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Title: The Romance of Modern Invention

Author: Archibald Williams

Release date: October 24, 2012 [eBook #41160]

Language: English

Credits: Produced by Chris Curnow, Matthew Wheaton and the Online
        Distributed Proofreading Team at http://www.pgdp.net (This
        file was produced from images generously made available
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*** START OF THE PROJECT GUTENBERG EBOOK THE ROMANCE OF MODERN INVENTION ***




Produced by Chris Curnow, Matthew Wheaton and the Online
Distributed Proofreading Team at http://www.pgdp.net (This
file was produced from images generously made available
by The Internet Archive)









     [Illustration: _The Sun-Motor used on the Pasadena
     Ostrich-farm, California. It works a pump capable of delivering
     1,400 gallons per minute._ [_See pp. 210, 211._] ]




    THE ROMANCE OF MODERN INVENTION

    CONTAINING INTERESTING DESCRIPTIONS IN
    NON-TECHNICAL LANGUAGE OF WIRELESS
    TELEGRAPHY, LIQUID AIR, MODERN ARTILLERY,
    SUBMARINES, DIRIGIBLE TORPEDOES,
    SOLAR MOTORS, AIRSHIPS, _&c. &c._

    BY

    ARCHIBALD WILLIAMS

    AUTHOR OF "THE ROMANCE OF MODERN MECHANISM"
    "THE ROMANCE OF MODERN ENGINEERING"
    _&c. &c._

    WITH TWENTY-FIVE ILLUSTRATIONS

    LONDON
    SEELEY AND CO. LIMITED
    38 GREAT RUSSELL STREET
    1907




Preface


The object of this book is to set before young people in a bright and
interesting way, and without the use of technical language, accounts
of some of the latest phases of modern invention; and also to
introduce them to recent discoveries of which the full development is
yet to be witnessed.

The author gratefully acknowledges the help given him as regards both
literary matter and illustrations by:--Mr. Cuthbert Hall (the Marconi
Wireless Telegraphy Co.); Mr. William Sugg; Mr. Hans Knudsen; Mr. F.
C. B. Cole; Mr. E. J. Ryves; Mr. Anton Pollak; the Telautograph Co.;
the Parsons Steam Turbine Co.; the Monotype Co.; the Biograph Co.; the
Locomobile Co.; the Speedwell Motor Co.

_September 1902._




    Contents


    WIRELESS TELEGRAPHY

    HIGH-SPEED TELEGRAPHY

    THE TELEPHONE--WIRELESS TELEPHONY

    THE PHONOGRAPH--THE HOTOGRAPHOPHONE--THE TELEPHONOGRAPH

    THE TELAUTOGRAPH

    MODERN ARTILLERY--RIFLES--MACHINE GUNS--HEAVY
    ORDNANCE--EXPLOSIVES--IN THE GUN FACTORY

    DIRIGIBLE TORPEDOES

    SUBMARINE BOATS

    ANIMATED PICTURES

    THE GREAT PARIS TELESCOPE

    PHOTOGRAPHING THE INVISIBLE--PHOTOGRAPHY IN THE DARK

    SOLAR MOTORS

    LIQUID AIR

    HORSELESS CARRIAGES

    HIGH-SPEED RAILWAYS

    SEA EXPRESSES

    MECHANICAL FLIGHT

    TYPE-SETTING BY MACHINERY

    PHOTOGRAPHY IN COLOURS

    LIGHTING




    List of Illustrations


    THE SUN MOTOR USED ON THE PASADENA OSTRICH-FARM

    A CORNER OF MR. MARCONI'S CABIN

    MR. MARCONI'S TRAVELLING STATION

    THE POLDHU TOWER

    GUGLIELMO MARCONI

    HIGH-SPEED TELEGRAPHY: A RECEIVING INSTRUMENT

    HIGH-SPEED TELEGRAPHY. SPECIMEN OF PUNCHED TAPE

    A UNIQUE GROUP OF PHONOGRAPHS

    THE TELAUTOGRAPH: RECEIVER AND TRANSMITTER

    THE TELAUTOGRAPH, SHOWING THE PRINCIPAL PARTS

    THE TELAUTOGRAPH, SPECIMEN OF THE WORK DONE

    THE SIMMS ARMOUR-CLAD MOTOR CAR

    THE "HOLLAND" SUBMARINE BOAT

    AN INTERIOR VIEW OF THE "HOLLAND"

    THE "HOLLAND" SUBMARINE IN THE LAST STAGES OF SUBMERSION

    THE GREAT PARIS TELESCOPE

    THE LIQUID AIR COMPANY'S FACTORY AT PIMLICO

    M. SERPOLLET ON THE "EASTER EGG"

    A MOTOR CAR DRIVEN BY LIQUID AIR

    DIAGRAM OF LIQUID AIR MOTOR CAR

    H.M.S. TORPEDO DESTROYER "VIPER"

    AIRSHIP OF M. SANTOS-DUMONT ROUNDING THE EIFFEL TOWER

    M. SANTOS-DUMONT'S AIRSHIP RETURNING TO LONGCHAMPS

    THE LINOTYPE MACHINE

    THE MONOTYPE CASTING MACHINE




The Romance of Modern Invention




WIRELESS TELEGRAPHY


One day in 1845 a man named Tawell, dressed as a Quaker, stepped into
a train at Slough Station on the Great Western Railway, and travelled
to London. When he arrived in London the innocent-looking Quaker was
arrested, much to his amazement and dismay, on the charge of having
committed a foul murder in the neighbourhood of Slough. The news of
the murder and a description of the murderer had been telegraphed from
that place to Paddington, where a detective met the train and shadowed
the miscreant until a convenient opportunity for arresting him
occurred. Tawell was tried, condemned, and hung, and the public for
the first time generally realised the power for good dormant in the as
yet little developed electric telegraph.

Thirteen years later two vessels met in mid-Atlantic laden with cables
which they joined and paid out in opposite directions, till Ireland
and Newfoundland were reached. The first electric message passed on
August 7th of that year from the New World to the Old. The telegraph
had now become a world-power.

The third epoch-making event in its history is of recent date. On
December 12, 1901, Guglielmo Marconi, a young Italian, famous all over
the world when but twenty-two years old, suddenly sprang into yet
greater fame. At Hospital Point, Newfoundland, he heard by means of a
kite, a long wire, a delicate tube full of tiny particles of metal,
and a telephone ear-piece, signals transmitted from far-off Cornwall
by his colleagues. No wires connected Poldhu, the Cornish station, and
Hospital Point. The three short dot signals, which in the Morse code
signify the letter S, had been borne from place to place by the
limitless, mysterious ether, that strange substance of which we now
hear so much, of which wise men declare we know so little.

