrel-shaped set of bones are the
heart and lungs.

[Sidenote: Back bone.]

[Sidenote: Bowing.]

The back bone, as we call it, is not one bone; it is a chain or pile of
twenty-four bones placed one above another. You can see a part of this
pile or column, as it is sometimes called, in the figure of the bones
of the chest. If it were all one bone, you could not twist your body
about as you do. And in making a bow, you could not bend your back.
You could only bend your head forward on the top of the back bone, and
bend your body forward on your lower limbs. A very awkward bow that
would be. As it is, whenever you make a bow, there is a little motion
between each two of the whole twenty-four bones, and this makes the bow
easy and graceful. Persons that bow stiffly do not have enough of this
movement in the column of bones, but move it altogether, very much as
if it were all one bone.

[Sidenote: Position of the head.]

The head rests on the top of this column of bones. When you move your
head backward and forward, it rocks on the topmost bone of this column.
There are two little smooth places hollowed out on this bone for it to
rock on, and the head has two smooth rockers that fit into these places.

 _Questions._--In what two ways does the mind use what it learns? With
 what does it do this? What are the inlets of the mind’s knowledge?
 What are its outlets? What move the bones on each other? What is said
 about the wearing of the joints? What is said about their being kept
 oiled? What are the bones to the body? What is said about the bones
 of the head? What of the bones of the chest? To what are the ribs
 fastened behind? To what in front? How many bones are there in what is
 called the back bone? Why are there so many? What does the head rest
 on? What is said about the motion of the head?




CHAPTER XVI.

MORE ABOUT THE BONES.


[Illustration]

[Sidenote: Bones of the arm and hand.]

Here are the bones of the arm and the hand. The head of the arm bone
that goes into the socket at the shoulder is, as you see, a smooth
round ball. It fits into a sort of cup. The joint here is what we call
a ball-and-socket joint. The ball turns in the socket very easily in
making any whirling motion with your arm, as you do when you jump the
rope.

[Sidenote: Shoulder joint and elbow joint.]

The joint at the elbow is of a different kind: it is what we call a
hinge joint. You can not make any whirling motion at your elbow as you
can at the shoulder; the motion is all one way, like a hinge. The chief
motion at the wrist also is a hinge motion, as you can see by working
your hand back and forth. There are two bones, you notice, in the arm
below the elbow: these roll on each other in such a way that you can
turn the palm of your hand in different directions.

[Illustration]

There are a great many little bones in the body of the hand and in
the fingers. There is a very great variety in their motions, so that
the hand can do almost any thing that you want it to do. I shall have
something more to tell you about this when you come to the chapter on
the hand.

[Sidenote: Bones of the leg and foot.]

You have here the bones of the leg and foot. You see only the lower end
of the stout thigh bone, at the knee joint: it makes a hinge joint with
the large bone of the leg. The motion of this joint is only one way,
backward and forward, as you see in walking. The small, thick bone,
called the knee-pan, is left out in the figure. One of the uses of this
bone is to be a shield to the joint. If you fall down in running, you
are apt to come upon the knee, and this shield keeps the joint from
being hurt.

You see that long, very slender bone at the side of the large one: one
would suppose that this would be very easily broken, but it is not,
because it is so well covered up with muscles. Its lower end is quite
thick and strong, and makes the outer part of the ankle. The ankle
joint is a hinge joint like that of the knee.

[Sidenote: Why there are so many bones in the foot.]

There are as many bones in the foot as there are in the hand. Why is
this? You remember that I told you that the hand had so many bones
because it had to perform so many different motions. But it is not so
with the foot; it does not have much variety of motion. There is some
other reason, then, for its having so many bones. It is this. If the
bones of the foot were all in one, the foot would be a very stiff and
clumsy thing; it would not be springy as it is now. You would make
awkward work in walking and running with such feet.

[Illustration]

[Sidenote: Skeleton of the bat.]

The bones of different animals are made differently, according to
the work which they do. Those that do heavy work have heavy, stout
skeletons; but those that have only light work to do have their bones
slender. A bird has a light skeleton, for it could not fly so well with
a heavy one. Here is the skeleton of a bat. The bones are exceedingly
light and slender, for it is light and nimble work that he does in
flying.

The bones in an old person are more brittle than those in a child. If
the child’s bones were brittle they would be very often broken, because
he so often tumbles down. If old persons were as careless as children
are, there would be broken limbs to be taken care of in almost every
house. They would not get off with a short crying spell and a bruise,
as children commonly do when they have a fall.

[Sidenote: The bones of a child’s head.]

There is one contrivance in the child’s head that prevents the bones
from breaking in its frequent falls. In the grown person the bones of
the head are fastened tightly together, and are almost like one bone.
But it is not so with the child. In an infant’s head they are very
loose, and you can feel quite a space between the bones at the top of
his forehead. Now, when the child falls and hits his head, the loose
bones give and do not break.

Though the teeth are like the bones, they are different from them in
one thing. The bones grow with the rest of the body, but the teeth
never grow any larger than they are at first. When the tooth first
pushes up through the gum, it is as large as it ever will be. Look at
the reason of this. The outside of the tooth--the enamel, as it is
called--is made very hard. It needs to be so, that the tooth may do its
work well. Such a hard substance, when once made, is finished. It never
can grow. No blood can get into it to make it grow, as it can into the
bones.

[Sidenote: Why we have two sets of teeth.]

And now you see the reason that every person has two sets of teeth. If
the teeth that one has when a child should remain in his head, they
would be too small for him when he became an adult; and as the jaws
grew they would become quite far apart, and so would look very strange.
To get rid of these difficulties, the first set begin to be shed about
the seventh year, and a new set of larger teeth take their places. As
the new teeth are not only larger, but are more in number, they fill
up all the room designed for them in the enlarged jaws.

[Sidenote: Skeletons of crabs and lobsters.]

All the bones of our bodies are inside, and are covered with muscles,
cords, and ligaments; and over all is the skin. But the bones of some
animals are outside. This is the case with crabs and lobsters. Their
bones make a sort of coat of mail to defend the soft parts from being
injured. The hard coats of many insects also may be considered as their
skeletons.

[Sidenote: How they are shed every year.]

Such animals as crabs and lobsters have new skeletons every year. The
old skeletons are too small for their growing bodies, and so they must
be cast off. The animal crawls into a retired place to go through the
operation. It is painful, and sometimes proves even fatal. He makes a
great effort, and the shell comes apart. He then, by hard struggling,
pulls himself out. He now keeps still a few days in his retirement, and
another case or skeleton, as hard as the old one, is formed. When he
comes out with his new armor on, he is as brave and as ready to fight
as ever.

 _Questions._--What is said about the shoulder joint? The elbow joint?
 The wrist? How is it that you can turn the palm of the hand one way
 and another? Why are there so many little bones in the hand? What is
 said about the knee joint? What is one of the uses of the knee-pan?
 What is said about the slender bone in the leg? What about the ankle
 joint? Why are there so many bones in the foot? What is said of the
 difference in brittleness between the bones of the old and of the
 young? What is said about the bones in a child’s head? How are the
 teeth unlike the bones? Why do we have two sets of teeth? What is
 said about the bones of some animals? What is related of crabs and
 lobsters?




CHAPTER XVII.

THE MUSCLES.


I have already told you some things about the muscles. There is no
motion in the body that is not made by them. They move the bones, and
they move other parts also, as the tongue, the corners of the mouth,
the eyes, the eyelids, etc.

[Sidenote: How the muscles act.]

But you will want to know how they do this. Stretch a strip of
India-rubber with your hands. Now let it go, and it will shorten
itself. When a muscle pulls a bone, it shortens itself just as this
strip of India-rubber does. But the cause of its shortening itself is
different. The mind makes the muscle shorten. You think to bend your
arm; and, as quick as thought, something goes by nerves to the muscle
that can do this, and it shortens itself and bends the arm.

[Illustration]

[Sidenote: The muscles that bend and straighten the arm.]

Here is a figure that shows the muscle that bends the arm, and also
the muscle that straightens it out. All the other muscles of the arm
are left out, so that you may see just how these operate. Look at the
muscle marked _a_: you can see that when this shortens itself it must
pull up the forearm, that is, that part of the arm which is below the
elbow. The muscle _b_ has a contrary effect. The end of this muscle is
fastened to the point of the elbow, and when it shortens it pulls the
forearm down and straightens the arm.

When a muscle shortens itself, it swells out and becomes hard.
Straighten your arm, and then take hold of it with your other hand a
little above the elbow; now bend up your arm as forcibly as you can,
and you will feel the muscle on the front of the arm swell out and
harden as you hold your hand upon it.

[Sidenote: Color of muscles in different animals.]

The muscles are the fleshy part of the body. The meat of animals is
made up of muscles. They are not of the same color in all animals. In
some they are quite red, while in others they are of a light color.
Beef--the meat of the ox or the cow--is, you know, a deep red, and
is very different from the meat of a fowl. The muscles of fishes are
generally very light in color.

[Illustration]

[Sidenote: Muscles that move the fingers.]

Your arm below the elbow is very fleshy. Most of the muscles that move
the fingers, as well as those that move the hand, are there. Take
hold of that part of the arm with your other hand while you work the
fingers back and forth, and you will feel the muscles as they shorten
themselves to pull the fingers. Here is a figure showing the muscles in
this fleshy part of the arm. You see that they are quite large. The
wrist is very slender. There are no muscles there; there are bright,
shining, smooth cords there, that run from the muscles to the fingers.
The muscles pull the fingers by these cords just as men pull any thing
by ropes. You can see the play of these cords very plainly on the back
of the hand of a thin person as the fingers are worked.

[Sidenote: Muscles in the hand.]

There are only some very small muscles in the hand, as those that
spread the fingers out, and those that bring them together again. If
you work your fingers in this way, you will see that the muscles, which
do such light work, need not be large and strong. The muscles that do
the hard work of the hand are up in the arm. They are very large. If
they were not, you could not grasp things so tightly, and pull so hard
as you sometimes do.

[Sidenote: The round fullness of the arm.]

Now see why it is that these large muscles are put so far away from
where they do their work. If they were put in the hand, they would make
it a large and clumsy thing. They are therefore put up in the arm,
where there is room for them, and they have small, but very strong
cords by which they pull the fingers. They give to the arm that round
fullness that makes its shape so beautiful.

[Sidenote: Drum-stick of the fowl.]

You can see the same kind of arrangement in the drum-stick, as it is
called, of the fowl. The large muscles that work the claws are up in
the full, round part of the leg, and there are small, stout cords that
extend from them down to the claws. Children often amuse themselves
with pulling these cords in the drum-stick of a fowl, making the claws
move just as they are moved by the muscles of the animal when he is
alive.

[Sidenote: Muscles of the toes.]

It is with the muscles that move the toes as it is with those that
move the fingers. They are put mostly up in the leg, and their slender
tendons, by which they pull, go down over the ankle to the toes, just
as in the arm the tendons go over the wrist to the fingers. If the
muscles of the toes were all put in the foot, they would make it very
clumsy, and at the same time the leg would be ugly from the want of
that fullness which it now has.

[Sidenote: Ligaments of the wrist and the ankle.]

Both at the wrist and the ankle the tendons are bound down very
tightly. If this were not so they would be always flying out of place,
stretching out the skin before them in ridges. This would be the case
especially with the tendons that go to the toes. Every time that the
muscles pulled on them, they would start out very much at the bend of
the ankle if they were not firmly held by the ligaments.

The muscles are of many shapes--round, flat, long, short, etc. They are
shaped to suit the work which they are to do.

They vary much in size also. Some are very large, and some are
exceedingly small. How large are the muscles of the arm that wield the
hammer and the axe! But how small are the muscles that work the musical
cords in your throat when you speak or sing! These little muscles make
all the different notes of the voice by pulling on these cords, and in
doing this many of their motions are exceedingly slight.

[Sidenote: Muscles in the ear.]

You remember that in the chapter on the hearing I told you about the
little bones in the ear. These have some very little muscles which move
them. The bones and the muscles, _a_ and _b_, are represented in the
following figure. The muscles, you see, have tendons or cords to pull
by, in the same way that the muscles in the arm have. Both the bones
and the muscles are larger in this figure than they are in the body.
As the bones are the smallest ones that we have, so it is with the
muscles. Very small machinery is this part of the hearing machinery.

[Illustration]

[Sidenote: Large and small muscles in birds.]

The birds that go swiftly on their wings have very large muscles to
work them. This gives them the full, round breast which you see that
they have. But the muscles that work the musical cords in their little
throats, as they sing so sweetly, are so small that it is difficult to
find them.

 _Questions._--By what is all motion in the body made? What do the
 muscles move? Explain how the muscles move things. Tell about the two
 muscles of the arm in the figure. What is said about the swelling out
 of the muscles as they shorten? What is the meat of animals? What is
 said about the color of muscles in different animals? What is said of
 the muscles in the arm below the elbow? What is said of the wrist?
 What of the muscles in the hand? Why are most of the muscles that move
 the fingers put up in the arm? What is said about the drum-stick of
 a fowl? What is said about the muscles of the toes? What about the
 ligaments of the tendons at the wrist and ankle? What is said of the
 shapes of muscles? What of their sizes? What are the smallest muscles
 in the body? What is said about the muscles of birds used in flying
 and those used in singing?




CHAPTER XVIII.

MORE ABOUT THE MUSCLES.


[Sidenote: Number of muscles in the body.]

There is a great number of muscles in the whole body to produce all its
motions. There are about fifty in each arm and hand. In the whole body
there are about four hundred and fifty, and each muscle is made up of a
great number of fibres or threads, every fibre having its own work to
do.

[Sidenote: All connected with the brain by nerves.]

Now all these muscles have nerves that connect them with the brain, and
the mind tells them by these nerves just what to do. Each muscle has a
great many little nervous ends scattered through it every where. The
message from the mind that tells the muscle to act does not go to the
whole muscle as one thing, as a message is sent to a person. It goes
to each fibre of it, telling that fibre what to do. Every fibre of the
muscle has its little nervous tube connecting it with the brain, for
the nerves are bundles of tubes, just as the muscles are bundles of
fibres. And each fibre gets its messages from the mind separate from
all the other fibres by its own tube, so that each fibre is a workman
by itself. How well these workmen pull together when they all get a
message from your mind by their telegraphic tubes!

[Sidenote: The endless variety of messages sent from the brain to the
muscles.]

Commonly it takes several muscles to make any motion, and sometimes
many muscles act together. When this is so, messages are sent to a
great multitude of fibres in these many muscles. Think of this. Raise
your hand. It is not one muscle that does this, but many. Your mind
has sent a message to all the fibres of these muscles, and they have
all done their part in raising your hand. But now raise it again a
little differently. A different message for this has been sent to all
the fibres; and so for all the different motions there are different
messages. It does not seem possible that so many different messages
should be sent through the nerves to the fibres of all the muscles, and
that these fibres should obey them so perfectly.

This is wonderful even in so simple a motion as raising the hand; but
how much more wonderful when a great variety of rapid motions are made
by the muscles, as in playing on a piano! How busy is the mind of the
player in sending its messages, one after the other, to the multitudes
of muscular fibres that work the arms and the fingers! And if he sings
at the same time that he plays, his mind is sending messages also to
the muscles of the chest, and throat, and mouth. And what adds greatly
to the wonder is, that all this time that the mind is sending out so
many messages, it is receiving messages from the senses. Messages are
going from the sounds of the piano and the voice along the nerves of
the ear to the mind. They go also from the tips of the busy fingers as
they press the keys. How wonderful that all these messages are going
back and forth so rapidly, and the mind in the brain manages them
without any confusion!

I have told you that there are some parts besides bones that are moved
by muscles. Different parts of the face are moved by them, and it
is this that gives it its different expressions. Thus, when you are
pleased and laugh, the muscles pull up the corners of the mouth. If
you laugh very hard, they pull them up very much, as you see in the
face drawn here. See how this face is wrinkled under the eyes. This is
because the muscles pull at the corners of the mouth so hard as to push
up the cheeks.

[Illustration]

[Sidenote: The muscles used in smiling and laughing.]

What do you think the difference is between laughing and smiling? It is
this. In laughing, the corners of the mouth are drawn up a good deal,
but in smiling they are drawn up only a little. Most people think that
the eyes have a great deal to do with laughing and smiling, and they
talk about a laughing eye and a pleasant eye. But this is not correct.
It is these muscles, which pull up the corners of the mouth, that make
the eye look pleasant and laughing; indeed, laughing and smiling can
be done with the eyes shut. We often see a beautiful smile in the face
of the sleeping infant. It is because some pleasant dream in his mind
plays on the nerves that go to his smiling muscles.

[Sidenote: The sad muscles.]

There are muscles to pull the corners of the mouth down, and these make
the face look sad; and if the muscles that wrinkle the eyebrows act
at the same time, the face is both sad and cross, as you see here.
Observe just what the difference is between this face and the laughing
face on the opposite page. The difference is merely in the corners of
the mouth and in the eyebrows. In this face the two wrinklers of the
eyebrows are in action, and so are the two muscles that pull down the
corners of the mouth. Four small muscles, then, make this face sad and
cross. But in the laughing face the eyebrow-wrinklers are quiet, and
the corners of the mouth are pulled up instead of being pulled down. It
is the two little muscles that pull up the corners of the mouth that do
all the laughing in the face.

[Illustration]

[Sidenote: “Down in the mouth.”]

You have often heard the expressions, “He had a down look,” and “His
countenance fell.” These refer to the effect produced by sadness on
the corners of the mouth. This explains also the meaning of the common
expression, “Down in the mouth.”

[Sidenote: The proud muscle.]

There is a certain muscle called the proud muscle. It pushes up the
under lip. It is chiefly by this that pouting, that ugly expression so
common with some children, is done. When the eyebrow-wrinklers act at
the same time, there is scowling with the pouting, and then the face
is very ugly. I beseech of you not to get into the habit of using
these cross muscles. Keep always pleasant and kind, and then those nice
little muscles that draw up the corners of the mouth will always be
ready to light up your face with a cheerfulness that shall be pleasant
to look upon.

[Sidenote: Snarling muscles.]

[Sidenote: The smiling of the dog.]

There are some animals that have certain muscles in the face that we
have not. These are the snarling muscles. They pull up the lip at the
sides of the mouth so as to show the long, tearing teeth. You see them
in operation in the dog, the tiger, etc., when they are angry. No
animal but man has in the face either the frowning, or the sad, or the
smiling muscles. Perhaps you will say that the dog smiles when he is
pleased and looks up at his master. He smiles, it is true, but he does
it only with his wagging tail, for he has no muscles in his face to do
it with.

[Sidenote: The chief muscles of expression.]

How wonderful is the variety of expression in the human face! And yet
all is caused by a few muscles, and the principal ones are those that
draw up and draw down the corners of the mouth, and those that wrinkle
the eyebrows.

 _Questions._--How many muscles are there in the arm and hand? How many
 in the whole body? What is each muscle made up of? What is said of
 the fibres? Is it common for a motion to be made by one muscle alone?
 What is said about raising the arm in different ways? What is said
 about the variety of rapid motions that are sometimes performed? What
 gives the face its different expressions? How is laughing done? What
 makes the wrinkling under the eyes in laughing? What is the difference
 between laughing and smiling? Has the eye any thing to do with them?
 What is said about the sad muscles? What about the cross ones? What is
 the difference between a cross and sad face and a laughing one? What
 is said about certain expressions in common use? What is said about
 the muscles of expression in the face of animals? What is said of the
 variety of expression in the human face?




CHAPTER XIX.

THE BRAIN AND NERVES IN ANIMALS.


[Sidenote: The brain the mind’s central workshop.]

I have told you how your mind learns about the world around you, and
how it makes use of its knowledge by means of the machinery of your
body--the muscles, bones, etc. Your mind is in the brain, and uses the
brain to think with; and from the brain branch out all the nerves by
which it works all the various machinery of the body. Your brain, then,
may be considered the central workshop of your mind; or it is like an
engine-room of a factory, where the engine is that keeps the machinery
in other parts of the building in motion.

[Sidenote: How animals learn.]

The different animals have a brain and nerves just as you have, and
their minds in their brains learn about things around them. They do not
learn so much as your mind does, it is true; but they really do learn.
If you look at a kitten when it is first born, it is very much like a
baby. It does not know any thing. But, like the baby, it knows more and
more every day, and when it gets to be a cat it knows a great deal; and
all that it knows has come to its mind in the same way as what you know
has come into your mind. It has come in through its senses. All its
knowledge came in at its eyes and ears, etc., and got to its brain by
the nerves.

[Sidenote: The mind of a kitten as it plays.]

The mind in animals, too, uses the muscles in the same way that your
mind does. Watch a kitten at play. The muscles that move her paws
are directed by her mind in the brain by means of the nerves. As she
pokes at the thing that you hold out to her, the nerves of her eyes are
telling the mind in the brain all the time about the string, and then
the mind is telling the muscles of the paws what to do. See her as she
springs to catch the string that you draw along on the floor. As she
watches it, messages are going from those bright eyes to her mind in
the brain; and then, as she springs, messages are sent from her brain
to a great many muscles in different parts of her body. The mind tells
the muscles just when and how to act, and they all do exactly as the
mind tells them. The mind of a cat sets a great deal of machinery at
work when she makes a spring to catch any thing.

[Sidenote: The minds and brains of insects.]

What I have told you about some animals is true of all. The little
insect that flies out of the way when you strike at him has a little
brain, and there his mind thinks about what it sees, and hears, and
feels, etc., just as your mind does; and when he flies away so quickly
from the blow that his eyes see coming, his mind tells the muscles to
make the wings go. There are nerves that carry messages from his senses
to the mind in his brain, and there are nerves that carry messages from
his brain to his muscles, as there are in you. The brain is very small,
and the nerves are very fine, but they do their work well. They make a
little telegraph, but it is a good one.

What a quantity of thinking there is done in the brains of all the
animals in the world! How busy their minds are, receiving reports from
their senses, and working all the machinery of their bodies. Go out
into the garden, and see the birds, the butterflies, the bees, the
flies, the ants, the frogs, the toads, and the worms; they are all busy
thinking. They can not move without thinking. It is their thinking that
makes their muscles move them. And they think about what they move for.

[Sidenote: Animals that think more than others have larger brains.]

Some of them think more than others. The bird thinks more than the
worm. Some think faster than others. The humming-bird, that darts so
quickly from flower to flower, thinks as fast as he works. But the lazy
toad is a slow thinker. His mind does not work the machinery of his
muscles much, and so does but little thinking. But even he once in a
while thinks quickly. Let a fly walk along pretty near him, and he will
catch it with his tongue so quickly that you can not see just how he
does it. He watches the fly intently, keeping very still all the while;
and when it gets near enough, he thrusts out his tongue, and the fly is
gone. You would hardly think that so lazy-looking an animal could do
any thing so quickly. But he is nimble as a fly-catcher, if he is not
nimble at any thing else; and very quickly must the mind in his brain
think when it is working its fly-catching machinery.

The more an animal thinks, the larger is the brain as compared with the
rest of the body. Man thinks more than any other animal, and so he has
a large brain. But the oyster has hardly any thing that can be called a
brain, for in his still life, shut up as he is in his shell, he thinks
but little. But such animals as horses, dogs, cats, birds, monkeys,
etc., have quite large brains, for they think a great deal. Their
brains, however, are not, by any means, as large as the brain of man is
in proportion to the size of the body.

[Sidenote: The brain compared to machinery.]

This is as we should suppose it would be. The brain is the machinery
with which the mind thinks. Now, whenever we see a great deal of
machinery together at work, we know that it is because there is much
to be done by it; and when we see a small machine that has not many
different parts, we know that it is not intended to do much. So it is
with the mind’s thinking machinery. The brain of an animal that thinks
but little is small and simple; but the brain of one that thinks much
is large and has many parts. Though animals do their thinking with
their brains as we do with ours, there is some thinking that we do that
they can not. There are some things about which they know nothing. But
I will tell you about this in another chapter.

 _Questions._--What does your mind do with your brain? How is your
 brain like the engine-room of a factory? What is said about the minds
 of different animals? How is a kitten, when it is first born, like a
 baby? How does it learn? What is said about the mind, and brain, and
 nerves of an insect? What is said about the quantity of thinking done
 in the brains of animals? How do some differ from others in their
 thinking? Tell about the toad. What is said about the size of the
 brain in different animals? How is the brain compared with machinery?




CHAPTER XX.

THE VARIETY OF MACHINERY IN ANIMALS.


You have seen what a variety of curious machinery there is in our
bodies for our minds to work, besides that which is needed to keep the
body in repair. But I have told you some things about other animals as
I have gone along. There is in them also a great deal of machinery,
and it is different in each. The variety of it is wonderful. You see
that the world is every where full of many kinds of animals, making
it a very busy world. I do not believe that you have ever thought how
different they are from each other. I will therefore tell you a little
about this.

[Sidenote: Machinery in the oyster suited to its wants.]

See what a difference there is between man and some animals. Look at
the oyster. He lives in the water, shut up in his rough shell. He is no
traveler. He has no eyes to see sights with. He has no sense of smell.
He has taste for his food, and, no doubt, enjoys it. He has the sense
of touch; this he needs, both to manage his food and to guard himself
against harm. As he does not move about, and has no feet or hands, he
has but few muscles. He has one to shut up his shell tight, which he
does when he is alarmed. His brain and nerves are very small affairs,
for he has little use for such things.

There is little machinery, then, in an oyster, as you compare it with
the machinery in your body; and it is simply because he does not need
so much as you do. If he had needed more, God would have given it
to him. But there is, after all, considerable machinery even in the
oyster. He has machinery for digesting his food. He has circulating
machinery--a heart with its arteries and veins. And he has gills like
fishes, by which his blood is aired by the air in the water. Then he
has a few muscles, some nerves, and a sort of brain.

[Illustration]

[Sidenote: The hydra--all stomach and arms.]

[Sidenote: How it acts when alarmed.]

Look, now, at another animal that has less contrivances in him than the
oyster. Look at the hydra. This is a very little animal which is found
in ponds, sticking to a straw or stick by a sort of sucker. Here is a
representation of it. The small figure shows it of its natural size.
The larger figure shows it as magnified by the microscope. This animal
is little else than a stomach with long arms. We can turn the body of
it--that is, the stomach, inside out, and the animal will do as well
as before. The arms are merely to catch things, as worms and insects,
which they put into the mouth of the stomach, marked _a_. One of the
arms is represented as having caught something, which it is about to
put into this mouth. When the little creature is alarmed, he gathers up
all his arms around his stomach, and looks like a little ball. No brain
has ever been discovered in him, but it is plain that he thinks some
in catching his food, and in gathering himself into a ball to escape
notice. He probably has a brain to think with, though it is so small
that it is not to be seen with the most powerful microscope.

[Illustration]

[Sidenote: One of the arms of the hydra magnified.]

[Sidenote: Contrivances in animals endless.]

Here is one of the arms of this animal as seen with a powerful
microscope. It is made up of little cells or bladder-like things. How
it is that these make the different motions of this arm we do not know.

The two animals that I have just told you about are very unlike to
man, but they are not more so than a multitude of others. The variety
in the shapes of animals and in the arrangements of their different
parts is almost endless; but, with all this variety, all are alike in
some things. All have organs to digest their food with, and organs to
circulate their blood. All have brains to think with, and nerves to use
in finding out about what is around them, and in making their muscles
work.

The variety in the contrivances in animals is so great, that when one
undertakes to study them, he continually finds something new. And one
thing is always true of the machinery in animals--it is perfect. It is
always exactly fitted to do just what it is made for. No machinery that
man ever made is equal to it.

Animals are suited in their shapes and arrangements to the way in
which they live. Some are made to fly. These have wings; and the wings
exhibit great variety, as you see if you look at the birds and insects
that are so busy in the air. Some animals are made to live in the
water; most of these have a broad tail and fins to swim with, but some
crawl, as the crab. Some float about, like the hydra, and some lie
still, like the oyster.

[Illustration]

[Sidenote: How different animals move.]

Some animals walk about on the ground. Man is the only animal that
walks about erect upon two feet. The beasts, you know, are four-footed.
The monkey is one of the most singular of beasts: he has neither feet
nor hands, but some things which are like both. With these he is more
of a climber than a walker. There are many small animals that walk on
many feet. And the snakes, without any feet, crawl along the ground.
Some animals hop, as the frog and toad. Some go by a long jump, as the
grasshopper, and the troublesome little flea, which is here represented
as magnified by the microscope. Very strong muscles must this animal
have to enable it to make such leaps with its long, crooked legs.

There is great variety in the coverings of animals. But I will tell you
about these in another chapter.

[Sidenote: The organs of some animals like those of man.]

Some animals are much more like man than others. The bones, and
muscles, and nerves, and heart, and brain of some are very much like
the same things in our bodies. This is true of many of the four-footed
animals. You can therefore know how the parts of the machinery inside
of you look by observing the different parts of animals at the
meat-market. In a calf’s head you can see how your brain looks. Its
lungs, or lights, as they are commonly called, are very much like
yours, and its heart is quite like your heart. And so of other parts.

[Sidenote: Variety of motion in man.]

[Sidenote: Has more muscles than any other animal.]

The more an animal moves, the more muscles he has to make his motions
with. Man has more variety of motion than any other animal, and so
has more muscles. God gives to each animal just the machinery that it
needs. Some have machinery that others do not have. Some have very
little, while others have a great deal. In our bodies there is a great
variety of machinery, for our busy minds want to know and to do very
many things.

The mind of man does more things with the hand than with any other part
of its machinery. I shall therefore now go on to tell you about the
hand, and then about those things that, in different animals, answer
somewhat in place of hands.

 _Questions._--What is said about the variety of machinery in the
 bodies of animals? What senses has the oyster? Why does he have these?
 What is said of his muscles? What of his brain and nerves? Why has
 not the oyster as much machinery in his body as there is in yours?
 What machinery has he? Tell all about the hydra. What is said about
 his brain? What are his arms made of? In what things are all animals
 alike? How does the machinery in animals compare with that made by
 man? What are the shapes and machinery of animals suited to? Tell
 about animals that fly--those that live in the water--those that walk.
 What is said about man? What is said about the monkey? Mention some
 animals that hop--some that make a long jump--those that crawl without
 feet. What animals are much like man, and in what? Why is there so
 great a variety of machinery in our bodies? What part of the machinery
 do our minds use most?




CHAPTER XXI.

THE HAND.


Man is the only animal that has a hand. The monkey has something like a
hand; but, if you watch him as he takes things, you will see that it is
a very awkward and bungling thing compared with your hand.

[Sidenote: The hand a set of machinery.]

The hand is often said to be a wonderful _instrument_. I would rather
say that it is a wonderful _set of machinery_. An instrument or tool is
commonly fitted to do only one thing, as a chisel, a spade, a saw, etc.
But how many and how different things can be done with the hand!

[Sidenote: It does both coarse and fine work.]

Let us look at some things that the hand can do. See the blacksmith
wielding the heavy hammer; how strongly his hand grasps the handle! See
how it is done. The fingers and thumb are bent by those large muscles
that are up in the arm. Now these same fingers, that grasp the hammer
so strongly, and do this heavy work, can be trained to do work of the
lightest and finest kind. They can take hold of the pen and write. They
can move the tool of the engraver, making those fine lines that you
sometimes see.

In the machines that man makes there is no such changing from coarse,
heavy work to that which is fine and delicate. A machine that does
heavy work does that only, and one that does fine work does that only.
No man ever made a machine that would pull a large rope one moment,
and the next pull a fine thread, and do the one just as well as the
other. But that wonderful machine, the hand, can do this. It can grasp
the rope firmly, and yet can take between its thumb and finger a thread
so fine that you can hardly see it.

[Sidenote: Variety of things done by the hand.]

But the difference in the work of the hand is not merely in coarseness
and fineness. It can do a great many different kinds of coarse work
and a great many different kinds of fine work. The hand works very
differently with different things. See how differently it manages a
rope, a hammer, a spade, a hoe, a knife and fork, etc. It takes hold
of them in different ways to work them. And then, as to fine work, how
differently it manages a pen, an engraver’s tool, a thread, a needle,
etc.

If you watch people as they do different things, you can get some
idea of the variety of the work that the hand can perform. See how
differently the fingers are continually placed as one is playing on an
instrument. You can see very well what a variety of shapes the hand
can be put into if you observe a deaf and dumb person talking with his
fingers. On the following page is a representation of the different
ways in which the letters are made.

[Sidenote: The most common things that it does wonderful.]

[Sidenote: Variety of shapes which the hand takes in the deaf and dumb
alphabet.]

[Illustration]

[Sidenote: A buttoning machine.]

The most common things that we do with our hands are really wonderful.
Watch one as he is buttoning up his coat: how easily his fingers
do it; and yet it is a wonderful performance. Suppose a man should
try to make a machine, shaped like the hand, that would do the same
thing, do you think that he would succeed? It would be very strange
if he did. Suppose, however, that, after working a long time, he did
really succeed, and that you saw his machine, with its fingers and
thumb, put a button through a button-hole in the same way that you do
it with your fingers. Do you think that it could manage buttons of
all sizes, large, middle-sized, and small? No; it could only button
those that are of one size. The different sized buttons would require
different machines; and, besides, a machine that could button up could
not unbutton. But your hand is a machine that, besides buttoning and
unbuttoning buttons of various sizes, is doing continually a great
variety of things that machines can not do. No machine can take up a
pen and write, or even move a stick about as your hand can. When some
ingenious man makes a machine that can do any one thing like what
the hand does, it excites our wonder, and we say, How curious! how
wonderful! how much like a hand it works!

[Sidenote: The hand an instrument of feeling.]

But the hand is not merely a machine that performs a great many
motions; it is also an instrument with which the mind feels things.
And what a delicate instrument it is for this purpose! How small are
the things that you sometimes feel with the point of the finger! As
you pass it over a smooth surface, the slightest roughness is felt. A
great deal of knowledge, as I told you in Chapter XIV., gets into your
mind through the tips of your fingers. Messages are going from them
continually by the nerves to the mind in the brain. The blind, I have
told you, read with their fingers. They pass them over raised letters,
and the nerves of the fingers tell the mind what the letters are, just
as the nerves of your eyes are now telling your mind what the letters
are in this book.

[Sidenote: The hand guided by the touch.]

Now, while the hand is performing its different motions as a machine,
it is generally very much guided by this sense of touch. If your hand
had no feeling in it, it would make awkward business even in such a
simple operation as buttoning; and it could not do it at all if you did
not look on all the time that it was doing it. Your eye-nerves would
have to take the place of your finger-nerves, as in the reading of the
blind the finger-nerves take the place of the eye-nerves. As it is, you
need not look at your fingers while they are buttoning, for they are
guided by the feeling that is in them.

There was once a woman who lost the use of one arm, and at the same
time lost all her feeling in the other. She had a baby to take care of.
She could hold it with the arm that had no feeling, because she could
work the muscles in that arm, but she could not do it without looking
at it all the time. If she looked away, the arm would stop holding the
baby and let it fall, for it could not feel that it was there. In her
case the eye-nerves had to keep watch in place of the arm-nerves that
could not feel.

[Sidenote: How it differs from machines made by man.]

You see that the hand is different from the machines that man makes
in two things--in the variety of things that it can do, and in the
connection which it has with the mind by the nerves. While the mind, by
the nerves, makes it do things, it knows by other nerves all the time
whether it is doing them right.

See, now, what are the parts of this wonderful set of machinery. There
are in the hand and arm thirty bones. There are about fifty muscles,
and all these are connected with the brain by nerves. It is by them
that the mind makes the muscles perform all the various motions of the
hand and fingers, and then there are other nerves that tell the mind
what is felt in any part of this machinery.

[Sidenote: How to get an idea of the variety of things which the hand
can do.]

I have mentioned in this chapter a few of the things that are done by
the hand, but there is no end to the things that can be done by this
set of machinery. You can get some idea of this in two ways--by moving
your hands and fingers about in all sorts of ways, and by thinking of
as many as you can of the different things that people, in work or
in play, do with their hands. And observe in how many more ways the
hand is useful than the foot is. The foot has but a few things to do
compared with the multitude of things done by the hand.

 _Questions._--What animal has something like a hand? How does it
 compare with your hand? Why would you call the hand a set of machinery
 rather than an instrument? What is said about the fingers doing heavy
 and light work? Tell about the rope and the thread. What is said
 about the different kinds of both coarse and fine work that the hand
 can do? What is said about playing on an instrument? What is said
 of the alphabet of the deaf and dumb? What is said about the common
 things done continually by the hand? What is said of the hand as
 an instrument for feeling? If your hand had no feeling, what would
 happen? Tell about the woman who lost the power of motion in one arm
 and feeling in the other. In what two things is the hand different
 from the machines made by man? What are the parts of the machinery
 of the hand? In what two ways can you get an idea of the variety of
 things that this machinery can do?




CHAPTER XXII.

WHAT ANIMALS USE FOR HANDS.


Though animals do not have hands, they have different parts which they
use to do some of the same things that we do with our hands. I will
tell you about some of these in this chapter.

[Illustration]

[Sidenote: How teeth can serve in place of hands.]

You see this dog dragging along a rope which he holds in his mouth. He
is making his teeth answer in place of hands. Dogs always do this when
they carry things. They can not carry them in any other way. You carry
a basket along in your hand, but the dog takes it between his teeth,
because he has no hand as you have.

I have told you, in another chapter, how the cow and the horse crop
the grass. They do it, you know, with their front teeth. They take up
almost any kind of food--a potato, an apple--with these teeth. These
teeth, then, answer for hands to the cow and horse. Their lips answer
also the same purpose in many cases. The horse gathers his oats into
his mouth with the lips. The lips are for hands to such animals in
another respect. They feel things with their lips just as we do with
the tips of our fingers.

[Sidenote: Cropping grass.]

[Sidenote: Anecdotes of horses.]

My horse once, in cropping some grass, took hold of some that was so
stout and so loose in the earth that he pulled it up by the roots. As
he ate it the dirt troubled him. He therefore knocked the grass several
times against the fence, holding it firmly in his teeth, and thus
got the dirt out, just as people do out of a mat when they strike it
against any thing. I once knew a horse that would lift a latch or shove
a bolt with his front teeth as readily as you would with your hand.
He would get out of the barnyard in this way. But this was at length
prevented by a very simple contrivance. A piece of iron was fixed in
such a manner at the end of the bolt that you could not shove the bolt
unless you raised the iron at the same time. Probably this puzzled the
horse’s brain. Even if he understood it, he could not manage the two
things together. I have heard about a horse that would take hold of a
pump-handle with his teeth and pump water into a trough when he wanted
to drink. This was in a pasture where there were several horses; and
what is very curious, the other horses, when they wanted to drink,
would, if they found the trough empty, tease this horse that knew how
to pump; they would get around him, and bite and kick him till he would
pump some water for them.

[Illustration]

[Sidenote: Monkeys great climbers.]

Monkeys have four things like hands. They are half way between hands
and feet. With these they are very skillful at climbing. There are some
kinds of monkeys, as the one represented here, that use their tails in
climbing as a sort of fifth hand.

[Sidenote: What cats use in place of hands.]

The cat uses for hands sometimes her paws, with their sharp claws,
sometimes her teeth, and sometimes both together. She climbs with her
claws. She catches things with them--mice, rats, or any thing that you
hold out for her to run after. She strikes with her paws, just as angry
children and men sometimes do with their hands. When the cat moves her
kittens from one place to another, she takes them up with her teeth by
the nape of the neck. There is no other way in which she can do it.
She can not walk on her hind feet and carry them with her fore paws.
It seems as if it would hurt a kitten to carry it in the way that she
does, but it does not.

[Illustration]

[Sidenote: The dormouse.]

When a squirrel nibbles a nut to make a hole in it, he holds it between
his two fore paws like hands. So also does the dormouse, which you see
here.

[Sidenote: The humming-bird’s bill.]

The bill of a bird is used as its hand. It gathers with it its food to
put into its crop. When you throw corn out to the hens, how fast they
pick it up, and send it down into their crops to be well soaked! The
humming-bird has a very long bill, and in it lies a long, slender, and
very delicate tongue. As he poises himself in the air before a flower,
his wings fluttering so quickly that you can not see them, he runs his
bill into the bottom of the flower where the honey is, and puts his
little long tongue into it.

[Illustration]

[Sidenote: The bill of a duck.]

The bill of the duck is made in a peculiar way. You know that it gets
its food under water in the mud. It can not see, therefore, what it
gets. It has to work altogether by feeling, and it has nerves in its
bill for this purpose. Here is a picture of its bill, showing the
nerves branching out on it. You see, too, a row of pointed things all
around the edge. They look like teeth, but they are not teeth. They
are used by the duck in finding its food. It manages in this way: it
thrusts its bill down, and as it takes it up it is full of mud. Now
mixed with the mud are things which the duck lives on. The nerves tell
the duck what is good, and it lets all the rest go out between the
prickles. It is a sort of sifting operation, the nerves in the sieve
taking good care that nothing good shall pass out.

[Illustration]

[Sidenote: The power of the elephant’s trunk and the variety of things
it can do.]

One of the most remarkable things used in place of a hand is the trunk
of the elephant. The variety of uses to which the elephant puts this
organ is very wonderful. It can strike very heavy blows with it. It
can wrench off branches of trees, or even pull up trees by the roots,
by winding its trunk around them to grasp them, as you see it is doing
here. It is its arm with which it carries its young. It is amusing
to see an old elephant carefully wind its trunk around a new-born
elephant, and carry it gently along.

[Illustration]

[Sidenote: The elephant’s trunk can do little things as well as great.]

But the elephant can also do some very little things with his trunk.
You see in this picture that there is a sort of finger at the very end
of the trunk. It is a very nimble finger, and with it this monstrous
animal can do a great variety of little things. He will take with it
little bits of bread, and other kinds of food that you hand to him,
and put them into his mouth. He will take up a piece of money from the
ground as easily as you can with your fingers. It is with this finger,
too, that he feels of things just as you do with your fingers. I once
saw an elephant take a whip with this fingered end of his trunk, and
use it as handily as a teamster, very much to the amusement of the
spectators.

The elephant can reach a considerable distance with his trunk. And
this is necessary, because he has so very short a neck. He could not
get at his food without his long trunk. Observe, too, how he can turn
this trunk about in every direction, and twist it about in every way.
It is really a wonderful piece of machinery. Cuvier, a great French
anatomist, says that there are over thirty thousand little muscles in
it. All this army of muscles receive their orders by nerves from the
mind in the brain, and how well they obey them!

[Sidenote: The elephant and the tailor.]

You see that there are two holes in the end of the trunk. Into these he
can suck water, and thus fill his trunk with it. Then he can turn the
end of his trunk into his mouth and let the water run down his throat.
But sometimes he uses the water in his trunk in another way; he blows
it out through his trunk with great force. He does this when he wants
to wash himself, directing his trunk in such a way that the water will
pour over him. He sometimes blows the water out in play, for even such
great animals have sports like children. Sometimes, too, he blows the
water on people that he does not like. You perhaps have read the story
of the tailor who pricked the trunk of an elephant with his needle. The
elephant, as he was passing, put his trunk into the shop window, hoping
that the tailor would give him something to eat. He was angry at being
pricked, and was determined to make the man sorry for doing such an
unkind act. As his keeper led him back past the same window, he poured
upon the tailor his trunk full of dirty water, which he had taken from
a puddle for this purpose.

 _Questions._--What is said about the dog? What answer for hands to the
 cow and the horse? Tell the anecdotes about horses. What does the cat
 use for hands, and how? What is said about the squirrel and dormouse?
 What is the bird’s hand? Tell about feeding the hens. Tell about the
 bill of the duck. What is told of the humming-bird? Mention some of
 the variety of uses to which the elephant can put his trunk. What is
 said about the finger on the end of it? Why does the elephant need
 so long a trunk? What is said about the muscles in it? How does the
 elephant drink? How does he wash himself? Tell about the tailor.




CHAPTER XXIII.

THE TOOLS OF ANIMALS.


[Sidenote: Man alone makes tools.]

Man is the only animal that makes tools to use. God has given him a
mind that can contrive tools, and he has also given him hands by which
he can use them. But he has given no such mind to other animals, and
therefore he has not given them hands. They do not know enough to make
tools, and so hands are not needed by them.

[Sidenote: Animals have some kinds of tools ready made.]

But, though other animals do not make tools, they have tools which they
use. God has given them ready made, as we may say, such tools as they
need. Let us look, then, at some of the tools that we find in different
animals.

[Illustration]

[Sidenote: The tail of a fish a sculling-oar.]

You see a man in the stern or hinder end of a small boat. He is
sculling, as it is called. He is making the boat go by working the oar
to the one side and the other. The oar is the tool or instrument by
which he does it. Now a fish has an instrument like this, by which he
goes through the water. His tail is like the sculling-oar that man has
contrived, and which he uses with his hands. If you watch the fish as
he goes through the water, you will see that he moves it to one side
and the other as the man does his oar; and while he goes ahead by means
of his tail, he uses his fins mostly as balancers to guide his motion.
He moves them rather gently except when he wants to change his course
quickly. When he is moving along fast, and wants to stop, he makes his
fins stand out straight on each side. This is just as rowers in a boat
use their oars when they want to stop the boat.

You see a man drilling a hole in a rock, and you hear the sound of the
tool as it goes click, click, all the while. The woodpecker has a drill
that works in the same way. With his bill he drills holes in the trees,
and you hear the sound of his tool as you do that of the tool of the
rock-blaster. It is a sort of knocking sound repeated many times very
quickly.

[Sidenote: The drill of the woodpecker.]

What do you think that the woodpecker drills holes for? It is to get
at worms and insects, which he eats. These are in the bark and wood of
dead trunks and branches of trees. The woodpecker knows this, and so
drills to find them. He does not drill into live bark and wood, for he
knows that there are generally no worms or insects there.

But the woodpecker’s instrument is something more than a drill. It
is a drill with another instrument inside of it. This instrument is
for pulling out the insect or worm that he finds in drilling. It is
shown in the following figure. It is a very long, straight tongue, and
ends in a bony thorn. This is, as you see, armed with sharp teeth
pointing backward, like the barbs of a fish-hook. Here are, then, two
instruments or tools together. And the way that the woodpecker manages
them is this: while he is drilling, the two parts of the bill are
closed together, making a good wedge-pointed drill, and at the same
time a snug case for the insect-catcher. As soon as he comes to an
insect he opens the drill, and pushes the barbed end of his long tongue
into the insect, and draws him into his mouth.

[Illustration]

[Sidenote: Tongue and claws of the woodpecker.]

As the woodpecker has to strike so hard in drilling, the bones of his
skull are made very heavy and strong. If this were not so, his drilling
would jar his brain too much. And another thing is to be observed:
while he is drilling he needs to stand very firmly. He must hold on
tightly to the tree, or he will slip as soon as he begins to drill. He
has, therefore, such claws as you see here to hold on with.

[Illustration]

[Sidenote: Digging tools of the elephant, the hen, and the pig.]

Some animals have tools to dig with. The elephant, you know, has long,
strong tusks. These he uses in digging up roots of different kinds from
the ground to eat. The hen digs in a small way with the claws of her
feet, to find grains and other kinds of food that happen to be mingled
with the earth. The pig can dig with its snout. It does not have much
use for this when shut up in its pen; but let it out, and see how it
will root, as we say. It does this to find things in the ground that
it can eat. When the pig runs wild, it roots to get acorns and other
things that become mixed up with the earth.

[Illustration]

[Sidenote: The mole’s plowing and digging tool.]

The mole has a similar contrivance to work in the earth with. This
animal also has heavy claws with which it plows and digs. Here is a
figure showing the bones of one of its fore paws. They are very heavy
and strong, and are worked by large muscles. The claws on its fingers,
you see, are very powerful. The mole does great execution with this
digging and plowing machine in making his tunnels and galleries in the
ground.

[Illustration]

[Sidenote: His habitation.]

The mole’s habitation is a singular affair. It consists of a large
circular room, with several galleries and passages. He makes all this
in this way. He first heaps a round hill or mound, pressing the earth
to make it very solid and firm; he then digs out his round room, where
he lives, and the passages. You can understand how he arranges these
by the figure. You can see that there are two circular galleries,
one above the other, and that these are connected together by five
passages. The circular room is connected with the upper gallery by
three passages. It also, you see, has a deep passage out from it at
the bottom, which opens into a passage that goes out from the lower
gallery; this passage, and another like it on the other side, lead
out into the open air. I suppose that the use of all these winding
passages is to enable the mole to keep out of the way of those who want
to catch it.

[Sidenote: How the woodchuck digs.]

The marmot, or woodchuck, as he is commonly called, is a great digger.
He digs his hole where he lives in this way. He loosens the dirt with
his fore paws, using his teeth also when the earth is very hard, or
where any roots happen to be in the way. He pushes back the dirt as he
loosens it. When he gets a considerable heap, what do you think that he
does with it? He shovels it out with his hinder feet, for they are so
shaped that he can use them as shovels. They have a strong skin between
the toes, so that when the toes are spread out the feet answer very
well to shovel dirt with.

[Illustration]

[Sidenote: How beavers build their cabins.]

Beavers are very singular animals. They do not live alone, but many of
them live together. They live in a sort of cabin, which they build with
branches of trees and mud, the mud answering for mortar. In gathering
the branches they often gnaw them off with their sharp and powerful
teeth. They are great diggers. They dig up the earth with their paws to
use in building their cabin. It is said that they use their flat tails
somewhat as masons do their trowels, spatting and smoothing the coating
of mud as they put it on. The tail, which you see is very stout,
answers another purpose. As the beaver builds the wall of the cabin,
when it gets rather high he props himself up on his tail as he works.

[Sidenote: The arrangement of the cabins and dams of beavers.]

The beavers build their cabin close to a stream of water, and their
entrance to it is below, so that they have to go down under water to
get to it; and a dam is built to keep the water over this entrance of
the proper height. If it were not for this, the door to the cabin might
get closed up with ice if the water should get low in the stream during
the winter. This dam the beavers build of branches of trees, and mud,
and stones. The stones are used to make the branches stay down. In the
cabin there are two rooms: in the upper one they live, and in the lower
one they stow their food. This is the arrangement of these animals for
the winter. In the summer they do not live together in companies, but
each one makes a burrow for itself. Every autumn they come together,
and unite in building their dams and cabins.

 _Questions._--Why does man make tools? Why do not other animals make
 them? Do they have tools? How is the swimming of a fish like sculling?
 What does the fish do with his fins? What is said about the bill of
 the woodpecker? What does he drill for? Tell about his tongue. What
 is said about the bones of his head? What about his claws? What is
 said about the digging of the elephant--of the hen--of the pig? How
 does the mole dig? What is said about his fore paws? Describe the
 arrangement of the mole’s habitation. How does the woodchuck dig? How
 does he shovel away the dirt that he digs? Tell about the beavers. In
 what two ways do they use their tails? What is the arrangement of the
 cabin? What is the dam for?




CHAPTER XXIV.

MORE ABOUT THE TOOLS OF ANIMALS.


[Sidenote: The saw-fly.]

Insects have various tools or instruments. There is a fly called the
saw-fly, because it really has a saw. It is a very nice one, much nicer
than any saw that man ever made. The fly uses the saw to make a place
to put its eggs, where they will be secure. And what is very curious,
it has a sort of glue with which it fastens the eggs in their place.

[Sidenote: The bee that cuts leaves so curiously.]

There are some insects that have cutting instruments, which will cut
as well as you can with scissors, if not better. There is a bee that
is remarkable in this respect. It has also a boring tool. Its nest is
commonly in old, half-decayed wood. It clears out a space in it with
its boring instrument; it then sets itself to work with its cutting
instrument to cut out pieces of leaves to line the nest and make the
cells in it. These are cut of different shapes, as they are needed, as
you may see in the next engraving. Below the leaves you see the nest
represented. It is opened by taking off some of the wood, and there you
see the lining of leaves. Great pains is taken by the bees in getting
each piece of leaf of the right shape to fit well, and the pieces are
very nicely fastened together.[A2]

[Footnote A2: A more full account of the operations of this little
animal you can find in a book published by Harper and brothers,
entitled Natural History, by Uncle Philip, which I recommend to my
young readers as a very interesting book about animals.]

There are some animals that have machinery for making things. All the
silk that is used in the world is made by worms. The silk-worm has a
regular set of machinery for spinning silk. It winds it up as it spins
it. Then man unwinds it, and makes a great variety of beautiful fabrics
with this silk thread.

[Illustration]

[Sidenote: The spinning machinery of the silk-worm and the spider.]

The spinning machinery of the spider is much finer than that of the
silk-worm. The thread which he spins is made up of a multitude of
threads, each one of these coming out from an exceedingly small hole in
the spider’s body. You know that there is a large number of fibres or
threads in a rope. So it is with the spider’s rope, for his thread that
you see, small as it is, is a rope to him. It is a rope that he walks
on like a rope-dancer; and you may sometimes see him swinging upon it.
Sometimes, too, he lets himself down from some height, spinning the
rope that holds him as he goes down. When he does this, his spinning
machine must work very briskly.

[Sidenote: Paper-making of the wasp.]

The wasp has a paper factory in him. He makes his paper out of fibres
of wood, which he picks off, I suppose, with his teeth, and gathers
them into a bundle. He makes this into a soft pulp in some way; then,
from this, he makes the paper with which he builds his nest. It is very
much, you know, like the common brown paper that man makes. The wasps
work in companies, and though each one can make but little paper, they
all together make their nest in a very little time. The pulp from which
they make their paper is very much like the pulp from which man makes
paper, and which you may see any time in the large tubs or vats of a
paper factory. This pulp is generally made from rags ground up fine,
but lately wood has been much used. Perhaps the hint was taken from the
wasps, who were the earliest paper-makers in the world.

[Sidenote: Teeth.]

Animals can not use knives and forks, as we do, in dividing up their
food. They therefore have instruments given them which do this very
well. Those long, sharp teeth that dogs, cats, tigers, etc., have,
answer to tear to pieces the flesh they eat, as thoroughly as we
can cut it up. We do not need such teeth, because with instruments
contrived by man’s mind for his hands to use we cut up the food
sufficiently.

[Sidenote: Pumps of some animals.]

I have told you that the elephant can draw up water into his trunk.
His trunk is therefore like the tube with which we suck up water or
any liquid. And it is like a pump too, for, as I shall show you in
Part Third, water is raised in the pump just as it is in a tube when
we suck through it. It is with a pump something like the elephant’s
that many insects get the honey from the flowers. This pump is called
a proboscis. It is with such an instrument that the musquito sucks
up your blood. At the end of his pump he has something with which he
pierces a hole in your skin, and then he pumps your blood up into his
stomach. In some insects the proboscis is very long, as you see here.
This is hollow, and with it the insect sucks up the honey from very
deep flowers, without being obliged to go to the bottom of them.

[Illustration]

[Sidenote: The proboscis in some insects.]

The proboscis is commonly coiled up when it is not in use. Here is the
proboscis of a butterfly coiled up. The two long things above it are
feelers.

[Illustration]

[Sidenote: The proboscis of the humming-bird.]

The tongue of the humming-bird is really a proboscis, and a very
curious one it is too. It has two tubes alongside of each other, like
the two barrels of a double-barreled gun. At the tip of the tongue
these tubes are a little separated, and their ends are shaped like
spoons. The honey is spooned up, as we may say, and then it is drawn
into the mouth through the long tubes of the tongue. But the bird
uses its tongue in another way. It catches insects with it, for it
lives on these as well as on honey. It does it in this way: the two
spoons grasp the insect like a pair of tongs, and the tongue, bending,
puts it into the bird’s mouth. The tongue, then, of the humming-bird
is not merely one instrument, but it contains several instruments
together--two pumps, two spoons, and a pair of tongs.

[Sidenote: Cat’s tongue a curry-comb.]

The tongue of a cat is a singular instrument. It is her curry-comb. For
this purpose it is rough, as you will find if you feel it. When she
cleans herself so industriously, she gets off the dirt and smooths her
coat just as the hostler cleans and smooths the horse’s coat with the
curry-comb. Her head she can not reach with her tongue, and so she has
to make her fore paws answer the purpose instead.

[Illustration]

[Sidenote: How the heron catches fish.]

There are some birds that live on fishes. They have instruments,
therefore, purposely for catching them. The heron is a bird of this
kind. He manages in this way: when the light is dim, either at dawn or
when there is moonlight, it is his time for going a fishing. He will
stand, as you see him here, in shallow water, so stiff and so still
that he might be mistaken for a stump of a tree or something else. He
is looking steadily and patiently down into the water, and the moment
a fish comes along, down goes his sharp bill, and off he flies to his
nest with his prey. The plumes of this singular bird are beautiful, and
are very highly prized as ornaments.

[Illustration]

There is one bird that lives chiefly on oysters. It has a bill,
therefore, with which it can open an oyster-shell as skillfully as an
oysterman can with his knife.

[Illustration]

[Sidenote: The tailor-bird.]

Some birds can sew very well with their beaks and feet. There is one
bird that sews so well that it is called the tailor bird. Here is its
nest hid in leaves which it has sewed together. It does this with
thread which it makes itself. It gets cotton from the cotton-plant, and
with its long, delicate bill and little feet, spins it into a thread.
It then pierces the holes through the leaves with its bill, and,
passing the thread through the holes, sews them together. I believe
that in getting the thread through the holes it uses both its bill and
its feet.

[Sidenote: The wingless bird.]

Here is a very strange-looking bird. It has no wings. It has a very
long bill, which it uses in gathering its food, which consists of
snails, insects, and worms. He uses his bill in another way. He often,
in resting, places the tip of his bill on the ground, and thus makes
the same use of his bill that an old man does of his cane when he
stands leaning upon it.

[Sidenote: The fish that shoots insects with a squirt-gun.]

There is a fish that has a singular instrument. It is a squirt-gun
for shooting insects. It can shoot them not only when they are still,
but when they are flying. It watches them as they are flying over the
water, and hits one of them, whenever it can get a chance, with a fine
stream of water from its little gun. The insect, stunned with the blow,
falls into the water, and the fish eats it.

I could give you a great many more examples of the different tools that
we find in animals, but these are sufficient. You can observe other
examples yourselves as you look at different animals.

 _Questions._--What is said about the saw-fly? Tell about the boring
 and cutting instruments of a certain kind of bee. What is said about
 silk-worms? What about spiders? What about wasps? Why do some animals
 have such long, sharp teeth? What kind of machine is an elephant’s
 trunk? What is the proboscis of an insect? Tell about the tongue of
 the humming-bird. How many instruments are there together in his
 tongue? What is said about the cat’s tongue? Tell about the heron.
 Tell about the bird that lives on oysters. What is told about the
 tailor-bird? Tell about the bird that has no wings. Tell about the
 fish that shoots insects with water.




CHAPTER XXV.

INSTRUMENTS OF DEFENSE AND ATTACK.


[Sidenote: Fighting instruments of animals.]

Animals have various instruments for defending themselves. Some have
claws, some horns, some hoofs, some spurs and beaks, some powerful
teeth, and some stings. These they use to defend themselves when
attacked.

[Sidenote: Why man has none of them.]

But man has none of these things. Why is this? It is because, as I have
told you about tools, with his mind he can contrive instruments of
defense, and with his hands he can use them. If men could not contrive
and use such things as spears, and swords, and guns, they would stand a
poor chance with some of the animals if obliged to contend with them.
A lion or tiger, you know, could tear the stoutest man in pieces if he
had nothing in his hands to defend himself.

It would be well if men would use the fighting instruments which
they make only for defending themselves. But they often use them in
attacking others, just as beasts do their weapons, and sometimes they
even use their hands, and teeth, and nails in the same way that beasts
do. Hands were made for useful work and innocent play; but they are
often used to strike with. Teeth are given to us to eat with; but
children, and even men sometimes, bite with them like an angry beast.
Nails are given us for various useful purposes, but I have known
children to use them in fighting as beasts do their claws and spurs.

[Illustration]

[Sidenote: Claw and beak of a cruel bird.]

The fighting instruments of some birds are very powerful. Here are a
claw and a beak of a very cruel bird. How fast this claw would hold the
victim, and how would this beak tear it in pieces! Very different are
they from the slender claws and the light beak of such birds as the
canary.

[Illustration]

[Sidenote: The vulture and the lamb.]

Here is a very rapacious bird, the vulture. He is on a rock, and has
under his feet a lamb which he found in the valley below. It had
perhaps wandered from the flock, and, as it was feeding, not thinking
of danger, the vulture espied it. Swiftly diving down, he caught it
with his strong claws and brought it up here. You see what a beak he
has to tear the lamb in pieces, that he may devour it.

[Illustration]

[Sidenote: The bill of the toucan.]

[Sidenote: How it trims its tail.]

The toucan, which you see here, has a larger bill than most other
birds. It uses it in crushing and tearing its food, which consists
of fruits, mice, and small birds. You see that its edges are toothed
somewhat like a saw, adapting it to tear in pieces the little animals
which this bird feeds on. But it can use its bill also for another
purpose. It is a powerful instrument of defense in fighting off the
animals that attack it. The toucan makes its nest in a hole of a tree,
which it digs out with its bill, if it does not readily find one
already made; and there it sits, keeping off all intruders with its big
beak. The mischievous monkeys are its worst enemies; but, if they get
a blow from that beak, they are very careful to keep out of the way of
it afterward. When the toucan sleeps, it manages to cover up this large
bill with its feathers, and so it looks as if it was nothing but a
great ball of feathers. There is one curious use which it makes of its
bill: it uses it to trim its tail, cutting its feathers as precisely as
a pair of scissors would. It takes great care in doing this, evidently
thinking that it is important to its beauty. It waits till its tail is
full grown before it begins to trim it.

[Sidenote: The cat’s paw and its cushions.]

The claws of the cat hold the rat very fast, while her long, sharp
teeth tear its flesh, and pull even its bones apart. If you see a cat
do this, you will get some idea of the way in which a lion or tiger
tears in pieces any animal. As your cat lies quietly purring in your
lap, look at her paws. The claws are all concealed, and the paw, with
its cushions, seems a very gentle, peaceable thing; but wake her up
and let her play with a string, and as she tries to catch it with her
paw, the claws now thrust out make it look like a powerful weapon, as
it really is in the eyes of rats and mice. There are muscles that work
those claws when the cat’s mind tells them to do it. When the claws are
not thrust out these muscles are quiet, but they are ever ready to act
when a message comes to them from the brain.

Did you ever think what the use is of those springy cushions in the
cat’s foot? They are to keep her from being jarred when she jumps down
from a considerable height, as she often does. Other animals that
jump have them. There is another use for these cushions. They are of
assistance to animals in catching their prey. If the cat had hard,
horny feet, as she went pattering around the rats and mice would take
the alarm and get out of the way.

[Sidenote: Horned animals.]

[Sidenote: The horns of the kudu.]

Some animals have horns which they use in attack and defense, and very
powerful weapons they are in some cases. Animals that have them often
defend themselves successfully against the attacks of lions, tigers,
etc., that are so powerful with their teeth and claws. They gore with
them. They can toss up quite a large animal into the air with them. In
this animal (called the koodoo) they are nearly three feet long. You
see that they have a beautiful spiral shape; indeed, the whole animal
is very handsome. It lives in South Africa, in woods at the side of
rivers. You might suppose that it would be rather difficult to get
about among the trees and bushes with such long horns; but the koodoo
manages to do this very well by throwing his head back and letting his
horns rest on his shoulders.

[Illustration]

[Illustration]

[Sidenote: The sword-fish.]

Here is a drawing of a sword-fish. Its sword is made of bone, and it
is so very strong that it has been known to be run through the bottom
of a ship. In the British Museum there is a piece of the bottom of a
ship with one of these swords run through it, and broken short off.
The fish must have died at once, for such a blow must have dashed his
brains out, as we say. This sword must be a powerful weapon of defense
or attack in the fights of this fish with other animals.

[Illustration]

[Sidenote: The saw-fish.]

Here is a fish that has a saw instead of a sword. The teeth, you see,
are on both sides of the saw. This fish is very large, and uses this
weapon with great effect in its fights with whales and other monsters
of the deep. It sometimes very foolishly pushes its saw into the bottom
of a ship, as the sword-fish does his sword.

[Illustration]

[Sidenote: The porcupine.]

[Sidenote: What the porcupine does with his quills.]

There are some animals that have very singular instruments of defense.
The porcupine is one. It is covered with two kinds of quills. Those
of one kind are long, slender, and curved. The others are short,
straight, very stout, and have a sharp point. Whenever the porcupine
is chased by any animal, and finds that he can not escape by running,
he stops and bristles up all his quills, as you see in the previous
engraving. He then backs, so that the short, sharp quills may stick
into the animal that pursues him. It has been said that he shoots his
quills at any one that attacks him. But this is not so. The error came
from the fact, that if any of the quills happen to be a little loose,
they fall out or stick into the flesh of his adversary.

[Illustration]

[Sidenote: The ink-bag of the cuttle-fish.]

The cuttle-fish has a curious way of escaping from those fishes that
attack him. He is a strangely-shaped animal, as you see. He has eight
long arms, and the little spots that you see on these are suckers, with
which he can stick to a rock, or can hold tightly any fish or shell
that he catches. This queer-looking animal has inside of him a bag
filled with a dark fluid like ink. This he uses as a means of defense
in this way: if he is chased by a fish larger than he is, he empties
his ink-bag in the water, and thus makes such a cloud that it blinds
his pursuer, and then the cuttle-fish very easily gets out of the way.

[Illustration]

[Sidenote: The torpedo.]

This singularly-formed fish, the torpedo, has two electrical
batteries--that is, machines for making electricity or lightning; and
it can give a shock when it pleases. If the fish is a large one, it
can give a shock powerful enough to knock a man down. It can disable,
of course, almost any fish that attempts to fight with him, and it
probably uses its battery also to overcome the animals that it devours.

[Illustration]

[Sidenote: The electric eel.]

Here is an eel, called the electrical eel, which has the same power,
and uses it for the same purposes. A sailor was once knocked down by a
shock from one of these eels, and it was some time before he recovered
his senses.

[Sidenote: The armor of turtles.]

The different kinds of turtles, while they have no great means of
attack, have most extraordinary means of defense. They have a complete
suit of thick, bony armor. Most kinds of turtles can draw in their
heads and limbs out of sight, and some can shut up their armor as tight
as a box, and so be secure against almost any attack. This is a picture
of the green turtle, which sometimes grows so large as to weigh as much
as three or four men. It is found in most of the islands of the East
and West Indies. Its flesh is considered a great luxury. The beautiful
tortoise-shell, from which combs are made, is obtained from this armor
of some kinds of turtles.

[Illustration]

 _Questions._--What are some of the instruments of defense and attack
 that animals have? Why has man none of these? What is the use which
 men ought to make of the weapons which they contrive? How are hands,
 teeth, and nails often improperly used? What are the fighting
 instruments of birds? Tell about the vulture. Tell the different uses
 of the large bill of the toucan. What are the weapons of the cat? What
 is said about the muscles of her claws? Of what use are the cushions
 on her feet? Tell about the koodoo. Tell about the sword-fish and
 about the saw-fish. What is said about the porcupine? What about the
 cuttle-fish? What about the torpedo and the electrical eel? What about
 the turtles?




CHAPTER XXVI.

WINGS.


[Sidenote: Bones of a bird’s wing like the bones of the arm and hand.]

Birds walk upon two legs as we do; but, instead of such hands as we
have, they have hands made for the purpose of lifting them up in the
air. The bones in a bird’s wing are very much like the bones in our
arms and hands; but they make a frame-work for the feathers of the wing
to spread out from. The bones that go out almost to the very end of the
wing are like the bones of our fingers, only they are much longer.

A bird’s wing, when it is stretched out, is a very large thing. It
needs to be large to do its work well. A bird could not fly with small
wings. You know that by trying very hard you jump up into the air a
very little way. But see, the bird goes up very easily as high as it
pleases, and does not seem to be tired. This is because its wings
spread out so broadly.

[Sidenote: Why wings are so large.]

The reason that birds need such large wings is this. As the bird rises
by pressing upon the air, it must press on a good deal of air to do
this. If it pressed upon only a little air it could not rise at all,
because the air gets out of the way so easily when it is pressed upon.
Swimming is flying in the water; and, as water when pressed does not
get out of the way as easily as air does, the tail and fins, with which
fishes swim, do not need to be as large as the wings of birds. For
the same reason, hands and feet answer very well for us to swim with,
though we can not fly with them. I shall tell you more particularly
about this in Part Third.

[Illustration]

[Sidenote: Wings of the condor.]

Here is a very large bird, the condor. To lift such a heavy body as he
has up into the air must require very large wings, and you see that he
has them.

[Sidenote: Muscles that work the wings of birds.]

Now, to work such broad wings, the bird has very stout muscles. You
know how the breast of a bird stands out. You see it here in the
condor. This is because the muscles with which it works its wings are
there. You can see that this is the reason when a bird is cooked. The
meat, you know, is very thick on the breast-bone--thicker than in any
other part of the body. If we had as large muscles on our breast-bones
we should look very strange. But we do not need such large muscles to
work our arms as birds do to work their wings.

[Sidenote: Why men can not fly.]

A man could not fly if he had wings fixed on to his arms. It has been
tried. I knew a man once to make something like wings for himself.
After he had made them, he went up on to the roof of a shed to try
them. He jumped off and flapped his wings, but down he came about as
soon as if he had no wings, and he was so much bruised that he was not
disposed to try the experiment again. Now why could he not fly? It
was not for want of wings. There the wings were, and he had made them
right, for he had shaped them like the wings of birds. They were large
enough and light enough; the difficulty was, that the muscles of his
arms were not strong enough to work them well. They were arm-muscles
and not wing-muscles. A man can not be like a bird merely by having
wings. He must have a bird’s flying muscles, or he can not fly.

[Illustration]

[Sidenote: Short wings.]

[Sidenote: The ostrich.]

Different birds have wings of different sizes. Those that fly very far
and swiftly have the largest wings. The wings of the hen are not large
enough to carry her far up into the air. The most that she can do is
to fly over a very high fence; and if her wings are partly cut off,
or cropped, as it is called, she can not even do that. There are some
birds that do not use their wings in flying. The ostrich, represented
on the previous page, is a great runner. He can not fly, but his wings
help him some in running.

In what way the wings act in raising birds and carrying them along I
will explain to you in Part Third, when I come to tell you about the
air.

[Sidenote: The beautiful motions of birds.]

[Sidenote: The swallow.]

How beautiful are the motions of many of the birds as they fly in the
air! How easily and gracefully their wings work! See that bird as it
goes up and up; and now see it as it makes a turn, and comes down so
swiftly on its outstretched wings, taking a beautiful sweep off at a
distance; and then up it goes again to come down, in the same way that
boys do when they travel up a long hill to slide down so swiftly on
their sleds. The swallow, as he has this fine sport, is, at the same
time, getting his living. As he skims along close to the ground or the
water, as represented here, quick as thought he catches any unlucky fly
that happens to be in his way.

[Illustration]

[Sidenote: The humming-bird.]

Especially beautiful are the motions of the humming-bird. See him as
he stops before some flower fluttering on his wings, or as he darts
with them from one flower to another. The muscles of his wings are very
nimble workmen. Our muscles can make no motions as quick as these.

[Sidenote: The structure of feathers.]

Did you ever examine a feather from a bird’s wing to see what a
curiously-made thing it is? The quill part of it is very strong, but,
at the same time, light. The plume or feather part is quite strong
also. It is made up of a great many very thin and delicate flat leaves,
as we may call them, which are locked together curiously by fine teeth
on their edges. If you separate them they soon come together again, and
are locked as fast as ever. You can see the teeth by which they hold on
to each other very well with a common microscope.

[Illustration]

[Sidenote: The delicacy of a bat’s wing.]

No wonder that the bat can fly so swiftly with such very broad and
light wings as he has. Did you ever observe how a bat’s wing is made?
It is a very curious and really beautiful thing. It is an exceedingly
fine, thin skin, on a frame-work of long, slender bones. These are
to it what sticks of whalebone are to an umbrella; and the wings can
be folded up somewhat as an umbrella is. This is done whenever the
bat is not flying. When it is on the ground it is very awkward in its
movements. It can not get a start to fly, and so it pushes itself along
with its hind feet, at the same time pulling by the hooks in its wings,
which it puts forward, first one and then the other, hooking them into
the ground. It never likes to get upon the ground, and it takes its
rest always, as you see represented on the previous page, by hanging
itself up by the two hooks in its wings.

[Illustration]

[Sidenote: The vampire bat.]

Here is a picture of the vampire bat, a native of South America, that
lives by sucking the blood of animals when they are asleep.

[Sidenote: Locust’s wing.]

Nothing is more delicate than the wings of insects. They are like
gauze; but they have a frame-work that makes them quite firm, just as
leaves are firm from the ribs that are in them. Here is a drawing of
the wing of a locust. But you can get no idea of the beauty of insects’
wings from such drawings. You must examine the wings themselves.
Even the wing of a common fly is very beautiful, so delicate is its
structure.

[Illustration]

[Illustration]

[Sidenote: Wing of the katydid.]

The wing of the katydid, as it is called, is peculiarly beautiful. Here
it is. You see that it is very delicate. Its color is a light green.
You see that rather thick three-cornered ridge at that part of the
wing which joins the body. There is a similar ridge on the wing of the
other side. In the space within this ridge there is a thin but strong
membrane or skin, so that it makes a kind of drum-head. It is the
rubbing together of these two drum-heads on the wings that makes the
noise. It is a queer sound. There is no music in it, but the katydids
seem to enjoy making it.

[Sidenote: How the katydid makes its noise.]

[Sidenote: How you can stop it.]

The katydid commonly makes three rubs at a time with its drum-heads. It
sounds somewhat as if it said Katy-did, and from this comes its name.
Sometimes there are only two rubs, and then you can fancy that it says
She did or She didn’t. The katydids, you know, are all quiet in the
daytime, but when evening comes they are very noisy. I have often been
amused to hear them as they begin just at dusk. One will begin, and
perhaps say its Katy-did several times; then another, on a neighboring
tree, will reply; and after a little time the whole tribe will be at
work. Each one appears to rest upon it after each rubbing, and so it
seems as if they answered each other from one tree and another. It is
curious that you can at once stop the noise of this insect by striking
the trunk of the tree on which he is with your hand.

 _Questions._--What are the bones in a bird’s wing like? What is said
 about the size of birds’ wings? What about the muscles that work them?
 Why can not a man fly if he makes wings for himself? What birds have
 the largest wings? What is said about the hen? What about the ostrich?
 What is said about the motions of birds in flying? What is said of the
 swallow? What of the humming-bird? Tell about the parts of a feather
 from a bird’s wing. What is said about the bat’s wings? What about its
 motions on the ground? How does it rest? What is said about the wings
 of insects? How does the katydid make its noise?




CHAPTER XXVII.

COVERINGS OF ANIMALS.


[Sidenote: The skin of man.]

The skin of man is his covering. It covers up like a case all the
machinery that I have told you is in his body--the bones, the muscles,
the nerves, the arteries, the veins, etc. It keeps them from being
injured. Besides this, how strange we should look if there were no skin
to cover up these parts from view.

The skin fits very nicely all parts of the body. On the hand it is like
a glove. See how well it fits. But observe that there are some places
where it is quite loose and full of wrinkles. It is so between the
thumb and forefinger, and around the joints of the fingers. In these
places it would not do to have it fit tight, because if it did you
could not move your thumb and fingers as freely as you do.

[Sidenote: Why it is different from the covering of animals.]

But the covering of man’s body is different from that of other animals.
It is, for the most part, bare skin, while most animals have either
hair, or feathers, or scales, or hard plates like armor, or shells.
Why is it that man has a covering that protects him so much less than
animals generally are protected by their coverings? It is because
he knows how to make such a covering as he needs to put on over his
skin. He can suit this to the degree of heat or cold. But animals know
nothing about this. No one ever saw an animal make clothes and put them
on. The Creator has given to each animal such covering or clothes as it
needs, ready-made. Let us look at this a little.

[Sidenote: Fur and hair.]

Animals in very cold climates need a very warm covering. They therefore
have a thick fur. But animals that live in warm countries have rather
thin hair instead of fur. The elephant has very little hair, and it is
only with the greatest care that he can be made to live through our
cold winters. The same is true of the monkey. If these animals had a
good covering of fur on their skins, the cold would not affect them in
this way.

[Sidenote: Blanketing the horse.]

The hair of the horse is rather thin. It is not like fur; and if the
horse’s master is kind, he is very careful to put a good blanket on him
whenever the cold makes it necessary. If he did not, the horse would
get chilled and take cold. The horse is not a native of cold countries,
but of such warm countries as South America and Arabia. There horses
run wild, and are always in large companies or herds.

[Sidenote: The fur of the cat.]

You know how thick the fur is on the cat. You can see how fine it is,
and how thickly the hairs stand together, if you blow on it so as to
separate the hairs. With this warm coat on her, she does not feel the
cold much. You see her often in cold weather out-of-doors, with her
feet gathered up under her to keep them warm. The monkey, with his thin
hair, could not do so. He has to be kept in a warm place in the winter.

[Sidenote: Feathers.]

The covering of birds, while it is such as to keep them warm, is very
light. If it were not so, they could not fly as well as they do.
Feathers are so light, that, when we wish to speak of any thing as
being very light, we say that it is as light as a feather. The downy
feathers on the breast of birds are especially light. The feathers of
the wings are different. They are made strong for the work of flying,
and at the same time they are quite light. How this is done I have told
you in the chapter before this.

[Sidenote: The oily feathers of the duck.]

Birds that go much into the water have an oil about their feathers
which keeps them from being soaked; for this reason, a duck, when it
comes out of the water, is almost as dry as before it went in. But if a
hen should go into the water in the same way, she would be wet through
her feathers to her skin. She was not made to go into the water, and so
has neither the oily feathers nor the webbed feet which are given to
the duck.

[Illustration]

[Sidenote: Why fishes have scales, and why they are oily.]

Why is it that fishes have scales? It is because they need a smooth
covering in order to get along easily in the water. A covering which is
rough, or which would soak in water, would be bad for them. The scales,
you know, lap over one upon another, as you see here in the herring.
They thus make quite a firm coat of mail, and at the same time do not
hinder the bending motions of the fish. If the same covering were all
in one, instead of being made up of many scales, it could not bend as
easily as it does now in turning its course in the water. The scales
are kept oiled, and this helps the fish to glide along swiftly. It is
this that makes the fish so slippery that it is difficult to hold it in
its struggles when it is first taken out of the water.

[Sidenote: How the hermit-crab guards his naked tail.]

I have told you, in another chapter, about the coverings of such
animals as lobsters and crabs. There is one kind of crab, called the
hermit-crab, that has no covering over his tail as he has over the
other parts of his body. It is therefore very liable to be injured
unless it is guarded in some way. And how do you think he guards it?
He just puts it into some shell that he finds, as you see here, and
then goes about, dragging it after him. As he grows the tail becomes
too large for the shell, and as soon as he feels the shell beginning
to pinch, he pulls his tail out and goes in search of another shell.
It is amusing to see him try one after another till he finds one that
fits well. Sometimes two of these crabs come to the same shell, and
then they have a fight about it. Very foolish must a crab feel when he
has driven another one off, and finds, after all, that the shell he has
been fighting for does not fit his tail.

[Illustration]

 _Questions._--What is said about our skin as a covering? What is said
 about its fitting well? Where are there wrinkles, and why? How is
 the covering of man’s body different from that of other animals, and
 why? What is said about animals in cold climates? What about those
 that live in warm countries? What about the elephant, the monkey, and
 the horse? What about the fur of the cat? What about the covering of
 birds? How are the feathers of the wing different from those of the
 breast, and why? Why are the feathers of some birds oily? Tell about
 the duck and the hen. Why do fishes have scales? Why are they kept
 oiled? Tell about the hermit-crab.




CHAPTER XXVIII.

BEAUTY OF THE COVERINGS OF ANIMALS.


[Sidenote: Beauty of some very small insects.]

There is great variety in the coverings of insects. In some the
covering is like burnished armor. The variety of colors is exceedingly
great, and in many they have a splendid brilliancy. Some of the
smallest insects, which most people never notice, are surpassingly
beautiful when examined with the microscope. It is with them in this
respect as it is with some of the smallest flowers. We know not how
much beauty there is all around us in the small things that God has
created till we take the microscope and look at them.

[Sidenote: Butterflies.]

The butterflies are among the most beautiful of insects. Almost every
variety of color is to be seen in them, and often many colors are seen
together, arranged in the most beautiful manner. You can not have
any idea of the great variety of their beauty unless you see some
collection of them in cases in some museum.

[Sidenote: Colors in shells.]

You have often admired the beauty of different shells. These are the
coverings of animals who lead a very quiet life in them, as I told you
about the oyster. Very splendid are the colors often on the inside of
these coverings, and sometimes on the outside also; and even when the
outside is not at all handsome when we get the shell from the water,
we often find that clearing off the outer coating with acid, or by
rubbing, will show us beautiful colors. Then, too, by grinding the
shell in different parts of it, different layers are seen of different
hues.

[Sidenote: Why God made shells so beautiful.]

The beauty of these coverings is of no use to the animals that live
in them. They have no eyes to see it. For what, then, is it intended?
It is for our gratification. The Creator strews beautiful things even
on the bottom of the ocean for us. If the coverings, or houses, as we
may call them, of all the animals that live there were as homely as
that of the oyster, they would be as useful and comfortable for them
as they are now, decked with their elegant colors. So far as they
are concerned, the beauty is thrown away. But men gather the shells,
and, while they admire them, they see in the beauty which the Creator
lavishes even in the depths of the sea the evidence of his abounding
goodness.

[Illustration]

The variety of beauty in the coverings of birds is very great. The
various colors are arranged in their plumage in every variety of
manner, and there are all shades of the colors, from the most brilliant
to the most delicate.

[Sidenote: The hoopoe.]

Commonly the greatest display in the plumage of birds is in the
delicate and downy feathers of the breast. But the bird that you see
here, the hoopoe, has its chief beauty in its crest, which is of an
orange color tipped with black. It is one of the most elegant of birds.


[Illustration]

[Sidenote: The beauty of the peacock.]

[Sidenote: Its pride.]

[Sidenote: Its disagreeable voice.]

In the peacock, a drawing of which you have here, there is a great
display of colors. The animal struts about, and, lifting its tail in
the air, spreads it like a fan, and seems to be very foolishly proud
of its beauty. Proud people generally have something disagreeable
about them, and so it is with the peacock. Its voice is so harsh and
screeching that no one wants it in his neighborhood.

[Illustration]

[Sidenote: A bird of paradise.]

[Sidenote: Its cleanliness.]

Birds of Paradise, as they are called, are exceedingly beautiful. There
are several kinds of them. The most common kind is the one pictured
here. I will give you an idea of its colors. Most of its body is a rich
brown; the throat is a golden green; the head is yellow; the long,
downy feathers that you see so abundant about the tail are of a soft
yellow color. This elegant bird is very careful to prevent the least
speck of dirt from getting on its plumage; and when it sits on a branch
of a tree it always faces the wind, so that its feathers may not be
ruffled.