Marconi's great achievement, which was of immense importance,
naturally astonished the world. Of course, there were not wanting
those who discredited the report. Others, on the contrary, were seized
with panic and showed their readiness to believe that the Atlantic had
been spanned aërially, by selling off their shares in cable companies.
To use the language of the money-market, there was a temporary "slump"
in cable shares. The world again woke up--this time to the fact that
experiments of which it had heard faintly had at last culminated in a
great triumph, marvellous in itself, and yet probably nothing in
comparison with the revolution in the transmission of news that it
heralded.

The subject of Wireless Telegraphy is so wide that to treat it fully
in the compass of a single chapter is impossible. At the same time it
would be equally impossible to pass it over in a book written with the
object of presenting to the reader the latest developments of
scientific research. Indeed, the attention that it has justly
attracted entitle it, not merely to a place, but to a leading place;
and for this reason these first pages will be devoted to a short
account of the history and theory of Wireless Telegraphy, with some
mention of the different systems by which signals have been sent
through space.

On casting about for a point at which to begin, the writer is tempted
to attack the great topic of the ether, to which experimenters in many
branches of science are now devoting more and more attention, hoping
to find in it an explanation of and connection between many phenomena
which at present are of uncertain origin.

What is Ether? In the first place, its very existence is merely
assumed, like that of the atom and the molecule. Nobody can say that
he has actually seen or had any experience of it. The assumption that
there is such a thing is justified only in so far as that assumption
explains and reconciles phenomena of which we have experience, and
enables us to form theories which can be scientifically demonstrated
correct. What scientists now say is this: that everything which we
see and touch, the air, the infinity of space itself, is permeated by
a _something_, so subtle that, no matter how continuous a thing may
seem, it is but a concourse of atoms separated by this something, the
Ether. Reasoning drove them to this conclusion.

It is obvious that an effect cannot come out of nothing. Put a clock
under a bell-glass and you hear the ticking. Pump out the air and the
ticking becomes inaudible. What is now not in the glass that was there
before? The air. Reason, therefore, obliges us to conclude that air is
the means whereby the ticking is audible to us. No air, no sound.
Next, put a lighted candle on the further side of the exhausted
bell-glass. We can see it clearly enough. The absence of air does not
affect light. But can we believe that there is an absolute gap between
us and the light? No! It is far easier to believe that the bell-glass
is as full as the outside atmosphere of the something that
communicates the sensation of light from the candle to the eye. Again,
suppose we measure a bar of iron very carefully while cold and then
heat it. We shall find that it has expanded a little. The iron atoms,
we say, have become more energetic than before, repel each other and
stand further apart. What then is in the intervening spaces? Not air,
which cannot be forced through iron whether hot or cold. No! the
ether: which passes easily through crevices so small as to bar the way
to the atoms of air.

[Illustration: _A Corner of M. Marconi's cabin on board S.S.
"Minneapolis," showing instruments used in Wireless Telegraphy._]

Once more, suppose that to one end of our iron bar we apply the
negative "pole" of an electric battery, and to the other end the
positive pole. We see that a current passes through the bar, whether
hot or cold, which implies that it jumps across all the ether gaps, or
rather is conveyed by them from one atom to another.

The conclusion then is that ether is not merely omnipresent,
penetrating all things, but the medium whereby heat, light,
electricity, perhaps even thought itself, are transmitted from one
point to another.

In what manner is the transmission effected? We cannot imagine the
ether behaving in a way void of all system.

The answer is, by a wave motion. The ether must be regarded as a very
elastic solid. The agitation of a portion of it by what we call heat,
light, or electricity, sets in motion adjoining particles, until they
are moving from side to side, but not forwards; the resultant movement
resembling that of a snake tethered by the tail.

These ether waves vary immensely in length. Their qualities and
effects upon our bodies or sensitive instruments depend upon their
length. By means of ingenious apparatus the lengths of various waves
have been measured. When the waves number 500 billion per second, and
are but the 40,000th of an inch long they affect our eyes and are
named light--red light. At double the number and half the length, they
give us the sensation of violet light.

When the number increases and the waves shorten further, our bodies
are "blind" to them; we have no sense to detect their presence.
Similarly, a slower vibration than that of red light is imperceptible
until we reach the comparatively slow pace of 100 vibrations per
second, when we become aware of heat.

Ether waves may be compared to the notes on a piano, of which we are
acquainted with some octaves only. The gaps, the unknown octaves, are
being discovered slowly but surely. Thus, for example, the famous
X-rays have been assigned to the topmost octave; electric waves to the
notes between light and heat. Forty years ago Professor Clerk Maxwell
suggested that light and electricity were very closely connected,
probably differing only in their wave-length. His theory has been
justified by subsequent research. The velocity of light (185,000 miles
per second) and that of electric currents have been proved identical.
Hertz, a professor in the university of Bonn, also showed (1887-1889)
that the phenomena of light--reflection, refraction, and concentration
of rays--can be repeated with electric currents.

We therefore take the word of scientists that the origin of the
phenomena called light and electricity is the same--vibration of
ether. It at once occurs to the reader that their behaviour is so
different that they might as well be considered of altogether
different natures.

For instance, interpose the very thinnest sheet of metal between a
candle and the eye, and the light is cut off. But the sheet will very
readily convey electricity. On the contrary, glass, a substance that
repels electricity, is transparent, _i.e._ gives passage to light. And
again, electricity can be conveyed round as many corners as you
please, whereas light will travel in straight lines only.

To clear away our doubts we have only to take the lighted candle and
again hold up the metal screen. Light does not pass through, but heat
does. Substitute for the metal a very thin tank filled with a solution
of alum, and then light passes, but heat is cut off. So that heat and
electricity _both_ penetrate what is impenetrable to light; while
light forces a passage securely barred against both electricity and
heat. And we must remember that open space conveys all alike from the
sun to the earth.

On meeting what we call solid matter, ether waves are influenced, not
because ether is wanting in the solid matter, but because the presence
of something else than ether affects the intervening ether itself.
Consequently glass, to take an instance, so affects ether that a very
rapid succession of waves (light) are able to continue their way
through its interstices, whereas long electric waves are so hampered
that they die out altogether. Metal on the other hand welcomes slow
vibrations (_i.e._ long waves), but speedily kills the rapid shakes of
light. In other words, _transparency_ is not confined to light alone.
All bodies are transparent to some variety of rays, and many bodies to
several varieties. It may perhaps even be proved that there is no
such thing as absolute resistance, and that our inability to detect
penetration is due to lack of sufficiently delicate instruments.

The cardinal points to be remembered are these:--

That the ether is a universal medium, conveying all kinds and forms of
energy.

That these forms of energy differ only in their rates of vibration.

That the rate of vibration determines what power of penetration the
waves shall have through any given substance.