[Sidenote: Humming-birds.]

There is, I think, in the humming-birds more variety of color than in
any other kind of birds. The colors are very brilliant, especially upon
the delicate feathers of their breasts; and they are shaded in the most
beautiful manner. I never saw a finer display of colors than I once saw
in a collection of humming-birds in a museum in Philadelphia. On the
following page is an engraving of a few varieties of these birds. You
can see what different shapes they have. They are alike only in their
long, slender bills. And when one sees a large collection of them,
with all their varied forms and colors, he is struck with admiration
and wonder.

[Illustration]

[Sidenote: Beauty of the furs of animals.]

Many of the furs of animals have much beauty, but there is no such
great variety of color as there is in the plumage of birds. As you blow
on a fine fur, and see how thickly its delicate fibres stand together,
you admire its richness. Each fibre of it is in itself a beautiful
thing.

[Sidenote: A caterpillar.]

We hardly know why it is that some animals that we dislike so much
should have so much beauty. Worms and caterpillars are disgusting to
us, and yet in many of them there is a great display of elegant colors.
While writing this, I see one crawling along on my coat-sleeve with its
numerous feet of curious shape. Its color is a brilliant green. On
its back stand up in a row three beautiful light yellow tufts. Behind
these, on a dark stripe, are two fleshy-looking round bunches, that are
a most brilliant red. On its side bristle out white hairs in bundles.
Its head is red, and from it extend forward dark colored but very
delicate feelers, in two bundles. I suppose they are feelers, because
they are shaped like the feelers of the butterfly, which you see on
page 118.

[Sidenote: Why such animals are often very beautiful.]

Now why is it that so much beauty is given to such animals? It does
not seem to be of any use. But this can not be so, for God has a use
for every thing that he makes. We are to remember that he can make a
thing beautiful as easily as he can make it homely. And it is just
this lesson, perhaps, that he means to teach us when he clothes such
creatures as worms and caterpillars in coverings of beautiful colors.
It is different with us. We try to make beautiful only those things
that we prize much. There are some things that it would be a foolish
waste of time for us to ornament. This is because we can do but little
in making things beautiful. But there is no end to God’s power in the
creation of beauty. He can, by the word of his power, make just as many
beautiful things as he pleases.

 _Questions._--What is said about the variety of colors in insects?
 What is said about butterflies? What about shells? Is their beauty of
 any use to the animals that live in them? Why is so much beauty put
 in them? What is said about the variety of colors in the coverings of
 birds? Tell about the hoopoe. Tell about the peacock and about the
 birds of Paradise. What is said about humming-birds? What is said of
 the furs of animals? What is said about worms and caterpillars? Why is
 so much beauty often given to such animals?




CHAPTER XXIX.

HOW MAN IS SUPERIOR TO ANIMALS.


[Sidenote: Man’s superiority in his mind.]

You see, from what I have told you, that man can do with his hands a
great variety of things that animals can not do. It has been said,
therefore, by some that the hand is the great thing that makes man
superior to animals. But this is not true. Of what use would the hand
be if there was not a mind in the head that knew how to use it? Suppose
that your cat had a hand instead of a paw, could she write with it? No;
the mind in her brain does not know enough for this. And so there are a
great many other things that we do with our hands which the cat would
not know enough to do with hands, if she had them.

So, then, it is not the hand merely that makes you superior to a cat,
but it is the mind that uses the hand. Your mind knows more than her
mind does, and wants to do more things than her mind ever dreams of.
Your mind, therefore, needs such an instrument as the hand to do these
things with, while a paw answers very well for the cat.

[Sidenote: Machinery of animals suited to their minds.]

[Sidenote: Machinery of the oyster, and of the cat and dog.]

God gives to every animal just such machinery as its mind can use. If
it knows a great deal, that is, if it has a great deal of mind, he
gives it a great deal of machinery; but if it has but little mind, he
gives it but little machinery; for if he gave it much, it would not
know how to work it. An oyster, as I have told you, knows but little as
it lies covered up in its shell. It knows how to do only a few things,
and so it has but little machinery. A dog or a cat knows a great deal
more than an oyster, and therefore it has paws, claws, teeth, etc., as
machinery for its mind to use. And as your mind knows so much more than
that of a dog or cat, it has that wonderful machine, the hand, to do
what it knows how to do.

The mind of man knows so much that it will contrive, when there are no
hands, to use other things in place of them. I once saw a man who had
no hands write, and do various other things very well with his toes.
You know that we generally use the right hand most, making the left
hand rather the helpmeet of the right. But when the right hand is lost
in any way, the mind sets the left to work to learn to do as the lost
one did. I once had to cut off the right arm of a very bright little
girl. But her busy mind did not stop working because it had lost the
best part of its machinery. In less than a fortnight I saw her sewing
with her left hand, fastening her work with a pin instead of holding it
as she used to do.

[Sidenote: Machinery in the face.]

There is some other machinery, besides the hand, that you have which
animals have not. It is the machinery that is in the face. I have told
you about this before, in the chapter on the muscles. A dog, when he
is pleased, looks up at you and wags his tail; but he can not laugh or
even smile; neither can he frown. Why? Because there is none of the
smiling, and laughing, and frowning machinery there. And so it is with
other animals.

[Sidenote: Variety of expression in the face.]

The variety of work that this machinery of expression does in the
face of man is very great, as you can see if you watch the varied
expressions of countenance in persons engaged in animated conversation.
But there is very little variety of expression in the face of an
animal. Now why is it that they have not the same muscles of expression
that we have? It is for the same reason that they have not hands. The
mind of man has a great many more thoughts and feelings than the mind
of an animal has. It needs, therefore, more machinery to express these
thoughts and feelings. The wagging of the dog’s tail answers very
well to express his simple feeling of pleasure; but you have so many
different pleasant thoughts and feelings that you need the varied play
of the muscles of the face to express them.

[Illustration]

[Sidenote: The wolf.]

[Sidenote: Why we have no snarling muscles.]

But some animals have certain muscles of expression in the face that
we have not. They are the snarling muscles, as they are called. They
draw up the upper lip on each side of the mouth in such a way as to
show the long, tearing teeth. In this wolf, about to devour a lamb
that he has caught, you see what a fierce and horrid expression these
muscles give to the face. Now the reason that we have no such muscles
is that we ought never to have snarling feelings. I have seen both
men and children look very bad when they were angry; but they would
have looked a great deal worse if they had snarling machinery in their
faces, as wolves, and cats, and dogs have in theirs.

[Sidenote: Why animals can not talk.]

There is some machinery that animals have just as we do, which they
can not use to do as many things as we can, because they do not know
how. I will give you an example, and then you will see what I mean. Did
you ever think why it is that animals can not talk? It is not because
they have not the machinery for talking. Many of them have tongues,
teeth, lips, etc. These are the things that we use to talk with, and
yet, though they have them, and have a voice that comes out from their
throats as ours does, they can not talk. Why is this? It is because
they do not know how to use these parts in talking, though they do know
how to use them in other things, as eating. The cow knows how to use
her teeth, and lips, and tongue in eating; but if she had a mind like
yours, she would use them in talking, and would not merely low.

The parrot, you know, does know how to talk, after a fashion. This
particular faculty is given to it, though it is rather a stupid bird
about other things. And, after all, its talking is a very awkward
imitation of the speech of man; it only says what it hears people say,
and that in a very bungling manner.

[Sidenote: Some things done better by some animals than by man.]

Though man has more machinery and can do more things than any other
animal, there are some things that some animals can do better than he
can. Man can climb, but he can not do it as well as a cat or a monkey.
He can swim, but not as well as a fish. The frog and the grasshopper
are better jumpers. The horse and the dog can run faster than he can.
He can not see as far as some birds. He has but two eyes, but the fly
has thousands of eyes, so that it can see in almost all directions at
once. He can not smell as well as the dog, who can follow the track of
his master by the scent left in his footsteps. He can mimic different
sounds, but the mocking-bird can beat him at this.

[Sidenote: Some animals can do things which man can not.]

But, besides all this, there are some things done by some animals that
man can not do at all. He can not fly like the birds and insects. He
can not go to roost like the birds. He can not walk along on the wall
over his head, as the fly does with the suckers on its feet.

Each animal is fitted to do just those things that it needs to do. For
example, the monkey needs to climb to get his living, and the Creator
has therefore made him so that he can climb very easily. For this
purpose, instead of having two hands and two feet, as we have, he has
four things shaped somewhat like hands, with which he can grasp the
limbs of trees. I might give you other examples, but you can find many
in the chapters on what animals use for hands, the tools of animals,
and their instruments of defense and attack.

 _Questions._--What is said about the hand? In what is man superior to
 animals? What is said about the machinery that God gives to different
 animals? Tell about the man that had no hands, and about the girl that
 had her arm cut off. What is said about the machinery in the face?
 What about the variety of work that this machinery does? Why do not
 animals have the same muscles of expression that man has? What muscles
 of expression do some animals have that man has not? Why does not man
 have them? Why can not animals talk? What is said about the parrot?
 Mention some things that some animals can do better than man. Mention
 some things done by animals that he can not do at all. What is every
 animal fitted to do?




CHAPTER XXX.

THE THINKING OF ANIMALS.


You saw in the last chapter that the great superiority of man over
other animals is in his mind. Let us look, now, at those things in
which their minds are like his, and those things in which they differ
from it.

[Sidenote: What animals think about.]

[Sidenote: The cat and the snow.]

I have already told you some things about the thinking of animals.
Some of them think a great deal. They think about what they see, and
hear, and feel very much as we do. I once had a cat that was born in
the spring, after the snow was all gone. In the beginning of the next
winter, the first snow that came was quite deep. It fell in the night.
It was, of course, a new sight to my cat. When she came out in the
morning, she looked at it with very curious eyes, just as we look at
any thing new. I suppose that she thought how clean, and white, and
pretty it was. After looking a little while, she poked the snow first
with one paw and then with the other several times, to see how it felt.
Then she gathered up between her paws as much as she could hold, and
threw it up in the air over her head; and then she ran swiftly all
around the yard, making the snow fly about like feathers wherever she
went. Now, though my cat could not talk, I could see by her actions
that her thoughts and feelings were very much such as children have
when they play in the snow.

[Sidenote: The sport of animals.]

Animals are much like children in their sports. We notice this very
often in dogs and cats. But the same thing is true of other animals.
It is amusing to see porpoises playing with each other in the water.
As they throw themselves up out of the water, and dive down again,
they chase each other as dogs and cats do. Some birds are very lively
in their sports. Insects have their sports also. The ants, industrious
as they generally are, have their times for play. They run races; they
wrestle; they carry each other on their backs in the same way that boys
do; they run one after another, and dodge each other behind stalks
of grass, as boys do behind trees and posts; they have scuffles and
mock-fights together. Very busy are their minds in their little brains
in these sports--as busy as your minds are in your sports.

[Illustration]

[Sidenote: Sober animals.]

[Sidenote: The Irishman and the owl.]

There are some animals that you never see engaged in sports. Their
thoughts seem to be always of the sober kind. You never see toads
and frogs play. They always look very grave. The owl is one of the
soberest-looking of animals. He looks as if he was considering
something. Here is a picture of one. A man once bought an owl,
supposing it to be a parrot. Some one asked him, a day or two after,
if his parrot talked yet. No, said he, but he keeps up a great
thinking, and I suppose he will speak his thoughts when he gets more
acquainted.

[Sidenote: The thinking of animals in taking care of their young.]

Animals think a great deal in taking care of their young. What care
the hen exercises over her brood of chickens! She has some of the same
thoughts and feelings of love that a mother has in taking care of her
child. And the bird, that has her little ones in the nest, has many
thoughts about them as she goes out to gather food, and then wings her
way back to put it into their open mouths.

It is interesting to watch canary-birds as they hatch and rear their
young. The male bird commonly insists upon it that the female shall
sit upon the nest all the time, while he takes upon himself the task
of feeding her. A male canary belonging to a friend of mine was
excessively particular on this point. He would not let his mate leave
the nest for a moment, and if she did he would fight her till she went
back. He was exceedingly busy in feeding her, and might certainly be
called a good provider.

A lady gave me a very interesting account of two orioles that built
their nest on a tree close by her father’s house. They came regularly
every year to the same spot, and the family always knew the very day
of their arrival by their joyous singing. They seemed to have the
same feelings of joy that people generally do when they return to a
much-loved home after a long absence. At one time one of their little
ones fell from the nest. The parents manifested their concern by flying
about in the most hurried, uneasy manner, and making mournful cries.
The family pitied the poor birds, and the little one was carefully
picked up, amid the flutterings and cries of the old birds, and was
replaced in the nest. And now the joy of the parent birds over their
restored one was expressed by a long and merry peal of song, as they
sat perched on the branch close by their little nestlings. At length
one of these orioles died, and the other left the nest and never more
returned.

[Sidenote: The spider.]

See that spider on his web. He is watching for flies. The mind in his
little brain thinks of every fly that comes buzzing along, and is
anxious that it should get its legs entangled in the snares that he has
woven. How glad he feels when he sees one caught by these snares! And
if he thinks that they are not strong enough to hold the fly, he runs
and quickly weaves some more threads about him. In the same way do all
animals that catch their prey think very busily while they are doing it.

[Sidenote: The thinking of animals in building their dwellings.]

Animals think much in building their dwellings. The bird searches for
what it can use in building its nest, and in doing this it thinks. The
beavers think as they build their dams and their houses. They think in
getting their materials, and also in arranging them, and in plastering
them together with mud.

 _Questions._--What is said about the thinking of animals? What is told
 about a cat? What is said about the sports of animals? Tell about the
 ants. Tell about the owl. What is said about animals taking care of
 their young? Tell about the canary-bird. Tell about the orioles. What
 is said about the spider? What is said about animals building their
 dwellings?




CHAPTER XXXI.

MORE ABOUT THE THINKING OF ANIMALS.


[Illustration]

[Sidenote: Stories about the shepherd’s dog.]

As animals think, they learn. Some learn more than others. The dog
learns a good deal; so do the monkey and the elephant. Some are good at
learning some particular things. The parrot learns to mimic talking,
though it is quite stupid about some other things. The mocking-bird
learns to imitate a great many different sounds. The shepherd’s dog,
seen here, though he does not know as much about most things as dogs
of some other kinds, understands particularly well how to take care
of sheep. If he is trained to this business, he will show great skill
in doing it. James Hogg, a Scotch poet, commonly called the Ettrick
Shepherd, relates many wonderful anecdotes of his dog, whom he called
Sirrah. He says that one night a large flock of lambs got out from
their fold and ran away among the hills. When the shepherd said,
“Sirrah, they’re a’ awa’!” the dog dashed off after them, and was soon
out of sight. The shepherd also, and his man, started off in pursuit.
They searched all night, but could find nothing of the dog or the
lambs; but in the morning they espied Sirrah standing guard at the
mouth of a gorge, or narrow pass, and anxiously looking for his master
to come. He had succeeded in finding all the scattered lambs, and here
they were in this gorge, into which he had driven them. It is told of
another dog of this kind that he would pick out any stray sheep from
the midst of a whole flock, and drive it back to the flock to which it
belonged. This dog was once observed trying to drive a flock over a
bridge which they were afraid to cross. He managed very well, and at
length succeeded in getting them over. It was amusing to see how he did
it. At one moment he was driving up some of the scattered ones, and the
next he was among the foremost, urging them forward. After a while he
made some of the foremost pass over, and then the whole flock followed.

[Sidenote: Animals build always the same way, and have no new fashions.]

Though animals think and learn, they do not have much originality. They
always do things very much in the same way. They do not keep contriving
some new ways of doing things as men do. Each kind of bird has its own
way of building a nest, and it is always the same way. The robins build
their nests now just as they did hundreds of years ago. The moles build
their tunneled habitations under ground year after year after the plan
that you see on page 112. And so of other animals. They have no new
fashions, and learn none from each other. But men, you know, are always
contriving new ways of building houses, or learning them from other men.

[Sidenote: What is done by instinct.]

Many of the things that animals know how to do they seem to know
either without learning, or without learning in the same way that we
learn. They are said to do such things by instinct; but what instinct
really is no one can tell. It is by this instinct that birds build
their nests, and bees their honeycombs, and beavers their dams and
huts. If these things were all contrived and thought out just as men
contrive houses, there would be some changes in the fashions of them,
and some improvements. Nearly all that we know about this instinct is
that some very nice things are done by it, without much thinking being
mixed up with it.

[Sidenote: Hens hatching duck’s eggs and sitting on pieces of chalk.]

This want of thinking sometimes leads to some queer mistakes. If you
put a duck’s eggs in a hen’s nest, she will sit on them as if they
were her own eggs, and after the ducks are hatched she will take care
of them, not seeming to know that, they are not chickens. One would
suppose that she would know, because they look so different from
chickens, and have bills so unlike theirs. But she does not seem to
think of this. And it is amusing to see her after the ducks get large
enough to go into the water. Off they run, and plunge in, and swim
about, while the old hen stands by the water, greatly alarmed lest they
should be drowned. She does not understand it; she does not know that
ducklings have an instinct different from chickens.

So, too, if the hen has rounded pieces of chalk put in her nest, she
will sit on them as if they were real eggs. Her instinct makes her sit;
but if she had much reason she would not sit on pieces of chalk. If she
thought much, she would find out what they were and quit her nest.

[Sidenote: The building instinct of the beaver.]

I have mentioned the building instinct of the beavers. An English
gentleman caught a young one and put him at first in a cage. After
a while he let him out in a room where there was a great variety of
things. As soon as he was let out he began to exercise his building
instinct. He gathered together whatever he could find, brushes,
baskets, boots, clothes, sticks, bits of coal, etc., and arranged them
as if to build a dam. Now, if he had his wits about him, as we should
say, he would have thought that there was no use in building a dam
where there is no water. It is from such mistakes as these that I have
mentioned that the instinct of animals is said to be blind.

It is plain that, while animals learn about things by their senses as
we do, they do not think nearly as much about what they learn, and this
is one reason that they do not know as much as we do. Even the wisest
of them, as the elephant and the dog, do not think over what they see
and hear very much.

[Sidenote: How the minds of animals differ from ours.]

But this is not all. There are some things that we understand about
which animals know nothing. They know nothing about what happened
before they were born, or what happens now in their lifetime away from
them in other places. They know nothing about what is to happen. They
know nothing about God and another world. You can not teach them any
thing about any such subjects. The reason is, that while their minds
are like ours in some things, they are different in other things.

You can see this great difference between your minds and the minds of
animals in one thing. You never would think of telling a story to a dog
or a cat as you would to a child, for you know that it would not be
understood.

The minds of animals are so much unlike ours that they do not know the
difference between right and wrong. Some suppose that a dog will not do
certain things because he knows that it is wrong to do them. But this
is not so. He is afraid to do what he would be whipped for. If he sees
a piece of meat on a table, he will not take it simply because he knows
his master would not like it, and not because he knows that it is wrong
to steal.

[Sidenote: What some wise men are foolish and wicked enough to say.]

I have told you that the mind uses the brain in thinking. Now some
learned men have been so foolish as to say that it is the brain itself
that does the thinking, just as if our brains, and the brains of all
animals, are only so many machines that make thoughts and feelings. Of
course, such men do not believe that, after death, the mind or soul
of man leaves the body and lives separate from it. They believe that
when the body dies there is an end to every thing. But God has told us
differently from this in his word, and he knows all about such things;
and those that pretend to know that it is not as God says it is, show
great wickedness as well as folly.

 _Questions._--What is said about the learning of animals? Tell about
 the shepherd’s dog. What is said about the contrivance of animals? Why
 do they have no new fashions? What is said about instinct? Tell about
 the hen’s hatching duck’s eggs. Tell about her sitting on pieces of
 chalk. What is told about the beaver? What is one reason that animals
 do not know as much as we do? What things do they know nothing about?
 Do they know the difference between right and wrong? What is said
 about the notions of some learned men?




CHAPTER XXXII.

WHAT SLEEP IS FOR.


[Sidenote: The machinery of the body needs seasons of rest for
repairing.]

All animals have their times for sleeping. It would not do for their
minds to use the machinery of the body all the time; if they did, the
machinery would soon wear out. The brain, and nerves, and muscles,
etc., are all repaired during sleep, so that they may be ready for use
again.

When you feel tired, it is because your mind has worn the machinery of
the body by using it. Now, when you lie down and sleep, the muscles
stop working; no messages pass through the nerves, and the brain is at
rest, because the mind pretty much stops thinking. But all this time
that you sleep the blood keeps circulating, and the breathing goes
on. What is this for? It is that the repairing of the machinery may
be done, so as to get the brain, and nerves, and muscles ready for
the work and the play of to-morrow. The repairing, you know, is all
done with the blood. This is the material for repairing as well as for
building, and therefore it must be circulating every where while you
are asleep, and the breathing must go on to keep the blood in good
order.

The repairing of the body is going on all the time while you are awake
as well as when you are asleep. But it goes on more briskly when the
machinery is not in use than when it is. So we may say that when you
are asleep the machinery is lying by for a full repair.

The same is true of the building of the body. More of it is done when
you are asleep than when you are awake. You are growing all the time,
but you grow most when you are asleep. And it is because the child
is growing that he needs more sleep than the adult does. The baby is
growing very fast, and so he sleeps a great deal of his time in the day
as well as in the night.

[Sidenote: The night the time for sleep.]

The night is given to us as the time to sleep. Then it is dark and
still, and we can go to sleep easily. Most animals sleep through the
night. You remember that I told you, in Chapter X., Part First, how
still the garden becomes as evening comes on. The flies, and bees, and
bugs, and birds have gone to rest, to get repaired for the next day;
so, too, have the larger animals. But it is curious that some animals
are busy in the night, and take their sleep in the day. It is so with
the owl and the bat. The katydid, you know, does not begin its noise
till evening. I suppose that it sleeps in the daytime.

Those people that stay up late at night, and do not get up early in
the morning, make a great mistake. They do not take the right time for
sleeping. They ought not to turn night into day, as bats, and owls, and
katydids do, for they are not made for it.

[Sidenote: Why merely keeping still will not answer.]

When you are tired and need sleep, the trouble is not merely in the
muscles. If it was, then keeping still merely, without sleeping, would
answer. But the brain and nerves need repairing as well as the muscles.
But as long as you are seeing, and hearing, and feeling, the nerves
are kept too busy to be repaired well; and as long as your mind keeps
thinking, the brain does not get thoroughly repaired. So, then, merely
keeping still will only repair the muscles; and sleep is needed to
repair the brain and the nerves.

[Sidenote: Dreaming.]

You know that when you dream very much you are not as much refreshed as
when you sleep soundly. What is the reason? It is because that when you
dream the mind is not wholly at rest, and works the brain, so that it
is not thoroughly repaired.

[Sidenote: The winter sleep of some animals.]

There is another kind of sleep into which some animals go. It is a
very long sleep. It lasts all winter. Great numbers of such animals as
frogs, bats, flies, and spiders, go into by-places in the fall to sleep
till spring comes. Many of the birds do this.

It is a deeper sleep than that which animals go into at night. It
is a different kind of sleep. In the sleep at night the blood keeps
moving, and the animal breathes; but in this winter sleep there is no
breathing, and the blood stops circulating. All is as still as death.
But there is life there, just as I told you, in Part First, there is
life in the seed, and in the trees that look so dead in winter. It is
life asleep. The warmth of spring wakes up again the life in these
animals, as it does the life in the trees. The blood then begins to
circulate in them, as the sap does in the trees, and they come out from
their hiding-places.

[Sidenote: The long sleep of a toad.]

I have said that this sleep which some animals go into lasts through
the winter. It may be made to last longer than this. Some frogs were
once kept in this winter sleep for over three years in an ice-house;
and then, on being brought out into the warm air, revived and hopped
about as lively as ever. We do not know how much longer they might have
been kept in this sleep. You remember that in Part First, Chapter XV.,
I told you about some seeds in which the life was asleep many hundred
years. And it may be that the life might be kept asleep in frogs and
other animals as long as this by steady cold. A toad was found lately
in the middle of a tree fast asleep. How he came there was not known,
but the wood had kept growing year after year, and as there were 67
rings outside of the toad, it was clear that he had been there 67
years. A long sleep it was, but he soon woke up and hopped about like
other toads.

[Sidenote: The winter sleep of some animals not perfectly sound.]

There are some kinds of animals that crawl into winter quarters in whom
life is not wholly asleep. The blood moves a little, and they once in a
while take a breath; and, besides, they now and then, when the weather
is quite warm, wake up enough to eat a little. Now it is curious that
such animals always lay up something to eat right alongside of them
when they go into their winter sleeping-places. But those who do not
wake up at all do not lay up any food, for it would not be used if they
did lay it up. They are governed by instinct in this matter.

The field-mouse lays up at its side nuts and grain when it goes into
its winter quarters, and when it is partly waked up by a warm day, eats
a little of his store. The bat does not lay up any thing, although he
wakes up when it is warm. He does not need to lay up any thing, because
the warmth that wakes him up wakes up also gnats and insects on which
he lives. He catches some of these, and then, as he finds himself going
to sleep again, he hangs himself up by his hooks as before. The marmot
or woodchuck does not wake up at all, but he always lays up some dried
grass in his hole. What is this for? He feeds on it when he first
wakes up in the spring, to get a little strength before he comes out
from his hole.

[Sidenote: How much life is asleep in the winter.]

How much life, then, is asleep in the winter in animals as well as in
plants! And how busy is life in its waking in the spring! While the
roots and seeds in the ground send up their shoots, and the sap again
circulates in the trees and shrubs, and the buds swell, multitudes of
animals are crawling out of their winter hiding-places into the warm,
balmy air. And when the leaves are fully out, and the flowers abound,
the earth swarms with the busy insects, and birds, and creeping things,
of which we saw none during the winter.

[Sidenote: Flight of birds south in winter.]

Some of the birds that we see in the spring have not been asleep
during the cold weather, but have spent their winter at the South, and
have now winged their way back to spend their summer with us. They go
back and forth in this way every year, guided by that wonderful and
mysterious thing, instinct. How this makes them take their flight at
the right time, and in the right direction, we do not understand.

 _Questions._--Why do animals need sleep? Why do you feel tired
 after work, or play, or study? Why does the blood circulate and the
 breathing go on in sleep? When is most of the repairing of the body
 done? How is it with its growth? What is said about night as the time
 for sleep? Mention some animals that sleep in the day and are awake
 in the night. What is said about people that turn night into day? Why
 would not merely keeping the body still, without sleeping, answer for
 our rest? What is said about dreaming? What is said of the winter
 sleep of some animals? Tell about the frogs and the toad. Why do some
 animals take food into their winter sleeping-places? Tell about the
 field-mouse, the bat, and the marmot. What is said about the waking up
 of life in the spring in animals and in plants? What is said about the
 birds?




    THE CHILD’S BOOK OF NATURE.

    FOR THE USE OF

    FAMILIES AND SCHOOLS.


    INTENDED TO AID MOTHERS AND TEACHERS IN TRAINING CHILDREN

    IN THE OBSERVATION OF NATURE.


    IN THREE PARTS.

    PART III.--AIR, WATER, HEAT, LIGHT, &c.


    BY WORTHINGTON HOOKER, M.D.,

    AUTHOR OF “FIRST BOOK IN CHEMISTRY,” “CHEMISTRY,”
    “NATURAL PHILOSOPHY,” “NATURAL HISTORY,” ETC.


    With Illustrations.


    NEW YORK:

    HARPER & BROTHERS, PUBLISHERS,
    FRANKLIN SQUARE.

    1882.




By Dr. WORTHINGTON HOOKER.


 THE CHILD’S BOOK OF NATURE. For the Use of Families and Schools;
 intended to aid Mothers and Teachers in training Children in the
 Observation of Nature. In three Parts. Illustrations. The Three Parts
 complete in one vol., Small 4to, Cloth, $1 00; Separately, Cloth, Part
 I., 40 cents; Parts II. and III., 44 cents each.

 PART I. PLANTS.--PART II. ANIMALS--PART III. AIR, WATER, HEAT, LIGHT,
 &c.


 FIRST BOOK IN CHEMISTRY. For the Use of Schools and Families. Revised
 Edition. Illustrations. Square 4to, Cloth, 44 cents.

 NATURAL HISTORY. For the Use of Schools and Families. Illustrated by
 nearly 300 Engravings. 12mo, Cloth, 90 cents.

 SCIENCE FOR THE SCHOOL AND FAMILY.

 PART I. NATURAL PHILOSOPHY. Illustrated by nearly 300 Engravings.
 12mo, Cloth, 90 cents.

 PART II. CHEMISTRY. Revised Edition. Illustrations. 12mo, Cloth, 90
 cents.

 PART III. MINERALOGY AND GEOLOGY. Illustrations. 12mo, Cloth, 90 cents.


Published by HARPER & BROTHERS, Franklin Square, N. Y.


☞ _Either of the above volumes will
 be sent by mail, postage prepaid, to any part of the United States or
 Canada, on receipt of the price._


Entered, according to Act of Congress, in the year one thousand eight
hundred and fifty-seven, by HARPER & BROTHERS, in the Clerk’s Office of
the District Court of the Southern District Court of New York.




PREFACE.


There is no obvious connection between the subjects now to be
considered and those which were presented in Parts First and Second.
But, after looking at what is of interest in the plants and animals
that live in air and water, it seems appropriate to pass to the
examination of the phenomena that air and water themselves furnish to
us. And then with these subjects are naturally associated the other
subjects contained in this Part--light, heat, electricity, etc.

Let me not be understood to say that the subjects treated in this Part
are entirely disconnected from those in the other two Parts. There are
many points of connection, resulting from the dependence of life upon
air, water, heat, etc., and also from the mechanical principles that
are brought into operation in the living machinery of both plants and
animals. Still, the connection is not of that obvious and intimate
character which we see between the subjects of Parts First and Second.

I have placed these subjects last in the Child’s Book of Nature
because they are not, for the most part, so easily understood as the
subjects contained in the other Parts. The mind of the learner needs
the training in observation and reasoning which it has in studying
the phenomena of plants and animals to enable it to grasp all of the
points which are here presented; and as in matter, so in style, I have
supposed an advance of mental power in the learner. I have relaxed a
little my strictness in simplicity. Indeed, I did so in a small degree
in the Second Part. I have been careful, however, not to allow myself
too much latitude in this respect, but have endeavored throughout
to make the advance both in style and matter to correspond with the
advance of mental capacity in the learner, and not go beyond it.

The subjects of this Part are those which are commonly ranged under
the general term Natural Philosophy. They are not presented either
formally or fully, but those points are selected which will interest a
young beginner and be intelligible to him. I have made it an object to
exclude all that are of a different character, for it is very important
that the young learner should not be discouraged with difficulties and
burdened with uninteresting matters at the outset.

It will be seen, however, that in making the selection alluded to, I
have, after all, given quite a full view of the fundamental parts of
the different subjects. The simple principles which form the basis of
Natural Philosophy are most of them very fully illustrated. And I can
not forbear remarking that many older scholars, who have pursued the
study in the more formal manner common in our schools, might find their
ideas rendered more clear and definite by looking at the simple views
here presented.

I would call the attention of the teacher to one feature in my mode
of developing scientific subjects to the young, which I deem to be of
great importance. I observe a natural gradation in their development,
beginning with the simplest views, and leading the learner gradually
to those that are more complex and less easily understood. Not only is
one thing given at a time, but each thing is put in its right place.
I will cite a single example. Take what is said about air. First, the
simple and single fact that it is a material thing is illustrated.
This is followed by noticing what it does when in motion. Then I show
how, by its resistance, birds and insects rise on the wing. Next I
pass to the pressure of the air, first illustrating, in a simple way,
the fact of its pressure in all directions, and then passing to show
how its pressure operates in the pump and in the barometer. Then come
illustrations of its pressure as exhibited in experiments with the
air-pump, the immense pressure which the body sustains from it, and the
manner in which it does this being especially noticed and explained.
Next follows the elasticity of the air when compressed, illustrated
by the operation of pop-guns, air-guns, etc. Then is illustrated the
pressure of the air in making balloons, bubbles, and other light things
rise in it. This leads naturally to the consideration of the rising of
smoke and the operation of chimneys. And then, lastly, in the latter
part of the book, the action of the attraction of gravitation upon the
air is noticed, thus ultimately arriving at the real cause of most of
the phenomena of the air’s pressure.

Another feature, to which I will barely allude, is a frequent reference
to analogies. Thus, for example, in giving the facts about air, I point
out the resemblance between flying and swimming, between the action of
compressed air and that of compressed steam, and of the gases produced
by burning powder, etc. This feature not only adds interest to the
various subjects, but makes the points in hand more clear, and gives a
wider range to the views of the learner.

It is the author’s intention to follow this with other books calculated
to carry forward the scholar in his observation of nature. Indeed, I
have already published two books, “First Book in Physiology” and “Human
Physiology,” by which the scholar can proceed with the study of the
subjects treated of in Part Second of this book; and as soon as I can
do so, I shall write some books for the purpose of enabling him to go
on with the study of the subjects treated of in the other Parts. The
whole together will constitute to some extent a series of books on the
sciences, adapted to the different degrees of advancement in the pupils.

It will be observed that in this Part there are many experiments
spoken of. These the teacher should try before the pupils so far as
is practicable. I have also made extensive use of common phenomena
as illustrations of the points presented. This will tend to form
in the scholar the habit of observing what is just around him--the
common things, so much overlooked in education--a habit which is a
never-failing source of information and enjoyment. And both teacher and
scholar, if they catch the spirit which I have endeavored to infuse
into the book, will from their own observation add to the illustrations
that I have given, and thus materially increase the interest of the
daily recitations.

  WORTHINGTON HOOKER.




CONTENTS.


  CHAPTER                                                        PAGE

        I. AIR                                                      9

       II. AIR IN MOTION                                           13

      III. FLYING AND SWIMMING                                     18

       IV. THE PRESSURE OF THE AIR                                 25

        V. PUMPS                                                   30

       VI. THE BAROMETER                                           36

      VII. THE AIR-PUMP                                            39

     VIII. GASES                                                   44

       IX. POWDER                                                  48

        X. POP-GUNS                                                53

       XI. BALLOONS AND BUBBLES                                    57

      XII. MORE ABOUT BALLOONS                                     63

     XIII. HEATED AIR                                              68

      XIV. CHIMNEYS                                                72

       XV. USES OF WATER                                           77

      XVI. WATER ALWAYS TRYING TO BE LEVEL                         81

     XVII. THE PRESSURE OF WATER                                   87

    XVIII. ATTRACTION IN SOLIDS AND FLUIDS                         92

      XIX. WATER IN THE AIR                                        97

       XX. CLOUDS                                                 101

      XXI. SNOW, FROST, AND ICE                                   105

     XXII. HEAT AND COLD                                          110

    XXIII. THE DIFFUSION OF HEAT                                  114

     XXIV. WHAT HEAT DOES                                         120

      XXV. STEAM                                                  125

     XXVI. LIGHT                                                  130

    XXVII. COLOR                                                  135

   XXVIII. MORE ABOUT COLOR                                       130

     XXIX. ELECTRICITY                                            144

      XXX. MORE ABOUT ELECTRICITY                                 150

     XXXI. MAGNETISM                                              155

    XXXII. GRAVITATION                                            159

   XXXIII. THE MOTION OF THE EARTH                                165

    XXXIV. FRICTION                                               172

     XXXV. CONCLUSION                                             176




THE

CHILD’S BOOK OF NATURE.




PART III.--AIR, WATER, HEAT, LIGHT, ETC.




CHAPTER I.

AIR.


[Sidenote: Air, a thing.]

We speak of a room having no furniture in it as being empty; but this
is not exactly so. There is one thing that it is full of up to its very
top. It is a thing that you can not see; but it is as really a thing as
the furniture that you can both see and feel. This thing is air.

If you take all your books out of a box in which you keep them, you
think of the box as having nothing in it; but it is full of air; and
when you shut it up and put it away, you put away a box full of air.
When the books were in it, it was full of books and air together; but
now it is full of air alone.

You see some boys playing foot-ball. What is it that they are kicking
about? It is an India-rubber ball, you will say. But is this all?
Is there not something else besides the India-rubber? Suppose that
you prick a hole in the ball. It is good for nothing now; but the
India-rubber is all there. What makes it good for nothing? It is
because the air escapes from the hole. The ball is of no use unless you
can keep it full of that thing that we call air; and in playing with
it, you kick about air locked up in the India-rubber.

[Sidenote: Life-preservers.]

You have heard of life-preservers, and perhaps you have seen them.
They are India-rubber bags that you can fill with air by blowing into
them. They are made of such a shape that they can be tied around the
body. When used in this way, a life-preserver will keep one from
sinking in water. But why? It is the air in it that does this. The air
is as really a thing as the water is, but it is a lighter thing, and
therefore a thing full of air will float on the water. If you kick a
foot-ball into the water, it will float, because it is full of that
light thing--air. But if you should prick a hole in it, and press out
the air, and then throw it into the water, it would sink. So, too,
the life-preserver would do no good if you tie it around you without
blowing it up. It is the air that you blow into it that buoys you up in
the water.

[Sidenote: Boats.]

Why does a boat float on the water? It is not because the boat itself
is lighter than the water is. It is commonly heavier, because there is
so much iron about it. The reason that it floats is that it is full of
air. Even a boat made entirely of iron will float for the same reason.
But if there should be a leak, so that the boat can be filled with
water, it will sink. So, too, it will sink if you put too much weight
in it.

[Sidenote: Life boats.]

[Sidenote: How life-boats are made.]

You have heard of life-boats. These are made in such a way that they
will not sink, even if they are filled with water. How do you think
that they are made to be so much lighter than other boats? It is not
because they are built of different materials. They are made of wood,
and are fastened together in every part with iron. Sometimes they are
made entirely of iron. But they are built in a different way from
common boats. They are made double, and in such a way that there are
chambers of air between the two parts. These chambers are air-tight.
If they were not they would do no good. If there were any opening into
these chambers, the water would go in and force out the air. The boat
would no longer be a life-boat. It would be of no more use than a
life-preserver with no air in it, or with water instead of air.

[Sidenote: We can feel air, but can not see it.]

You can not see air, although it is a thing; but you can sometimes feel
it. You can not feel it while it is still, as you can such things as
a table or water. You can only feel it when it is in motion. When the
wind blows upon you, it is air in motion that you feel. When there is
a gust of wind, as we say, the air comes against you just as a wave of
water does. When you fan yourself, you make the air strike upon your
face, and you feel it as you feel any thing else that strikes you, as
water or a stick.

The air is transparent, or clear, like glass; that is, it lets the
light come through it to your eyes. Sometimes glass is not clear,
and you can not see things plainly through it. So, also, the air is
sometimes not clear, as when there is dust flying in it, or when there
is a fog.

Though you can not see air, you can see what it does when it is in
motion. You can see it move the trees and other things. This I will
tell you about in the next chapter.

The air is a thing which is necessary to our life. If it be shut out in
any way from our lungs, great distress is immediately produced; and if
it be shut out only for a few minutes, death occurs. I have told you in
Part II., in the chapter on breathing, why it is that breathing air is
so necessary to life.

[Sidenote: Air necessary to life.]

Air is as necessary to the life of plants as it is to the life of
animals. In animals the air is used by lungs, but in plants it is used
by the leaves. This I have told you about in the chapter on the uses of
leaves, in Part I.

[Sidenote: Nothing can burn without air.]

Air is needed for another thing. Nothing can burn without air. It is
the air that makes wood, and coal, and oil, and gas burn when fire is
put to them.

The air that is all around the earth does not reach to the sun, and
moon, and stars. It extends about forty-five miles above the earth.
Beyond this there is no air. You will want to know how this was found
out, as no one has ever been so far from the earth. I will not explain
this to you now, for you are not old enough to understand it.

 _Questions._--What is a room full of when the furniture is all taken
 out? Tell about the box of books and about the foot-ball. What is said
 about life-preservers? Why does a boat float on the water? How are
 life-boats made? Can you see air? Can you feel it when it is still?
 What is wind? What is said about the transparency of air? What is said
 about its being necessary to the life of animals? What about its being
 necessary to the life of plants? What else is air needed for? How high
 does the air extend?




CHAPTER II.

AIR IN MOTION.


[Illustration]

[Sidenote: How a ship is moved along by air.]

The air, when it is in motion, does a great deal of work for us. It
pushes along the ships in the water. Perhaps you think that it hardly
sounds right to say that the air pushes the ships; but it really does
push them. The sails are large, broad handles for the air to press
against in pushing the vessels along in the water. On the preceding
page is a ship with many sails, and most of them are unfurled, or put
out for the breeze to press upon.

The air would push a vessel along to some extent, even if there were
no sails, by pressing or blowing against the body of the vessel; but,
unless the wind blew very strong, the air would not push it along very
fast in this way. And so sails are put up on masts, that more of the
air may get hold, as we may say, so as to press on the vessel.

[Illustration]

[Sidenote: A coat used as a sail.]

Sometimes the wind helps you along as you are walking. Now, if you
take hold of your coat, and spread it out wide, as you see this boy
is doing, it will be like a sail, and the wind will carry you along
faster, because there is more for the air to press upon. So, too, if
you have an umbrella open when the wind is blowing on your back, it
will be to you as the sail is to the ship. But if you are going against
the wind, the outspread coat and the open umbrella would prevent your
getting along fast.

[Sidenote: Trees blown by the wind.]

When a tree is bare, the wind scarcely moves its branches; but how it
bends when it is full of leaves and the wind blows strongly upon it! It
is then like a ship with its sails all unfurled; there is a great deal
for the air to press upon.

[Sidenote: Fast-moving air.]

Sometimes we say the wind blows very hard or very strong; this is when
the air moves very fast. The faster it moves, the more it will do. This
is so with other things. When you strike any thing very hard with a
stick, you do it by making the stick move fast. When there is only a
gentle breeze, that you can just feel, the air is moving very slowly;
it is like the gentle touch with the stick. But when the wind blows so
hard that you can scarcely stand up, the air is moving very fast.

[Sidenote: The bullet.]

If a bullet is tossed to you, it will not hurt you to catch it, because
it does not move very fast; but if a bullet shot from a gun should hit
your hand, it would wound it, and perhaps go through it. The reason is,
that the bullet moves so fast. The faster it moves, the more harm it
will do. So the air, when it moves very fast indeed, is apt, like the
bullet, to do harm.

[Sidenote: The locomotive.]

You have seen a locomotive backed up against a train of cars to be
hitched on. It does no damage, because it is backed up slowly. It only
gives a little jerk, you know, to the whole train. Now, if it moved
very fast, it would, when it came to the cars, break them to pieces. It
is for the same reason that fast-moving air roots up trees, blows down
houses, and drives ships on shore, dashing them against the rocks.

[Sidenote: Ship in a storm.]

When the wind blows hard, the sailor takes in some of his sails. The
vessel would go too fast if he left them all out, because there would
be so much for the air to press on. If the wind blows very hard indeed,
he takes down all the sails, fastening them very tightly, so that the
wind may not loosen them. Even with all the sails down the ship will
go quite fast enough, perhaps even too fast, pushed along by the wind
that strikes right upon it. Here is a ship in a storm. You see how the
sailors have tied up most of the sails. One of them has been torn from
its fastenings by the violence of the wind, and is in tatters.

[Illustration]

[Sidenote: How waves are made.]

The waves that you sometimes see rise so high are made by the striking
of the air upon the water; and the faster the air moves over the water,
the higher they rise. When the air is very still there is scarcely a
ripple, and the water looks like smooth glass; and you would hardly
think, as you look upon it, that such a light thing as air is could
whip it into such waves as you sometimes see.

The waves in the ocean are much higher than they are in a river. This
is because the wind blows over so much greater an extent of water in
the ocean.

[Sidenote: Small and great whirlwinds.]

You have heard of whirlwinds. In these the air moves in a whirling way
instead of straight forward. You sometimes see little whirlwinds in the
street; and as shavings and other light things are whirled about in
them, and are carried up in the air, you can imagine what damage large
whirlwinds can do, twisting up trees and tearing houses in pieces.

As you can not see the air, and it is a very light thing, you commonly
think of it as being almost nothing, and yet it does these great things
that I have mentioned. When we see this light thing raise the waves,
and move the heavy ships along so swiftly, we see that there is great
power in it.

 _Questions._--How does the air make a ship go? What is the need of
 sails? What is said about the air’s helping you along in walking? Why
 does the wind bend a tree so much that is covered with leaves? What is
 true about the air when the wind blows hard? Give the comparison about
 the stick, the bullet, and the locomotive. Why does the sailor take
 down some of his sails when the wind blows hard? What is said about
 waves? Why are they higher in an ocean than in a river? What is said
 about whirlwinds?




CHAPTER III.

FLYING AND SWIMMING.


You can jump off from the ground just a little way into the air, but
you can not fly into it, as the birds do. It is because you have no
wings. But how is it that the birds fly with their wings? They push
themselves up with them into the air. But perhaps you will say that
they do not have any thing to push against, for there is nothing but
air about them. Now it is the air itself that they push against. They
press down upon the air with their wings, just as you press with your
feet on the ground when you jump up; and as the bird, when it gets
once started, keeps working its wings, it goes up and up, pushing down
against the air each time that its wings are moved.

[Sidenote: How wings raise the birds in the air.]

[Sidenote: Why they are so large.]

It is necessary that birds should have very large wings to raise
themselves up thus in the air. If their wings were small, they would do
no good, because they would not press upon enough of the air. You can
move your hands in the same way that the bird does its wings, but you
can not raise yourself off from the ground. Why? Because your hands are
so small that they press only upon a little of the air. If your hands
were as broad for you as the wings of birds are for them, and you had
the proper muscles to work them, you could fly.

[Sidenote: Flying in water.]

[Sidenote: The kite.]

You can learn to fly, but it is in the water, and not in the air, that
you can do it. Swimming is really flying in water. The hands and feet
do for the swimmer what the wings do for the bird. He presses against
the water with his hands and feet in the same way that the bird does
against the air with its wings. Sometimes you see a bird dive down from
a great way up in the air, in the same way that the swimmer does in the
water. When it does this its wings are very still, and are folded close
to its side, as you see here in the kite; but when it goes up again it
works its wings up and down, just as the swimmer works his feet and
hands when he is rising in the water.

[Illustration]

[Sidenote: The tail of a fish like a sculling oar.]

Fishes swim chiefly with their tails. The tail is to a fish in the
water what wings are to a bird in the air. It acts like a sculling
oar in a boat, as I told you in Part Second, Chapter XXIII. The fins
are the balancers, while the tail works the fish forward by its quick
movements to one side and the other. You can see this very plainly if
you watch gold-fishes as you see them in a glass vessel.

[Sidenote: Why we can not fly in the air with our hands.]

Observe why it is that you can not fly with your hands in the air in
the same way that you can swim with them in the water. The water gives
way under your hands just as the air does, but the air gives way much
more easily than the water, because it is so much lighter. As the air
gets out of the way so easily, you can not fly in it unless you have
something very broad, so as to press down on a great deal of it at the
same time. To fly, you must have large wings instead of small hands.

You can see what a difference there is between hands and wings by
trying a little experiment. Move about your hand in the air. You do it
with perfect ease, and the air does not seem to resist the hand at all.
Now take a large palm-leaf fan and move that about. You can not do this
so easily as you moved your hand, unless you move it edgewise. Why is
this? Because it presses upon so much more air than your hand does,
and the resistance of so much air to the fan you can feel as you push
it out of the way. The fan takes hold, as we may say, of more air than
your hand does, and so does also the wing of a bird.

Did you ever think how large wings you would need to fly with? You
would have to press upon a great deal of air to carry your body up as
the birds do theirs. See how large the wings of a bird are, as they are
stretched out. They are both very long and very broad; and, besides,
the bird is not so large as he seems to be. You will see this if all
the feathers are stripped from its body. If this be done while the
wings are left whole, it will seem to you that it takes very large
wings to raise a very little body. You can see, then, that it would
require very large wings indeed to carry your body up in the air; and
still larger ones to carry up a man.

[Illustration]

[Sidenote: Wings of the swift.]

Here is a bird that flies so fast that it is called the swift. Its
wings, you see, are very long. You do not see how broad they are,
because they are not fully spread out in the figure.

[Illustration]

[Sidenote: Wings of the bat.]

But there is no animal that has a greater extent of wing than the bat,
unless it be some of the insects. This is the reason why it flies so
swiftly. You can see in this figure of the long-eared bat what a large
amount of air its wings press upon as it works them. The wings of
insects that fly very swiftly are very large in proportion to their
bodies. This you can see in the butterfly that flies so nimbly from
flower to flower. Those that fly rather slowly, as the bumble-bee, have
not very large wings.

[Illustration]

[Sidenote: The flying fish.]

I believe that there is only one kind of fish that can fly in the air.
It is represented here. You can see that the fins with which it flies
are not nearly so large as the wings of a bird of the same size would
be. It therefore can not fly very high or far. The highest that it was
ever known to fly is twenty feet, and usually it skims along only two
or three feet above the water. It does not go up into the air in the
same way that a bird does. It gets its upward start from the water, and
all that it does with its wing-like fins is to keep itself up, which
it sometimes does for perhaps five or six hundred feet. It takes this
flight in the air in fleeing from some large fish, and in this way
often escapes being devoured.

[Illustration]

[Sidenote: The flying squirrel.]

That beautiful animal, the flying squirrel, which you see here, has a
fold of skin extending from the fore leg to the hind leg on each side.
These folds answer somewhat as wings when they are stretched out. Very
graceful is the movement when the animal takes a long, flying sweep
from one tree to another. But he can not go up in the air as a bird
does, for the folds are not nearly so large as real wings, and so do
not press upon enough air to carry him up. He can only take the sweep
that I have mentioned.

[Sidenote: Shape of the wings of birds.]

[Sidenote: How they are used in flying.]

Observe the shape of the wings of birds. They are rather rounded on the
upper surface, and hollowed out underneath. They are shaped in this way
to make the flying easy. This I will explain to you. When raising the
wing, the air goes easily off from the rounded surface; but when it
is moved downward, the air can not get away easily from the hollowed
surface. The wing gets hold, as we may say, of some of the air, and,
pressing upon it, raises up the bird.

You can see how this is by moving an open umbrella in the air. You can
move it very easily if you push the outer rounded surface straight
forward against the air. This is because the air moves off from the
round surface of the umbrella as easily as it does from the upper
surface of the bird’s wing. But if you move the umbrella with the inner
hollowed surface against the air, you find it rather hard work. Why? It
is because the air is caught in the hollow of the umbrella as it is in
the hollow of the bird’s wing.

But this is not all. The bird, in raising its wing, does not move it
straight upward. It moves it in such a way that it rather cuts the air
with its forward edge. It does this to get it up with little resistance
from the air. But when it moves it downward, it wants to get as much
resistance from the air as it can, so it moves it straight down, and
not edgewise. You can see how this works by moving a palm-leaf fan
about in the air. Move it edgewise, and it goes very easily. This
is like the upward motion of the bird’s wing. But move it broadside
against the air, and you feel considerable resistance. That is, the air
resists the pressure of the fan, just as it resists the pressure of the
wing in the downward stroke.

[Sidenote: How the hands are used in swimming.]

The swimmer manages his hands in the water in the same way that the
bird does its wings in the air. When he raises his hands forward, he
does it edgewise; but when he presses them down, he moves them flat
against the water, so as to press upon as much water as he can.

 _Questions._--How is it that birds fly? Why do they have large wings?
 Why can you not fly? How is swimming like flying? What do fishes swim
 with? Why can not you fly in the air as well as swim in the water?
 Tell about the experiment with the fan. What is said about the size
 of birds’ wings? Tell about the bird called the swift. Tell about
 the bat. What is said about the flying fish? What about the flying
 squirrel? What is said of the shape of wings of birds? Give the
 comparison of the umbrella. Tell how the bird moves its wings upward
 and downward. Give the comparison of the fan. Give the comparison
 about swimming.




CHAPTER IV.

THE PRESSURE OF THE AIR.


[Sidenote: Air presses in wherever room is made for it.]

The air is every where. It is always ready to go where there is room
made for it. If we move a bureau or any thing out of a room, the air
fills up all the place where it stood. If you make a hole in any thing,
the air at once presses in to fill it up. Every crack and crevice is
filled with air.

You know how much water a sponge will hold. There are a great many
little cells or spaces in it that hold the water. Now squeeze the water
out, and as the water goes out of these cells, the air presses into
them and fills them up. So, too, if you have any liquid in a barrel,
just so fast as you draw it off, the air goes in to take its place.

[Illustration]

When you pull the handles of a pair of bellows apart, as represented
here, you make more space in the bellows, and the air rushes in to fill
up this space. It is the same with breathing. When you breathe in, or
draw a breath, as we say, the air goes down into your lungs through the
windpipe. This is because the chest is made larger as it heaves, and so
there is more room in the lungs; and the air goes in to fill up this
room, just as it does in the bellows.

When the air moves very fast, it is, you know, often very inconvenient,
and sometimes does much harm, as when houses are blown down, or
when ships are driven upon a rocky shore. But commonly it is very
accommodating. It is so easily moved out of the way that we do not
think of its being in the way at all. When you are walking, your body
pushes the air one way and the other, just as a man pushes persons to
the one side and the other when he goes through a crowd; and as the
people close up behind him as he moves along, so the air closes up
behind you as you walk through it. Now, if the crowd were facing him,
and should push against him, he would find it slow and hard work to
get through. So, when the wind blows strongly in your face, it is hard
walking, and you get along slowly, because the air presses against you
so hard.

[Sidenote: Air easily moved out of the way.]

[Sidenote: Why it is easier to walk in air than in water.]

The air is pushed out of the way easily because it is so light. This is
the reason that it is easier to walk in air than in water. The water,
as you wade in it, is pushed to the one side and the other, as the air
is when you walk in it; but it is not done so quickly and easily; and,
as it is easier to walk with the wind than against it, so it is easier,
in a running stream, to wade down stream than up against the current.

The air is so light a thing that you hardly think of it as pressing
on any thing; but it does press on every thing. Let us see what this
pressure does.

[Illustration]

See this glass tube. It is open at the end which is in the vessel of
water, but it is closed at the other end. It is full of water. But
water is apt to run down whenever it can get a chance to do it. Now
what makes it stay up in this tube? It is kept up by the air that
presses on the water in the vessel. If you could take away the air from
all about the vessel, the water in the tube would come down into the
vessel, because there would be nothing there to hold it up.

[Illustration]

[Sidenote: Experiments showing the pressure of the air.]

There is another way in which the water in the tube can be made to run
down into the vessel. Let a little hole be made in the top of the tube,
and the air will go into it, and make the water run down by pressing on
it. Even if it be only a pin-hole, the air, ready to go in every where,
will rush in, and down the water will all go. Now you can not very well
make a hole in the top of the tube, but you can try the experiment
in another way, so as to show what letting the air in will do. The
experiment is represented here. You take a glass tube open at both
ends. Covering one end tight with the palm of your hand, you fill the
tube with water. Then carefully put the other end under water, and hold
it as you see here. The water will stay up in the tube as long as you
keep the palm of your hand tight over the top of it; but loosen your
hand, and the air will go in and push down the water into the vessel.

You can see, from what I have told you, why a vent-hole is needed in
a barrel from which we draw any liquid. If the barrel be tapped, the
liquid will not run out, unless the air can get in above so as to press
it out. Till the vent-hole is made, the liquid will stay in, just as
the water stays up in the tube in the experiment. When we make the
vent-hole, we do the same to the barrel as we should do to the tube if
we should make a little hole in the top of it, or as you do to the tube
in the second experiment when you loosen your hand at the top of it to
let the air in.

[Illustration]

[Sidenote: Experiment showing that the air presses upward as much as
downward.]

This pressure of the air that I have told you about is in every
direction. It is upward and sideways as well as downward. This may be
shown by another experiment with a glass tube, as represented here.
Fill the tube with water, and then place carefully over its open end a
smooth slip of paper. You can then turn it over so that the open end
shall be downward, as seen in the figure, and the water will not run
out. What is the reason of this? It is because the pressure of the
air on the paper keeps the water in. We can often succeed with this
experiment with a wine-glass, or even a common tumbler, though we can
do it more easily with something that has a smaller opening.

[Sidenote: How bubbles of air rush in among the particles of a liquid.]

But you will ask, perhaps, this question: If it be the pressure of
the air that keeps the water from running out, what need is there of
the paper? The paper merely serves to keep the surface of the water
smooth and whole. If the paper were not there, the air would get in
between the parts of the water, and would rush up and force the water
out. For the same reason, if, instead of the small hole commonly made
in tapping, a large hole be made in the barrel, the liquid will run
out without any vent-hole. In this case, the air has a chance to work
itself in among the parts or particles[A3] of the liquid, and go in
bubbles up into the upper part of the barrel. A mere slip of paper put
on the hole would keep the liquid in, as in the case of the tube or the
wine-glass, and for the same reason. You know that there is a gurgling
sound made when a liquid is poured from a jug or a bottle. This is
caused by the bubbles of air that pass in while the liquid is coming
out.

 _Questions._--What is said about the air’s being every where? Tell
 about the sponge and the barrel. How is breathing like using a pair
 of bellows? What is said about the ease with which air is moved out
 of the way? Give the comparison about going through a crowd. Why is
 the air pushed out of the way so easily? What is said about wading in
 water? Tell about the experiment with the glass tube open at one end.
 Why is a vent-hole needed in a barrel when we want to draw off what is
 in it? Give the comparison to the experiments with the tube. How can
 you show that the air passes upward and sideways as well as downward?
 What does the paper do in this experiment? Why is there no need of a
 vent-hole when a large opening is made in a barrel? What makes the
 gurgling when a liquid is poured from a jug or a bottle?

[Footnote A3: I explain about the particles of water farther on, in the
16th and 17th chapters.]




CHAPTER V.

PUMPS.


[Sidenote: Explanation of the operation of sucking.]

You know that you can suck up water or any fluid through a straw or any
other tube. Now what is it that makes the water go up through the tube
into your mouth? I will tell you. When you put the tube into your mouth
it is full of air, and so long as the air is there the water will be
kept out; but when you suck you remove the air from the tube; and as
the air goes out, the water comes in, following right on after the air.
But what makes the water come in? Does it come in of itself because
there is room made for it? No. Water can not move itself. It must be
moved by something else. It is the air pressing on the water in the
vessel you are sucking from that pushes it up into the tube. You do not
really draw up the water. You get the air out of the way in the tube,
and then the air that is all the time pressing on the water in the
vessel pushes it up into your mouth. As soon as you stop sucking, and
take your mouth from the tube, the water that is in the tube will run
down into the vessel, because it is pressed down by the air that goes
in at the top of the tube.

You know that you have to suck commonly several times before the water
will reach your mouth. If the tube is a very large one, you suck a
great many times to get all the air out of it. At first you suck out a
little of the air in the tube, and the water is pushed up to take its
place; then you suck a little more out, and more water is pushed up,
and so on till it reaches the top of the tube. Here is a boy that has
partly filled his tube, and one more suck would bring the fluid to his
mouth.

[Illustration]

[Sidenote: How pumping is like sucking.]

You can now see how we pump up water out of a well or cistern. The
water is not drawn up, but it is pushed up just as it is in the tube
when you suck. When you work the handle, you do the same thing for the
pump that your mouth does for the tube in sucking any liquid; and when
the pump has not been worked for some time, you have to move the handle
up and down several times before the water comes, just as you have to
suck several times to fill a tube of any length with water.

[Sidenote: The operation of a pump explained.]

I will show by some figures how a pump operates. In the first figure
the hand is raising the handle, as you know we always do when we begin
to pump. The raising of the handle, you see, makes the piston, as it
is called, go down in the pump. Here it is going down through air, for
the water has not as yet got up as far as the piston. Now, if this
piston were a whole solid piece of wood, it would do no good, for it
would press the air down before it. But it is not solid. It has a hole
through it, and a sort of clapper or valve on the hole. Therefore, as
the piston goes down, the air pushes up the valve, and goes up through
the hole. You see that this air is shut in between the piston and the
water; and when the piston presses down, the only way for it to get
out of the way is to press upon that little door, and go up above the
piston.

[Illustration]

[Illustration]

[Sidenote: Explanation of the pump continued.]

Well, the handle is up. The next thing is to bring it down, as
represented in this picture. As the handle goes down, the piston goes
up, as you see. You remember that I told you that, as the piston was
going down, as seen in the first figure, some of the air went up
through the hole and got above the piston. Now this air can not get
down again, for the moment that the piston begins to move up, the air,
pressing on the valve, shuts it down. Now, as the piston goes up, there
is room made below it. How is this room filled? The air that is there,
as you see, rises up to fill it, and the water follows the air.

[Illustration]

The next moving of the piston down will carry it below all the air and
down into the water; and the water will go up through the little door,
just as the air has done before it. Then the moving of the piston up
will carry this water so high as to make it run out of the mouth of the
pump, as seen in this figure.

But there is a valve in the pump that I have said nothing about as yet.
This lower valve operates in this way: As the air or the water goes up
in the pump, the valve is pushed open by it, as you see in the second
figure and in the last one; but when the piston works down, as seen in
the first figure, this valve is shut, so that all the water that gets
above it is safe, and can not go back.

What is it that makes the air and the water rise in the pump? All that
gets above the piston is lifted up by the piston, as you see. But what
makes that rise which is below the piston? It is the pressure of the
air on the water in the well or cistern. This pushes up the water as
fast as there is room made for it.

If a cistern were full of water, and were air-tight also, you could
not pump up the water from it. You must have air there to push up the
water, or it will not come up when you make room for it by working the
pump.

[Sidenote: How the tongue in sucking acts like the piston of a pump.]

You see, then, that sucking and pumping are very much alike. In the
pump the piston makes the room for the air and the water to be pushed
up into. Now, when you suck, there is a piston that operates very much
as the piston of a pump does. Your tongue is the piston. See how this
is. When you suck through a tube held in water, you move your tongue
in such a way as to make a space in the mouth, and the air in the tube
is pushed in to fill up this space; and when the air is all pushed in,
the water is pushed in after it. Both are pushed in, as I have before
told you, by the air pressing on the water in the vessel. It is just
as water is pushed up into a squirt-gun when you draw the piston. This
piston does in the gun, when you draw it, the same thing that your
tongue does in your mouth when you move it in sucking. It makes space,
and the water is pushed into the gun, as it is into the mouth, to fill
up this space. The way in which the space is made in the mouth in
sucking is this. Before you begin to suck, the tongue fills the mouth,
so as to be up against its roof; but when you suck, you move the tongue
down from the roof of the mouth, and this makes a space there; and
whatever is in the tube, whether it be air or water, is pushed in to
fill this space.

[Sidenote: The common language about sucking and pumping incorrect.]

The common language, then, which is used about sucking and pumping is
not exactly correct. When we suck or pump, it seems to us as if the
liquid was drawn up, and so we use the word draw in regard to it. So,
too, we talk about the suction or drawing power. But, as I have showed
you, the liquid is pushed up instead of being drawn. All that the
piston in a pump does is to make room. It does not draw the water into
that room, but the pressure of the air forces it in. Whenever there is
any room made, the air is always ready either to go in itself or to
force something else in.

 _Questions._--Explain the operation of sucking up water through a
 tube. Why does the water in the tube run down into the vessel when you
 stop sucking and take your mouth away? Why is it that you commonly
 have to suck several times before the water reaches your mouth? How is
 pumping like sucking? What is shown by the first figure? What by the
 second? What by the third? Explain the operation of the lower valve of
 the pump. What makes the air and the water rise in the pump? Why would
 they not rise if the cistern were full and were air-tight? Explain how
 the tongue acts as a piston in sucking. Give the comparison about the
 squirt-gun. What is said about the language used about sucking and
 pumping?




CHAPTER VI.

THE BAROMETER.


Water can be raised in a pump only to a certain height, and the mistake
has sometimes been made of getting the pump so long that it would not
work. If it be more than about thirty-four feet from the water up to
the piston, the water can not be made to go up so high. What is the
reason? It is because the air, pressing on the surface of the water in
the cistern or well, will raise it only to the height of thirty-four
feet. It does not press hard enough to force it up any higher.

Suppose you had a glass tube over thirty-four feet long, with one end
open, and used it as represented in the first experiment in Chapter
IV., on page 27. The water would be kept up in it only the thirty-four
feet. The weight of a column of water of that height just balances the
pressure or weight of the air. Above that height in the tube there
would be a space in which there would not be any thing.

[Sidenote: Pressure of the air holds up water in the pump and mercury
in the barometer.]

Quicksilver or mercury, as perhaps you know, is a fluid like water, but
very much heavier. The pressure of the air, therefore, will hold up a
column of this not nearly as high as the column of water it holds up.
The column of mercury held up in a glass tube is not quite three feet
long, while that of water is thirty-four feet.

[Illustration]

You can now understand how the instrument called a barometer is made.
The object of this is to tell how heavy the air is, for the air is
heavier at some times than it is at others. A glass tube, open at one
end, and about three feet in length, is taken, and is filled with the
mercury. Then the open end is put into a dish of mercury, as seen in
the figure. There will be a space in the tube above the mercury, as
represented, for the air will support by its pressure a column of only
about thirty inches of mercury--six inches less than three feet, the
length of the tube. A scale, divided into inches, is added, as seen in
the figure; and the whole, neatly inclosed in a case, makes what we
call a barometer. This means a measurer of the pressure or weight of
the air.

[Sidenote: Barometer on a mountain.]

If the barometer be carried up a mountain, the mercury falls. Why is
this? It is because there is less height of air pressing on the mercury
than there is in the valley below, and of course it will not hold up so
long a column of mercury. In the valley, as I have told you in Chapter
I., the air is forty-five miles high; and if we carry the barometer
up a mountain three or four miles high, it will make a difference of
several inches in the height of the mercury in the tube.

[Sidenote: Air heavier at some times than at others.]

I have said that the air is heavier at some times than at others. In a
bright, clear day, the air is heavy, and then the mercury rises high,
or, rather, is pushed up high in the tube. But when it is cloudy and
rainy, the mercury falls, for the air is then lighter than usual,
though people often say at such a time how heavy the air is. The truth
is that we feel better when the air is clear and heavy, and so the air
seems light to us. On the contrary, we do not feel so well when it is
cloudy and the air is light.

[Sidenote: How the barometer is of use to the sailor.]

The barometer is of use to the sailor in telling him of threatened
storms; for when a storm is coming the air is light, and the mercury
in the barometer falls of course. The sailor, therefore, looks now
and then at his barometer, and if he at any time sees the mercury
fall suddenly, he gets ready for a storm, for he knows that it may
come on very rapidly. Dr. Arnot says that he was once on board of a
vessel where the captain was enabled to save his ship and all on board
because he took warning in season from his barometer. The sun had just
set, and, as the evening was very pleasant, all on board were enjoying
themselves in various ways. But the captain’s orders were given to take
down sails and prepare for a storm. All were astonished, for nobody
could see any signs of a storm. But the captain had seen the mercury
sink down very suddenly in his barometer, and he knew that trouble was
coming, and probably very soon. He hurried the men, therefore, but the
storm came before he was quite ready. It was a violent hurricane. But
the ship, though much damaged, was saved, and in the morning the wind
was still, and all were rejoicing in their deliverance. Probably, if
the captain had not looked at his barometer, the ship, with all on
board, would have been lost.

 _Questions._--How high can water be raised in a pump? Why can it not
 be raised higher? Tell about the experiment with a long glass tube.
 How high a column of mercury will the pressure of the air hold up?
 Explain the barometer. Explain the falling of the mercury when the
 barometer is carried up a mountain. How does the barometer show that
 the air is heavier at some times than it is at others? Why does the
 air seem light to us when it is heavy, and heavy when it is light? How
 is the barometer of use to the sailor? Tell about the storm as related
 by Dr. Arnot.




CHAPTER VII.

THE AIR-PUMP.


[Illustration]

[Sidenote: Description of the air-pump.]

A great many interesting experiments about the pressure of the air can
be tried with the air-pump, which you see represented here. This I will
describe, so that you may understand how it works. At _a_, _a_, are two
pump-barrels. In them are two pistons with valves, such as there are in
common pumps, except that they are made a great deal more nicely. These
pistons are worked by the handle, _b_. The frame-work, _e e_, that
holds the pump-barrels, is made very strong and firm, so that the pumps
may work true. There is a large plate, _f_, of metal, made very even
and smooth. At _c_ is a large glass vessel, close at the top, but open
at the bottom. Its edge is made very smooth, so that it may fit well on
the smooth plate. In the middle of the plate is a hole. This opens into
a passage which leads to the bottom of the two pump-barrels.

Now you can see how the instrument works. The two pump-barrels work in
the same way that a common water-pump does. With them the air is pumped
out of the glass vessel by the passage which leads to them from the
centre of the plate. By this means most of the air may be pumped out.
If we want to let the air in after pumping it out, we loosen the screw
_g_, for from the opening here there is a passage that leads to the
hole in the centre of the plate.

[Illustration]

[Sidenote: Experiments.]

[Sidenote: India-rubber ball.]

I will mention only a few of the experiments that may be tried with the
air-pump. If you put an India-rubber bag, or a foot-ball, with but a
little air in it, under the glass jar, when you begin to pump this will
begin to swell, as represented here; and if you pump for some time,
it will swell very much. The reason is this. As you take away the air
from around the ball, the air in the ball expands. If you then turn the
screw that lets the air into the jar, the ball will become small again,
because it is pressed upon by the air that is let in.

[Sidenote: Bubbles.]

So, too, if some soap-bubbles be put under the jar, when you pump out
the air they will swell; that is, the air shut up in the bubbles will
expand, because the pressure of the air around them is lessened.

[Sidenote: Shriveled apples.]

It is amusing to see a shriveled apple under the jar of the air-pump.
After pumping a little it will swell out, and appear like a plump,
fresh apple; but let in the air again, and the apple becomes shriveled
as before. This is owing to the air that is in the apple, for there
is air in every thing. There is air in our bodies; and if the air all
about us could be lessened very much, just as it is in the jar of the
air-pump, we should swell up like a puff-ball. It is the pressure of
the air all around us that keeps us just of the size we are.

[Illustration]

[Sidenote: The degree of pressure of the air.]

The air does more in pressing than you think for. As you move about in
it, it does not seem to press upon you at all; but it really presses
upon you very hard. It presses on you with the weight of about fifteen
pounds upon every square inch--that is, a space of this size. It would
take many such spaces to cover over your hand. The air really presses
upon your hand, as you hold it out flat, with more than the weight of a
hundred pounds. You can hardly believe this, and you will want to know
how it is that you do not feel this weight or pressure of the air. I
will tell you.

[Illustration]

[Sidenote: How this is borne.]

Hold out your hand flat in the air. You know that there is air
underneath your hand as well as over it. And this air underneath
presses up just as much as that above presses down. Now this is the
reason that you do not feel the pressure. If the air underneath your
hand could be taken away, you would feel the pressure of that which is
above. You would not only feel it, but you could not bear it. This we
can prove by the air-pump. Take the jar off from the plate, and then
put upon it a small glass vessel, open at both ends, such as you see
here. Place your hand over it tightly as represented, and then let some
one work the pump. Your hand will be pressed down into the cup so hard
after a little pumping that you will be glad enough to have the pump
stopped and the air let in.

Observe what is done to your hand by the pumping. Some of the air is
taken away from beneath your hand--that is all; and, this being done,
you feel now the pressure of the air above it, because there is no
pressure below to balance it.

[Illustration]

You can show the same in another way with this glass cup. Tie a piece
of bladder or India-rubber over one end of it, and then place this over
the hole in the plate of the air-pump. As you pump out the air, the
India-rubber will be pressed down into the cup by the air above, as
represented here.

[Illustration]

[Sidenote: How the boy’s sucker operates.]

The pressure of the air is very well shown by the sucker, as it is
called, with which boys sometimes amuse themselves. This sucker is a
round piece of leather, with a string fastened to the middle of it.
The leather is moistened, and then pressed evenly upon the smooth
surface of a stone, and now the stone can be raised, as you see here,
by the string, even if it be a pretty large one. But how is it that
the leather sticks so fast to the stone? It is by the pressure of the
air upon it. When you pull on the string, you raise the middle of the
leather a little from the stone, and this makes a little space there
in which there is no air. But all the leather around by its edge is
pressed very tight upon the stone by the air outside; and it is because
no air can get between the leather and the stone that the leather holds
on to it so well. If the leather is not pressed down exactly even, or
if there be some unevenness in the stone where the leather is put upon
it, the air will get in between the leather and the stone, and the
sucker will not operate.

[Sidenote: Suckers in the feet of flies.]

[Sidenote: The sucking-fish and the shark.]

Flies and other insects, that walk along so well on the ceiling and on
smooth glass, have suckers on their feet, that work very much in the
same way that the boy’s sucker does upon the stone. Some fishes have
suckers by which they can stick to rocks or any thing else. In this
case, it is water that makes the pressure instead of air. Here is the
drawing of a fish that has a sucker, or, rather, a set of suckers,
on the upper part of its head. With this it can adhere to any thing
very firmly. A singular story is told by a traveler about one of these
sucking-fishes. He saw a shark attempt to seize it, but the fish dodged
him, and then fastened itself to the shark’s back by its suckers. It so
happened that one of the sailors had tied to the fish a stick of wood
by a short line. The shark dashed off with this fish thus fastened to
him towing the stick of wood astern. He soon stopped, and, getting hold
of the cord, jerked the fish off, and then dove at it as before. The
fish dodged him again, and got hold with its suckers a second time,
and when last seen, the shark was struggling in vain to get rid of the
troublesome fellow.

[Illustration]

 _Questions._--Describe the air-pump, and tell how it works. Tell about
 the experiment with the India-rubber ball, with the soap-bubbles, and
 with the shriveled apple. How much is the pressure of the air on every
 square inch of your body? How much is it on your whole hand? Why do
 you not feel this pressure? What experiment with the air-pump makes
 this plain? Give the other experiment that shows the same thing in
 another way. How is the boy’s sucker made? Explain how it holds on
 to the stone. How do flies and other insects walk on ceilings and on
 glass? Tell about the sucking-fish.




CHAPTER VIII.

GASES.


[Sidenote: How the gas that we burn differs from air.]

I have told you about the air which we breathe, and which is all around
us; but there are other kinds of air. When we light the gas, what is it
that we set on fire? It is an air, or gas, as we call it, that comes
through the pipe to the burner. It is like the air which we breathe in
some respects. It is transparent; that is, you can see through it as
you can through common air. It moves about as easily as air does. But
it is different from the air in some things. It is lighter. The air has
no smell; but this gas has a very bad smell, as you may know when it
leaks out of the pipes. Air does not burn, but this gas does; and it is
curious that when it burns the bad smell is all gone.

Sometimes, when the gas leaks out of a pipe, it is very dangerous. If a
close room should get very full of it, and you should go into it with
a light, the gas in the room would all take fire and explode. Persons
have been killed in this way. It is well that the gas does smell badly,
for this lets us know when it leaks, so that we may guard against the
danger. We should let the gas out by opening doors and windows before
we bring a light in.

Persons have sometimes been killed by the gas in another way. You know
that there is in every gas-pipe something that you can turn so as to
shut the pipe, and thus keep the gas from coming out. Now persons
that do not know how the gas is managed have blown it out instead of
shutting it off. When this is done, the gas continues to come out
from the open pipe just as it did when it was burning, and gradually
fills the room; and if the person in the room goes to sleep, he will be
injured, and perhaps even killed by breathing the gas.

[Sidenote: Gas burning in a common fire.]

Did you ever think what flame is in a common wood or coal fire? It is
burning gas. The heat makes the gas out of the wood or coal, and this
takes fire just as the gas does that comes out of the burner when you
put a light to it. Sometimes you see a little stream of gas blowing out
of some part of a stick of wood, as gas blows out of a burner. It makes
quite a noise as it blows. If it is not on fire, you can set fire to it
just as you light the gas from a burner.

You see, then, that every fire-place, or grate, or stove is a gas
factory; but the gas is burned up as fast as it is made. The gas which
is made at the gas-works is made in such a way that it is not burned at
the time. It is made generally by heating coal, and is kept in large
reservoirs called gasometers. From them pipes branch out in the same
way that they do from water-works; and through these the gas goes all
about to different buildings, as water goes in aqueduct pipes; and as
the water comes out when you open the faucet, so does the gas when you
open the burner.

[Sidenote: Gas from burning charcoal.]

There is one gas that every one ought to know about, because many
persons have been killed by it from want of this knowledge. This gas
is made whenever charcoal is burned; and many deaths have occurred
from it by burning charcoal in small furnaces in close rooms. This is
often done to warm a room where there is no stove or fire-place. As the
charcoal burns slowly, the gas is made, and as it is heavier than air,
it spreads, at first, all over the floor. It gets higher and higher,
and at length reaches the mouths, of the persons in the room. If they
happen to be asleep, they are very apt to be killed by breathing the
gas; but if they are awake, they are conscious of the unpleasant
feelings the gas produces, and either go out into the air, or make some
noise which brings others to their relief.

[Sidenote: Gas sometimes in wells.]

This gas sometimes collects in wells, and kills men that go down into
them. Now there is one way by which we can always tell whether this gas
is in a well. If there be none there, we can lower a lighted candle
down to the water and it will not go out; but if there be any of this
gas there, the candle will go out as soon as it reaches it.

[Sidenote: The Grotto of the Dogs.]

There is in Italy a cave or grotto, which is called the Grotto of the
Dogs. The reason that this name was given to it will appear from what
I will tell you about it. This deadly gas is constantly made there in
some way that we do not understand. There is enough of it to reach
above a dog’s head, but it never gets up as high as a man’s head. While
a man, then, can breathe in the grotto perfectly well, a dog can not,
for he is down in the gas. A dog is kept there by some one living close
by, for the purpose of showing the effect on him to visitors. When he
is carried into the grotto, he soon falls down, and would die if he
were left there; but as they wish to keep him for exhibition to others,
they bring him out, and though he looks as if he were dead, dashing
some cold water on him and letting him breathe the fresh air soon
revive him.

[Sidenote: Gas breathed out from the lungs of animals.]

This gas is constantly breathed out from our lungs. It is the bad air
that I told you about in Chapter XX., Part First, that leaves take
from the lungs of animals, giving them back good air in return. You
see, then, how important it is that this gas shall get from us to the
leaves, and that the good gas from the leaves shall come freely into
our lungs. But this can not be done unless there is a free circulation
of the air. When people are shut up in a close room, a great deal of
this bad gas is made in a little while, and unless it is let out of
the room it does harm. It does not often kill any one at once, but it
injures the health; and the poisonous effect repeated every day, though
it be but a little, after a while may destroy life. A few persons are
killed quickly by this gas made from burning charcoal; but a great many
are killed slowly by it as it is given out from their lungs, because
they do not take enough pains to let it escape.

 _Questions._--In what things is the gas that we burn like air? In what
 does it differ from air? What is said about the smell of gas? In what
 two ways is life sometimes destroyed by gas? What is flame in a common
 wood or coal fire? Tell about the blowing we sometimes see in wood on
 the fire. What is said about the making of gas? What is said about the
 gas that comes from burning charcoal? How are people sometimes killed
 by it? What is said about its being in wells? Tell about the Grotto
 of the Dogs. What is said about the lungs giving out this gas? How
 does it often do harm when given out in this way? Which kills the most
 people, the gas that comes from burning charcoal or that which comes
 from people’s lungs?




CHAPTER IX.

POWDER.


Powder is a very harmless thing of itself. You can take it into your
hand and it will not hurt you; but touch it with fire, and it flashes
and explodes; and if there is much of it, it breaks every thing in
pieces all around it. When a magazine or a powder-mill blows up, there
is great destruction of every thing that is near.

You know that powder is used in blasting rocks. A hole is drilled and
the powder is put in. The blaster lights something which will burn very
slowly down to the powder, so that he may have time to get out of the
way. When the powder explodes, the rock is all broken apart into large
and small pieces.

[Sidenote: Powder produces its effects by changing into gas.]

Now, how is it that the powder does all this? It does it by changing
all at once into a great quantity of gas. That is all. When you look
at some powder, a heap of black grains, there is no gas in it; but the
moment that the fire touches it the powder is all gone. But how? Has
it become nothing? No; it is changed into something else. The black
powder is chiefly gas now. It is not all gas; if it were, you could not
see it. The smoke that you see is gas, with something else from the
burning powder mixed with it. This gas pushes out every way as soon as
it is made, so that it may get room, and it does it so quickly that it
carries every thing before it. It does the same that the air does when
it moves very quickly, only it moves a great deal more quickly, and so
does a great deal more.

[Sidenote: Boy blasting a log.]

This changing of powder into gas is done very quickly--as quick as a
flash, as we say. I knew a boy that once forgot this in using some
powder. He put some powder into a log of wood in order to split it;
but, instead of fixing a slow match, as men do in blasting rocks, he
touched off the powder, intending to get out of the way by running. But
the powder was, of course, too quick for him. It blew him over, burning
him a little, and frightening him a great deal.

[Sidenote: Bursting of a steam-engine.]

Sometimes water is changed into steam so quickly that it is like the
changing of powder into gas in its effects. This is seen in the way
that the boiler of a steam-engine is sometimes burst, as I will explain
to you. By carelessness, there is not a proper supply of water in it.
The fire will, of course, heat the boiler very hot. Now see what must
be the consequence when more water is let into it. The boiler, being so
very hot, changes this fresh supply of water all at once into steam,
and you know it takes but little water to make considerable steam, just
as it takes but little powder to make a great deal of gas. All this
steam so suddenly made acts precisely like the gas made by burning
powder. It must have room, and as there is not room enough for it in
the boiler, it must get out somewhere. The strong boiler can not hold
so much steam in, and it bursts.

But perhaps you will ask, Is it nothing but air or gas that throws the
ball out of the cannon, or the bullet out of the gun, so fast that
you can not see it? Can such a light, thin thing as gas drive a ball
through even thick beams of wood? Yes, the gas that the powder turns
into can do all this.

[Sidenote: How powder sends the ball out of a cannon.]

Now see the reason why the powder and the ball must be put into a
cannon to do this. If the powder should be laid upon the ground, with
the ball lying upon it, and fire should be touched to it, there would
not be much of a sound, and the ball would not be moved much. Why?
Because the gas that the powder turns into has a chance to escape
in every direction; but when the powder and the ball are put into a
cannon, the gas is all shut in, so that it can escape but one way,
instead of every way, as it did when the powder was on the ground. It
goes out of the mouth of the cannon, pushing the ball before it. It
does to the ball just what the air does to you when it blows against
you and pushes you along. It is a very hard blowing of gas that throws
out the ball so fast. The gas is made all at once, as I have before
told you, and it must find room somewhere. There is not room for it in
the cannon, and in going out to find room it throws the ball out.