Now, it is generally true that whereas matter of any kind offers
resistance to light--that is, is not so perfect a conductor as the
ether--many substances, especially metals, are more sensitive than
ether to heat and electricity. How quickly a spoon inserted into a hot
cup of tea becomes uncomfortably hot, though the hand can be held very
close to the liquid without feeling more than a gentle warmth. And we
all have noticed that the very least air-gap in an electric circuit
effectively breaks a current capable of traversing miles of wire. If
the current is so intense that it insists on passing the gap, it leaps
across with a report, making a spark that is at once intensely bright
and hot. Metal wires are to electricity what speaking tubes are to
sound; they are as it were electrical tubes through the air and ether.
But just as a person listening outside a speaking tube might faintly
hear the sounds passing through it, so an instrument gifted with an
"electric ear" would detect the currents passing through the wire.
Wireless telegraphy is possible because mankind has discovered
instruments which act as _electric ears or eyes_, catching and
recording vibrations that had hitherto remained undetected.

The earliest known form of wireless telegraphy is transmission of
messages by light. A man on a hill lights a lamp or a fire. This
represents his instrument for agitating the ether into waves, which
proceed straight ahead with incredible velocity until they reach the
receiver, the eye of a man watching at a point from which the light is
visible.

Then came electric telegraphy.

At first a complete circuit (two wires) was used. But in 1838 it was
discovered that if instead of two wires only one was used, the other
being replaced by an earth connection, not only was the effect equally
powerful, but even double of what it was with the metallic circuit.

Thus the first step had been taken towards wireless electrical
telegraphy.

The second was, of course, to abolish the other wire.

This was first effected by Professor Morse, who, in 1842, sent signals
across the Susquehanna River without metallic connections of any sort.
Along each bank of the river was stretched a wire three times as long
as the river was broad. In the one wire a battery and transmitter were
inserted, in the other a receiving instrument or galvanometer. Each
wire terminated at each end in a large copper plate sunk in the water.
Morse's conclusions were that provided the wires were long enough and
the plates large enough messages could be transmitted for an
indefinite distance; the current passing from plate to plate, though a
large portion of it would be lost in the water.[1]

     [1] It is here proper to observe that the term _wireless_
     telegraphy, as applied to electrical systems, is misleading,
     since it implies the absence of wires; whereas in all systems
     wires are used. But since it is generally understood that by
     wireless telegraphy is meant telegraphy without _metal
     connections_, and because the more improved methods lessen more
     and more the amount of wire used, the phrase has been allowed
     to stand.

About the same date a Scotchman, James Bowman Lindsay of Dundee, a man
as rich in intellectual attainments as he was pecuniarily poor, sent
signals in a similar manner across the River Tay. In September, 1859,
Lindsay read a paper before the British Association at Dundee, in
which he maintained that his experiments and calculations assured him
that by running wires along the coasts of America and Great Britain,
by using a battery having an acting surface of 130 square feet and
immersed sheets of 3000 square feet, and a coil weighing 300 lbs., he
could send messages from Britain to America. Want of money prevented
the poor scholar of Dundee from carrying out his experiments on a
large enough scale to obtain public support. He died in 1862, leaving
behind him the reputation of a man who in the face of the greatest
difficulties made extraordinary electrical discoveries at the cost of
unceasing labour; and this in spite of the fact that he had undertaken
and partly executed a gigantic dictionary in fifty different
languages!

[Illustration: _M. Marconi's Travelling Station for Wireless
Telegraphy._]

The transmission of electrical signals through matter, metal, earth,
or water, is effected by _conduction_, or the _leading_ of the
currents in a circuit. When we come to deal with aërial transmission,
_i.e._ where one or both wires are replaced by the ether, then two
methods are possible, those of _induction_ and Hertzian waves.

To take the induction method first. Whenever a current is sent through
a wire magnetism is set up in the ether surrounding the wire, which
becomes the core of a "magnetic field." The magnetic waves extend for
an indefinite distance on all sides, and on meeting a wire _parallel_
to the electrified wire _induce_ in it a _dynamical_ current similar
to that which caused them. Wherever electricity is present there is
magnetism also, and _vice versâ_. Electricity--produces
magnetism--produces electricity. The invention of the Bell telephone
enabled telegraphers to take advantage of this law.

In 1885 Sir William Preece, now consulting electrical engineer to the
General Post-Office, erected near Newcastle two insulated squares of
wire, each side 440 yards long. The squares were horizontal, parallel,
and a quarter of a mile apart. On currents being sent through the one,
currents were detected in the other by means of a telephone, which
remained active even when the squares were separated by 1000 yards.
Sir William Preece thus demonstrated that signals could be sent
without even an earth connection, _i.e._ entirely through the ether.
In 1886 he sent signals between two parallel telegraph wires 4-1/2
miles apart. And in 1892 established a regular communication between
Flatholm, an island fort in the Bristol Channel, and Lavernock, a
point on the Welsh coast 3-1/3 miles distant.

The inductive method might have attained to greater successes had not
a formidable rival appeared in the Hertzian waves.

In 1887 Professor Hertz discovered that if the discharge from a Leyden
jar were passed through wires containing an air-gap across which the
discharge had to pass, sparks would also pass across a gap in an
almost complete circle or square of wire held at some distance from
the jar. This "electric eye," or detector, could have its gap so
regulated by means of a screw that at a certain width its effect would
be most pronounced, under which condition the detector, or receiver,
was "in tune" with the exciter, or transmitter. Hertz thus established
three great facts, that--

     (_a_) A discharge of static (_i.e._ collected) electricity
     across an air-gap produced strong electric waves in the ether
     on all sides.

     (_b_) That these waves could be _caught_.

     (_c_) That under certain conditions the catcher worked most
     effectively.

Out of these three discoveries has sprung the latest phase of wireless
telegraphy, as exploited by Signor Marconi. He, in common with
Professors Branly of Paris, Popoff of Cronstadt, and Slaby of
Charlottenburg, besides many others, have devoted their attention to
the production of improved means of sending and receiving the Hertzian
waves. Their experiments have shown that two things are required in
wireless telegraphy--

     (i.) That the waves shall have great penetrating power, so as
     to pierce any obstacle.

     (ii.) That they shall retain their energy, so that a _maximum_
     of their original force shall reach the receiver.

The first condition is fulfilled best by waves of great length; the
second by those which, like light, are of greatest frequency. For best
telegraphic results a compromise must be effected between these
extremes, neither the thousand-mile long waves of an alternating
dynamo nor the light waves of many thousands to an inch being of use.
The Hertzian waves are estimated to be 230,000,000 per second; at
which rate they would be 1-1/2 yards long. They vary considerably,
however, on both sides of this rate and dimension.