If you should blow a little ball of paper from your mouth, it would not
go far. This is for the same reason that a ball laid upon a heap of
powder is not moved much when the powder is exploded. But put the paper
ball into a quill, and blow through it, and you can send it across a
room quite swiftly. The reason is, that the air which you blow out can
escape only through the quill, just as it is with the gas in the cannon.

When the gas comes out of the mouth of the cannon, it spreads out in
all directions, because it has room now. It is exactly as it is with
a crowd of people coming through a door; as fast as the crowd gets
through, it spreads out.

[Sidenote: How rocks are blasted.]

Observe, now, how rocks are rent in pieces in blasting. Quite a large
hole is drilled into the rock. It is like the space in the barrel of
a gun when it is done. This is filled with powder. Why, now, when the
powder explodes, does not the gas come out of this in the same way that
it does out of a cannon or a gun? Why, instead of this, does it break
the rock in pieces? It is because the hole is not large enough for so
much gas to come out. If we should put as little powder into it as we
do into a gun, the gas would all come out, as it does out of a gun,
without breaking the rock at all; but it is filled quite full of the
powder, and so a great deal of gas is made. If we should put as much
powder into a gun, it would burst like the rock, because there would
not be room enough for the escape of so much gas unless it went out
slowly, and that it will not do.

[Sidenote: How a rocket goes up in the air.]

[Sidenote: The going up of a rocket compared to jumping and flying.]

Powder is used in various ways. Some kinds of fire-works are made in
such a way that the powder does not burn all at once, as it does in
a gun or cannon. You know that when a rocket goes up, it is not sent
up by one blast of the powder, as a ball is sent out of a gun. The
powder is placed in the tail of the rocket, which is so made that the
powder burns all the time that it is going up, the last of it making
an explosion high up in the air, scattering the sparks which fall in
so beautiful a shower. Now, did you ever think just how it is that the
rocket is made to go up so swiftly? It is the gas of the burning powder
which streams out from its tail all the time that makes it go up. This
pushes down against the air, and it is the resistance of the air to
this that raises the rocket. It is just as the resistance of the air
to the downward stroke of the bird’s wings raises the bird. It is also
just as, in jumping up off the ground, the resistance of the ground to
your feet makes you go up. You press with your feet on the ground, and
so the rocket presses with its gas on the air; and so long as gas keeps
coming out of its tail to press on the air, the rocket keeps going up.
When the gas is exhausted the rocket comes down.

[Illustration]

You have sometimes seen whirling wheels in fire-works. The powder in
the wheel is arranged as you see here; and as it burns, the resistance
of the air to the gas makes the wheel fly around, for the same reason
that it makes the rocket go up into the air.

 _Questions._--What is said about powder when no fire touches it? How
 is the power of burning powder shown? How are its effects produced?
 What is the smoke from powder? What is said about the quickness with
 which powder changes into gas? Tell about the boy that split a log of
 wood with powder. Give the comparison about steam. How is it that the
 gas made by burning powder makes a ball go out of a cannon or gun so
 swiftly? Give the comparison of the quill and the ball of paper. Why
 does the gas from a cannon spread after it gets out? Tell what is said
 about blasting rocks. Explain how a rocket is made to go up in the
 air. What is the comparison about flying and about jumping? What is
 said about the whirling wheel in fire-works?




CHAPTER X.

POP-GUNS.


[Sidenote: Operation of the pop-gun explained.]

Every boy and girl has played with a pop-gun, but did you ever think
how it works? I will tell you about this.

You know that the cork does not fly out till the rod is pushed a
considerable way down into the tube or barrel of the gun, and then it
flies out all at once with a popping noise. What makes it fly out? It
is not the rod alone, for it does not touch the cork. It is the air
that is between the rod and the cork that gives it the push that makes
it fly out, and it gives so quick a push as to make the pop.

I will explain this to you a little more particularly. When you put the
cork into the end of the gun, the barrel is full of air. Now, if the
cork were not in, as you pushed the rod the air would all go out before
it; but the cork in the end keeps all the air in. As you push the rod,
you crowd the air into a smaller space. If you push the rod half way,
then the same air that filled the whole gun has half the room that it
had before you pushed the rod. Now, when air is pressed or crowded in
this way, it tries, as we may say, to get away from the pressure. In
doing this, it presses on the cork; but the cork sticks fast in the
mouth of the gun till the pressure is enough to push it out, and when
it gives way it does it all at once, and so makes the popping sound. It
is as if the air gave the cork a sudden kick, and out it flies.

[Sidenote: Explanation of the potato and quill pop-gun.]

When I was a boy, we had no such nice pop-guns as boys now have. We had
to make them ourselves. We would sometimes make the tube or barrel part
out of elder, which, you know, has a large pith. We would sometimes
take a quill for a barrel. To this we would fit a stick as a rod. We
would then punch each end of the quill through a thin slice of raw
potato. This would, of course, leave a round piece of potato in each
end. Now, by pushing the rod quickly through the quill, the piece of
potato in the farther end would fly out with a pop, in the same way
that a cork does from the pop-guns nowadays. You see how this is done.
The air which is shut up in the quill between the two pieces of potato
is crowded into a small space when the stick is pushed in. It tries to
escape from this pressure, and so presses on the potato at the farther
end. This gives way all at once and flies out. But why must we have the
potato in both ends? It would not be necessary if the stick could be
made to fit the quill exactly; but it can not, and so there would be a
leaking of air by it if we should have the potato in only one end. The
piece of potato in the end where you put in the stick prevents this
leaking of air. It makes, in fact, a tight piston for the stick to work.

It is the springiness of the air that makes the pop-gun work. This you
can see by some experiments. Fill your pop-gun with water, and see how
different from the air it will act. The moment that you push the rod,
the cork will be pushed out without any popping, and the water will run
out. What is the reason of this? It is because you can not crowd the
water, as you do the air, into any smaller room. It moves straight
along, and pushes out the cork.

[Sidenote: Experiments with the pop-gun.]

As the water can not be crowded into any smaller space, it has no
spring. But the air can be shrunk up, as we may say, by pressure, and
it is ready to swell out again whenever it can have a fair chance to do
so; and the harder you press it, the greater is this springiness. You
can see that this is true by a little experiment that you can try with
your pop-gun. Press the cork end of the gun firmly against something,
so that the cork can not come out. Now push in the rod quickly, and
then let go of it. It will fly back, because the crowded air, by
a spring, throws it back. And the harder you push it in, the more
forcibly will it fly back.

Now, if you try the same experiment with the water in the gun, you
will find that you can not push the rod unless the gun leaks, and then
the water will come back by the piston. Why is this? It is because the
water can not be crowded into any smaller space, as the air can be. If
it could be, the water would do just as well in the pop-gun as air does.

You see, then, that it is the spring of the air that forces the cork
out of the gun; and the air has this spring because it is pent up and
crowded together, as we may say, into so small a space. It wants more
room, and pushes to get it.

The cork is shot out of the pop-gun in the same way that the ball is
shot out from the cannon. The air, pent up in a little space in the
pop-gun, does the same thing as the gas, pent up in the cannon, does.
The air wants more room, and so it kicks out the cork; and the gas, so
suddenly made out of the powder, wants more room, and so it kicks out
the ball. The gas has the same springiness that the air has.

[Sidenote: Elasticity of the air.]

It is this springiness of the air, called its elasticity, that makes
the foot-ball bound so. If the ball were filled with water instead of
air, it would not bound at all, because the water has no elasticity.

[Sidenote: Operation of the air-gun explained.]

I have told you that the more the air is pressed the greater is its
springiness. In what is called the air-gun, a great deal of air is
crowded into a very small space--much more than there is in a pop-gun;
and a bullet can therefore be fired from it with force enough to go
through a board. It is done in this way: The pressed air is shut up
tight, and all at once it is let into the barrel of the gun where the
bullet is. It throws the bullet out just in the same way that the gas
of the powder does in a common gun. This air-gun is only a curiosity.
It will never come into use, for it is quite a tedious operation to
load it with pressed air. The common gun, you know, is very easily
loaded with powder, and the gas which it turns into does the work even
better than the pressed air in the air-gun.

 _Questions._--What makes the cork fly out of the pop-gun? Explain just
 how the pop-gun operates. Tell how the quill pop-gun is made. Why do
 we have the potato in both ends of the quill? What is said about the
 springiness of the air? How would the pop-gun work if it were filled
 with water? Why is this? Give the experiment with the pop-gun showing
 how springy the air is. How is it when you try the same experiment
 with the gun filled with water? Give the comparison between your
 pop-gun and a cannon. What is said about the foot-ball? Tell about the
 air-gun. Why is this not in common use?




CHAPTER XI.

BALLOONS AND BUBBLES.


[Sidenote: What makes the balloon go up?]

What is it that makes a balloon go up in the air? It is because it is
so light, you will say; but what it is made of is not as light as air
is. It will not, you know, fly off into the air before it is filled. It
is what it is filled with, then, that makes it so light.

[Sidenote: Its car.]

The balloon is filled with a gas that is much lighter than the air is
around it. This makes it so light that it flies up in the air very
rapidly, and to a great height; and if the balloon is very large, it
can carry up a person, or even two or three persons, in a sort of car
or boat attached to it, as represented on the following page.

The car is attached to the balloon in this way: A netting covers the
balloon, and the cords that hold the car are fastened to this netting.
It would not do, you know, to fasten them to the balloon itself, for
that is made of such light material that the cords would tear out with
the slightest pull upon them.

[Sidenote: How the balloon is made to come down.]

[Illustration]

[Sidenote: How the balloon is prevented from going down too fast.]

[Sidenote: The parachute.]

How do you think the person in this car manages when he wants to come
down? So long as all the light gas remains in the balloon, it will stay
up in the air. So, when he wants to come down, he lets out some of
this gas. He does this very carefully; for, if he lets out too much,
he will go down too fast. Sometimes he will go down too fast in spite
of all his care. He is prepared for this, however, in two ways. There
are sand-bags in the car, which he can throw out when the balloon is
falling too fast. This makes the car so much lighter that it commonly
relieves the difficulty; but if it does not, he can use the parachute.
This is a sort of umbrella, made very large and very strong. It is
represented here both as shut and as opened. You can see how the
resistance of the air against this when open would make him go down
much slower than he would go without his parachute.

[Illustration]

[Sidenote: The danger of going up in balloons.]

[Sidenote: A great escape.]

[Illustration]

Balloons are sometimes used in warfare, to observe battle-fields, or
send messages to and from besieged cities. They were so used in our own
war and at the recent siege of Paris. They will probably never come
into use in traveling; for, besides the expense and danger, a balloon
will always go with the wind, and you never can tell just how the wind
blows very high up in the air. It may blow there in a direction wholly
different from what it does below, close to the earth. An Englishman,
Major Money, went up in a balloon, with the wind blowing from the sea;
and he supposed that he should be carried far into the country, and
come down safely upon dry land. All was right till he had got up about
a mile. Then suddenly the balloon changed its course, and went out
toward the sea. This was because the wind up there blew in a direction
just opposite to that of the wind below. This wind took him far out to
sea, and when he came down he was nine miles from the land. He came
near being drowned. He held on to the cords of his balloon, as you see
here, for some time. After a while, a vessel came to his relief, and
took him on board. As such dangers attend going up in balloons, it is
wrong for any one to do it.

[Illustration]

[Sidenote: The hot-air balloon.]

You can fill a balloon with common air so as to make it fly up like
the gas balloon; but the air must be heated to do this. A boy can make
such a balloon very easily out of thin paper. He pastes the paper
together so as to shape it like a balloon, leaving one end open. It can
be filled with hot air by holding it over something burning, with its
open end down. It is sometimes done in another way. A sponge wet in
turpentine or alcohol is fixed under the opening of the balloon by a
little frame-work, as represented here; and if the balloon goes up with
the sponge still burning, it will stay up longer than it will if the
sponge goes out before it is let off, because the air will keep heated
longer.

It is because heated air is so much lighter than the air around it
that a balloon filled in this way goes up; but such a balloon comes
down soon. It will not keep up so long as a gas balloon will. Why is
this? It is because the heated air in the balloon becomes cooled, and
then it is no longer lighter than the air around it. The balloon itself
is heavier than air, and it goes up and stays up only when it is full
of something which is lighter than air.

[Illustration]

[Sidenote: How soap-bubbles are like balloons.]

Children often make balloons in another way. They make them of soap and
water, as you see here; for the soap-bubble that flies up in the air is
really a balloon; and how beautiful a one it is! How thin and delicate
is the covering of this ball of air! It is a sheet of nothing but soap
and water, and a touch breaks it; but it answers the purpose. It holds
the air, and away it flies.

Now what is the reason that the bubble flies up a little way and then
comes down? It flies up because the air in it is slightly heated, and
so is lighter than the air around it. It is heated or warmed air,
because it comes from the warm lungs of the person that blows the
bubble. But it soon becomes cool, and then the bubble comes down, just
as the balloon filled with hot air does when the air in it becomes
cool.

[Sidenote: Some things about bubbles that are not commonly thought of.]

There are some things to be noticed about this ballooning with soap
and water. The water must be warm, or your little balloons will not go
up. Why is this? If the water is cold, it will cool the air that comes
from your warm lungs, and so your soap and water balloon will be filled
with cold air instead of warm air. It will therefore drop to the floor
when you expect to see it go up. So, too, the bubbles will not go up so
easily and so high in a warm room as they will in cold air. The greater
the difference is in warmth between the air in the bubble and that
around it, the better it will go up.

The reason of this is plain. The cooler the air is, the heavier it is;
and the warmer the air inside of the bubble, the lighter is the bubble;
and the very light bubble goes up quickly in the heavy cold air for
the same reason that any light thing, like cork, rises very quickly in
water. Why it is that light things go up in the air and the water I
shall explain in the next chapter.

 _Questions._--What is it in a balloon that makes it so light? How is
 the car attached to the balloon? How does the person in the car manage
 when he wants to come down? What does he do if he is coming down too
 fast? What is a parachute, and of what use is it? Why will balloons
 never be used for traveling? Tell about the Englishman. Tell about the
 air balloon. Why will not this stay up as long as the gas balloon?
 How do children often make balloons? Why does the soap-bubble go up a
 little way and then come down? Why is it that the bubbles do not go up
 if you use cold water? Why will they go up better in the cold air than
 they will in a warm room?




CHAPTER XII.

MORE ABOUT BALLOONS.


[Illustration]

[Sidenote: A curious balloon that would not answer.]

Here is a balloon which was contrived in 1670, two hundred years ago,
by a man whose name was Lana. You would suppose, from the picture of
it, that it would go very well with its large sail for the wind to blow
it along. There are, you see, four large balls. These, made of copper,
were hollow. The air was to be pumped out of them, so that they might
be very light. Now with this balloon Lana did not expect to go up very
high, but to travel along considerably above all the houses and hills,
just in the direction in which the wind would carry him by his sail.
But his plan, though it looks well, as you see, on paper, failed. The
reason was this. If the balls were made quite thin, the air outside
would burst them in as soon as the air in them was pumped out; and if
they were made thick enough to prevent this, they were so heavy that
the balloon would not go up. From what I have told you in the chapter
on the air-pump, you will understand why the balls, when made thin,
were burst in by the outside air.

The first successful attempt at ballooning was made by Montgolfier, a
Frenchman, in 1783. His invention was that of the hot-air balloon, or
fire balloon, as it is often called. An improvement on this is to fill
the balloon with a light gas instead of hot air. It is in this kind of
balloon that persons go up, though some have gone up in the hot-air
balloon.

I have not yet told you the real cause of the rising of the balloon in
the air. Why, you will say, it is because it is so light, and light
things always rise. But what makes light things rise? That is the
question.

Light things do not go up of themselves. The birds and the insects, as
I have told you in Part II., make themselves go up by working their
wings with their muscles. But light things that have no life can not
rise of themselves. They are pushed up. And when any light thing has
got up as high as it can go, it stops merely because it can not be
pushed any higher.

[Sidenote: Balloons and other light things do not really go up, but are
pushed up.]

But how are balloons and other light things pushed up? This I will now
explain to you. The air around the balloon is heavier than the balloon
itself, which is filled with a light gas, or with air that is light
because it is heated; and so the air is trying all the time, as we may
say, to get below the balloon. In doing this, it pushes up the balloon;
and the balloon continues to be pressed upward till it comes to air
that is as light as the balloon is. If it be a gas balloon, it will
remain there till some of the gas is let out; and if it be a hot-air
balloon, it will stay there till the heated air begins to cool.

[Sidenote: Every thing gets as low as it can.]

Now, when the balloon goes down, it is because it has become heavier
than the air around it. It goes down because it tries, as we may say,
to get underneath the lighter air. In going up, the air pushed it up;
but now the balloon pushes the air up. The balloon presses the air that
is below it out of the way so as to get under it. This is what it keeps
doing all the way as it comes down.

[Sidenote: Experiment with a phial.]

I can make this clear by a comparison. Take a long phial. Before you
put any thing into it, you know it is filled with air. Pour some oil
into it. The oil is in the bottom of the phial, and the air is above
the oil. The reason is that the oil, being heavier than the air, has
gone down through it, and has pushed the air up from the bottom of the
phial and taken its place there. It has done to the air in the phial
what the falling balloon does to the air below it. Now pour a little
water in. This will do to the oil as the oil did to the air. It will go
down to the bottom, pushing the oil up above it; for water, you know,
is heavier than oil. If you pour now some quicksilver into the phial,
this heavy fluid will go down and push the water up above it.

You see, in this experiment, that what is heaviest always goes to the
lowest place, and so pushes up out of the way what is lighter. The oil
pushed up the air; then the water pushed up the oil; and then, again,
the quicksilver pushed up the water. And now you have all the four
things in the phial in their order. The heaviest, the quicksilver,
is at the bottom, and next is the water, and next the oil, and the
lightest, the air, is at the top.

[Sidenote: Another experiment with the phial.]

If you cork the phial and shake it well, you mix quicksilver, water,
oil, and air all together. Then, if you let it stand, you see a good
deal of confusion among them as they push to get their places. In
getting right again, each pushes up above it what is lighter than
itself. The struggle, as we may say, is to get the lowest place. Every
thing, no matter how light it is, stays down as low as it can till it
is pushed up.

[Sidenote: Experiment with a heavy gas.]

Now what you see with these different things in a phial is true of
different kinds of air, or gases. A heavy gas takes the lowest place,
while a lighter one goes up, or, rather, is pushed up. You remember
that I told you, in Chapter VIII., about a gas that is sometimes in the
bottom of wells, just above the water. This gas is heavier than air,
and so it stays at the bottom of the well, below the air, as the oil
in the phial lay between the lighter air above and the heavier water
below. If it were lighter than air, as the gas is with which balloons
are filled, the air would go down to the bottom of the well and push up
this gas, for the same reason that the oil in the phial pushed up the
air, and the water pushed up the oil, and the quicksilver pushed up the
water.

This gas can be poured out of a vessel very much as you would pour
water out of it. A pretty experiment with it is to pour it out upon a
lighted candle. It will flow down upon the flame and put it out. In
doing this, it pushes up the air that is around the candle.

Now you can see how the balloon is pushed up into the air. If a gas is
set loose that is lighter than air, it will be pushed up in the air in
the same way that, in the phial, air is pushed up by the oil, or the
oil by the water; and so the balloon, filled with the light gas, is
pushed up by the air. It makes no difference whether the gas is loose
or is in a light silk bag; in either case it will be pushed up. If
loose, it will be scattered about as it is pushed up; if in the bag or
balloon, it will be kept together.

[Sidenote: Comparison of the cork and the balloon.]

A cork rises in water for the same reason that a balloon rises in air.
The balloon is pushed up by the air around it because it is lighter
than the air, and so the cork is pushed up by the water because it is
lighter than the water. As you hold the cork under water, your hand
does to it what the fastenings do to the balloon: it keeps it from
being pushed up. And when the fastenings of the balloon are let go,
away it flies in the air, as the cork flies up in the water when you
let go of it.

When the cork gets to the surface of the water, it stops. It will not
go up in the air simply because it is heavier than air. But if you put
a bag full of light gas in the water and let it go, it will not stop,
like the cork, when it gets to the surface, but will keep on going up
because it is lighter than air, and so the air pushes it up just as the
water did.

 _Questions._--Do light things, like balloons, rise in the air of
 themselves? Tell about Lana’s balloon. Why did it not succeed? Who
 invented the hot-air balloon? How many years ago was it? What kind of
 balloon is used for going up into the air? What makes it rise? How is
 it that the air pushes up a balloon? What makes the balloon go down?
 What does it do to the air in going down? Tell about the experiment
 with a long phial? How is it if you shake the phial well? What is
 said about gases? Tell about the gas which is sometimes in wells.
 Tell about the experiment with a candle. What becomes of a gas that
 is lighter than air when it is set free? Does it make any difference
 whether it is loose or is in a silk bag? Give the comparison of the
 balloon and the cork.




CHAPTER XIII.

HEATED AIR.


Balloons are sometimes, as I have told you, filled with heated air.
This heated air is lighter than the cool air around it, and so the
balloon rises, or, rather, is pushed up. Now observe why the heated air
is lighter than the cool air. It is because the heat swells the air, or
_expands_ it, as it is commonly expressed. The heat, in expanding it,
makes it thinner, and of course it is lighter.

[Sidenote: Experiment with a bladder.]

You can see by a little experiment that heat swells or expands air. Lay
a bladder, partly filled with air, before the fire. The heat will fill
out the bladder, making it plump and hard, for it will expand the air
that is in it; and if the bladder is already filled with air before you
lay it down on the hearth, the swelling air will burst the bladder.

[Sidenote: Roasting apples.]

You remember that I told you about putting an apple under the jar of
an air-pump. If the apple is shriveled, the moment that you begin to
pump the air from around it the apple begins to swell out, because the
air in it swells or expands. In this experiment the air in the apple
expands because the pressure of the air around it is lessened by its
becoming thinner. Now the air in the apple can be made to expand in
another way--by applying heat. If you observe an apple put down to the
fire for roasting, you see that it swells. If it happens to be rather
wilted, the swelling of it will be very manifest; it will become as
plump as it would in the air-pump when the air is pumped out. This is
because the air in it is expanded by the heat. And when it sputters,
it is the expanded air that throws out some of the juice through the
broken skin.

[Sidenote: Popping of roasting chestnuts.]

[Sidenote: Why pricking them prevents it.]

You know that, if you roast chestnuts, they pop open with quite a
noise, and sometimes fly half across the room. This is owing to the
expansion of the air in the chestnut by the heat. This air is shut up
in the tight skin of the chestnut; and when it is considerably swelled
by the heat, it makes the skin give way all at once, and so produces
the popping noise. This is because of the springiness or elasticity of
the air. That I have explained before. If you prick a hole in the skin
of the chestnut before you put it down to the fire, there will be no
popping, for the air will gradually escape from this hole as fast as it
is expanded. This hole is to the chestnut what the safety-valve is to
a steam-engine. The engine will not burst while the steam can go out
by the valve, and so the chestnut, with a hole for the air to get out,
does not burst. In the case of both the apple and the chestnut, there
is steam mixed with the air. The steam comes from the moisture in the
apple and the chestnut, and this has the same springiness that air has,
and so helps to produce the effect. I shall tell you about steam in
another chapter.

Heated air always rises, for the same reason that a light gas rises. It
is pushed up by the cold air, which is heavier. In warming a room, the
cold air is constantly pushing the warmed air up, and the air is always
warmer in the upper part of the room than it is near the floor. So,
also, it is warmer in the galleries of a church than it is in the body
of the house, as you perhaps have sometimes noticed.

[Sidenote: Paper wind-mills on a stove-pipe.]

[Sidenote: The toy wood-sawyer.]

Around a stove-pipe, the motion of the heated air as it goes up is very
manifest. Light things are often seen flying up in the current of the
air about the pipe. Sometimes, for amusement, little paper wind-mills
are fastened to a stove-pipe, the heated air whirling them around
as it strikes them in going up. I have seen a very curious toy, in
which a wood-sawyer is made to work by the whirling of a little paper
wind-mill. Whenever there is a strong current of hot air, the wind-mill
turns quite rapidly, and this sets the sawyer to working his paper saw
most furiously. The little figure goes through the motions of sawing
very perfectly. It has sawed into the middle of the log, but never gets
any farther.

The stream or current of air about a stove-pipe is made by the cooler
air, which pushes up that which is warm. As fast as the air is heated
by the pipe, cooler air takes its place by pushing it up out of the
way; and then this air, coming thus near the pipe, gets heated, and is
pushed up in its turn by some more air. As this is constantly going on,
there is a constant upward current of air; and the hotter the pipe is,
the more rapid is the current, because it heats the air so quickly and
so much.

[Sidenote: Why heated air goes up.]

You know, in a house heated by a furnace, how the heated air comes up
from the registers. This air is pushed up. As soon as the air around
the furnace is heated, cool air comes in to push it up out of the way,
and then this cool air is heated and is pushed up by more cool air,
and so on. The heated air escapes from the pressure of the cool air
by going up in the large tin pipes. The cool air is always driving the
warm up, just as it is with the air about a stove-pipe.

[Sidenote: Why a great fire makes the wind rise.]

Whenever a great fire occurs, after it has continued some time, the
wind rises, as it is expressed; though perhaps it blew very gently
at first, now it blows very hard. What is the reason of this? It is
because the air just about the fire becomes much heated, and therefore
very light. The cold air all around rushes therefore toward the fire,
just as it does toward a stove or a fire-place in a room, and pushes the
light heated air up. In doing this it becomes itself heated, and is
pushed up by other cold air, and so on. In this way the air all around
the fire is set in motion toward it, and the hotter the fire the more
brisk is this motion--that is, the harder does the wind blow. I shall
tell you something about the way in which heat makes winds in another
chapter.

 _Questions._--Why is heated air lighter than cool air? What experiment
 shows that heat expands air? Tell about the shriveled apple. Why do
 chestnuts often pop open when they are roasted? How can you prevent
 their popping? Give the comparison of the safety-valve. In warming a
 room, what is done to the heated air? What is said about the galleries
 of a church? What is said about the air around a stove-pipe? Tell
 about the paper wind-mills and the wood-sawyer. How is the current of
 air about a stove-pipe made? What makes the hot air come up from the
 registers of a furnace? Why does the wind rise in a great fire?




CHAPTER XIV.

CHIMNEYS.


[Sidenote: Smoke is not drawn up a chimney, but is pushed up.]

You hear people sometimes say of a chimney that it _draws_ well, as
if the smoke were in some way drawn up the chimney. This is not so.
It is pushed up. Smoke is mostly heated air and gas. What you see in
the smoke is something from the wood that is carried up in the heated
air, in the same way that down or any light thing is carried up by the
heated air around a stove-pipe. It is this part of the smoke which you
can see that makes the soot. The heated air is pushed up the chimney
by the cooler air in the room. It is done in this way: The air close
to the fire is heated; the air next to it presses it up, and then gets
heated itself, and is pressed up by some more air that comes in its
turn to be heated, and so on. In this way there is a constant stream of
air up the chimney, just as there is around a stove-pipe.

The air in a room where there is a fire is ever pushing toward the
fire; and air is coming into the room, too, in every way that it
can get in, to take the place of that which goes up the chimney. It
comes through the door when it is opened, and through every crack and
crevice. If you hold a light near the fire-place, the flame will bend
toward it, because the air is pressing that way. If you hold it near a
crack, the air that is coming in will blow it toward you.

[Sidenote: A lady in trouble from a smoking fire-place.]

If there are two rooms connected by folding-doors, with a fire-place
in each, when a fire is made in one alone, cold air will come down
the other chimney; for, as the air in the room, as I have told you,
is all moving toward the fire, the cold air comes in wherever it can
get in to take its place. A lady of my acquaintance was once in great
trouble because she did not understand this. Her house was filled
with smoke. It happened in this way. There were two rooms connected
by folding-doors. A fire had been built in one fire-place, and, after
this was well agoing, a fire was built in the other; but the moment
this second fire was lighted, the smoke puffed out into the room. How
was this? It was pushed out by the cold air coming down the chimney.
The lady sent for a neighbor who understood about such things, and he
relieved her of the trouble at once. He shut the folding-doors, and
opened a window in the room where the fire-place smoked, and now the
smoke went directly up the chimney. After the fire had been burning
for a little time, and had warmed the chimney, the folding-doors were
opened, and both fires burned well.

The reason of all this, I suppose, is plain to you. While the
folding-doors were open, there was a movement of the air in both rooms
toward the fire first kindled, and so the cold air came down the
chimney where there was no fire. When the fire, therefore, was kindled
in the second fire-place, this cold air, coming down, blew the smoke
out, and would not let it go up to warm the chimney. But when the doors
were closed between the rooms, there was a stop put to all this. The
movement of the air toward the fire first made was now confined to
that one room. There could no air come from the other room now. And
then opening the window let in cold air that pushed the smoke up the
chimney of this room at once.

[Sidenote: Why opening a door stops the smoking of a fire-place.]

You can now understand why it is that we open a door or window to stop
the smoking of a fire-place. It is because we want the help of some
more cold air to push the smoke up. In some fire-places we can never
make a fire without its smoking, unless we have a door or a window open
a little while at first. The reason that the fire is not apt to smoke
after it has been going some time is that the chimney has become well
heated, and so makes the air very thin and light as it goes up; and the
lighter the air is, you know, the more easily it is pushed up, just as
you can raise a bag of feathers more easily than you can raise a block
of wood.

[Sidenote: Experiments with a light.]

One thing more I must tell you about the cold air coming into a room
where there is a fire. Suppose that you open a door into a cold entry.
Now, if you hold a light near the floor by the open door, the flame
will be blown inward; but if you hold it up at the top of the door, it
will be blown outward toward the entry. Why is this? It is because the
cold air of the entry comes in at the lower part of the opening, while
some of the warm air of the room goes out at the upper part to take the
place of the cold air that comes in. The warm air is above the cold
air, because it is lighter. It is the cold air coming in that blows
the light when you hold it low down, and it is the warm air going out
that blows it when you hold it up high. The warm air that goes out is
less in quantity than the cold air that comes in. The reason is that
there is cold air coming into the entry all the time from outdoors, by
every crevice and hole, and this, in part, supplies the place of the
air that goes in from the entry to the room. The flame, therefore, is
not blown as strongly when you hold the light above as when you hold it
below.

I told you in Chapter I. that nothing will burn without air. The air
that presses toward a fire feeds it, as it is expressed. It does not
all go up the chimney as heated air. Some of it is used in the burning
of the wood and coal; and what goes up the chimney is, as I have told
you in the first part of this chapter, partly heated air and partly gas.

[Sidenote: A free supply of air necessary to make a fire burn well.]

[Sidenote: Anecdote.]

Now a fire will not burn well unless it has a free supply of air. Fresh
air must keep coming to it to feed it. But this can not be unless there
is a good upward current from the fire. Firemen very well understand
this in putting out fires. If the fire be inside of a building, the
more shut up it can be kept the less rapidly will the fire spread, and
the more easily can it be put out. If all the doors should be opened,
and the windows broken out, the fire would rage, because the air would
come in freely at the doors and lower windows, and go out freely at
the upper windows. The fire would then have the same upward current
that it has in a chimney. I will relate to you an anecdote, which will
show how much can be saved by understanding such things. A fire was
discovered early one morning by a flickering light shining through the
windows in the upper room of a shop. An acquaintance of mine was among
the first to get there, and he found a man about to beat the door in
with an axe, so as to get at the fire. He kept him from doing this,
and would not let him touch the door till they had got a good supply
of water on hand. After he was satisfied that there was enough water
to put out the fire, he then let the man use the axe, and they rushed
up and easily put out the fire. If he had let him break open the door
at first, it would have let in the air to feed the fire, and the fire
would have got well agoing before the water was brought; and, as it was
in a block of wooden buildings, we should have, had a great fire.

[Sidenote: Tall chimneys of factories.]

[Sidenote: Lamp chimneys.]

The brisker the upward current of a fire is, the more briskly does the
fire burn. This is the reason that foundries and other factories, where
they want a very hot fire, have such tall chimneys. The air and gas in
such a chimney are kept hot for some time, instead of being cooled by
spreading out in the open air. The current, therefore, up the chimney
is very rapid, and so fresh air comes rapidly to the fire, and makes it
burn very briskly. For the same reason, a very brilliant light is given
by those lamps that have tall glass chimneys. The wick is thus made to
burn briskly.

 _Questions._--Why does smoke go up a chimney? What is smoke? What is
 there in smoke that you can see? What is soot? Tell how it is that the
 smoke is pushed up the chimney. What is said about the air in a room
 where there is a fire? What will happen to a light if you hold it near
 the fire-place? What if you hold it near a crack in the wall of the
 room? Tell about the rooms with folding-doors between them. Why do we
 open a door or a window to stop the smoking of a fire-place? Why is
 a fire-place not apt to smoke when the fire has been going for some
 time? Tell about holding a light at the lower part and at the upper
 part of a door that opens out into a cold entry. How is some of the
 air that presses toward a fire used? What is necessary to have a fire
 burn well? What is said about a building that is on fire inside? Tell
 the anecdote about the fire in a shop. Why do some factories have tall
 chimneys? What is said about the chimneys of some lamps?




CHAPTER XV.

USES OF WATER.


[Sidenote: The beauty of water.]

What a beautiful thing is water! How pure and clear, like a crystal!
How “sparkling and bright it is,” as you see its ripples in the sun!
How we admire it, as it is gathered in little dew-drops on the flowers
and leaves in the morning! What a beautiful mirror the water makes when
the wind is hushed, showing us on its smooth surface the trees, the
houses, and every thing upon the shore!

[Sidenote: Ice, snow, and frost.]

And what beauty water has when the cold turns it into crystals in the
ice, the snow, and the frost! It is the same pure, clean thing then as
it is when it runs in the brook, or forms the dew-drop, or falls in the
gentle shower.

[Sidenote: Water the world’s cleanser.]

How useful, too, water is! It is the world’s cleanser. It washes every
thing. See how dusty every thing looks after a long dry time. Even the
grass and the leaves are covered with dust. But let a brisk shower
come, and how changed the scene! The trees, the flowers, and the grass
look as clean, and fresh, and bright as the washed face of a beautiful
child.

And then how the animals love to wash themselves in the water! See the
dog rush into it, and then, on coming out, give himself a thorough
shaking. It would be well if all children would be as fond of being
clean as he is. It is amusing to see the canary bird take his morning
bath in his cup of water. How he makes the water fly as he flutters his
wings!

[Sidenote: The washing of the air.]

Did you ever think that the air every once in a while needs a washing?
It does, just as much as you do and every thing else in the world. Even
when it seems clean as you look up through it, there are some things
in it that would be very bad for us if they remained there. They would
produce disease in us. They would be injurious also to other animals,
and even to plants. The air, therefore, must every now and then have a
washing to purify it; and every time that it rains you can think of the
air as taking a shower-bath for this purpose. You see, then, how true
it is that water is the world’s cleanser. It washes every thing, even
the air.

[Sidenote: How plants drink.]

But, besides being the world’s cleanser, water is the world’s drink. It
is the drink of plants as well as of man and animals. The plants drink
it from the ground by the mouths in their roots. A great part of the
sap, as I have told you in Part I., is water.

[Sidenote: Water in fever.]

We use water so constantly as a drink that we do not think how good and
refreshing it is. We think of this once in a while when we happen to be
very thirsty. When one is parched with fever, he thinks of cold water
as the very best thing on the earth; and when he is asleep, he dreams
of the well or spring from which he drank so often in his childhood.
A lady who was sick with yellow fever, far away from home, in her
delirium talked continually about a pump that was behind a house she
had long lived in, some time before this, and kept calling for water
from that pump.

[Sidenote: Sea water.]

The salt water of the sea, you know, is not fit for drinking. And you
have heard of persons in a shipwreck escaping in a boat from a sinking
ship, and then living almost without food and water for many days. How
careful are they not to waste any of the water which they happen to
have! Each drinks but little, though they are suffering greatly with
thirst. And when it is all gone, they would give any thing for the
smallest draught of fresh water. So dreadful is the suffering from
thirst that water is almost the only thing which they think of. They
wish that it would rain, so that they might catch some water. There is
water all around them, but it seems to mock them with its briny waves.
It is not the water which they want; they know that it would do no good
to drink it.

[Sidenote: Feeling of the shipwrecked man about water.]

One who had been in a boat for some days without water said that it
seemed to him always after as if it was wrong to waste pure fresh
water, and he never could use it as freely as he did before his
shipwreck. How thankful should we be that God has given it to us so
abundantly that we can commonly use it without stint or measure. It is
one of his most precious gifts, and yet it is so common that, when we
want to speak of any thing as being very free and abundant, we say that
it is as free as water.

[Sidenote: Water in every thing.]

But we do not merely drink water. It is mixed up with every thing that
we eat. There is much water in all fruits. There is so much in the
watermelon that it gives it its name. It is almost all water, with a
little sugar in it. Much of the sap in plants and trees is water; so,
also, it is with the blood. It could not run in the arteries and veins
if there was not water in it. More than three quarters of your blood is
water. There is much water, too, in the air. So you see that water is
every where, just as the air is.

But I have not told you all the uses of water. The running water turns
the water-wheels by which the machinery in mills and factories is
put in motion. We sail about on the water in boats, and ships, and
steamers. The steam-engines are worked by water changed into steam.

[Sidenote: The multitudes of animals that live in water.]

We must not forget the multitudes of fishes and other animals that
live in the water, as we do in the air. There is a world of life in
the water. It is so much out of sight that we do not think much about
it. We only get glimpses of this water-world now and then, and do not
think how many animals there are that live in the brooks, and rivers,
and ponds, and seas. Besides the fishes that swim in the water, there
are multitudes of animals that live on the bottom. There are oysters,
and clams, and lobsters, that you are familiar with; and there are
multitudes of animals that live in their beautiful shell houses, some
of which are very small, and almost as countless often as the sands
with which they are mingled.

 _Questions._--What is said about the beauty of water? What is said
 about its being the world’s cleanser? Tell about the dog and the
 canary bird. What is said about the air’s being washed? How do the
 plants drink water? Do we commonly think how good a drink water is?
 Tell about the lady sick with fever. What is said about the salt
 water of the sea? What about the suffering from thirst so common with
 shipwrecked persons? Tell about the feeling of one who had suffered
 in this way. What is said about the abundance of water? What is said
 about water’s being in every thing? How much of your blood is water?
 Mention some more uses of water. What is said about the animals that
 live in water?




CHAPTER XVI.

WATER ALWAYS TRYING TO BE LEVEL.


If you look at water in a bowl, you see that its surface is smooth and
level. If now you stir it about, you make it uneven. Watch it as it
becomes still and smooth again. There seems to be a kind of struggle as
all the particles of water take their places.

But you will ask me what I mean by the particles of water. We suppose
that water is made up of exceedingly fine balls. These balls or
particles are so round and smooth that they move among each other very
easily. This is the reason that water runs so readily, and so soon
becomes level when nothing is disturbing it. If the particles were not
so smooth, they would rub each other. They would not roll over each
other so freely as they do.

[Sidenote: The particles of water compared to shot.]

To make this plain, we will compare water to small shot. If you put
these into a bowl, they will not lie level, as water does. Now what is
the reason that these round balls of lead do not act as the smaller
round balls of the water do? It is because they are not as smooth. They
can not roll over each other easily, for they rub together. They can
not in any way be made as smooth as the particles of water are.

If you pour the shot from one bowl into another, they will run somewhat
as the water does; but they will not slip along as easily, for they
rub each other as they go, while there is almost no rubbing among the
particles of water.

[Sidenote: The particles of water round and smooth.]

The balls or particles of water are exceedingly small. They are so
small that no one has ever seen them. How, then, you will ask, do we
know that they are round and smooth? We say that they are, because we
can not see how they could move about among each other so easily if
they were rough, or had corners or points on them. You can not roll
about blocks or nails as you can roll shot; and the smoother the shot
the more easily they will roll. So then we know, from what we see in
other things, that the particles of water that roll so easily must be
round, and must be smooth also.

If the particles of water were large enough for us to see them, they
would look to us, on the surface of still water, as a level layer of
little shot or round beads, and we should see them rolling about among
each other whenever there is the least motion of the water; but, as we
can not see the particles, the surface of the water looks like smooth
glass when they are all still.

As water moves so easily, it is almost always in motion. It is moved by
the wind, and is raised by it sometimes into very high waves. It runs
in the brooks and rivers.

[Sidenote: Why water runs.]

In all its motions the water is always trying to be level; and this is
the only reason that water ever runs. Water that is level will not run;
it will be still. But, when you disturb this level, it will run till it
finds its level again.

I will make this plain to you. Suppose that you have a trough stopped
at both ends. Put some water in it as it lies on level ground. The
water is level in it, and is quiet. Now raise up one end of the trough
a little. The water is at once in motion. Why? Because you have
disturbed the level. The water runs from the end that you raise toward
the other end. Now hold the trough still a little time with the end
raised, and as soon as the water gets its level again, it will be as
still as it was before.

[Sidenote: Brooks and rivers.]

Suppose the trough is open at both ends, and water is running in all
the time at the raised end. It will keep running toward the lower end.
It will be all the time trying to get on a level, but never can. You
see here the reason that water runs in a brook or river. You can think
of a brook or a river as a trough with one end a little raised; and the
water in it is always, as we may say, running after a level, but never
finds it. The sea is to a river as a tub would be to the trough that
pours its water into it.

[Sidenote: The power of running water.]