Marconi's transmitter consists of three parts--a battery; an induction
coil, terminating in a pair of brass balls, one on each side of the
air-gap; and a Morse transmitting-key. Upon the key being depressed, a
current from the battery passes through the coil and accumulates
electricity on the brass balls until its tension causes it to leap
from one to the other many millions of times in what is called a
spark. The longer the air-gap the greater must be the accumulation
before the leap takes place, and the greater the power of the
vibrations set up. Marconi found that by connecting a kite or balloon
covered with tinfoil by an aluminium wire with one of the balls, the
effect of the waves was greatly increased. Sometimes he replaced the
kite or balloon by a conductor placed on poles two or three hundred
feet high, or by the mast of a ship.

We now turn to the receiver.

In 1879 Professor D. E. Hughes observed that a microphone, in
connection with a telephone, produced sounds in the latter even when
the microphone was at a distance of several feet from coils through
which a current was passing. A microphone, it may be explained, is in
its simplest form a loose connection in an electric circuit, which
causes the current to flow in fits and starts at very frequent
intervals. He discovered that a metal microphone stuck, or cohered,
after a wave had influenced it, but that a carbon microphone was
self-restoring, _i.e._ regained its former position of loose contact
as soon as a wave effect had ceased.

In 1891 Professor Branly of Paris produced a "coherer," which was
nothing more than a microphone under another name. Five years later
Marconi somewhat altered Branly's contrivance, and took out a patent
for a coherer of his own.

It is a tiny glass tube, about two inches long and a tenth of an inch
in diameter inside. A wire enters it at each end, the wires
terminating in two silver plugs fitting the bore of the tube. A space
of 1/32 inch is left between the plugs, and this space is filled with
special filings, a mixture of 96 parts of nickel to 4 of silver, and
the merest trace of mercury. The tube is exhausted of almost all its
air before being sealed.

This little gap filled with filings is, except when struck by an
electric wave, to all practical purposes a non-conductor of
electricity. The metal particles touch each other so lightly that they
offer great resistance to a current.

But when a Hertzian wave flying through the ether strikes the coherer,
the particles suddenly press hard on one another, and make a bridge
through which a current can pass. The current works a "relay," or
circuit through which a stronger current passes, opening and closing
it as often as the coherer is influenced by a wave. The relay actuates
a tapper that gently taps the tube after each wave-influence, causing
the particles to _de_cohere in readiness for the succeeding wave, and
also a Morse instrument for recording words in dots and dashes on a
long paper tape.

The coherer may be said to resemble an engine-driver, and the "relay"
an engine. The driver is not sufficiently strong to himself move a
train, but he has strength enough to turn on steam and make the engine
do the work. The coherer is not suitable for use with currents of the
intensity required to move a Morse recorder, but it easily switches a
powerful current into another circuit.

Want of space forbids a detailed account of Marconi's successes with
his improved instruments, but the appended list will serve to show
how he gradually increased the distance over which he sent signals
through space.

In 1896 he came to England. That year he signalled from a room in the
General Post-Office to a station on the roof 100 yards distant.
Shortly afterwards he covered 2 miles on Salisbury Plain.

In May, 1897, he sent signals from Lavernock Point to Flatholm, 3-1/3
miles. This success occurred at a critical time, for Sir W. Preece had
already, as we have seen, bridged the same gap by his induction
method, and for three days Marconi failed to accomplish the feat with
his apparatus, so that it appeared as though the newer system were the
less effective of the two. But by carrying the transmitting instrument
on to the beach below the cliff on which it had been standing, and
joining it by a wire to the pole already erected on the top of the
cliff, Mr. Marconi, thanks to a happy inspiration, did just what was
needed; he got a greater length of wire to send off his waves from.
Communication was at once established with Flatholm, and on the next
day with Brean Down, on the other side of the Bristol Channel, and
8-2/3 miles distant. Then we have--

    Needles Hotel to Swanage          17-1/2 miles.
    Salisbury to Bath                     34   "
    French Coast to Harwich               90   "
    Isle of Wight to The Lizard          196   "
    At Sea (1901)                        350   "
    Dec. 17, 1901, England to America   2099   "

[Illustration: _Poldhu Towers, the Station put down by the Marconi
Wireless Telegraph Company, Limited, for carrying on a system of
transatlantic wireless telegraphy between England and America. From
the four towers are suspended the ærial wires which are carried into
the buildings in the centre. The towers are 215 feet in height, and
are made of wood._]

A more pronounced, though perhaps less sensational, success than even
this last occurred at the end of February, 1902. Mr. Marconi, during a
voyage to America on the s.s. _Philadelphia_ remained in communication
with Poldhu, Cornwall, until the vessel was 1550 miles distant,
receiving messages on a Morse recorder for any one acquainted with the
code to read. Signals arrived for a further 500 miles, but owing to
his instruments not being of sufficient strength, Mr. Marconi could
not reply.

When the transatlantic achievement was announced at the end of 1901,
there was a tendency in some quarters to decry the whole system. The
critics laid their fingers on two weak points.

In the first place, they said, the speed at which the messages could
be transmitted was too slow to insure that the system would pay. Mr.
Marconi replied that there had been a time when one word per minute
was considered a good working rate across the Atlantic cable; whereas
he had already sent twenty-two words per minute over very long
distances. A further increase of speed was only a matter of time.

The second objection raised centred on the lack of secrecy resulting
from signals being let loose into space to strike any instrument
within their range; and also on the confusion that must arise when the
ether was traversed by many sets of electric waves.

The young Italian inventor had been throughout his experiments aware
of these defects and sought means to remedy them. In his earliest
attempts we find him using parabolic metal screens to project his
waves in any required direction and prevent their going in any other.
He also employed strips of metal in conjunction with the coherer, the
strips or "wings" being of such a size as to respond most readily to
waves of a certain length.

The electric oscillations coming from the aerial wires carried on
poles, kites, &c., were of great power, but their energy dispersed
very quickly into space in a series of rapidly diminishing vibrations.
This fact made them affect to a greater or less degree any receiver
they might encounter on their wanderings. If you go into a room where
there is a piano and make a loud noise near the instrument a jangle of
notes results. But if you take a tuning-fork and after striking it
place it near the strings, only one string will respond, _i.e._ that
of the same pitch as the fork.

What is required in wireless telegraphy is a system corresponding to
the use of the tuning-fork. Unfortunately, it has been discovered that
the syntony or tuning of transmitter and receiver reduces the distance
over which they are effective. An electric "noise" is more
far-reaching than an electric "note."

Mr. Marconi has, however, made considerable advances towards combining
the sympathy and secrecy of the tuning system with the power of the
"noise" system. By means of delicately adjusted "wings" and coils he
has brought it about that a series of waves having small individual
strength, but great regularity, shall produce on the receiver a
_cumulative_ effect, storing, as it were, electricity on the surface
of the receiver "wings" until it is of sufficient power to overcome
the resistance of the coherer.

That tuned wireless telegraphy is, over moderate distances, at least
as secret as that through wires (which can be tapped by induction) is
evident from the fact that during the America Cup Yacht Races Mr.
Marconi sent daily to the _New York Herald_ messages of 4000 total
words, and kept them private in spite of all efforts to intercept
them. He claims to have as many as 250 "tunes"; and, indeed, there
seems to be no limit to their number, so that the would-be "tapper" is
in the position of a man trying to open a letter-lock of which he does
not know the cipher-word. He _may_ discover the right tune, but the
chances are greatly against him. We may be certain that the rapid
advance in wireless telegraphy will not proceed much further before
syntonic messages can be transmitted over hundreds if not thousands of
miles.

It is hardly necessary to dwell upon the great prospect that the new
telegraphy opens to mankind. The advantages arising out of a ready
means of communication, freed from the shackles of expensive
connecting wires and cables are, in the main, obvious enough. We have
only to imagine all the present network of wires replaced or
supplemented by ether-waves, which will be able to act between points
(_e.g._ ships and ships, ships and land, moving and fixed objects
generally) which cannot be connected by metallic circuits.

Already ocean voyages are being shortened as regards the time during
which passengers are out of contact with the doings of the world. The
transatlantic journey has now a newsless period of but three days.
Navies are being fitted out with instruments that may play as
important a part as the big guns themselves in the next naval war. A
great maritime nation like our own should be especially thankful that
the day is not far distant when our great empire will be connected by
invisible electric links that no enemy may discover and cut.

The romantic side of wireless telegraphy has been admirably touched in
some words uttered by Professor Ayrton in 1899, after the reading of a
paper by Mr. Marconi before the Institution of Electrical Engineers.

"If a person wished to call to a friend" (said the Professor), "he
would use a loud electro-magnetic voice, audible only to him who had
the electro-magnetic ear.

"'Where are you?' he would say.

"The reply would come--'I am at the bottom of a coal mine,' or
'Crossing the Andes,' or 'In the middle of the Pacific.' Or, perhaps,
in spite of all the calling, no reply would come, and the person would
then know his friend was dead. Let them think of what that meant; of
the calling which went on every day from room to room of a house,
and then imagine that calling extending from pole to pole; not a noisy
babble, but a call audible to him who wanted to hear and absolutely
silent to him who did not."

[Illustration: _Guglielmo Marconi._]

When will Professor Ayrton's forecast come true? Who can say? Science
is so full of surprises that the ordinary man wonders with a semi-fear
what may be the next development; and wise men like Lord Kelvin humbly
confess that in comparison with what has yet to be learnt about the
mysterious inner workings of Nature their knowledge is but as
ignorance.




HIGH-SPEED TELEGRAPHY.


The wonderful developments of wireless telegraphy must not make us
forget that some very interesting and startling improvements have been
made in connection with the ordinary wire-circuit method: notably in
the matter of speed.

At certain seasons of the year or under special circumstances which
can scarcely be foreseen, a great rush takes place to transmit
messages over the wires connecting important towns. Now, the best
telegraphists can with difficulty keep up a transmitting speed of even
fifty words a minute for so long as half-an-hour. The Morse alphabet
contains on the average three signals for each letter, and the average
length of a word is six letters. Fifty words would therefore contain
between them 900 signals, or fifteen a second. The strain of sending
or noting so many for even a brief period is very wearisome to the
operator.

Means have been found of replacing the telegraph clerk, so far as the
actual signalling is concerned, by mechanical devices.

In 1842 Alexander Bain, a watchmaker of Thurso, produced what is known
as a "chemical telegraph." The words to be transmitted were set up in
large metal type, all capitals, connected with the positive pole of
a battery, the negative pole of which was connected to earth. A metal
brush, divided into five points, each terminating a wire, was passed
over the metal type. As often as a division of the brush touched metal
it completed the electric circuit in the wire to which it was joined,
and sent a current to the receiving station, where a similar brush was
passing at similar speed over a strip of paper soaked in iodide of
potassium. The action of the electricity decomposed the solution,
turning it blue or violet. The result was a series of letters divided
longitudinally into five belts separated by white spaces representing
the intervals between the contact points of the brush.

[Illustration: _The receiving instrument used by Messrs. Pollak &
Virag in their high-speed system of telegraphy. This instrument is
capable of receiving and photographically recording messages at the
astonishing speed of 50,000 words an hour._]

The Bain Chemical Telegraph was able to transmit the enormous number
of 1500 words per minute; that is, at ten times the rate of ordinary
conversation! But even when improvements had reduced the line wires
from five to one, the system, on account of the method of composing
the message to be sent, was not found sufficiently practical to come
into general use.

Its place was taken by slower but preferable systems: those of duplex
and multiplex telegraphy.

When a message is sent over the wires, the actual time of making the
signals is more than is required for the current to pass from place to
place. This fact has been utilised by the inventors of methods whereby
two or more messages may not only be sent the _same_ way along the
same wire, but may also be sent in _different_ directions. Messages
are "duplex" when they travel across one another, "multiplex" when
they travel together.

The principle whereby several instruments are able to use the same
wire is that of _distributing_ among the instruments the time during
which they are in contact with the line.

Let us suppose that four transmitters are sending messages
simultaneously from London to Edinburgh.

Wires from all four instruments are led into a circular contact-maker,
divided into some hundreds of insulated segments connected in rotation
with the four transmitters. Thus instrument A will be joined to
segments 1, 5, 9, 13; instrument B to segments 2, 6, 10, 14;
instrument C with segments 3, 7, 11, 15; and so on.

Along the top of the segments an arm, connected with the telegraph
line to Edinburgh, revolves at a uniform rate. For about 1/500 of a
second it unites a segment with an instrument. If there are 150
segments on the "distributor," and the arm revolves three times a
second, each instrument will be put into contact with the line rather
oftener than 110 times per second. And if the top speed of fifty words
a minute is being worked to, each of the fifteen signals occurring in
each second will be on the average divided among seven moments of
contact.

A similar apparatus at Edinburgh receives the messages. It is evident
that for the system to work satisfactorily, or even to escape dire
confusion, the revolving arms must run at a level speed in perfect
unison with one another. When the London arm is over segment 1, the
Edinburgh arm must cover the same number. The greatest difficulty in
multiplex telegraphy has been to adjust the timing exactly.