There is often great power in the water of a running stream. It works a
great deal of machinery in mills of various kinds; and, if the stream
be swollen with heavy rains, the water carries away bridges, houses,
etc. It does all this in trying to get on a level. If it all could be
made level in some way, as you see it in a bowl or a pond, it would do
no such violence.

[Sidenote: Dams.]

Sometimes men build a dam across a river. This is for the purpose of
turning the water off one side into a canal. The dam stops some of the
water running in the river, sometimes all of it. In doing this the
water is made about level just above the dam, and so is much more quiet
than it is any where else in the river.

Children often build mud dams, and the water that they stop is very
still because it is level. When the dams give way, how briskly the
water runs to try to get on a level again.

[Sidenote: Pouring from a coffee-pot.]

Water is always on the same level in the spout of a coffee-pot that it
is in the pot itself, as represented in the first of these figures. If
the coffee-pot be turned up, as seen in the second figure, the level is
still preserved. If it be turned up a little more, the liquid in the
spout, in trying to be on a level with that in the pot, runs out, as
represented in the third figure.

[Illustration]

[Illustration]

[Sidenote: A supposed discovery of perpetual motion.]

A man once thought that he had discovered a way of keeping up perpetual
motion. He thought that he could make a vessel of such a shape that
some water in it would never stop moving. The vessel was to be of the
shape that you see here. His idea was, that there was so much more
water in the vessel than there was in the spout, that it would press
the water in the spout up its whole length, and make it run into the
vessel. You can see that, if it would operate in this way, the water
would be always in motion--it would be going the rounds by way of the
spout all the time. But the difficulty is that it would not operate in
this way. After the man made his vessel, he found that the water was
only as high in the spout as in the vessel, as you see in the figure.
It is just as it is with the spout of the coffee-pot.

[Illustration]

[Sidenote: Water can rise in the pipes of an aqueduct as high as it is
in the fountain.]

In the same way, if an aqueduct pipe extend from a spring, the water
will not rise any higher in the pipe than it is in the spring. The
pipe is to the spring what the spout is to a coffee-pot. And it makes
no difference how long the spout is. The water will stand at the same
height in a pipe that extends for miles that it does in one that
goes but a little way from the reservoir or fountain. This can be
illustrated in a vessel with two pipes, as seen here. The water stands
in the branch pipe that is farthest from the vessel at the same height
that it does in the near one. Sometimes an aqueduct will supply the
lower stories of a building with water, but not the upper stories. The
reason is that the upper stories are higher than the level of the water
in the fountain from which the water comes.

[Sidenote: The playing of a fountain explained.]

You have often seen a fountain playing. How beautifully the stream
rises and spreads out, dropping in a shower all around! Now why is it
that the water rises? It is because the spring from which the water
comes is so much higher than the pipe of the fountain. The water in
the pipe tries, as we may say, to get on a level with the water in the
spring. This I will make plain to you by two figures. In the first
figure you see represented a vessel of water, with a pipe extending
from its lower part up at its side. The water stands at the same
level in the pipe that it does in the vessel, as in the case of the
coffee-pot. Now suppose, as represented in the second figure, the pipe
is quite short. If the vessel be filled with water, the water in the
pipe, seeking to get to the same level as that in the vessel, will be
thrown up in a stream, as you see. The reason that the stream spreads
out and drops in a shower is, that the air resists the stream, and so
divides it up, because water is so easily separated into parts.

[Illustration]

 _Questions._--What is said about water in a bowl? What is said about
 the particles of water? Give the comparison about shot. Why will not
 shot run as easily as water from one vessel into another? What is
 said about the smallness of the particles of water? How do we know
 that they are round or smooth? If we could see the particles, how
 would water look to us? What is said about water’s being in motion?
 What makes it run? Tell about water in a trough. Give the comparison
 about a trough and a river. What is said about the power of running
 water? What is said about dams? Tell about the level of water in a
 coffee-pot. Tell about the man’s contrivance for perpetual motion.
 What is said about the pipes of an aqueduct? Why will water sometimes
 come only to the lower story of a building, and not to the upper? Tell
 about the playing of water from a fountain. Why does the water come
 down in a shower of drops?




CHAPTER XVII.

THE PRESSURE OF WATER.


[Sidenote: The pressure of the particles of water upon each other.]

Any thing that is solid presses only one way, directly down; but water
or any fluid presses all ways. It presses just as much sidewise, or
even upward, as it does down. The reason is, that the particles of
water move about among each other, and are not fastened tight together
as they are in a solid. When water freezes, its particles become all
fastened together, and then the pressure is all downward.

[Illustration]

To see how this pressure of the particles of water operates, look at
some shot lying together. One shot does not lie right upon another shot
below it in this way, _a_, but they lie in this way, _b_. You see that
each shot presses down between those that are underneath it. Each shot
is trying, as we may say, to get down between its neighbors below; and
if there was nothing to prevent it, it would press them apart.

[Sidenote: The pile of balls.]

You can see that this is so by trying a little experiment. Put some
shot close together on a very smooth surface. Now put another shot on
top of them, and you will see that it will press them all apart. If the
shot should be rough, and the surface on which you lay them should be
rough also, your experiment will not succeed, because the shot will not
roll easily. It is for this reason that cannon balls, as you see them
piled up in an ordnance-yard, as represented in the annexed figure, do
not roll away. If they were smooth, and the place which they were piled
on were smooth, they would all be pressed apart, and the pile would
thus be spoiled.

[Illustration]

Now see what this sidewise pressure will do in a vessel filled with
shot if there should be an opening made in the side. The shot close by
the opening will run out, because they are pressed sidewise by the shot
lying right above them; and as they go out, those that press them out
will be pressed out in their turn by those above them, and so on.

[Sidenote: Particles of water compared with shot.]

Just so it is with the little fine balls or particles of water. They
lie on each other in the same way that shot do. Each particle is
pressing always to get down between the particles that are underneath
it, as I have showed you it is with the shot. And if you make an
opening in the vessel that holds the water, its particles will run,
or rather roll out, like the shot, only a great deal easier, because
they are so smooth. They are pushed out by this pressing down of each
particle between those that are below it.

[Sidenote: About water running from openings in different parts of a
vessel.]

If you make an opening near the top of a vessel filled with water, it
does not run out with much force; but if the opening be made near the
bottom, it spouts out as if it was in a great hurry to get out of the
vessel. What is the reason of this difference? To understand this,
observe that all the particles are pushing downward in the way that I
have shown. Those particles, therefore, that are near the bottom, have
a great deal more pressure on them than those that are near the top;
so that when the opening is made near the bottom, the particles there
are pushed out with great force. There is a large crowd of particles
pushing down to get out at that opening. And observe, as the water in
the vessel lessens, the force of the stream from the opening lessens;
it does not leap out so straight as it did at first. It is very much
as it is with a crowd pressing through a door. When the crowd is very
great, those that are pushed through the door are pushed with great
force; but as the crowd lessens, the pressure lessens.

It is found that water runs out of a vessel from an opening in the
side close to the bottom just as quickly as it does from an opening of
the same size in the bottom itself. What is the reason of this? It is
because the little round particles of water roll so easily. They roll
out just as easily as they drop out.

See the difference between pressing on a fluid and on a solid. If you
press on a block of ice, you press it all one way. If you press it
down, you press it all down. If you press it sidewise, it all moves
sidewise. And it makes no difference whether your hand, or whatever you
push with, covers the whole side of the block or not. But it is not so
with water. If you press your hand down into a vessel of water, you
press down some of the water, but not all of it. Some of it is pressed
up; for, as you press down what is right under your hand, this pushes
what is below it off each way to the side, and this pushes up the water
that is over it. This is because the round, smooth particles roll so
easily on each other. When pressure is made upon them, they roll away
from it just where they can--downward, or sidewise, or upward.

[Sidenote: Water moving in a tube.]

There is one way in which you can make all of a body of water go
straight along. It must be in a tube, so that it can not escape
sidewise, and then there must be something to fit this tube which
will push along the water. It must fit exactly, or some of the little
particles will slip back by it.

In this way you can push the round body of water in the tube straight
along, just as you push a round stick or a long icicle. But suppose
that there is a little hole in the tube. This would make no difference
if the water were ice, because the particles of a solid are so tightly
fastened together; but the pressed liquid, you know, will spout out of
the hole, because the particles, not being well fastened together, will
escape from the pressure wherever they can. Open a door any where, and
out they will leap.

[Sidenote: Squirt-guns and stick-guns.]

[Sidenote: The gas and the ball.]

You see the difference between a liquid and a solid in the operation of
a squirt-gun, and of one of the stick-guns so common among children.
So long as the water is in the squirt-gun, it is all pushed along
together, as the stick is in the stick-gun. But as soon as it gets
out, it becomes all divided up by the air, just as you saw in the last
chapter the water from a fountain does. But the stick, as it flies
out of the gun, keeps whole, because its particles are well fastened
together. If the water were changed into ice, it would fly out whole as
the stick does, for its particles would be so fastened together that
the air could not separate them as it does the particles of water.

[Sidenote: Attraction in solids, and fluids, and gases.]

The difference is still greater between solids and gases. You see this
in the firing of a gun or a cannon. The gas into which the powder
changes keeps together while it is in the gun, just as the water does
in the squirt-gun; but as soon as it gets out, it spreads like the
water when it gets out of the squirt-gun, only a great deal more. This
is because the particles of the gas are disposed to separate instead
of keeping together. They have no attraction for each other; but the
ball which the gas drives out of the gun leaves the gas behind it, and
goes on whole, because its particles are so well fastened together by
attraction.

You see, then, that in a solid there is considerable attraction between
the particles; in a fluid there is much less; and in a gas there is
none at all.

 _Questions._--How does the pressure of a fluid differ from that of
 a solid? Give the comparison about shot. Relate the experiment with
 shot. Tell about the pile of cannon balls. Give the comparison about
 shot and water running for an opening in a vessel. Why does water
 run faster from an opening near the bottom of a vessel than from an
 opening near the top? Why does it run more slowly as the water in the
 vessel lessens? Give the comparison about a crowd going through a
 door. Why does water run out from an opening in the side of a vessel
 close to the bottom as fast as from a hole in the bottom itself? What
 is the difference between pressing on a solid and pressing on a fluid?
 How can you make a fluid all go one way in pressing it? What will
 happen if there be a hole in the tube? Tell about the squirt-gun and
 the stick-gun. Tell about the ball and the gas in a common gun. Tell
 about attraction in solids, and fluids, and gases.


CHAPTER XVIII.

ATTRACTION IN SOLIDS AND FLUIDS.


You saw by what I told you in the latter part of the last chapter that
the great difference between a solid and a fluid is that the particles
of a solid are fastened tightly together, while those of a fluid are
not. If you should tie some people tightly together so that they could
not move away from each other at all, they would be like the particles
of a solid. If you moved them, you would move them all together as you
do a stick of wood, a lump of ice, or any thing else that is solid. You
can not move them, one one way, and another another way, as you can the
particles of water; but if they are all pretty close together, and yet
can move about among each other, as you often see in a crowded company,
they are like the particles of a fluid. You can make your way among
them just as you do among the particles of water when you wade.

[Sidenote: Attraction of the particles of solids illustrated.]

But you will ask, Are the particles of a solid really tied together in
any way? No; but there is something that does the same thing to them as
tying together would. It makes them stick together very tight. We know
not what it is, but we call it attraction. We say that the particles of
a solid attract each other very much. This is really just what a child
would mean by saying that they stick together very close or very tight.
Why they thus attract each other, or how they do it, no one has ever
yet found out.

[Sidenote: Experiment with India-rubber and with bullets.]

It seems to be necessary that the particles should be very near
together to attract each other as hard as they do in a solid. If a
solid is divided in any way, you know that you can not make the two
parts stick close together again. The reason is that you can not bring
the particles near enough to each other to hold together. This is
commonly so, but not always. If you divide a piece of India-rubber,
making a smooth cut with a very sharp knife, you can press the two
parts together so as to make them adhere. Boys often try the following
experiment: A piece is cut off from two bullets, and each cut place
is scraped as smooth as it can be. The two bullets are then pressed
together at these smooth surfaces, and they adhere so well that it
takes considerable pulling to get them apart. Here enough of the
particles on the surfaces are brought near enough together to hold on
to each other, or to attract each other, as it is commonly expressed.

[Sidenote: Drops of water.]

The particles of solids, then, attract each other very much, and it is
this attraction that makes them solid. But how is it with the particles
of liquids? Do they not attract each other? See that drop of water on
a window. Why is it in the shape of a drop? If the particles of water
did not attract each other they would be spread out on the glass. They
would not be in the shape of a drop. They do not attract each other
very much, but enough to keep them together in that shape.

But you can spoil that drop very easily. Put your finger on it, and it
is gone. It is all spread out now, partly on your finger and partly on
the glass. Why is this? It is because the particles attract each other
so little that they are easily separated.

[Sidenote: Drops of water and shot compared.]

Put your finger on a shot, and it remains shot still. Why is it not
gone like the round drop of water? Because its particles attract each
other so much that they are not easily separated. A mere touch will
separate the particles of the drop of water, and make them roll about
any way; but you can not do this to the shot without heating it very
hot. You can melt it, and then it will be, like the water, a liquid.
Its particles now attract each other but little, just as the particles
of water do. And then, again, you can freeze the water, and its
particles attract each other like the particles of the solid shot.

[Sidenote: Quicksilver.]

In some fluids the particles attract each other more strongly than
they do in others. And the more they attract each other, the better
they keep their drop shape. Pour a very little quicksilver on a flat
surface. See the round drops of it roll about! How well they keep their
shape! If you touch them you do not spoil them, as you do a drop of
water when you touch it. If you break one as you touch it, its parts
make only so many little drops or balls. Why is this? It is because the
particles of the quicksilver attract each other so much more than the
particles of water do. They are so attractive to each other that they
are disposed to keep together in little companies.

[Sidenote: Drops on leaves.]

You sometimes see drops of water on the leaves of plants more round and
separate than you see them on window-panes. They roll about like the
little balls of quicksilver. See the reason of this. The particles of
the drop like each other, as we may say, better than they do the leaf.
They are more ready to stick together than they are to stick to the
leaf, and so they roll about on it like little balls. As you see the
drops on the glass, they are not round, because the particles on one
side stick to the glass--that is, they are attracted by it; but the
leaf does not attract the particles so much as the glass does, for it
lets them keep together in a round form. There is a difference between
different leaves about this. On some, the drops of water act as they do
on the window-pane, and on others they do as I have just told you; and
then, on the same leaves, the drops act differently at different times.

[Sidenote: Oil on water.]

If you pour a little oil on water, you see the oil floating in drops.
This is for the same reason that water stands in round drops on some
leaves. The water has no attraction for the oil, and so the particles
of the oil hold together in little companies on the surface of the
water. It is different when oil is spilled upon cloth or wood. It has
so much attraction for them that it mingles up with their fibres,
instead of forming into round companies as it does on the water.

[Sidenote: How shot are made.]

[Sidenote: How shot are round.]

Whenever there is a little of any liquid by itself, it tends to take a
round shape, as seen in the quicksilver, and in the drops of water on
windows and leaves. We see a pretty example of this in the manufacture
of shot. Perhaps you have seen a shot tower. It is very high. All the
shot that are made drop from the top to the bottom. At the top they
have the melted lead. They pour it into a sort of cullender--that is, a
vessel with holes in it. These holes are quite small. From each one of
these holes come out, one after another, drops of the melted lead. Each
drop is round. It cools as it goes down all this long distance in the
air, and by the time that it gets to the bottom of the tower, it is
cold and solid. The shot all fall into a tub of water, so that they may
keep their round shape.

Now why is it that the shot are round? Simply because when they begin
to fall they are melted lead--that is, a fluid. Their particles are
disposed, therefore, to hold together in a round form, like the
particles of quicksilver, or of a drop of water.

[Sidenote: Bullets.]

Bullets are made by pouring the melted lead into moulds. Think, now,
why they can not be made in the same way that shot are. The reason is
that there are more particles in a bullet than can hold together in a
round shape while the lead is fluid. You can not have very large drops
of any fluid. The particles will hold together only in small companies.

[Sidenote: Making soap-bubbles roll.]

There is one thing that you can do with soap-bubbles which perhaps you
have never thought of. You can make them roll on a table or on the
floor by blowing them along. The reason is that the particles of soap
and water mixed together hold on to each other, or attract each other,
better than the particles of water alone.

 _Questions._--What is the great difference between a solid and a
 fluid? Give the comparison about a crowd. Do we know what it is that
 fastens the particles of a solid together? What is it called? What
 is said about the particles being near together? Tell about the
 experiment with the India-rubber and the lead. How do liquids differ
 from solids in attraction? Why is water on a pane of glass often in
 drops? Why is it that you can spoil a drop by a touch? Tell how a shot
 differs from a drop of water. Is the attraction between the particles
 alike in all fluids? Tell about the quicksilver. Tell about the drops
 of water on leaves. Tell about oil dropped upon water. How is it with
 oil spilled upon cloth or wood? Describe shot-making. Why are the shot
 round? How are bullets made? Why can not they be made in the same way
 that shot are? What is said about soap-bubbles?




CHAPTER XIX.

WATER IN THE AIR.


I have told you how water is in motion whenever it can be. It runs
whenever it can get a chance to do it; but it is in motion in another
way, which I will now tell you about.

[Sidenote: From what water goes up into the air.]

You hang out a wet cloth to dry. When it is dry, what has become of the
water that was in it? It has gone somewhere. Where has it gone? It has
flown, like the birds, into the air; but it has gone so quietly that
nobody has seen it go. The little fine particles of the water that I
have told you about have mixed up with the air, and are blown about
with it every where. And so, when you write, as the ink dries on the
paper, the water in it flies off into the air, leaving the dark part of
the ink behind.

There is a great deal of water that is going up into the air in this
way all the time. It goes up from every thing that is wet. After a
shower, the ground, the stones, the houses, the trees, and plants are
all very wet, but in a little time they are dry again. Most of the
water on them has gone up in the air, and is mingled up with it. It
has mingled with it in such a way that you can not see it. The air
is generally as clear with all this water in it as it is when it is
perfectly dry. Even in a bright, clear day, there is a great deal of
water mixed up with the air.

But water goes up into the air not merely from things that appear wet.
You remember that, in Part First, I told you that water is all the
time going out from the pores of the leaves. A great deal of water is
furnished to the air in this way.

[Sidenote: Experiment with the arm and a glass jar.]

Then there is water going up from the skins of animals. Much water goes
from your skin into the air constantly, even when you can not see that
you are perspiring. You can prove this by putting your arm into a glass
jar, and holding it there some time. The inside of the jar will become
covered with the water that comes from the pores of the skin on your
arm. This is like the experiment with leaves noticed on page 77 of Part
First.

[Sidenote: Water in the breath.]

There is water, too, coming out from the lungs of animals and mixing
with the air. It comes from their lungs just as it does from the
leaves, which you know are the lungs of plants. You can see this if you
breathe upon a cold window. The moisture or water that is breathed out
with the air from the lungs gathers upon the glass. In the morning you
often see the panes of the windows in your chamber very wet. All this
water has come from your lungs as you have slept. In a very cold day
the water in your breath freezes upon whatever is about your mouth. You
see the water of the breath of a horse frozen on the hairs about his
mouth.

So you see water is going up into the air all the time from the ground,
the leaves, the animals, and indeed from every thing that is at all
moist. It goes up also in great quantities from seas, rivers, lakes,
etc. Water, then, is always moving. It runs and it flies. It flies up
into the air, and comes down again in the rain to run in the streams.
It is ever going its rounds, going up and coming down, and none of it
ever stays long in one place. The only way in which it can be made to
keep still is to shut it up. Let it be free, and it will soon be gone,
either by running or flying.

[Sidenote: Water in the air seen in fog.]

Commonly the water in the air is not seen, as I have before told you;
but sometimes you can see it. You see it in the breath in a very cold
day. The cold air makes it look like smoke coming out of the mouth. You
see it, too, in the fog. When there is a fog there is a great deal of
water in the air. The reason that you can see it is that the particles
of water are not as finely divided up as when the air is clear. They
are in little companies, as we may say, but there are not enough of
them together to make drops. If they were in companies large enough to
make drops, they would fall to the ground--that is, we should have a
rain.

[Sidenote: A beautiful scene.]

Sometimes the fog is every where; sometimes it hangs only just over
the water. If you are on a very high hill, where you can look off and
see a river in the distance, you can sometimes see in the morning a
line of fog stretching along where the river is, while it is nowhere
else. I once saw a very singular and beautiful scene made by the fog.
I had been out on horseback in the night to visit a sick person. As I
returned, just before sunrise, I saw from a very high hill a thick fog
over all the river below. From the river arose high hills, irregular in
their shape, and on the sides of these hills were houses at different
heights. The lower houses were all so covered by this dense fog that I
could not see them, while those that stood high up on the hills I could
see as plainly as ever. It looked as if a sea had come in while I was
gone on my visit, and had filled up the valley where the river ran, for
the fog rose to the same height on the sides of all the hills. Many
of the houses stood upon the very edge of this sea. The scene was so
beautiful that I waited to see the sun rise upon it. As it rose, it
shone over the tops of the hills, and lighted up this sea of fog, which
it in a little time scattered by its heat.

[Sidenote: Dense fogs often hanging over large cities.]

Very thick fogs often hang over large cities, while all around in the
country the air may be perfectly clear. London is often covered with
such a fog. Sometimes it has been so dense that people could not see
to do any business. It is related that the fog over the city of Paris
was once so thick that persons who went about with torches often ran
against each other, because even lights could not be seen unless they
were very near. And in Amsterdam, in a fog in the year 1790, there were
over two hundred persons drowned by falling in the darkness into the
canals which run through every part of that singular city.

 _Questions._--What becomes of the water when a cloth is dried? Tell
 about the drying of ink on the paper. Tell about water’s going up in
 the air after a shower. Can you commonly see the water that is in the
 air? Does water go into the air from things that do not appear wet?
 What is said about its going from the skins of animals? Tell about
 the experiment with the glass jar. What is said about water’s being
 breathed out from the lungs? In what ways do you see this shown? What
 is said about water’s being in constant motion? When there is a fog,
 why is it that you see the water that is in the air? Tell what is said
 about fogs. Tell about the fogs that hang over large cities.




CHAPTER XX.

CLOUDS.


[Sidenote: Clouds made of fog.]

You see water in the air in another shape besides fog. You see it in
the clouds. A cloud is really fog, but it is high up in the air, while
what we commonly call fog is near the ground.

[Sidenote: Mists.]

Sometimes rain comes from the clouds, and sometimes they give out no
rain. Why is this? When the clouds do not rain, the water in them keeps
in the state of fog. The particles are all in small companies; but
when the rain comes from the clouds, it is because the cold air makes
the particles gather into larger companies, so as to form drops. Then
they fall. A mist is different from rain in this way--the companies
of particles are not as large as in rain. On the other hand, they are
larger than they are in fogs or in clouds.

[Sidenote: How the rain is made to come from clouds.]

You remember what I have told you about the gathering of water upon the
tumblers in warm weather. It is the coldness of the tumbler that does
this. It gathers, or _condenses_, as we commonly say, the water in the
air into companies or drops on the tumbler, just as cold air coming
upon a cloud condenses the water into drops that fall to the earth in
rain.

How swiftly these collections of water, the clouds, are sometimes
carried along by the wind! It seems as if they were chasing each other
across the sky.

[Sidenote: Shapes of clouds.]

How different are the shapes of the clouds! Sometimes they lie along,
stretched out like long straight stripes; and sometimes they are in
heaps, piled up one above another. Then, again, they are spread like
feathers. It seems strange that fog high up in the air should collect
into such different forms, when near the ground it always appears very
much the same.

[Sidenote: Their beauty.]

At morning and evening the clouds are often very beautiful. How do
you think that the rich bright colors are made? They are made by the
sun shining upon the little companies of water-particles of which the
clouds are made. I will tell you more about this when I come to speak
of Light.

The clouds are not so high up in the air as most people think they
are. Some clouds are higher than others, because they are lighter;
and sometimes you can see the clouds that are very high up going in a
different direction from those that are nearer to the earth. This is
because there are often currents of air very high up that do not go
the same way with the winds below. Persons that go up in balloons have
found this to be so, as I have before told you.

[Sidenote: Clouds about mountains.]

Clouds are often seen about the sides of high mountains while the
sun is shining upon their tops; and persons that are on the top of a
mountain may sometimes see clouds below them, while the sky is clear
overhead. I was once on the top of Catskill Mountain when a shower
passed over. The cloud, after it had passed over the mountain, spread
over the country below, so that I looked down upon it. As the cloud was
rather a thin one, it was broken into parts. The sun, therefore, shone
through the openings here and there; and I remember seeing through one
opening in the cloud a beautiful spot, where there was a farm-house
and a pond near by, lighted up by the bright sun shining through
another opening.

[Sidenote: What goes up from the earth to make clouds.]

It is the water that goes up from the earth into the air that makes the
clouds. I have told you from what a variety of things this water comes.
Even the perspiration from your skin and the moisture that is breathed
out from your lungs often help to form the clouds that you see floating
so high in the air.

As I have told you before, water is ever changing, ever moving. It is
silently going up into the air from almost every thing on the earth.
Then you see some of it moving along in the clouds. It falls down in
the rain. It runs in the brooks and the rivers. In the sea it is lashed
into waves by the wind, and is so continually in motion there that the
restless sea is a common expression. Water is always going somewhere.
Even in places where it seems to be still, it is not so; even there,
some of it is all the time going up into the air, and other water comes
to take the place of that which goes up.

[Sidenote: Water a great traveler.]

Water is a great traveler. If any particle of water could write its own
history, and tell where it had been ever since it was created, what a
varied history it would be! Now it is tossed in the waves; now it is
flying off in the air on the wings of the wind; now it is in a cloud;
now it falls in a drop from high up in the air; now it sinks into the
ground, and is sucked up by some plant; and now, perhaps, from the
plant, eaten by some animal, it goes into the blood of that animal.
Thus it goes every where and in all sorts of company. Clean as is the
draught of water that so refreshes you, it is made up of particles
that have been in company with all sorts of things, clean and unclean,
in all parts of the earth.

Observe in what very different ways the water takes its start to go
off up into the air. Much of it goes up from the ground, and from the
surface of lands, and lakes, and seas, and rivers; but a great deal
also is sucked up from the ground by the roots of trees and plants, and
travels up to the leaves to take its flight into the air from them. And
then, too, animals drink water, and eat it in their food, and some of
this flies off into the air from their skins and lungs.

[Sidenote: Water goes up in the air in various ways, and comes down in
different forms.]

The water that goes up in these different ways has also different ways
of getting down upon the earth again. That which is high up in the
form of clouds comes down in different shapes. When cold air meets the
clouds, and changes the water so finely divided in them into drops, it
falls in rain. When the air is cold enough to freeze it, it falls in
the shape of snow or hail.

 _Questions._--What is a cloud? Why does it not always rain when it
 is cloudy? What is the difference between mist and rain? Give the
 comparison between the rain and the gathering of water on a tumbler.
 What is said about the shapes of clouds? What about their colors at
 morning and evening? What is said about the heights of clouds? What
 about clouds around mountains? Tell about the shower on the Catskill
 Mountain. What is said about the moisture from your skin and lungs?
 Tell how the water is always moving and changing. What is said about
 water as a traveler? Tell in what different ways the water goes up in
 the air. In what different ways does it come down, and why?




CHAPTER XXI.

SNOW, FROST, AND ICE.


How different snow is from water! How white it is as it lies upon the
earth like a winding-sheet, covering up the dead leaves and plants! How
the wind that makes waves in the water heaps up the snow in drifts! The
water slips from your hand as you grasp it, but the snow you can make
into hard balls, or roll it up on the ground into larger ones to build
snow forts. The snow lies quietly on the sides of hills and mountains,
from which, the moment that it melts, it runs down into the valley
below.

[Illustration]

[Sidenote: The different forms of the crystals of snow.]

But, different as the snow is from water, it is nothing but frozen
water. It is water made solid; and, as the water becomes solid up in
the air before it falls, it forms itself into many different shapes.
The snow seems to be all alike as you look at it as it falls. But it is
not so. There is variety even here. The snow-flakes have various forms.
We can see how different their shapes are if we look at them with a
microscope, as they are here represented.

Snow-flakes are beautiful things to look at even with the naked eye.
How light, and delicate, and feathery they are! When they are very
large and the air is still, how slowly and steadily they fall! Let a
few of them light upon your coat sleeve, where you can look at them,
and you will admire their beauty; and when we look at them through a
microscope, we see that there is not only beauty, but a great variety
of beauty in them, as there is in all the other works of God.

[Sidenote: Snow-flakes clusters of crystals.]

[Sidenote: The power of God seen in them.]

Perhaps you have sometimes seen large crystals of quartz or other
minerals, and you have admired them because they are so smooth, and
regular, and clear. Now every snow-flake is a bundle of little crystals
as regular and beautiful as the crystals of quartz. There are millions
of these crystals in the snow that you take up in your hand, and in the
falling snow they are put together in all the varied forms that you see
in the figures above. As I told you about the leaves and the flowers
in Part First, so we see, when we examine the snow-flakes, the more we
look into the works of God, the more beauty we shall find in them.

How easy it is for God to fill the air with falling crystals, and to
pile them up thick on the ground! With a free hand he thus scatters
beautiful things in the desolate winter as well as in the blooming
summer, and his power is as much seen in the pure crystals of the
snow-flake as in the delicate and beautiful structures of the leaf and
the flower.

How beautiful is the scene when the snow has fallen gently without
wind, and has covered the branches of trees and bushes! Look up into
a tree thus covered. There the crystals lie, piled up, like tufts of
cotton, out to the very tips of all the branches. Millions and millions
of them are on every twig. How many must there be on the whole tree!
And how many on all the trees and bushes, and over the whole surface of
the ground!

How easily now can God destroy all these crystals! He can send a warm
sun, the wind, or a rain, and they are dissolved and changed into water
again. The earth’s winter robe, all made of pure white gems, is gone.
But God can, whenever he will, turn the clouds above us again into
crystals, and strew the earth with them as before.

[Sidenote: Variety in the figures of frostwork.]

The great variety of forms which water takes when it becomes solid is
often seen on our windows in winter. The figures of the frostwork on
them are, you know, almost endless in their variety. These figures are
made up of little fine crystals, and these crystals are made out of the
water as the cold turns it from a fluid into a solid. How it is that
the little particles of water arrange themselves in these clusters of
crystals, branching out on the glass in all sorts of shapes, we do not
know. God makes them do so in a way that we can not understand. How
little do most people think of the wonderful things he is doing before
them continually! If they are told that God, with his cold, makes the
moisture from their breath into beautiful crystals, they can hardly
believe it, and yet they have seen these crystals in the delicate
frostwork on their windows winter after winter all their lives.

The figures of this crystal frostwork are often like leaves and
flowers, such as we sometimes see on vessels of silver, only much more
delicate and beautiful. It is as if God would smile on us in the very
frosts of winter as he does in the flowers of summer. In these figures,
made of the clustered crystals of the water from our breath, he teaches
us, just as he does in the flowers, that he loves to make things
beautiful for us to enjoy looking upon them.

[Sidenote: Why ice is made lighter than water.]

The ice, often so very thick, is all crystal. And how beautiful it
is when it is formed from clear water in a still place! There is one
thing very singular about ice which I must mention. You know that it is
lighter than water, for it swims on the top of it instead of sinking in
it. This is rather strange. One would suppose that when the fluid water
changed into a solid, it would be heavier, because the particles stick
tighter together then; but somehow, although they stick together much
more tightly, they are farther apart than they were before. It is this
that makes the ice lighter. If they were closer together, of course it
would be heavier.

We do not understand how God has made this to be so, but we can
understand what reason he had for it. It would be very bad to have ice
heavier than water. If it were heavier, there would be a great deal of
ice on the bottom of our rivers, and ponds, and lakes in the winter.
Then it would take a long time for the warm weather to melt this
covered-up ice, and in some places it would not all be melted before
another winter came. This would make bad work, and every year it would
become worse, for there would be additions from year to year to the ice
that is not melted. As it is now, the ice is all cleared out of the way
in most parts of the world in the early spring, because the sun and the
warm rains get at it, and thus the earth becomes ready in a very short
time for the summer.

[Sidenote: Regions of perpetual ice and snow.]

With us the ice and the snow bear rule but a part of the year, but
there are regions in the far north where they are always present. No
summer comes there to melt them. You have heard of the icebergs in the
seas of those regions. These piles of ice often rise like mountains,
and many a noble ship has been crushed by them.

There are mountains, too, in some parts of the world so high that
winter ever rules on their summits. The ice and the snow are ever there
glistening in the sun, even while in the valleys below the golden
harvests are ripening in all their beauty.

 _Questions._--What is said about the difference between snow and
 water? What is snow? Is the snow all alike? What is said about the
 beauty of snow-flakes? What are snow-flakes? Give the comparison
 between them and other crystals. What is true of the flakes of snow
 just as it is of leaves and flowers? What is said about the abundance
 of the crystals of snow? Tell about the tree covered with snow. What
 is said about God’s destroying the crystals of the snow? What is the
 frostwork on the windows in winter? What is said about the figures
 in it? What is ice? What is there very singular about it? What would
 happen if ice were heavier than water? Tell about the regions where
 there are always ice and snow. What is true of some mountains?




CHAPTER XXII.

HEAT AND COLD.


We do not know what heat is. Wise men have tried to find out what it
is, but they have never been able to do it. But we know some things
that heat comes from, and some things that it does, and these I will
tell you about.

[Sidenote: Most of the heat in the world comes from the sun.]

Most of the heat in the world comes from the sun in company with the
light. A long way it travels to get here. It is millions and millions
of miles that it comes in straight lines to us. Then there is the heat
that comes from the fires that we make. Here there is generally light
with the heat, just as there is with that which comes from the sun.

Heat and light, when they come together, do not always keep together,
but are sometimes separated from each other. If you are standing before
a fire and holding a pane of glass before your face, it keeps off the
heat--that is, the heat does not come through the glass, or so little
of it comes through that you do not feel it. The glass stops the heat,
but lets its companion, the light, pass through. Now, if the light of
the sun comes through a window, you feel the heat with it. The light
and heat come through the glass in company. They are not separated
after traveling so many millions of miles together. Why it is different
with the fire and the sun we know not. I suppose that the heat and
light that come from the sun are in some way more closely united than
the heat and light that come from the fire, and therefore are not so
easily parted.

[Sidenote: Heat made in our bodies.]

But heat is often made without any light. This is the case with the
heat of our bodies. There is a sort of burning every where within us
to make the heat, but it is a burning without any flame or light. Our
bodies are not made warm by fire and clothing, but they keep themselves
warm. The only use of our fires and clothing generally is to keep the
heat which is made in our bodies from flying off too fast in the air
around us. A great deal of heat is made in the bodies of all animals,
and the more active they are the more heat they make. You know that
when you play very hard you become very much heated. This is because,
when the heart beats so quickly, sending the blood all over the body so
rapidly, there is more heat manufactured than when the body is still.

[Sidenote: Friction a source of heat.]

Heat is also produced by friction without causing any light. Rub two
smooth sticks together, and see how warm they become. The woodwork of
machinery has been known to take fire from the heat caused by friction;
and Indians used often to kindle their fires by rubbing two sticks
together.

You know how easily a match takes fire by rubbing it. This is because
there is on the end of it a substance that takes fire with a very
little heat, and so requires but a little friction to set it on fire.
This curious substance is phosphorus. It is mixed with sulphur on the
ends of the matches. When once the phosphorus is set on fire with the
friction, it burns the sulphur with it.

[Sidenote: Lucifer matches.]

[Sidenote: The tinder-box.]

It is not many years since the lucifer matches, as they were at first
called, were invented. Before this we had a most inconvenient way of
getting a light when there was no fire at hand. A flint was struck upon
a piece of steel again and again over some tinder. The object was to
make a spark which would set fire to the tinder. This was not always
readily done, and I remember getting out of patience many a time in
working over my tinder-box when I was a student in college.

[Sidenote: Heat made in the earth.]

There is a great deal of heat made inside of the earth, and it is
supposed by some that all the middle of this great round ball that is
called the earth is an immense fire like a furnace. The earthquakes are
supposed to be caused by the heavings of this fire, and the volcanoes
are so many chimneys where the fire of this great furnace gets vent.

[Sidenote: Cold not a thing.]

Heat is a thing, but there is really no such thing as cold. Any thing
is cold when there is but little heat in it. Whether all the heat can
get out of any thing we do not know. There is heat even in ice. This
has been proved in this way: Two pieces of ice were rubbed together
in a very cold day, and some of the ice became melted. How was this?
The air all about the ice was too cold to melt it; and it must be,
therefore, that it was the heat in the ice, waked up, as we may say,
and brought out by the rubbing, that melted the ice.

What feels cold to you may feel warm to another. If, when your hand is
very warm, you take hold of some one’s hand that is only moderately
warm, it will feel cool to you, and perhaps even cold; but if some one
whose hands are quite cold takes hold of the same hand, it will feel to
him quite warm.

[Sidenote: Experiment with three vessels.]

Try a little experiment, which will show the same thing in another way.
Take three vessels. Put into one water as hot as your hand can bear,
into another ice-cold water, and into the third water that is a little
warm, or that has had the chill taken off. Now put one of your hands
into the vessel of hot water, and the other into the vessel of cold
water. Keep them there a little while. Then take them out, and put both
into the vessel that has the water which is slightly warmed. The water
in this will feel cold to the hand which was in the hot water, and warm
to the hand which was in the cold water.

[Sidenote: Drinking water after eating ice-cream.]

For the same reason, water standing in a room will feel quite warm to
you if you have been handling snow, though it is cold to others. So,
also, water that was very cold to you before eating ice-cream, seems,
after eating it, to have lost all its coldness.

So you see that heat and cold are not two things separate from each
other, of which you can tell where one begins and the other ends. It is
convenient to speak of the cold as if it were a thing, just as heat is,
though, as I have told you, it is not; and it is well enough to do so
if we understand the matter right.

 _Questions._--What do we know about heat? From what does most of the
 heat come? What does it come with? What is said about sun-heat and
 fire-heat? Tell about the making of heat in our bodies. What is the
 use of our fires and clothing in cold weather? Why do you become so
 much heated on playing hard? What is said about friction? Explain the
 operation of Lucifer matches. What is said about tinder-boxes? What is
 said about the inside of the earth? When is any thing cold? Is there
 any thing that has no heat in it? How is it proved that there is heat
 in ice? Does what feels cold to one always feel cold to another? Give
 the experiment of the three vessels of water. What other things can be
 explained in the same way?




CHAPTER XXIII.

THE DIFFUSION OF HEAT.

[Sidenote: Experiment showing how heat spreads.]

Heat always tries to spread itself in all directions. If you put the
end of a poker in the fire and hold it there, you do something more
than heat that end. You heat the whole of it up to the end that you
hold in your hand. The reason is, that the heat that comes into the
end of the poker which is in the fire spreads through all of it to the
other end.

[Illustration]

This figure represents an experiment that you can try, which shows
how the heat spreads through any thing solid. A rod or bar of iron
is taken, and small balls of wood are fastened to it, as you see, by
some wax. Now, on heating one end of the bar with a lamp, as the heat
spreads along the bar, the balls one after another drop off, because
the wax that holds them melts.

Heat spreads from one thing to another when it can get a chance to do
it. If one thing that has a good deal of heat in it touches or is near
by another that has less heat in it, it parts with some of its heat,
and lets it go into the other thing, and after a little while one will
be as warm as the other. For this reason, in a warmed room, all the
furniture, the tables, the bureaus, the carpet, and the walls of the
room become heated alike. The heat from the fire spreads through them
all. It takes some time to do this, but it is done.

[Sidenote: How ice is melted.]

It is because heat goes from one thing to another that ice melts in
warm water or warm air. Some of the heat in the water or air goes into
the ice and melts it, and the melting ice cools the water or air by
thus taking a part of its heat.

The heat which I have told you is made in our bodies spreads
continually in the air around us. This is the reason that a room which
is comfortably warm becomes uncomfortably so when a large company has
been in it for a little time. A great deal of heat spreads into the air
from so many bodies.

[Sidenote: How fanning cools us.]

[Sidenote: Blowing on the fingers.]

Did you ever think how fanning cools you? It is by making the heat
go off faster from your body into the air. It moves off the air that
has become heated by your body, and brings some other air to take its
place. For the same reason, blowing upon any thing that is hot helps
to cool it. It brings the air to it faster than it would come without
the blowing, and so the heat passes off faster. But perhaps you will
ask me to explain why it is that blowing on your fingers when they are
cold warms them, when blowing on any thing hot cools it. This is plain
enough. The air that you blow on to your fingers is warmer than they
are, and gives some of its heat to them. If, on the contrary, your
fingers were hot with fever, blowing on them would cool them, for they
would then give some of their heat to the air that is cooler than they
are.

[Sidenote: Wood a poor conductor.]

Heat spreads through some things more easily than it does through
others. It spreads through iron very easily indeed, as you know by
holding an iron poker with one end in the fire, but it does not spread
any thing like as easily through wood. If you hold a stick of wood
with one end in the fire, you can let it burn off without feeling the
heat at the other end; but you could not hold a poker so long in the
fire, for the heat would spread to the end in your hand so much that
it would soon be too hot for you to hold it. So iron is said to be a
better _conductor_ of heat than wood, for the heat is conducted through
it more easily than through the wood.

[Sidenote: Wooden handles.]

[Sidenote: Holders.]

[Sidenote: Ice kept in flannel.]