Paul la Cour of Copenhagen invented for driving the arms a device
called the Phonic Wheel, as its action was regulated by the vibrations
of a tuning-fork. The wheel, made of soft iron, and toothed on its
circumference, revolves at a short distance from the pole of a magnet.
As often as a current enters the magnet the latter attracts the
nearest tooth of the wheel; and if a regular series of currents pass
through it the motion of the wheel will be uniform. M. la Cour
produced the regularity of current impulses in the motor magnet by
means of a tuning-fork, which is unable to vibrate more than a certain
number of times a second, and at each vibration closed a circuit
sending current into the magnet. To get two tuning-forks of the same
note is an easy matter; and consequently a uniformity of rotation at
both London and Edinburgh stations may be insured.

So sensitive is this "interrupter" system that as many as sixteen
messages can be sent simultaneously, which means that a single wire is
conveying from 500 to 800 words a minute. We can easily understand the
huge saving that results from such a system; the cost of instruments,
interrupter, &c., being but small in proportion to that of a number
of separate conductors.

The word-sending capacity of a line may be even further increased by
the use of automatic transmitters able to work much faster in
signal-making than the human brain and hand. Sir Charles Wheatstone's
Automatic Transmitter has long been used in the Post-Office
establishments.

The messages to be sent are first of all punched on a long tape with
three parallel rows of perforations. The central row is merely for
guiding the tape through the transmitting machine. The positions of
the holes in the two outside rows relatively to each other determine
the character of the signal to be sent. Thus, when three holes
(including the central one) are abreast, a Morse "dot" is signified;
when the left-hand hole is one place behind the right hand, a "dash"
will be telegraphed.

In the case of a long communication the matter is divided among a
number of clerks operating punching machines. Half-a-dozen operators
could between them punch holes representing 250 to 300 words a minute;
and the transmitter is capable of despatching as many in the same
time, while it has the additional advantage of being tireless.

The action of the transmitter is based upon the reversal of the
direction or nature of current. The punched tape is passed between an
oscillating lever, carrying two points, and plates connected with the
two poles of the battery. As soon as a hole comes under a pin the pin
drops through and makes a contact.

At the receiving end the wire is connected with a coil wound round the
pole of a permanent bar-magnet. Such a magnet has what is known as a
north pole and a south pole, the one attractive and the other
repulsive of steel or soft iron. Any bar of soft iron can be made
temporarily into a magnet by twisting round it a few turns of a wire
in circuit with the poles of a battery. But which will be the north
and which the south pole depends on the _direction_ of the current.
If, then, a current passes in one direction round the north pole of a
permanent magnet it will increase the magnet's attractive power, but
will decrease it if sent in the other direction.

The "dot" holes punched in the tape being abreast cause first a
positive and then a negative current following at a very short
interval; but the "dash" holes not being opposite allow the positive
current to occupy the wires for a longer period. Consequently the
Morse marker rests for correspondingly unequal periods on the
recording "tape," giving out a series of dots and dashes, as the inker
is snatched quickly or more leisurely from the paper.

The Wheatstone recorder has been worked up to 400 words a minute, and
when two machines are by the multiplex method acting together this
rate is of course doubled.

As a speed machine it has, however, been completely put in the shade
by a more recent invention of two Hungarian electricians, Anton Pollak
and Josef Virag, which combines the perforated strip method of
transmission with the telephone and photography. The message is sent
off by means of a punched tape, and is recorded by means of a
telephonic diaphragm and light marking a sensitised paper.

In 1898 the inventors made trials of their system for the benefit of
the United Electrical Company of Buda-Pesth. The Hungarian capital was
connected by two double lines of wire with a station 200 miles
distant, where the two sets were joined so as to give a single circuit
of 400 miles in length. A series of tests in all weathers showed that
the Pollak-Virag system could transmit as many as 100,000 words an
hour over that distance.

From Hungary the inventors went to the United States, in which country
of "records" no less than 155,000 words were despatched and received
in the sixty minutes. This average--2580 words per minute, 43 per
second--is truly remarkable! Even between New York and Chicago,
separated by 950 odd miles, the wires kept up an average of 1000 per
minute.

The apparatus that produces these marvellous results is of two types.
The one type records messages in the Morse alphabet, the other makes
clearly-written longhand characters. The former is the faster of the
two, but the legibility of the other more than compensates for the
decrease of speed by one-half.

[Illustration: _Specimens of the punched tape used for transmitting
messages by the Pollak-Virag system, and of a message as it is
delivered by the receiving machine._]

The Morse alphabet method closely resembles the Wheatstone system. The
message is prepared for transmission by being punched on a tape. But
there is this difference in the position of the holes, that whereas in
the Wheatstone method two holes are used for each dot and dash, only
one is required in the Pollak-Virag. If to the right of the central
guiding line it signifies a "dash," if to the left, a "dot."

The "reversal-of-current" method, already explained, causes at the
receiver end an increase or decrease in the power of a permanent
magnet to attract or repel a diaphragm, the centre of which is
connected by a very fine metal bar with the centre of a tiny mirror
hinged at one side on two points. A very slight movement of the
diaphragm produces an exaggerated movement of the mirror, which, as it
tilts backwards and forwards, reflects the light from an electric lamp
on to a lens, which concentrates the rays into a bright spot, and
focuses them on to a surface of sensitised paper.

In their earliest apparatus the inventors attached the paper to the
circumference of a vertical cylinder, which revolved at an even pace
on an axle, furnished at the lower end with a screw thread, so that
the portion of paper affected by the light occupied a spiral path from
top to bottom of the cylinder.

In a later edition, however, an endless band of sensitised paper is
employed, and the lamp is screened from the mirror by a horizontal
mantle in which is cut a helical slit making one complete turn of the
cylinder in its length. The mantle is rotated in unison with the
machinery driving the sensitised band; and as it revolves, the spot at
which the light from the filament can pass through the slit to the
mirror is constantly shifting from right to left, and the point at
which the reflected light from the mirror strikes the sensitised paper
from left to right. At the moment when a line is finished, the right
extremity of the mantle begins to pass light again, and the bright
spot of light recommences its work at the left edge of the band, which
has now moved on a space.

The movements of the mirror backwards and forwards produce on the
paper a zigzag tracing known as syphon-writing. The record, which is
continuous from side to side of the band, is a series of zigzag
up-and-down strokes, corresponding to the dots and dashes of the Morse
alphabet.

The apparatus for transmitting longhand characters is more complicated
than that just described. Two telephones are now used, and the punched
tape has in it five rows of perforations.

If we take a copy-book and examine the letters, we shall see that they
all occupy one, two, or three bands of space. For instance, _a_,
between the lines, occupies one band; _g_, two bands; and _f_, three.
In forming letters, the movements of the fingers trace curves and
straight lines, the curves being the resultants of combined horizontal
and vertical movements.

Messrs. Pollak and Virag, in order to produce curves, were obliged to
add a second telephone, furnished also with a metal bar joined to the
mirror, which rests on three points instead of on two. One of these
points is fixed, the other two represent the ends of the two diaphragm
bars, which move the mirror vertically and horizontally respectively,
either separately or simultaneously.

A word about the punched paper before going further. It contains, as
we have said, five rows of perforations. The top three of these are
concerned only with the up-and-down strokes of the letters, the bottom
two with the cross strokes. When a hole of one set is acting in unison
with a hole of the other set a composite movement or curve results.

The topmost row of all sends through the wires a negative current of
known strength; this produces upward and return strokes in the upper
zone of the letters: for instance, the upper part of a _t_. The second
row passes _positive_ currents of equal strength with the negative,
and influences the up-and-down strokes of the centre zone, _e.g._
those of _o_; the third row passes positive currents _twice_ as strong
as the negative, and is responsible for double-length vertical strokes
in the centre and lower zones, _e.g._ the stroke in _p_.

In order that the record shall not be a series of zigzags it is
necessary that the return strokes in the vertical elements shall be on
the same path as the out strokes; and as the point of light is
continuously tending to move from left to right of the paper there
must at times be present a counteracting tendency counterbalancing it
exactly, so that the path of the light point is purely vertical. At
other times not merely must the horizontal movements balance each
other, but the right-to-left element must be stronger than the
left-to-right, so that strokes such as the left curve of an _e_ may be
possible. To this end rows 4 and 5 of the perforations pass currents
working the second telephone diaphragm, which moves the mirror on a
vertical axis so that it reflects the ray horizontally.

It will be noticed that the holes in rows 3, 4, 5 vary in size to
permit the passage of currents during periods of different length. In
this manner the little junction-hooks of such letters as _r_, _w_,
_v_, _b_ are effected.

As fast as the sensitised paper strip is covered with the movements of
the dancing spot of light it is passed on over rollers through
developing and fixing chemical baths; so that the receiving of
messages is purely automatic.

The reader can judge for himself the results of this ingenious system
as shown in a short section of a message transmitted by Mr. Pollak.
The words shown actually occupied two seconds in transmission. They
are beautifully clear.

It is said that by the aid of a special "multiplex" device thirty sets
of Pollak-Virag apparatus can be used simultaneously on a line! The
reader will be able, by the aid of a small calculation, to arrive at
some interesting figures as regards their united output.




THE TELEPHONE.


A common enough sight in any large town is a great sheaf of fine wires
running across the streets and over the houses. If you traced their
career in one direction you would find that they suddenly terminate,
or rather combine into cables, and disappear into the recesses of a
house, which is the Telephone Exchange. If you tracked them the other
way your experience would be varied enough. Some wires would lead you
into public institutions, some into offices, some into snug rooms in
private houses. At one time your journey would end in the town, at
another you would find yourself roaming far into the country, through
green fields and leafy lanes until at last you ran the wire to earth
in some large mansion standing in a lordly park. Perhaps you might
have to travel hundreds of miles, having struck a "trunk" line
connecting two important cities; or you might even be called upon to
turn fish and plunge beneath the sea for a while, groping your way
along a submarine cable.

In addition to the visible overhead wires that traverse a town there
are many led underground through special conduits. And many telephone
wires never come out of doors at all, their object being to furnish
communication between the rooms of the same house. The telephone and
its friend, the electric-bell, are now a regular part of the equipment
of any large premises. The master of the house goes to his telephone
when he wishes to address the cook or the steward, or the
head-gardener or the coachman. It saves time and labour.

Should he desire to speak to his town-offices he will, unless
connected direct, "ring up" the Exchange, into which, as we have seen,
flow all the wires of the subscribers to the telephone system of that
district. The ringing-up is usually done by rapidly turning a handle
which works an electric magnet and rings a bell in the Exchange. The
operator there, generally a girl, demands the number of the person
with whom the ringer wants to speak, rings up that number, and
connects the wires of the two parties.

In some exchanges, _e.g._ the new Post-Office telephone exchanges, the
place of electric-bells is taken by lamps, to the great advantage of
the operators, whose ears are thus freed from perpetual jangling. The
action of unhooking the telephone receiver at the subscriber's end
sends a current into a relay which closes the circuit of an electric
lamp opposite the subscriber's number in the exchange. Similarly, when
the conversation is completed the action of hanging up the receiver
again lights another lamp of a different colour, given the exchange
warning that the wires are free again.

In America, the country of automatic appliances, the operator is
sometimes entirely dispensed with. A subscriber is able, by means of
a mechanical contrivance, to put himself in communication with any
other subscriber unless that subscriber is engaged, in which case a
dial records the fact.

The popularity of the telephone may be judged from the fact that in
1901 the National Telephone Company's system transmitted over 807
millions of messages, as compared with 89 millions of telegrams sent
over the Post Office wires. In America and Germany, however, the
telephone is even more universally employed than in England. In the
thinly populated prairies of West America the farm-houses are often
connected with a central station many miles off, from which they
receive news of the outer world and are able to keep in touch with one
another. We are not, perhaps, as a nation sufficiently alive to the
advantages of an efficient telephone system; and on this account many
districts remain telephoneless because sufficient subscribers cannot
be found to guarantee use of a system if established. It has been
seriously urged that much of our country depopulation might be
counteracted by a universal telephone service, which would enable
people to live at a distance from the towns and yet be in close
contact with them. At present, for the sake of convenience and ease of
"getting at" clients and customers, many business men prefer to have
their homes just outside the towns where their business is. A cheap
and efficient service open to every one would do away with a great
deal of travelling that is necessary under existing circumstances,
and by making it less important to live near a town allow people to
return to the country.

Even Norway has a good telephone system. The telegraph is little used
in the more thinly inhabited districts, but the telephone may be found
in most unexpected places, in little villages hidden in the recesses
of the fiords. Switzerland, another mountainous country, but very
go-ahead in all electrical matters, is noted for the cheapness of its
telephone services. At Berne or Geneva a subscriber pays £4 the first
year, £2, 12s. the second year, and but £1, 12s. the third. Contrast
these charges with those of New York, where £15, 10s. to £49, 10s. is
levied annually according to service.

The telephone as a public benefactor is seen at its best at
Buda-Pesth, the twin-capital of Hungary. In 1893, one Herr Theodore
Buschgasch founded in that city a "newspaper"--if so it may be
called--worked entirely on the telephone. The publishing office was a
telephone exchange; the wires and instruments took the place of
printed matter. The subscribers were to be informed entirely by ear of
the news of the day.

The _Telefon Hirmondo_ or "Telephonic Newsteller," as the "paper" was
named, has more than six thousand subscribers, who enjoy their
telephones for the very small payment of eighteen florins, or about a
penny a day, for twelve hours a day.