It is for this reason that wooden handles are put upon some iron tools
that are used in operations about the fire. The tool which the tinman
uses in soldering has a wooden handle. If it had not, his hand would be
burned by the heat going up to it by the iron handle; but very little
of it goes into the wooden handle and spreads there, because wood is so
poor a conductor of heat. We do not need wooden handles for tongs and
pokers, because we do not have to keep them in the fire so long as the
tinman does his soldering-iron. The handle of a metallic tea-pot is,
you know, made of wood; for, if it was metallic, the heat from the tea
would spread through it, and make it so hot that it could not be held
in the hand. The holder which is used in ironing is of service, because
it is so poor a conductor of heat. The heat does not readily go through
it to the hand; so, also, we sometimes use paper to take up things that
are hot, because the paper, being a poor conductor, does not let much
of the heat pass through it to the hand. You have seen people wrap up
ice in flannel to keep it from melting. The flannel here does for the
ice what the woolen or paper holder does for the hand--it prevents the
heat in the air around from getting to the ice.

[Illustration]

[Sidenote: Experiment on a stove.]

Here is represented an experiment which shows how heat spreads through
different things with different degrees of rapidity. Some pieces of
different things of the same size and shape are put on top of a stove.
They are pieces of iron zinc, copper, lead, marble, and brick. On the
top of each is put a little bit of wax. The wax on the copper melts
first, because this is a better conductor of heat than any of the
others. Next is the iron; next, the zinc; next, the lead; next, the
marble; and last of all, the brick.

[Sidenote: Air a poor conductor of heat.]

In air that is kept still heat spreads very slowly; but heat, when it
can, always sets air in motion. I have told you, in Chapter XIII., how
heated air rises and cold air takes its place. This is going on all
the time about a stove. As fast as the air is heated, it goes up by
the stove and the pipe, and cold air keeps coming to the stove to be
heated. In this way all the air in the room is, after a little while,
warmed. Now, if the air could all be kept still instead of being kept
in motion in this way, it would take a long time for the heat to
be spread from the stove through it, for air, like wood, is a poor
conductor of heat.

[Sidenote: Double windows.]

We see the fact that confined air is a poor conductor of heat in a
great many things. Some of them I will mention. You have sometimes seen
double windows. It is the confined air between the outer and the inner
windows that prevents the heat of the air in the room from spreading
to the air out doors. When the window is single, the outside air cools
the air in the room through the window in this way: The air in the room
close to the window gives some of its heat to the glass, and, being
thus cooled, it falls, and some more warm air comes to be cooled in
like manner, and then falls, and so on continually. All this time the
cold air on the outside keeps coming to get warmed by the glass, and as
it is warmed it goes up, and more cold air comes to take its place. But
all this is pretty much prevented where the windows are double, by the
confined air between them.

[Sidenote: A pear kept in snow.]

There is a great deal of air in snow. This is the chief reason that
snow is so apt to keep the ground from being frozen. It is the earth’s
winter coat of confined air, for there is air mingled with its flakes
as they are piled upon each other on the ground. Last spring I picked
up a pear in my garden that was as fresh as it was when it fell upon
the ground in the fall. It happened to lie in a spot where the snow lay
all the winter, and was thus kept from freezing.

[Sidenote: How furs keep in warmth.]

Furs are commonly spoken of as if they had some warmth in them. This
is a mistake. They are not warm of themselves. They only serve to keep
in the heat that is made in the body, and they do this by the air that
is mingled up with the fibres of the fur. This confined air is a poor
conductor, and so the heat made in the body does not readily pass off
through it into the air around. Fur is therefore to an animal, in
this respect, what snow is to the ground, or what double windows are
to a room; and the finer the fur is, the better does it keep the heat
in, because the air is more confined among fine fibres than it is in
coarse hair. And it is curious, that if an animal with thick fur is
taken from the cold country where he belongs to a warm climate, and
kept there, his fur gradually loses its fineness and thickness, and
becomes like hair. This is because he does not need his thick, furry
coat where the weather is warm.

You remember that I told you in Part First that inside of the covering
with which every one of the buds on the trees is protected from the
cold of winter there is a fine down. This, I told you, was the bud’s
little blanket. You can understand, now, how this keeps it from being
chilled by the wintry blasts. It is the air that is confined between
the fibres of this downy blanket that does it.

[Sidenote: Downy blankets of buds.]

[Sidenote: How straw protects trees from cold.]

You remember, also, that I told you in Part First about tying straw
around trees to protect them from the winter’s cold. Now you know that
every stalk of straw is hollow, and so is full of air, and it is the
air in all the stalks of the straw that makes it so good a coat for
the trees. This coat protects them just in the same way, then, that an
animal is protected by its furry coat, or the bud by its blanket of
down.

 _Questions._--What is said of the spreading of heat? What is said
 about its going from one thing to another? How is ice melted? What is
 said about heat’s spreading from our bodies? Tell how fanning cools
 you. Why does blowing a hot thing help to cool it? Why does blowing
 upon cold fingers warm them? Explain what is meant when we say that
 some things are better conductors of heat than others. Give the
 illustrations. How does heat commonly spread in air? How would it be
 if the air could be kept still? Explain how double windows keep the
 heat in. What is said about snow? What about furs? Why does a fine fur
 keep the heat in better than a coarse one? How does taking an animal
 to a warm climate affect the fur? Tell about the blankets of the buds.
 Tell about covering trees with straw.




CHAPTER XXIV.

WHAT HEAT DOES.


Heat makes most things larger, or _expands_ them, as it is commonly
expressed. I will give you some examples of this.

I have already told you in Chapter XIII. how heat expands air. You
remember the two experiments with the bladder before the fire. You
remember also what I told you about the expansion of the air in apples
and chestnuts by heat.

[Illustration]

[Sidenote: Experiment showing how air is expanded by heat.]

Here is represented another experiment which shows that heat expands
air. A glass tube, with a bulb on the end of it, is put with its open
end into a tumbler of water. Of course the tube is full of air. Now, on
putting the warm hand on the bulb, as represented, the air in it will
be warmed. The air, therefore, swells, and there is not room for it all
in the tube; and so some of it escapes in bubbles, as you see, through
the water.

[Sidenote: Snapping of burning wood.]

The snapping wood, you know, often throws out sparks. These are parts
of the wood partly burned that happen to be right on the spot where the
confined heated air was that has broken loose. The more porous wood
is, the more apt it is to snap. The solid walnut seldom snaps; but the
chestnut, which is very porous, is always snapping. So, too, dry wood
snaps more than green, because the sap has dried up, and air has taken
its place in the pipes of the wood.

Air expanded by heat, as you have before seen, always rises. It is
pushed up, as I have already told you, by the colder air, which is
heavier. This keeps the air always moving. It is never still, for heat
is always acting upon it. Even when it is so still that we say there
is no wind, it is not perfectly still. There is all the time the going
up of warm air and the coming down of that which is colder. You can
see this in a room if you shut it up so as to make it quite dark, and
let only a little light in by partly opening one shutter. Though the
air seems to you to be perfectly still, you will see, where this light
is let in, little motes flying up and down. This is because there are
currents in the air, and these are made by heat.

[Sidenote: Air set in motion by heat.]

[Sidenote: Sea breeze.]

It is heat that puts the air in motion so as to produce winds. You have
heard people talk about the cool, refreshing sea breeze. This comes up
commonly in the afternoon. It is caused in this way: The earth becomes
very much heated by the hot sun during the day, and so heats the air
above it. This heated air rises, and the air which comes off from the
cool water to take its place makes the sea breeze.

You see why it is that heated air is lighter than cold air. It is
swelled by the heat without having any thing added to it. Its particles
are put farther apart. It is made thinner, and air, as it becomes
cold, is contracted or made smaller. Its particles are brought closer
together, and so it is made thicker and heavier.

[Sidenote: Liquids expanded by heat.]

And so it is with water or any liquid. When it is heated it becomes
larger and thinner, just as air does, and so is lighter. It rises,
therefore, being pushed up by the heavier cold water. There are,
therefore, the same up and down currents in water that there are in the
air. When one is heating water, the warm water is all the time going
up, and the cold water is going down. If you heat it in a glass vessel,
and have some little light things in the water, you can see them go up
and down in the currents in the same way that you see motes moving up
and down in the currents of the air.

The grocer knows very well that heat expands all liquids. His molasses
and oil are much thinner, and so run more freely in summer than in
winter. And the gallon of molasses or oil that you buy in summer does
not weigh so much as the same quantity in winter, for the same reason
that heated air is lighter than cold air.

[Sidenote: Thermometer explained.]

In the thermometer you see the expansion or swelling of a fluid by
heat. Put your finger on the bulb, and hold it there a little while.
The mercury rises, you see. What is the reason? The warmth of your
finger swells or expands the mercury, and it rises, because it needs
more room. You can do the same thing by breathing on it. Your warm
breath will expand the mercury. This is just what the warm air does to
it; and when the weather is cold, the cold air shrinks or contracts it.
When it is very cold indeed, the mercury is very low down in the tube,
because it is so much contracted by the cold air; and when it is hot
weather, the mercury is very high, because it is so much swollen by
the heat. You can understand, by what I have told you, how it is that
we judge of the heat of the air by the thermometer.

[Sidenote: Setting tires.]

Heat expands solid substances, though not as much as it does the air,
and gases, and liquids. If a rod of iron will just go through a hole in
another piece of iron, you can not get it into that hole when the rod
is heated, because it is swollen or expanded by the heat. The tire of
a wheel is heated when it is put on the wheel. Why this is done I will
explain to you. The tire is made a little too small for the wheel. You
can not put it on the wheel while it is cool, but when it is heated it
goes on very easily, because the heat has made it larger. Cold water is
now poured upon it, and as it contracts it fits very tightly, giving
great firmness to the wheel. It could not be made to fit so tightly in
any other way.

[Sidenote: Heat changing solids into fluids.]

So I have showed you how heat expands various things. It sometimes does
more than this when there is enough of it. It changes a solid into a
fluid. For example, it changes ice into water. So it makes the hard
iron into a fluid so that you can pour it like water, as you can see
in an iron foundry when the workmen are casting. It takes more heat to
melt iron than it does to melt ice, and it takes more to melt ice than
to melt mercury. It takes so little to melt mercury that we can seldom
get a chance to see it solid. In some of the coldest regions of the
earth, however, it is often seen solid.

But heat does more than this. It changes some liquids into something
like air or gas. For example, it changes water into steam. There must
be a great deal of the heat to do this--much more than is required to
change ice into water.

[Sidenote: What heat does to animals and plants.]

[Sidenote: Making of birds in eggs.]

I have told you in Parts First and Second much about what heat does to
life in vegetables and animals. The heat of spring wakes up the seeds
and the buds; and stalks, and leaves, and flowers, and fruits come
forth from them, making the earth cheerful and gay. It wakes up, too,
multitudes of animals, that with their moving about and their various
voices make the world every where so busy. Thus, almost like magic,
does heat work in the animal and vegetable world. I know not any thing
in which the effects of heat are so wonderful as in the egg. Look at a
hen’s egg as it is opened, and see the golden yolk in the midst of the
pure, glairy white. It does not seem that this could be changed into
a chicken, with its bones, and muscles, and nerves, and feathers, and
claws, and by nothing but heat; but so it is. The hen has only to keep
the egg warm by sitting on it, and all this happens; and the chicken,
when it is all formed, bursts the shell, and comes out from its round
white prison.

 _Questions._--How does heat affect most things? Explain the snapping
 of wood on the fire. What are the sparks that are thrown out? What
 kinds of wood snap most? What keeps air moving, and how? How can you
 know that air is not still when it seems to be? What makes the wind?
 What is said about the sea breeze? Why is heated air lighter than cold
 air? How is it with water? What is said about heating water? What
 effect does heat have on molasses and oil? Explain the operation of
 the thermometer. What is said about the expansion of solids by heat?
 Give the experiment of the rod of iron. Explain the putting of a tire
 on a wheel. What is said about the changing of solids into fluids by
 heat? What change does very great heat produce in water? What does
 heat do in the animal and the vegetable world? What is said about the
 egg?




CHAPTER XXV.

STEAM.


[Sidenote: How steam is like air.]

Steam is like air in three things. It is very thin; it is very elastic,
or has a great deal of springiness; and you can not see it. Now perhaps
you will say that this last is not true, and that we often see steam
puffing out of a steam-engine or out of a tea-kettle; but this that we
see is not really steam. It is not like the steam that is in the boiler
of the engine or in the tea-kettle. It is a cloud of fog that the steam
has turned into on coming out into the air. It is just like common fog,
except that it is hot. Real steam you can not see as you see this.

[Sidenote: Steam in boilers and tea-kettles.]

Perhaps you will ask how I know that we can not see steam, as I can not
look into a boiler or a tea-kettle. If we boil water in a glass vessel,
we can see the steam if it can be seen; but we see nothing in the
vessel over the water, and yet we know that there is a plenty of steam
there, for the steam-fog is made in the air by the steam coming out at
the mouth of the vessel.

[Sidenote: How steam is made.]

But we do not need this proof to show us that steam can not be seen.
Look at the nose of a tea-kettle when the water is boiling in it quite
briskly. Close to it, for half an inch or more, you can not see the
steam-fog at all. What is the reason? There is a stream of steam coming
out as fast as it can get out, but the air has not yet had a chance to
change it into fog. It must spread out a little first. When it begins
to spread out, the cool air makes the particles of steam form into
companies, and it is a multitude of these companies that you see in the
cloud of steam, as it is called, that comes from a steam-engine or from
a tea-kettle. The air really changes the steam into water, for fog, as
I have told you in Chapter XIX., is water in companies that are too
small to make drops.

[Sidenote: Simmering.]

See, now, how steam is made out of the water in a tea-kettle. The fire
heats the water that is nearest to it in the kettle. This rises, and
more water comes to take its place and be heated, and so the water
keeps circulating up and down, the warmer going up and the cooler going
down. After a while, when the water all gets to be very hot, you hear a
simmering noise. Now the steam begins to be made. The sound is made by
little bubbles of steam which are formed at the bottom of the kettle.
Soon larger bubbles of steam are made, because so much more of the
water becomes hot enough to be readily made into steam; and the rising
of these bubbles makes a great commotion, as you can see if the water
be in an open pot. All this process of steam-making you can see if the
water is boiled in a thin glass bottle, or flask, as it is called.

[Sidenote: Force of steam.]

There is a great deal of force in steam. It is steam that works the
locomotive, and moves along the great steamship in the water. Sometimes
it shows its power in destruction, as when it bursts a boiler.

Now what is it that makes steam so powerful? To understand this, look
at a locomotive when it is standing still, with its boiler full of
steam. A valve is opened, and out rushes the steam, spreading itself,
and turning into a cloud of fog. It is this trying to spread itself
that makes the steam so powerful. If the valve were not opened the
boiler might explode; for, as the steam is not used as it is while the
locomotive is going, there would be more and more of it in the boiler,
for it is making all the time. The force with which it rushes out when
the valve is opened shows how much power it exerts in trying to spread
itself.

[Sidenote: What makes the lid of a tea-kettle rattle.]

You see the same thing in the rattling of the lid of a tea-kettle when
the water is boiling in it. The steam which is made has not room in the
kettle to spread itself. It gets out, therefore, wherever it can. It
blows out at the nose; and if the water boils very briskly, it can not
get out fast enough at the nose, and so it keeps lifting the lid and
puffing out there.

[Sidenote: Bursting of boilers.]

When the steam is shut up very tightly, as it is in the boiler of a
steam-engine, it has very great power, and the more steam there is thus
shut up the greater is the power. Men are sometimes careless about
this, and get so much steam made in the boiler that it bursts. This is
just as the roasted chestnut is burst by the steam and heated air that
are in it. The boiler bears the pressure of the steam as long as it
can. This pressure is made by the steam’s trying to spread itself, or
by its expansive force, as it is expressed. After a while, the steam
being made all the time, and being crowded together, as we may say, the
boiler all at once gives way with a loud noise. The noise is caused
in the same way as the pop of the roasted chestnut. It is the sudden
shaking that the escaping steam gives to the air.

[Sidenote: Safety valves.]

There is always a safety-valve to a steam-engine. This is commonly
kept shut by a weight which is upon it. But when there comes to be a
great deal of steam in the boiler, it has expansive power enough to
raise the valve, and so some of the steam escapes. This prevents the
boiler from bursting, and hence the valve is called a safety-valve.
Now, if there happen to be a weak place in the boiler, and the weight
on the valve is heavier than it should be, the weak place will be apt
to give way rather than the valve, and an explosion results. Many a
boiler is burst in this way.

[Sidenote: Steam compared to powder.]

I have told you about another way in which boilers are burst in the
chapter on Powder. It is this. The boiler is carelessly left to get
nearly empty, and the fire therefore makes it very hot. Then, when more
water is let into it, a great deal of steam is made all at once. This
exerts its expansive force with such violence that the boiler gives
way. You can understand how this is if you see a little water dropped
upon red-hot iron. A great cloud of steam arises, spreading itself in
the air, and you can see that if this were pent up it would make a
strong pressure in trying to get free.

[Sidenote: Boy melting lead.]

A boy was once much surprised to see the melted lead which he poured
into a piece of elder, from which he had scooped the pith, thrown with
great force against the ceiling. The reason was, that the elder was
moist, and the moisture inside being changed all at once into steam,
the expansive force of the steam threw out the lead, just as the
expansive force of the gas made all at once from powder throws the ball
out of a gun.

[Sidenote: Explosion of a foundry.]

It takes but a little water to make a good deal of steam, and this
explains an explosion that once occurred in a cannon foundry in London.
There happened to be some water in one of the moulds, and, therefore,
when the melted metal was put into it, this water was at once made
into steam, and this, in trying to get free, made such an explosion as
to blow up the whole foundry. Perhaps you can hardly believe that so
little water could do so much when turned suddenly into steam. But you
must remember that the steam occupies, if set free, about 1700 times as
much room as the water does from which it is made. It tries to get this
room, and in doing this it exerts great force, especially if it be made
very suddenly.

[Sidenote: How the sound of the steam-whistle is made.]

You will like to know how the sound of the steam-whistle is made. In
the chapter on the hearing, in Part Second, I told you that sound is
always caused by the vibration or shaking of something. Now in the
steam-whistle there is a sort of bell-shaped thing with a thin edge or
rim. The steam, as it is let out through the whistle, strikes against
this rim, and makes it vibrate, and so produces the sound. The sound is
very loud, because the steam comes out with great force.

 _Questions._--In what three respects is steam like air? Tell about the
 steam-fog. How do we know that steam can not be seen? What is said
 about the steam that comes from the nose of a tea-kettle? Describe how
 steam is made. In what way can you see the whole process? What is said
 about the force of steam? How is its force shown in the locomotive
 when it is stopped at a station? Tell about the rattling of the lid
 of a boiling tea-kettle. Explain how boilers are commonly burst. How
 does the safety-valve operate? How is it that the safety-valve does
 not always keep boilers from bursting? What other way in which boilers
 are burst is mentioned? Tell about the accident with the melted lead.
 Tell about the blowing up of an iron foundry. How is the sound of the
 steam-whistle made?




CHAPTER XXVI.

LIGHT.


As I told you about heat, that we do not know what it is, so, also, we
do not know what light is. But we know many things about light, just as
we do about heat.

[Sidenote: The chief use of light.]

The chief use of light is to enable us and different animals to see. I
have told you something about seeing in Part Second. It is the light
entering the eye that makes us see. When we see the sun, or the flame
of a candle, or a flash of lightning, the light which is made by these
different things goes into the eye, and so we see them.

These things that I have mentioned make light, and some of this light
comes directly to our eyes. But we see things that do not make any
light. No light is made by the houses, and trees, and persons, and many
other things that we see about us. How is it that we see them? It is in
this way: The light that shines on them bounds off from them and goes
into our eyes. Thus, if you see a tree, the light strikes upon it, and
then bounds from it into your eyes, and makes a picture or image there
of the tree. When the light bounds off in this way, it is said to be
_reflected_.

[Sidenote: Reflection of light.]

[Sidenote: Images of things in the eye.]

There is a great deal of this reflection of light. It is often
reflected more than once, sometimes many times. Thus, if you see a tree
in a looking-glass, the light is reflected twice. First, it bounds off
or is reflected from the tree, and then it is reflected from the glass
to your eyes. So if you look at your own face, the light first strikes
your face, and is reflected from it to the glass; and then it is
reflected from the glass to your eyes, and pictures the image of your
face there.

Now observe that the light that is reflected from your face makes an
image or picture of it in the glass. It is precisely such an image that
the light entering your eye makes in the back part of it, on a thin
sheet or membrane that is there, except that it is a much smaller image.

[Sidenote: Smooth and rough things.]

Every thing reflects light, but some things reflect it more than
others. Rough things do not reflect as much as smooth things. How
perfectly the smooth water of a pond reflects the houses and trees at
its side when there is no wind! You know that all polished surfaces
shine. This is because they reflect a great deal of light.

[Sidenote: Moon and stars.]

It is a reflected light that comes to us from the moon and from some of
the stars. The light goes to them from the sun, and then is reflected
from them. They are said, therefore, to shine by a borrowed light. The
reason that we can not see the stars in the daytime is, that the light
from the sun is so much brighter than their light. The moon shines so
much more brightly than the stars, that we can see it in the daytime
when it is above the horizon, though the greater brightness of the sun
makes it quite faint.

I have told you that light is sometimes reflected more than twice, even
many times. When you look at a person in a room into which the sun is
not directly shining, where does the light by which you see him come
from? It is not the light that comes straight from the sun, for this is
not shining upon him. It is the light reflected from things around him.
This reflected light strikes upon him, and is thus again reflected from
him, and some of it enters your eyes, enabling you to see him.

[Sidenote: Light reflected back and forth.]

Light is thus reflected back and forth from one thing to another; and a
great deal of light is reflected from every thing all the time, and in
all directions. Suppose a great assembly are all looking at one person.
The light is reflected from him, and goes into a thousand eyes at once
in all parts of the house, making a picture of him in all of them.
What a wonderful painter light is! How many pictures it is making all
the time in the eyes of men and animals, and on mirrors and all smooth
things every where!

[Sidenote: Light makes plants and animals grow.]

Another use of light is to make plants and animals grow. I have told
you in Part I. how plants turn toward the light, as if they loved it.
It really has a great deal to do with their growth.

This is very plain whenever we see a plant that has grown in the dark.
It looks pale and sickly. A good deal of light is needed as really as a
free circulation of air to make plants healthy and strong; and the same
is true of animals. People that live in dark, under-ground rooms in
cities are injured by the want of light as well as by the want of good
air.

Most of the light in the world comes from the sun. It comes from there
with the heat, as I have before told you. They travel in company. It
is a very long journey. It is many millions of miles. The light is a
little more than eight minutes coming from the sun to the earth.

[Sidenote: Light travels faster than sound.]

Light travels very fast. It travels faster than sound does. You see a
man cutting wood a considerable distance off, and you hear the sound of
each blow of his axe a little after you see it. The reason is that the
light comes from him to your eye quicker than the sound comes to your
ear. You see a cannon fired at a distance; you first see the flash,
and then afterward hear the report. The thunder comes generally some
time after the flash that causes it; that is, the light of the flash
gets to your eye some time before the sound of it reaches your ear. By
observing, it has been found out just how fast sound and light travel;
and so, by looking at a watch in a thunder-storm, we can tell how far
off the lightning is.

Light, besides traveling faster than sound, can travel a great deal
farther. Lightning may be so far off that you can not hear the thunder.
The light reaches your eye, but the sound dies away before it reaches
your ear.

[Sidenote: Light of burning substances.]

Most of our light, I have said, comes from the sun; but much light
comes from burning substances--burning wood, coal, oil, tallow, gas, &c.

[Sidenote: Fire-flies.]

[Sidenote: Shining flowers.]

[Sidenote: Light-wood.]

Light is made by some animals. The glow-worm gives out a soft and
beautiful light. The fire-fly sparkles as it flies about in the
evening. In Cuba and in South America ladies wear in their hair as
ornaments, in evening parties, some small insects that give a very
brilliant light. Sometimes the sea sparkles beautifully with light,
which is made by multitudes of very little animals in it. We see
this light often in the wake of a vessel, or behind the wheel of the
steamer, or in the water that falls from the lifted oar. It is when
the water is disturbed in some way that these animals make their light.
There are some flowers in very warm countries that shine in the night.
You have seen what is called light-wood. This is decayed wood, and it
is something in the decay that makes the light. Light is also sometimes
given out by animal substances that are decaying. It is most often seen
in putrid fish.

[Sidenote: Phosphorus.]

It is supposed that in all these cases the light is made by phosphorus,
the same substance that lights so easily in the Lucifer match. This
curious substance is commonly kept in water. If a stick of it be taken
out of the water in the evening, it appears lighted like a glow-worm;
and if you rub it upon any thing, the streaks of it will give a
brilliant white light. Sometimes, on rubbing a match, if it does not
take fire, you see for a little time lighted streaks where you rubbed
it. This is caused by the phosphorus rubbed off from the match. When
the match burns, you do not see these lighted streaks, for the same
reason that you do not see the stars when the sun shines.

 _Questions._--What is the chief use of light? How do we see? How
 do we see things that do not make light? How do we see things in a
 mirror? How is the image in the mirror like that in the eye? What
 difference is there in things in reflecting light? What is said about
 the light of the moon and the stars? Why can not we see the stars in
 the daytime? Why can we see the moon in the daytime? What is mentioned
 which shows that light is often reflected many times before it comes
 into the eye? Tell what is said about an assembly all looking at a
 speaker. What effect has light upon plants and animals? What is said
 about living in dark rooms? How long is light in coming from the sun?
 Give some examples which show that it travels faster than sound. Can
 sound go as far as light? From what besides the sun does light come?
 Tell about the fire-flies--the sparkling that we often see in the
 sea--light-wood. What is said about phosphorus?




CHAPTER XXVII.

COLOR.


[Sidenote: Why the sun’s light is white.]

[Sidenote: Made up of seven colors, as Newton showed.]

The light that comes from the sun is, you know, a white light. Now in
this white light are the different colors of the rainbow. Indeed, it
is these colors mixed together that make the white color of the sun’s
light. This was proved by Sir Isaac Newton in this way: He had a hole
in a shutter through which he let a very little of the sun’s light into
a dark room. He had a screen for it to strike upon, and on this it made
a bright white spot. He then let it shine through a three-cornered
piece of glass, called a prism. This turned the ray of light out of its
way, and made it shine upon another part of the screen; and, besides
this, the spot of light on the screen, instead of being round, as it
was before, was now lengthened out, and had seven different colors in
it.

[Illustration]

All this is represented on this figure. At O is the hole in the
shutter, and _m_ is a mirror by which a little of the bright sunlight
is thrown into this hole. Without the prism it would go straight to the
screen, S _r_, and make a round white spot where the word _white_ is.
But with the prism, P, the beam of light is turned out of its straight
path, and is divided into the different colors as marked in the figure.
The reason that these colors are seen so distinct from each other is,
that they are bent out of their way in different degrees--the orange a
little more than the red, the yellow a little more than the orange, and
so on, the violet being most bent of all. You see this represented on
the figure.

[Sidenote: Colors in ice.]

This and various other experiments, tried by Newton and others, show
that the white light of the sun is not a simple thing. It can be cut
up, as we may say, into different parts. The glass prism does this. You
have often seen it done without thinking much about it. You have seen
it done by ice. When there has been a rain, and the rain, as it fell,
froze upon the branches of the trees, and the wind and the sun have
together broken the ice on the trees, and strewed the ground with it,
you have seen these pieces of the ice brilliant with all the colors
into which they have divided the bright light of the sun. It seemed as
if the ground was covered with gems of every hue; and as you looked up
into the tree, it seemed to you that every twig also was strung with
gems.

[Sidenote: The rainbow.]

[Sidenote: Colors in dew-drops.]

You see the same thing in the rainbow. The white light of the sun is
separated by the drops of rain into its different colors just as is
done by the glass prism, and thus the bow is made. Exactly how this
is done you are not old enough yet to understand. What you see in the
rainbow and in the scattered pieces of ice you can also sometimes see
in the dew-drops in the morning. They sparkle with all the different
colors. The grass seems to be filled with gems of every variety. The
drops of dew do this by dividing up the sunlight, as the drops of rain
do when the rainbow is made.

[Sidenote: Black no color.]

Now see how it is that different things have different colors. When
a thing is white it is because all the different parts or colors of
the light are reflected from it to our eyes. On the other hand, when
a thing is perfectly black, it is because none of the colors are
reflected. Black is, then, no color at all, while in white all the
colors are mixed together.

[Sidenote: Newton’s experiments with a wheel and with powders.]

Newton proved that white is a mixture of all colors in a very pretty
way. He made a wheel, on the edge of which he painted all the seven
colors. When he whirled it round very fast indeed he could not see the
colors separate from each other. The colors all went to his eye mixed
up together, and being mixed, they made a white color, just as they do
in a beam of light. The rim of the wheel then looked to him as if it
was white.

He proved the same thing in another way. He took powders of these seven
different colors, and ground them together very finely. The colors all
disappeared. The mixed powder was almost white. It would have been
entirely white if he could have mixed the powders as thoroughly as the
colors are mixed by the Creator in the light of the sun.

But I have not yet told you how one thing looks green, another yellow,
another blue, etc. I have only told you why one thing is black and
another white. When a thing looks blue, it is because none but the blue
part of the light is reflected to your eye. All the rest of the colors
stop right there in the thing. They do not bound off from it as the
blue does. So, when a thing is green, the green part of the light is
reflected to your eye. When a thing is orange color, the orange part of
the light is reflected, and so on.

[Sidenote: Why things have different colors explained.]

If you have pieces of glass, and let the light come through them, you
see the same thing in another way. Light coming through blue glass
comes to your eye blue, because all the other colors stop in the glass,
while the blue passes on; and light coming through green glass is green
for the same reason.

Now what is done with the colors that stay in things that they come to
we do not know. If a thing looks blue, only one color out of the whole
seven in the light is thrown off from it. The other six colors, red,
orange, yellow, green, indigo, and violet, stop right there in the
thing. What it does with them is a mystery. It puts them out of sight
in some way, and sends only one of the seven colors to our eyes.

 _Questions._--What makes the color of the sun’s light white? How many
 colors are there in a ray of the sun? Mention Sir Isaac Newton’s
 experiment. Tell what is represented by the figure. What does the
 glass prism do to the light? Tell about the colors of the scattered
 ice. How is the rainbow formed? Tell about the colors in the dew. When
 is a thing white? When is a thing black? Tell about Newton’s painted
 wheel. Tell about his mixture of powders. Explain how it is that one
 thing is blue, another green, another yellow, etc. How is it when
 light comes through things, as colored pieces of glass? What is said
 about the parts of the light that are not reflected by things that we
 see?




CHAPTER XXVIII.

MORE ABOUT COLOR.


[Sidenote: How color is made.]

You see that the color of a thing is not a part of the thing itself. It
is something which the thing throws off or lets pass through it. The
color of a thing depends upon what a thing will do to the light when
the light comes to it. It has no color in the dark. Its color is made
out of the light that shines on it.

[Sidenote: Color not a fixed thing shown in various ways.]

Color is something that is made every moment. The color that you see
now in any thing is made now, out of the light that is shining. If a
piece of cloth looks blue to you, it makes the blue color out of the
light while you are looking at it. The dyer did not really make the
color. The dye that he put it into altered the cloth so that it would
make a blue color go to your eye from the light that comes to the cloth.

You have seen changeable silk. Here the colors change as the silk is
moved. The reason is that, as the light strikes it in different ways,
different parts of the light are reflected from it, and come to our
eyes. For the same reason, as the hanging prisms of a chandelier or a
girandole move, you see the colors in them change. So when the wind
moves the tree covered with ice, or blows along the little pieces
scattered on the ground, you see the same play of colors.

There is another fact which shows that color is not a fixed thing.
It changes with different kinds of light. The light of a lamp or of
a fire is not exactly like the light of the sun. It is not so white,
and so we very often find that a thing which we have looked at in the
evening has quite a different color when we come to see it by the
sunlight. A piece of cloth that looks white by candlelight may look
quite yellow the next morning by the light of day.

[Sidenote: Variety of colors in flowers.]

I have told you in Part First about the great variety of colors in
flowers. All these colors are made out of the same light. If a flower
is yellow, it is because the yellow part of the light is sent to our
eyes, while the flower, as we may say, keeps the other six colors to
itself. Some flowers are more yellow than others. The reason is that
they reflect more of the yellow part of the light. Some leaves are
greener than others because they send to our eyes more of the green
part of the light.

In some flowers there are different colors close by each other. In the
iris you have the blue and the yellow. Here one part of the flower
sends to your eye the blue part of the light, and another the yellow
part. In some flowers you see white close by other colors. Thus one
kind of poppy is white except by the edges, which look as if they had
been dipped in a red dye. How singular it is that, while some parts of
the flower are fitted to send to your eye one color alone, the other
parts send all the seven colors mixed together so as to make a white
color!

[Sidenote: Shading off of colors.]

Look, too, at the gradation of colors. This is very beautiful in some
flowers. In some roses you see the red color shade off into white. You
look at one of its leaves, and see a part of it that is quite red,
and as your eye goes from this part, the red is less and less deep,
till at the very edge it is all gone. Now remember that the more of
the red part of the light is reflected, and the less there is of the
other parts, the greater is the redness, and see how wonderful all this
is. How nicely must the flower be made in order to give this shading
off! In the very red part a great deal of the red color is sent to our
eyes, and none of the other colors. Then from the part close by it a
little less of the red is sent, and a little of the other colors mixed
together is also sent; and so on, a little less and a little less of
the red, and a little more and a little more of the others, till at the
edge all the colors are reflected so as to make it look white.

[Sidenote: In what sense colors are said to come from the sap.]

In Part First I told you that the colors of flowers are made out of the
sap, and now in this chapter I have told you that the colors are really
made from the light. It may seem to you that both of these things can
not be true; but while the colors are made from the light, in one sense
they may also be said to be made from the sap. The flowers are so made
out of the sap that they reflect the right colors from the light that
comes to them. Thus a blue flower is so made as to reflect the blue
part of the light. It is just as blue cloth is fitted by the dye that
it is put into to reflect blue; and as we say that the dyer makes the
cloth blue by his dye, so we say that the flower is made blue from the
sap.

[Sidenote: Colors of leaves in autumn.]

I have told you in Part First about the change of color in the leaves
in the autumn. All the summer the leaves send the green part of the
light to your eyes; but when autumn comes there is some change made in
them, so that some kinds of leaves reflect the red part of the light,
some the yellow, some the orange, etc.

I have told you about the great variety of colors in the plumage of
birds and in the coverings of insects. This variety is all owing to the
different ways in which the light is reflected. Some reflect one of
the seven colors of the light, and others some other color. Some that
reflect all the colors of the light are white, as the swan; and some
that reflect none of them look black, as the crow.

[Sidenote: Colors of clouds.]

Some of the most splendid displays of colors that can be witnessed we
occasionally see in the clouds at morning or evening. Now all this is
caused by nothing but sunlight and water, for you know that the clouds
are made up of water in the shape of fog. The light, as we may say,
paints these gorgeous colors upon the drops of water as they hang in
the air. The reason that we see these displays of colors in the clouds
only at morning and evening is, that the light from the sun strikes
them in the right way then. It strikes them in such a way that some of
the colors are reflected to our eyes, while others are not. The most
common color reflected to our eyes by the clouds is red.

[Sidenote: Play of colors in changeable silks, ice, &c.]

[Sidenote: When and how the rainbow is formed.]

You can see in other things that the color of a thing depends on the
way in which the light strikes it, and is reflected to your eyes. You
see this in the changeable silk. As you move it, the light strikes
it differently, and so different colors are reflected to your eyes.
When you see the ice scattered on the ground from the trees in winter,
shining in the bright sun, you see in one direction all the colors of
the rainbow sparkling from the millions of pieces of ice; but if you
look in the opposite direction you see none of these colors, but the
ice looks white. Why is this? It is because the light on one side of
you strikes the ice and is reflected differently from what it is on
the other side. And you know that it is not after every thunder-shower
that you see a rainbow. The light must strike the rain, and be
reflected to your eyes in a particular way, in order to let you see
the light divided up in the rain into its seven colors in the bow.
You never see a rainbow if the rain is in the same direction with the
sun. If the sun is in the west, the rain must be in the east to have
the bow form; so that you are between the sun and the rain, with your
back to the sun, as you see the bow. Sometimes a rainbow is seen in
the morning, when a cloud comes from the east and it clears off by the
cloud’s passing to the west. But this seldom happens, and the rainbow
is commonly seen in the latter part of the day, the cloud coming from
the west and passing off to the east.

 _Questions._--What is the color of a thing? Does the dyer make color?
 What does he do? What is said about changeable silk? Mention some
 other things in which we see the colors change. What is said about the
 changes of color in different kinds of light? How are the different
 colors of flowers made? How is it when there are different colors in
 the same flower? What is said about the shading off of colors? In what
 sense are the colors of flowers made from the light? And in what sense
 are they made from the sap? What is said about the change of color in
 leaves in autumn? What is said about the colors of birds and insects?
 Tell about the colors of the clouds. Why do we see them at morning and
 evening? What is said about the way in which light strikes a thing and
 is reflected to our eyes? Where and in what part of the day do you
 commonly see the rainbow? Explain this.




CHAPTER XXIX.

ELECTRICITY.


[Sidenote: Lightning in a cat’s back.]

[Sidenote: Lighting gas.]

When you see the lightning in a thunder-storm, you would think it
strange if I should tell you that there is lightning in every thing;
but so it is, as you will see. Did you ever have your fingers tingle,
and hear a snapping when you stroked a cat’s back? This is because you
waked up, as we may say, the lightning in her fur and in your hand
together. There is lightning in you as well as in the cat. It only
needs a little rubbing to show it. I have known persons to light the
gas with the lightning that is in them as readily as you would with
a match. They wake up or excite the lightning by walking across the
carpet, rubbing their feet on it as they go, and then put a finger to
the open gas-burner. A spark of lightning goes to it from the finger
and lights the gas.

It is in very clear cold weather that it is most easy to excite the
lightning or electricity that is in different things. It is then that
you can make the cat’s fur snap. Then, too, silk things will snap when
you rub them or fold them up.

[Sidenote: Lightning is electricity.]

Though it is really lightning that is made by rubbing things, we do
not call it so. We call it electricity. We did not know that lightning
and electricity were the same thing till Dr. Franklin showed that they
were. He found it out by an experiment with a kite, which I will relate
to you after I have told you some other things about electricity.

You can make electricity more easily by rubbing some things than by
rubbing others. I have already told you how easily it is waked up on
the cat’s back by stroking it. If you rub a stick of sealing-wax back
and forth rapidly across your coat sleeve, you wake up a good deal
of electricity for so small a thing. It is shown in this way: If you
bring the sealing-wax near some light thing like down, this will cling
to it for a moment, and then fly off again, as if it did not like the
sealing-wax. It is the electricity which you have excited that does
this.

A good deal of electricity can be made by rubbing glass. In the machine
which is used in making electricity for experiments there is a large
glass cylinder, which is turned round quickly against a leather rubber
that has a preparation of mercury on it.

[Sidenote: Description of an electrical machine.]

[Illustration]

In this machine, represented here, _a_ is the glass cylinder, and _b
b_ are the wheels by which it is made to turn round. These wheels
are worked by the handle which you see on the lower one. The rubber
is pressed against the glass cylinder on the side of it that you do
not see. You can see the standard that holds the rubber. At _c_ is a
piece of oiled silk that is fastened to the rubber, and lies upon the
glass cylinder, serving to keep it free from dust. At _d_ you see a
receiver, as it is called, which receives the electricity as fast as it
is produced. This is made of brass, and has a glass standard, _e_. Now,
as the machine is worked, the electricity excited by the rubber and
the glass passes off continually to this receiver, and there it stays
collected on the surface of it, for it can not go down the standard.
Why is this? you will ask. It is because glass, though a very good
thing to make electricity with, is very slow to let the electricity
pass over it. I shall tell you more about this soon.

[Sidenote: Electricity in the receiver.]

Well, here is the electricity all over this receiver. It stays there
because it can not get away. It is ready to go whenever it can get a
chance. You would find this out if you should put your finger near
that knob that you see on the end of the receiver. Almost all of the
electricity in the receiver would pass through your finger into your
body, and give you a shock; and if there was much electricity in the
receiver, the shock would be harder than you would wish to bear.

[Illustration]

[Sidenote: How a person can be a receiver.]

Now a person can act as a receiver and be charged with electricity
just as this brass receiver is. It can be done in this way. The person
stands on a stool, such as you see here. The top of this, _a_, is
wood, and the legs, _c_, _c_, are glass. These glass legs answer for
him as the glass standard does for the receiver of the machine. They
prevent the electricity that he gets from passing off. If he stood on
the floor, it would pass to the floor as fast as it came to him. As he
stands on this stool, he holds in his hand a chain that is fastened
to the knob on the end of the brass receiver. You can see now what
will happen when the machine is worked. The electricity that goes
from the glass cylinder to the receiver does not all stay there, but
most of it goes on through the chain to the person on the stool. It
can not get from him to the floor, for the glass legs prevent this.
Therefore, after working the machine some time, he becomes filled with
electricity, just as the brass receiver does on its glass standard, and
you can receive a shock from him, for he is now a receiver. If you put
your finger to his nose, or chin, or any other part, the electricity
will pass to you with a spark, and will give you a shock.

[Illustration]

[Sidenote: How electricity affects the hair.]

A curious effect is produced on the hair when one is thus charged with
electricity. The hair stands out straight. This effect is seen in a
very amusing way by having a figure of a head with hair on it fastened
to the receiver. The hair will stand out as you see here.

[Illustration]

[Sidenote: Bottling it up in the Leyden jar.]

The electricity that is collected on the brass receiver can be taken
off and be bottled up, as we may say, so as to be convenient for use.
This can be done with what is called the Leyden jar, as represented
here. This is a glass jar coated inside and out with tin foil to within
a few inches of the top. Then there is a knob on the end of a wire
that extends down into the jar. Now see how we do this bottling up of
the electricity. The knob of the jar is held close to the knob of the
receiver as the machine is worked. The electricity, therefore, passes
to the knob of the jar, and by the wire to all the inside of the jar
where the tin foil is. It can not get outside, because it can not pass
over or through the glass.

So, then, the electricity is shut up in the jar, but it is ready to
come out when it has a way made for it to come. If the inside foil and
the outside foil be connected together by something that will let the
electricity pass through it, it will come out of the jar. You can be
that something if you please. If you put one hand on the tin foil on
the outside, and touch the other to the knob on the end of the wire,
the electricity will come out by the wire, and give you a shock in your
wrists, and elbows, and chest.

[Sidenote: Taking shocks from the jar.]

A great many persons can take a shock in this way at the same time.
Suppose there are a hundred persons standing in a ring and taking
hold of each other’s hands. Let there be two in this ring that do not
have hold of each other. Now, if one of these touches the jar on the
outside, and the other touches the knob, the whole hundred will feel a
shock at the same time, for the electricity will go through them all
around the whole ring as quick as lightning, as we say; and it is, in
this case, really so, for the electricity is lightning. And so, when in
the telegraph the electricity passes along the wire, it takes almost no
time for it to go very great distances.

[Sidenote: An electrical battery.]

[Illustration]

Sometimes a great deal of electricity is collected in a number of these
jars, which are connected together in such a way that the electricity
can be discharged from them all at once. A collection of jars thus
connected, as represented here, is called an electrical battery. There
is need of great care in experimenting with a battery; for if, when
the jars are well filled, they should all be discharged into any one,
he would be killed in the same way that one is who is struck with
lightning.

[Sidenote: Electrical batteries in some animals.]

You remember that I told you, in Part Second, Chapter XXV., that there
are some animals that have electrical machines or batteries in them.
There are only a few such animals, and they are great curiosities. They
can fire off their batteries when they please, but exactly how they do
it we do not know. These batteries are more nicely and curiously made
than any that man makes, and have much more power. They are so small
that it is wonderful that they can give such severe shocks.

 _Questions._--Why does the fur of a cat sometimes snap when it is
 stroked? How can some persons light the gas by their electricity?
 When is the best time to wake up electricity? Who discovered that
 lightning and electricity were the same thing? What things will give
 out electricity easily when rubbed? Describe the electrical machine.
 Why does the electricity stay on the receiver? What will happen if
 you put your finger near the knob on the end of it? Tell how a person
 can be made to act as a receiver. Why can not the electricity go from
 him into the floor? Tell about taking shocks from him. What effect is
 produced on his hair? Tell how electricity can be bottled up. How can
 you get it out of the bottle again? Tell how a great many persons can
 take a shock from the jar at the same time. What is said about the
 quickness with which electricity goes? What is an electrical battery?
 What is said about electricity in some animals?




CHAPTER XXX.

MORE ABOUT ELECTRICITY.


Electricity passes through some things more easily than it does
through others. Those that it passes through easily are said to be
good conductors of electricity. There are some things that let so very
little pass through or over them that they are called non-conductors.
Such are glass and silk. The different metals, copper, silver, iron,
etc., are good conductors.

[Sidenote: The supports of lightning-rods and telegraph wires.]

You have seen how a lightning-rod is fastened to a house. It rests
against pieces of wood. Observe what the object of this is. Iron lets
the electricity or lightning pass much more easily than the wood
does. Now, if the rod was fastened to the house by iron supports, the
lightning, as it came down the rod, might go into the house by some of
these supports, instead of going down by the rod into the ground.

The iron is called a good conductor, while the wood is a poor
conductor. Glass is a poorer conductor still. It is so poor a conductor
that it is called a non-conductor, as I have before told you. It is for
this reason that the telegraph wires are fastened to glass knobs on
the posts. The object is to have all the electricity go along on the
wires, and not let any of it escape down the posts. If a very little of
it should escape down each post, by the time it came to the end of the
journey there might not be enough left to do any good.

[Illustration]

[Sidenote: Dr. Franklin experimenting with his kite.]

Silk, I have told you, is one of the non-conductors. Dr. Franklin made
use of silk in the experiment by which he discovered that lightning
and electricity are the same thing. He managed in this way: He made
his kite of a large silk handkerchief instead of paper. He had on it
a pointed iron wire, and the string of the kite was fastened to this
wire. This kite he sent up in a thunder-storm, when there was a plenty
of electricity in the clouds. The iron wire would of course receive
some of the electricity, and it would not go from the wire to the kite,
because that was made of silk, which, you know, is a non-conductor. It
would go down the string, this being tied to the wire. Passing down the
string, it would go to Dr. Franklin’s hand, and down his body into the
earth. It would do this silently, because it would keep going a little
at a time all the while. But he managed to prevent the electricity from
coming to his hand. He stopped it on the way. He did this by tying a
silk ribbon to the hemp string, and holding the kite by this ribbon, as
you see in the picture. The electricity could not go through this silk,
and so it staid in the hemp string.

[Sidenote: How Dr. Franklin drew the lightning down from the clouds.]

Dr. Franklin now fastened a key to the end of the hemp string. A great
deal of the electricity now passed to the key, because the metal of
which the key was made was so good a conductor. It was a much better
conductor than the string, and so the electricity, as we may say,
spread all over it. It was a real receiver of the electricity, like the
brass receiver of the electrical machine. Accordingly, when Franklin
put his knuckle near the key, he received a shock from it, just as
one does from the knob of the brass receiver. After a little time it
began to rain, and then the shocks were harder. The reason was, that
the string, when wet, was a better conductor than when dry, and so the
electricity came on it faster to the key.

In this way Dr. Franklin drew the lightning down from the clouds in so
small a quantity that he could find out what it was. He found that it
was just the same as the electricity that we make by the electrical
machine, and he could bottle it up in the same way that we do the
electricity from the brass receiver. This he could do by holding the
Leyden jar with its brass knob to the key. The electricity would go
into it just as it does from the receiver when we are working the
machine.

[Sidenote: What Franklin proved.]

Before Franklin tried this experiment with his kite it was supposed
that the lightning was electricity, but it was only supposition. No
one knew that it was so. It was never proved till Franklin sent up
his silk kite to find out about it. It was supposed that lightning
was electricity simply because the effects of lightning were similar
to the effects of the electricity of the machine when a great deal of
this electricity was made. Experiments were tried which showed that
the machine electricity, when there was enough of it, tore things to
pieces, and killed animals, just as lightning does; but the difficulty
was that no one had ever seen what a little of the lightning would do.
This Franklin found out by bringing some of it down out of the clouds
by the string of his kite, and bottling it up for use in the Leyden
jar. Before his experiments nothing was known about lightning except as
it was seen in large quantities going from cloud to cloud, or coming
down to the earth and shivering a tree, or plowing up the ground, or
perhaps killing some animal or some man. Nothing was known of it in a
small way until Franklin showed us so much about it by his experiments.

[Sidenote: Suggested the use of lightning-rods.]

[Sidenote: Lightning-rods protect in two ways.] It was these
experiments of Dr. Franklin that suggested the use of lightning-rods.
These rods protect houses in two ways. One way is this: If the
lightning comes down directly toward a house in a considerable
quantity, instead of striking the house, it will go down the rod into
the ground. Another way in which the rod affords protection is this:
Sometimes the lightning or electricity goes down the rod from the
clouds above in a continual stream of very small quantity, just as it
went down the string of Franklin’s kite. A cloud with a great deal of
electricity in it often has it discharged in this quiet way.

[Sidenote: Use of the points on them.]

You know that there are points on the ends of lightning-rods. These are
to receive the electricity. It will go to them better than it would to
a blunt rod. We know that this is so in working the electrical machine
described on page 145. Instead of having simply the blunt end of the
receiver near the rubber, there are points on that end of it to receive
the electricity as fast as it is made.

 _Questions._--What things are called good conductors of electricity?
 What are called non-conductors? Why are lightning-rods supported
 against a building by pieces of wood? Why are telegraph wires fastened
 to glass knobs on the posts? How did Franklin make his kite? Why
 did he make it of silk instead of paper? How did he prevent the
 electricity that came down the string from going through him into the
 ground? Why was the key so good a receiver of electricity? Tell about
 his taking shocks from it. Why were the shocks stronger after it began
 to rain? How did he bottle up the electricity that he thus drew from
 the clouds? Why was it supposed before his experiment that electricity
 and lightning were the same thing? Why was it not known to be so? In
 what two ways do lightning-rods protect houses? Why are lightning-rods
 pointed?




CHAPTER XXXI.

MAGNETISM.


[Sidenote: The loadstone.]

In some parts of the world a kind of iron ore is found which is called
loadstone. It has a peculiar power. It attracts iron very strongly.
Hold it close to some iron filings, and they will cling to it in quite
a cluster as you raise it up; so, also, you can take up with it a great
many needles, and if it be a large piece of the ore, it will hold
up a very heavy weight. This powder which the loadstone has we call
magnetism.

Now this power in the loadstone can be communicated to iron and steel.
If a loadstone be moved along in a particular way on a piece of iron
or steel several times, the iron or steel will receive this power, and
will act as a magnet, just as the loadstone does. Common iron will not
keep the power long, but steel will.

[Illustration]

[Sidenote: How common magnets are made.]

Most of the magnets that we see are not real loadstone, but they are
steel that has been magnetized by the loadstone. They are commonly
made in a horse-shoe shape, as represented here. They will hold up a
considerable weight of iron, and sometimes twenty-eight times their
own weight; and it is curious that a magnet which holds a weight all
the time will have its power increased. There is no tiring out of its
power; and, on the contrary, if you give a magnet nothing to do, its
power will grow weak--it will not be able to hold up so much weight
as it did at first. It is for this reason that magnets are never left
without a weight hanging to them.

[Sidenote: Toy fishes and ducks moved by a magnet.]

You have perhaps often been amused in making toy fishes or ducks swim
about in the water with a little magnet. You have seen how readily they
follow the magnet, and how quickly they spring forward to hold on to
it, if you happen to put it very near them. This is because each has a
little piece of steel in its mouth which is attracted by the magnet.

[Sidenote: Strangeness of the magnetic power.]

How very strange this power of the magnet is! It is not any thing that
you can see, and yet there the power is. You see what it does. This
unseen power in the magnet takes hold of things and draws them to it,
as our hand, that we see, takes hold of things and draws them to us.
How it does this we do not understand.

This power does not seem to do much at any distance from the magnet. If
you hold your little magnet quite away from the toy duck or fish, it
will not make it move; but bring it near, and now you see it follows
the magnet all about; and if you bring it very near, the little thing,
as quick as a wink, darts forward and clings to the magnet very firmly.
So, too, if you bring an iron weight slowly nearer and nearer to a
large magnet, there does not seem to be any influence from the magnet
upon it till you bring it very near, and then all at once away goes the
weight out of your hand to cling to the magnet. It is as if the magnet
had very short hands that could not reach far; but so far as they do
reach, they are very strong and hold fast. Whenever you get a chance
to see a magnet of considerable size, you can try this experiment.

[Sidenote: The mariner’s compass.]

[Sidenote: How to make one in a simple way.]

You have heard of the mariner’s compass, but perhaps it has never been
explained to you. There is a slender piece of steel in this compass
which always points to the north. It is balanced on a pivot, so that it
can move around easily to the one side or the other. However much it is
jostled, however much you may turn the box of the compass round, this
needle is always tremblingly but surely pointing one way. This needle
is a magnetized piece of steel. We may consider the whole earth, with
all its loadstone and iron, as a great magnet, and it is the influence
of the earth upon the magnetic needle that makes it always point to the
north. You can at any time make a mariner’s compass in a very simple
way. All that you need is a magnetized needle, a piece of cork, and a
bowl of water. Put the cork in the water, and lay the needle across it,
and the needle will point north and south. You see how this is. The
cork moves so readily in the water that the needle in getting right can
turn it as is needed. It will turn almost as easily as the needle does
on its pivot in the compasses that are made.

[Sidenote: St. Paul’s voyage.]

The mariner’s compass, you can see, must be of great use to the
mariner. When he is far out at sea, where no land can be seen, he
always knows by this which way north is, and so he judges how to direct
his vessel in order to reach the desired port. If it were always
sunshine, he would do very well without the compass, for he could tell
by the sun which way was north, and south, and east, and west; but in
stormy weather and in the night he would be at a loss. At such times,
by looking at his ever faithful compass, he knows in what direction to
steer his vessel. You remember about the voyage and shipwreck of the
apostle Paul, related in the 27th chapter of Acts. Nothing was known
about the mariner’s compass then. So “when neither sun nor stars in
many days appeared,” they did not know all this time where the wind was
carrying them. Perhaps if they had had a compass on board they could
have kept the ship from going ashore and being dashed to pieces.

[Sidenote: Electricity and magnetism in the telegraph.]

Magnetism often has a great deal to do with electricity, and some
persons suppose them to be the same thing. Electricity may wake up the
magnetic power to even a wonderful degree. In Morse’s telegraph there
are both electrical machinery and magnetic machinery. The electricity
that comes over the wires excites the magnetic machinery, and it is
this magnetism that delivers the message sent by the electricity. Just
how this operates you can understand better when you are a little older.

 _Questions._--What is loadstone? What peculiar power has it? To what
 can it communicate this power? What are the magnets in common use?
 Why is a weight always kept hanging to a magnet? Tell about the toy
 fishes and ducks. What is said about the strangeness of the magnetic
 power? Does it do much at any distance from the magnet? Give the
 illustrations. What is the mariner’s compass? How can you make one?
 What makes the needle always point to the north? How is the mariner’s
 compass of use at sea? Tell about St. Paul’s shipwreck. What effect
 does electricity often produce upon magnetism? How is it in Morse’s
 telegraph?




CHAPTER XXXII.

GRAVITATION.


If I should ask you why things in the air fall to the ground, you would
probably say it is because it is downward, and every thing must come
down that is not held up in some way. But what is down, and what is up?
This I will explain to you.

[Sidenote: How it is known that the earth is round.]

The earth, as perhaps you know, is as round as an orange, and people
can travel around it just as you can pass your finger around over the
orange. This, indeed, was one of the ways in which it was found to be
round. Another proof of its being round is this: As you see a ship go
out to sea, if you watch it for a long time, after a while the body of
the ship will go out of sight, and you will see nothing but the sails,
and then the sails will gradually go out of sight also. What does this
prove? Why, that the water is not flat, as it appears to be to us, but
that it makes a part of the rounded surface of the earth. This figure
will make this plain to you. The eye that is represented sees the whole
ship at _b_; but when it gets as far as _a_, the eye can see only the
streamer at the top of the mast.

[Illustration]

The reason that we do not see that the earth is round is that we are
so small and the earth is so large. We see that a globe is round, but
it probably seems flat to any little fly that lights upon it, just as
the earth does to us.

[Sidenote: What is up and what is down.]

You can see, then, that as the earth is round, what is down to people
on the other side of the earth is up to us. If a boy there throw up a
ball at the same time that you throw up one here, the two balls fall
toward each other when they come to the ground.

[Sidenote: Figure illustrating this.]

What we call down, then, is simply toward the ground, or, rather, it
is toward the middle of the earth, for we say down in a well or down
in the ground. Indeed, if any thing could keep on in the same line in
which it falls, it would go right to the centre of the earth. If the
ball which you throw up and the ball thrown up by a boy on the other
side of the earth should keep on in the ground in the same direction
that they fall, they would meet exactly at the earth’s centre. This is
represented in this figure. The circle represents the round earth. The
lines drawn from the two falling balls to the middle of the circle show
how they would come together at the centre of the earth if they could
keep on, instead of being stopped when they reach the ground. And all
the things that are falling any where on the earth are going toward the
same point.

[Illustration]

Now why is this? What is it that makes things in the air come to the
ground when they are not held up? They do not come down of themselves.
They are drawn down. The earth attracts or draws them. How it does
this we do not know. We can not see how it is done, but the earth does
it as really as if we could see it put up a hand and pull things down.

[Sidenote: Attraction not a thing that we can see.]

There are other kinds of attraction that operate in a way that we can
not see nor understand. There is the attraction of magnetism. If, as I
have told you in the last chapter, you bring a magnet toward a piece of
iron or steel, for example a needle, when you get it quite near, all
at once the needle will go to the magnet and stick to it. You can not
see any thing between the magnet and the needle to draw the needle to
it. You only know that the needle is drawn or attracted, but you do not
know how this is done.

It is just so with this attraction which the earth has for all things,
drawing them to it. You can not see any thing any more than you can in
the case of the magnet and the needle, but the attraction is as real as
if you could see it. You can see what it does, as you can see what is
done by the attraction of magnetism.

This attraction is called the attraction of gravitation. It is stronger
with some things than it is with others. When any thing is drawn
strongly to the earth, we say that it is very heavy; but when a thing
is not strongly attracted, we say that it is light. When you take
hold of a stone to raise it up, you have this attraction of the earth
acting against you. This is pulling the stone down while your muscles
are trying to raise it. If the stone is very large, the earth attracts
it so strongly that the force of your muscles can not overcome the
attraction. If the earth would only stop pulling upon the stone, you
could raise it easily enough.

[Sidenote: Attraction the cause of weight.]

You see, then, what weight is. It is the pressure made by a thing as
the earth draws or attracts it to itself. The stronger this attraction
is, the greater is the pressure--that is, the weight. If you lay a
foot-ball upon your foot, you scarcely feel the pressure of it; but
if you lay a stone of the same size upon your foot, it presses very
hard. The reason is, that the stone is drawn toward the earth much more
strongly than the foot-ball. The foot-ball is drawn lightly, and so
presses a little; but the stone is drawn much, and so presses a great
deal. Your foot, being between the stone and the earth, is pressed by
the stone as the earth draws it to itself. It is just as you would be
pressed if you were between me and some one that I was drawing toward
me.

The reason that the stone is attracted more strongly, or has more
weight, than the foot-ball is, that there is more substance to it--that
is, the particles in it are closer together. So lead or iron is heavier
than wood, because the wood is much more porous: you can see pores and
spaces in it, while you can not in the lead and iron. You remember
what I told you about the hot-air balloon. This has not as much weight
as it would have if it were full of cold air. The reason is, that the
particles of cold air are closer together than the particles of hot
air; for, you know, heat swells air--that is, it puts its particles
farther apart.

If you drop a bag of feathers, it falls to the ground because the earth
attracts it. If, now, you drop a stone upon this bag, it sinks down
in the midst of it, because the earth attracts it much more strongly
than it does the loose feathers. It is for the same reason that a stone
sinks in water. The earth attracts the stone more than it does the
water.

[Sidenote: Why light things rise in the air and in the water.]

Wood will not sink in water as the stone does, for it is not drawn down
to the earth as hard as the water is; but wood will fall through air to
the ground, because the wood is attracted by the earth more strongly
than the air is. If you put a block of wood down in the water, and
then let it go, it rises to the surface. Why is this? It is because
the water, being more strongly drawn down by the earth than the wood,
pushes the wood up out of the way. It is for the same reason that
the balloon filled with hot air or with light gas rises. It is not
attracted to the earth as much as the cool air around it is, and so it
is pushed up out of the way.

Every thing, you see, then, is attracted by the earth. The air itself
is kept close to the earth by this attraction. It makes a sea, as we
may say, all around the earth about forty-five miles deep. Beyond that
there is no air except around some of the other worlds that we see
far off in the sky. Now the air would fly off and spread every where
among the stars if the earth did not attract it and thus keep it around
itself. The air moves about freely like the water, but it can not fly
away from the earth any more than the water can. The earth keeps both
its air and water all to itself by attraction.

[Sidenote: Every thing tries to get as close to the earth as possible.]

Every thing gets as close to the earth as it can, because every thing
is attracted by the earth. There is nothing that is of itself disposed
to go up, but every thing, even the air, is pressing down, the heaviest
always getting the lowest if it can, and there is sometimes a sort of
strife as to which shall be lowest. When a stone is put upon a heap
of feathers, the earth pulls upon it so much harder than it does on
the feathers that the stone presses to get through them to the earth;
but as it can not thrust them out of the way, it crushes them down in
the struggle to get below them. The struggle is a different one with
the stone in water. The water clings to the earth, but it is easily
pushed away by the stone as it tries to get below the water. Even in
the going up of a balloon you can see the same struggle. It would stay
down if it could. It goes up, as I have before told you, simply because
the cold air about it, being more strongly attracted by the earth than
the balloon is, tries to get below the balloon. If the cold air could
be taken away, the balloon would stay down, for the same reason that
a block of wood would remain in the bottom of a bowl if there were no
water in it. The block, attracted by the earth, will stay as near the
earth as it can. The water pushes it up because it is attracted by the
earth more than the block is, and for the same reason the air pushes up
the balloon.

 _Questions._--What is the common idea about the falling of things to
 the ground? What is one of the proofs that the earth is round? What
 is another proof? Why can not we see that the earth is round? What is
 meant by down and up? Tell what is represented by the figure. What is
 it that makes things fall to the ground? Give the comparison about the
 attraction of magnetism. What is said about the earth’s attracting
 some things more strongly than others? What is weight? Explain by
 telling about the foot-ball and the stone. Why is the stone attracted
 more strongly than the foot-ball? Why are lead and iron heavier than
 wood? Why is a hot-air balloon lighter than the air around it? Tell
 about the feathers and the stone. Why will not wood sink in water as
 stone does? Give the comparison between the block of wood and the
 balloon. What is said about the earth’s attracting the air? Is there
 any thing that does not press down? Which always gets the lowest if
 it can? Tell about the stone put on the feathers and dropped in the
 water. Give the comparison between the balloon and the block of wood
 in a bowl.




CHAPTER XXXIII.

THE MOTION OF THE EARTH.


[Sidenote: Why a ball thrown up comes down.]

When a boy throws a ball up into the air, he thinks that it comes down
of itself. He thinks that it comes down merely because the force with
which he sent it up is spent or lost; but this is not so. It is pulled
down. The earth pulls it down. The earth is pulling upon it all the
time as it goes up, and gradually overcomes the force with which he
threw it up.

There is another thing that helps to overcome the force by which the
ball is sent up. It is the resistance of the air. As the ball goes up,
it has to spend a part of its force in pushing the air away to make a
path for itself.

These two things--the pulling of the earth and the resistance of the
air--gradually stop the going up of the ball. If there was no air, and
if the earth would let the ball go, instead of drawing upon it, it
would not come down. It would fly off out of sight; and more than that,
it would never stop till something stopped it. It could never stop of
itself.

This, perhaps, seems strange to you; but look at it. A ball, you know,
has no power. It lies still if you do not touch it. It can not move
itself, and, for the same reason, it can not stop itself. Once set it
agoing, and it would move on forever if it was not stopped by something.

[Sidenote: Matter can not move itself or stop itself.]

This is true of all matter that is not alive. You can set yourself in
motion, and stop yourself, for you are alive; but common dead matter
can do neither. It moves because it is moved, and it stops because it
is stopped by something.

[Sidenote: How fast the earth moves.]

Now the earth is a ball that is always moving. It never stops for an
instant, but is all the time rolling on around and around the sun. God
a long time ago set it agoing, and it never has been still since. It
takes a year for it to go round the sun; and how fast do you think it
goes? About 68,000 miles an hour--that is, over a thousand miles every
minute. This is two thousand times as fast as the cars go when they are
going very fast indeed. What a ride we are taking on this round ball of
earth!

[Sidenote: Why it does not seem to us to move.]

But you will ask why it is that we do not feel any thing of this
motion, or know something about it, just as we do about the motion of
traveling. The reason of this is very easily seen. Just observe how it
is that you know about the motion in traveling. You see trees, houses,
fences, etc., as you pass by them. You feel the air as you go through
it. If the motion is uneven, you feel it. It is by these things that
you know that you are moving along. But as we are carried along on the
earth as it goes around the sun, there are none of these things to let
us know that we are moving. Every thing goes along with us--trees,
houses, fences, and every thing else. We do not go through the air, but
the air goes along with us. Then, too, the motion is very even. The
earth is not jostled and jarred in its course.

Sometimes, when you are riding in the cars, you hardly seem to move at
all, though you may be really going very fast. The reason of this is
plain. First, the motion is very even; then the air that is in the car
goes along with you, though the air that is outside does not; and the
people in the car that you are looking at are going along with you also.

[Sidenote: Illustrations from the motion of cars in traveling.]

But the moment you look out of the car window you know that the cars
are going quite rapidly, because you see that you are going so fast
by the trees and houses. So, too, if the cars come to a place where
the rails are not so even, the irregular motion lets you know that
you are going fast. Sometimes, when you seem to be going along quite
moderately, because the rails are so even and the road is so straight,
all at once you seem to be twitched along with a very sudden, quick
start. It seems to you as if the cars suddenly went a great deal
faster, but it is not so. The cars are really moving no faster than
before. A turn in the road makes it seem so, because it makes the
motion irregular instead of even.

Now, if the motion of the cars were perfectly even, and you did not
look out, you would not know that they were moving at all. Just so it
is with the earth. Its motion is so even that we do not feel that it
moves at all, though it is carrying us two thousand times as fast as
the cars carry us when they are going thirty-four miles in an hour.

It is true that we look away from the earth as we are riding along on
it just as we look out of the cars; but the sun, and moon, and stars
that we see are so far off that we can not tell by looking at them that
the earth is moving. It seems to us to be standing still. For the same
reason, the cars do not seem to be moving if you look at things a great
way off, instead of those that are near by.

[Sidenote: Mistakes about the earth’s motion.]

A great many mistakes have been made about the motion of the earth,
for things are not always as they appear to be. It seems to us as if
the earth did not move at all; while the sun, and moon, and stars seem
to move, because they are not always in the same direction from us. We
look one way for them at one time, and another way at another time. Now
they do move, but not in the way that they appear to us. The sun seems
to rise, and go up and up, and then go down in the west. But this is
not so. This is all owing to a motion of the earth that I have not yet
told you about. As the earth goes round the sun, it also turns every
day around on itself. It is this motion that makes day and night for
us. As the earth thus rolls over, where the sun shines upon it it is
day, and where it does not shine upon it it is night.

[Sidenote: Its two motions illustrated.]

The earth, then, has two motions. First, it goes round the sun. This,
as I have told you, takes a year; but in every twenty-four hours it
turns over also. This is its second motion. It performs this 365 times
while it is doing the first motion once.

These two motions can be made plain to you with a candle and some round
thing, as an orange. Let the candle represent the sun. Carry the orange
around it in a circle, and this will represent the earth going round
the sun. Now, by turning the orange so that the candle will shine upon
one part of it, and then upon another, and so on all around it, you
will see how the second motion of the earth is done, and how night and
day are made. Any thing that you do not quite understand about this
your teacher will explain to you.

[Sidenote: Leap-year explained.]

The earth, I have told you, turns around on itself 365 times in a
year. But there is one thing about this that I must mention to you. It
takes about six hours over the 365 days for the earth to go round the
sun. Now what is done with this six hours in reckoning the year? It
is managed in this way. It is a quarter part of twenty-four hours, or
a day, and so, to make the reckoning come right, a day is added every
fourth year. It is added to the month of February. Every fourth year
this month has twenty-nine days instead of twenty-eight, and the year
is called leap year.

[Sidenote: Idea of a boy.]

[Sidenote: Galileo.]

Astronomers have discovered a great many things about the shape and the
motions of the earth. Before these were understood, people supposed
that the earth was still, and was flat instead of round, and that
the sun really rose in the east and set in the west; and it seems
so to every body now that has not learned what the astronomers have
discovered. A bright little boy said to a lady who was teaching him
about the earth, You don’t mean to say that the world is round? I know
that it isn’t. I can see that it is flat with my own eyes. She assured
him that the earth was round, but he could not believe it, and replied,
Well, I shall ask my father, for gentlemen commonly know more about
such things than ladies do. You will think it strange when I tell
you that, a little more than two hundred years ago, people generally
believed as this little boy did, and that they put a learned man, named
Galileo, into prison because he said that the earth was round, and that
it went around the sun.

[Sidenote: Why we see only a part of the moon most of the time.]

[Illustration]

You will want to know something about the motion of the moon. As the
earth goes round the sun, so the moon moves around the earth. It takes
a little less than a month for it to get round the earth, and it goes
around it about thirteen times a year. As I have told you in another
chapter, the silvery light which the moon sheds upon us is the light of
the sun reflected by the moon. Why it is that only a part of the moon
shines upon us much of the time, I will explain to you. When there is a
new moon, as it is termed, the moon is in such a position that we can
see only a little of that part of it which the sun shines upon. But
when the moon is at the full, it is in such a position that we see all
of it that is lighted up by the sun. So when the moon quarters, as it
is expressed, we see but a half of the lighted portion, and so on. All
this is made plain by this figure. S is the sun, E is the earth, and
_a_, _b_, _c_, &c., the moon in different positions. When the moon is
at _a_ we can not see any of it, because it is between the earth and
the sun. The sun shines upon the half of the moon that is toward it,
and this half is now all away from our sight. As it leaves _a_ we see
a little of it, and a little more every night; and when it gets to _b_
we see a quarter of the part which the sun shines upon. Then, when it
comes to _c_, we see half of it. When it is at _d_ we see rather more
than half: it is then called gibbous. When it is at _e_ we can see the
whole of the lighted-up part, and so the moon is full. Then at _f_ it
is gibbous again, and at _g_ half moon.

[Sidenote: Eclipse of the moon explained.]

[Illustration]

And now you will want to know how an eclipse of the moon happens. This
I can make plain to you by this figure. A B is the sun, C D the earth,
which is smaller than the sun, and M the moon, which is much smaller
than the earth. Now, as the sun shines upon the earth, there is a dark
shadow beyond the earth, as represented. When the moon, therefore,
happens to pass through this shadow, it is in the dark, and no one on
the earth can see it till it comes out from the shadow. While it is in
the shadow there is an eclipse, as it is termed.

 _Questions._--What two things gradually stop the going up of a ball in
 the air? Could the ball stop of itself? Why can you set yourself going
 and stop yourself? How is it with dead matter? What is said about the
 earth? How fast does it move? How do you know about the motion in
 traveling? Why is it that sometimes, when the cars are going quite
 fast, you scarcely seem to be moving at all? How is it if you look
 out? How is it if the cars come to a place where the rails are uneven,
 or where there is a turn in the road? Give the comparison about
 looking out of the cars and looking away from the earth. Tell about
 the mistakes that have been made about the motion of the earth. How
 is it that day and night are made? Tell about the two motions of the
 earth. Describe how you would make these plain with a candle and an
 orange. Why is a day added to every fourth year, making it leap year?
 What did people suppose about the earth and sun before astronomers
 found out so much about them? Give the anecdote of the little boy.
 Tell about Galileo. Tell about the motion of the moon. Tell about the
 new moon and the full moon. Tell about the eclipse of the moon.




CHAPTER XXXIV.

FRICTION.


Friction sometimes assists motion, and sometimes lessens or prevents
it. I will tell you about this in this chapter.

[Sidenote: Walking on ice.]

When one is walking on ice, he finds that he must be careful, and he
gets along slowly. The reason is that there is not enough rubbing or
friction between his feet and the ice. When he walks on the ground, the
friction between his feet and the ground keeps him from slipping, and
he walks along with perfect ease. If sand or ashes be thrown upon the
ice, the difficulty is removed, for this makes a friction that keeps
him from slipping.

[Sidenote: Sleighing.]

[Sidenote: Sliding down hill.]

How swiftly the horse carries the sleigh along on the trodden snow! It
is because there is so little friction on the smooth iron shoes of the
runners; but let him come to a spot of bare ground, and he has to tug
very hard to draw the sleigh along, because there is so much friction.
You can not slide down hill on your sled when the ground is bare,
simply because the friction is so great; but you can roll down on any
thing that has wheels, because there is less friction with wheels than
with runners.

In carrying heavy loads in carts down steep hills, there is a
contrivance, which perhaps you have seen, to keep the carts from going
down too fast. At the top of the hill the teamster stops his team, and
fastens upon one of the wheels an iron shoe in such a way as to keep
the wheel from turning round. The rubbing of this wheel with its shoe
upon the ground makes the load go down slowly, and therefore safely.

[Sidenote: Driving-wheels of the locomotive.]

It is the steam in the locomotive that makes it go. Did you ever
think how it does this? It is by friction. This I will explain to
you. You see the large wheels of the locomotive. These are called
the driving-wheels, because it is the whirling round of these that
makes the locomotive go. These wheels are whirled around by the steam
machinery, as you can plainly see. It is different with the small
wheels. They turn because the locomotive goes. It is just as the wheels
of a carriage turn round when the horse draws it along. So the large
wheels are to the locomotive what a horse is to a carriage, while the
small wheels do as the common wheels of a carriage do.

[Sidenote: Frosty rails.]

Now see how it is that the driving-wheels carry along the locomotive.
They do it by their rubbing on the rails of the road. If the rails and
the wheels were very smooth indeed, the locomotive would not get along
so well. We sometimes see this in a frosty morning, when the rails are
very slippery. With the rails so smooth, the wheels slip; and they slip
back as readily as forward, just as it is with any one walking on the
ice. They sometimes throw some sand on the rails when they are icy to
give the locomotive a start, as people scatter sand and ashes on icy
sidewalks that they may walk easily on them.

After the wheels of a locomotive are once well started on the frosty
rails, they will go well enough. Indeed, it is sometimes rather
difficult to stop them, because they slide along so easily, for the
motion is partly sliding and partly rolling when the rails are so
smooth. It is for the same reason that one can not stop easily when he
is running on the ice. If he is running on the ground, he can stop very
readily, because the ground is rough, and his feet rub upon it, and
they do not slip as they do on the ice.

[Sidenote: Operation of brakes.]

The way that brakes, as they are called, stop a train of cars, I will
explain to you. You know that the brakeman on each car turns around a
ring-like thing as hard as he can when the signal is given to stop the
cars. In doing this, he brings the brakes against the wheels of the
cars, and the rubbing soon stops them.

When they want to stop the cars very quickly, they do another thing
besides using the brakes. They manage to make the driving-wheels of the
locomotive roll backward instead of forward. In this way the rubbing is
backward on the rails; and as long as the locomotive is going forward,
the wheels slide forward instead of rolling, as they commonly do.

[Sidenote: Oiling machinery.]

[Sidenote: Joints of our bodies.]

You see that sometimes we want friction, and sometimes the less we
have of it the better. We want the friction of the driving-wheels of
a locomotive on the track. But in the middle of these wheels, where
they turn round on their axles, we want to have as little friction as
possible. It is for this reason that all the wheels of the cars and
of the locomotive are kept oiled at this part. So, also, we grease
the wheels of carriages and oil the joints of machinery to lessen the
friction. You will recollect that in the chapter on the bones, in Part
Second, I told you that the joints of our bodies are tipped with a very
smooth substance, and that they are kept oiled, so that there may be
little friction in their motions.

[Sidenote: Friction by water and air.]

Friction is not confined to solid substances. Any substance can make
friction. Water can do it. The rocks over which it flows, or against
which it dashes, are worn by its constant friction, just as the
constant friction of passing feet in the course of years wears the
stone steps of a building which is much frequented.

Air, too, makes friction. It is by friction that the air, moving along
over the smooth water, raises it into waves; and it is the friction of
the air, as it passes over a field of grain, that gives it the wavy
motion which makes it so beautiful.

[Sidenote: Earth moves round the sun without friction.]

Wherever there is motion on the earth, it is lessened more or less by
friction. Nothing moves without rubbing something, but this is not so
with the earth as it goes around the sun. As it flies through space so
swiftly, it rubs against nothing, not even against air, for the air, as
I have told you, goes along with it.

 _Questions._--What does friction do? What is said about walking
 on ice? What about sleighing and sliding down hill? What is the
 contrivance for making heavily-loaded carts go down steep hills
 safely? How does the steam make the locomotive go? What is the
 difference between the driving-wheels and the small wheels? What
 comparison is made about these two kinds of wheels? How do the
 driving-wheels move the locomotive along? What is said about the rails
 being too smooth? How is the difficulty remedied? How is it after the
 locomotive is well agoing when the rails are slippery? What is the
 comparison about running on the ice? How do brakes operate in stopping
 the cars? What else is done when they want to stop the cars quickly?
 What is said about greasing and oiling wheels? What is said about the
 joints of machinery and the joints of our bodies? What is said about
 the friction of water on rocks? What about the friction of air? What
 is true of all motion on the earth? What is said about the earth as it
 goes around the sun?




CHAPTER XXXV.

CONCLUSION.


[Sidenote: Very many things to be learned in this world.]

I have thus, in the Three Parts of this book, described to you some of
the wonderful things that are all around you upon the earth and in the
water. But there are many more things than I have described. In this
book you have only begun to learn what is in the world, and you could
not learn all if you should study all your lifetime, and even if your
life should be as long as Methuselah’s was. But I hope that you will
go on to learn as much as you can. With your mind wide awake, you will
see and hear, as you go about from day to day, a great many interesting
things that I have not mentioned. I have told you about many things
in plants; but if you look at different plants as you meet with them,
you will soon see that you can learn much about them that you can not
find any where in this book. So, also, if you watch animals, large and
small, as you see them, you will find many more interesting things in
them than I have told you. And the same is true of the subjects of the
Third Part--air, water, light, etc. I have only opened to you a few of
the leaves in the Book of Nature, and you can go on to open more of
them for yourselves.

[Sidenote: Think while you look.]

[Sidenote: Every fact valuable.]

To know much about things, you must not merely look at them. You must
examine them--that is, you must think while you look. You must think
what this is for and what that is for. In this way you can find out a
great deal for yourselves. You will not merely see that what I and
others tell you is true, but you will find out things that no one has
told you, and perhaps some things that no one has found out before
you. Newton, who found out so many things that men did not before
know, always thought about things as he saw them; and so did Franklin,
who, as you remember, discovered that lightning is electricity. They
began early, when they were children, to think while they looked. They
had a _habit_ of doing it. If they had not, they would not have been
such discoverers. Though perhaps none of you may ever discover as
many things or as great things as they did, any of you may make some
discoveries. Though your discoveries may be small ones, they are not to
be despised. They will be worth something. _Every fact that is found
out is of some value._ And if you always think while you see and hear,
you may find out for yourselves many facts, and some of them may prove
to be of great value.

Sometimes a fact that would appear to be of no value turns out to be
worth a great deal. Most people would not think that there was much to
be learned from a hen’s muddy tracks on a pile of sugar; but, as you
remember I told you in Part First, Chapter XXIX., some one observed the
fact that the sugar was whitened wherever the tracks were, and thought
about this fact; and the result was that moistened clay came to be used
in every sugar refinery in whitening sugar.

One that is in the habit of thinking while he looks will find something
interesting wherever he goes. He will not be obliged to go to some
museum to see wonderful things, but he will find them all about him.
In the most common plants and animals, which most people do not think
of much, he will see many things to interest and astonish him; and to
him the air and the water, and even the stones under his feet, will be
full of wonders.

[Sidenote: Much to be learned that is not in books.]

You see by what I have said that there is a great deal to be learned
that is not in books. Indeed, books will not do you much good if they
do not wake up in you a disposition to learn more than they tell you.
People that know much are not content with learning merely what they
find in books, but learn what they can from every body and from every
thing. They use books only as helps, and the most of what they know
they learn by observing--that is, seeing and thinking upon what they
see.

[Sidenote: Knowing the reasons of things.]

It is very pleasant to know the reasons of things. I have therefore
told you in this book, as I have gone along, as much as I could do,
why things are as I have described them; but you will remember that I
have now and then said about some things that you are not old enough
yet to understand them. As you grow older you can learn more and more,
and so the things that you will be interested in will be all the time
increasing. But, though you may keep on learning all your lives, there
are some things that you never can understand. God understands the
reasons of every thing, but there are many, very many things that the
wisest of men can not explain.

[Sidenote: What Newton said about what he knew.]

Very wise men are not apt to be proud of their wisdom. They commonly
feel that what they know is very little when it is compared with what
they do not know. Newton was one of the wisest men that ever lived. He
was so wise that he discovered more things than any other man ever
has. But he was very humble about his knowledge. He said this about it:
He felt that what he knew was like a few pebbles that he had picked up
on the sea-shore, and that there was so much of what he did not know
that it was like the great ocean that was before him.

[Sidenote: Our knowledge in another world.]

You remember that I told you in Part Second that all that we know we
learn by the senses of our bodies--the sight, the hearing, etc. But the
glorified bodies which the Bible says that we shall have in another
life will be fitted with better means of getting knowledge. Some things
that are mysterious to us now we shall then understand. We shall know
more than Newton and all the wise men of this world ever knew here, and
we shall ever be learning more and more of the wonders of God’s power,
and wisdom, and goodness.

 _Questions._--What is said about learning all that is in the world?
 How can you learn about things for yourselves? What is said about
 Newton and Franklin? Can you make some discoveries? What is said about
 the value of facts? What about finding wonders all around us? How
 can books help you to learn more than is in them? What is said about
 understanding the reasons of things? What is said about the feelings
 of very wise men? Tell what Newton said about his knowledge. What is
 said about our getting knowledge in another world?


THE END.






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