News is collected at the central office in the usual journalistic way
by telephone, telegraph, and reporters. It is printed by lithography
on strips of paper six inches wide and two feet long. These strips are
handed to "stentors," or men with powerful and trained voices, who
read the contents to transmitting instruments in the offices, whence
it flies in all directions to the ears of the subscribers.

These last know exactly when to listen and what description of
information they will hear, for each has over his receiver a programme
which is rigidly adhered to. It must be explained at once that the
_Telefon Hirmondo_ is more than a mere newspaper, for it adds to its
practical use as a first-class journal that of entertainer, lecturer,
preacher, actor, political speaker, musician. The _Telefon_ offices
are connected by wire with the theatres, churches, and public halls,
drawing from them by means of special receivers the sounds that are
going on there, and transmitting them again over the wires to the
thousands of subscribers. The Buda-Pesthian has therefore only to
consult his programme to see when he will be in touch with his
favourite actor or preacher. The ladies know just when to expect the
latest hints about the fashions of the day. Nor are the children
forgotten, for a special period is set aside weekly for their
entertainment in the shape of lectures or concerts.

The advertising fiend, too, must have his say, though he pays dearly
for it. On payment of a florin the stentors will shout the virtues of
his wares for a space of twelve seconds. The advertising periods are
sandwiched in between items of news, so that the subscriber is bound
to hear the advertisements unless he is willing to risk missing some
of the news if he hangs up his receiver until the "puff" is finished.

Thanks to the _Telefon Hirmondo_ the preacher, actor, or singer is
obliged to calculate his popularity less by the condition of the seats
in front of him than by the number of telephones in use while he is
performing his part. On the other hand, the subscriber is spared a
vast amount of walking, waiting, cab-hire, and expense generally. In
fact, if the principle is much further developed, we shall begin to
doubt whether a Buda-Pesthian will be able to discover reasons for
getting out of bed at all if the receiver hanging within reach of his
hand is the entrance to so many places of delight. Will he become a
very lazy person; and what will be the effect on his entertainers when
they find themselves facing benches that are used less every day? Will
the sight of a row of telephone trumpets rouse the future Liddon,
Patti, Irving, or Gladstone to excel themselves? It seems rather
doubtful. Telephones cannot look interested or applaud.

What is inside the simple-looking receiver that hangs on the wall
beside a small mahogany case, or rests horizontally on a couple of
crooks over the case? In the older type of instrument the transmitter
and receiver are separate, the former fixed in front of the case, the
latter, of course, movable so that it can be applied to the ear. But
improved patterns have transmitter and receiver in a single movable
handle, so shaped that the earpiece is by the ear while the
mouthpiece curves round opposite the mouth. By pressing a small lever
with the fingers the one or the other is brought into action when
required.

The construction of the instrument, of which we are at first a little
afraid, and with which we later on learn to become rather angry, is in
its general lines simple enough. The first practical telephone,
constructed in 1876 by Graham Bell, a Scotchman, consisted of a long
wooden or ebonite handle down the centre of which ran a permanent
bar-magnet, having at one end a small coil of fine insulated wire
wound about it The ends of the wire coil are led through the handles
to two terminals for connection with the line wires. At a very short
distance from the wire-wound pole of the magnet is firmly fixed by its
edges a thin circular iron plate, covered by a funnel-shaped
mouthpiece.

The iron plate is, when at rest, concave, its centre being attracted
towards the pole of the magnet. When any one speaks into the
mouthpiece the sound waves agitate the diaphragm (or plate), causing
its centre to move inwards and outwards. The movements of the
diaphragm affect the magnetism of the magnet, sometimes strengthening
it, sometimes weakening it, and consequently exciting electric
currents of varying strength in the wire coil. These currents passing
through the line wires to a similar telephone excite the coil in it,
and in turn affect the magnetism of the distant magnet, which
attracts or releases the diaphragm near its pole, causing undulations
of the air exactly resembling those set up by the speaker's words. To
render the telephone powerful enough to make conversation possible
over long distances it was found advisable to substitute for the one
telephone a special transmitter, and to insert in the circuit a
battery giving a much stronger current than could possibly be excited
by the magnet in the telephone at the speaker's end.

Edison in 1877 invented a special transmitter made of carbon. He
discovered that the harder two faces of carbon are pressed together
the more readily will they allow current to pass; the reason probably
being that the points of contact increase in number and afford more
bridges for the current.

Accordingly his transmitter contains a small disc of lampblack (a form
of carbon) connected to the diaphragm, and another carbon or platinum
disc against which the first is driven with varying force by the
vibrations of the voice.

The Edison transmitter is therefore in idea only a modification of the
microphone. It acts as a _regulator_ of current, in distinction to the
Bell telephone, which is only an _exciter_ of current. Modern forms of
telephones unite the Edison transmitter with the Bell receiver.

The latter is extremely sensitive to electric currents, detecting them
even when of the minutest power. We have seen that Marconi used a
telephone in his famous transatlantic experiments to distinguish the
signals sent from Cornwall. A telephone may be used with an "earth
return" instead of a second wire; but as this exposes it to stray
currents by induction from other wires carried on the same poles or
from the earth itself, it is now usual to use two wires, completing
the metallic circuit. Even so a subscriber is liable to overhear
conversations on wires neighbouring his own; the writer has lively
recollections of first receiving news of the relief of Ladysmith in
this manner.

Owing to the self-induction of wires in submarine cables and the
consequent difficulty of forcing currents through them, the telephone
is at present not used in connection with submarine lines of more than
a very moderate length. England has, however, been connected with
France by a telephone cable from St. Margaret's Bay to Sangatte, 23
miles; and Scotland with Ireland, Stranraer to Donaghadee, 26 miles.
The former cable enables speech between London and Marseilles, a
distance of 900 miles; and the latter makes it possible to speak from
London to Dublin _viâ_ Glasgow. The longest direct line in existence
is that between New York and Chicago, the complete circuit of which
uses 1900 miles of stout copper wire, raised above the ground on poles
35 feet high.

The efficiency of the telephone on a well laid system is so great that
it makes very little difference whether the persons talking with one
another are 50 or 500 miles apart. There is no reason why a
Cape-to-Cairo telephone should not put the two extremities of Africa
in clear vocal communication. We may even live to see the day when a
London business man will be able to talk with his agent in Sydney,
Melbourne, or Wellington.

A step towards this last achievement has been taken by M. Germain, a
French electrician, who has patented a telephone which can be used
with stronger currents than are possible in ordinary telephones;
thereby, of course, increasing the range of speech on submarine
cables.

The telephone that we generally use has a transmitter which permits
but a small portion of the battery power to pass into the wires, owing
to the resistance of the carbon diaphragm. The weakness of the current
is to a great extent compensated by the exceedingly delicate nature of
the receiver.

M. Germain has reversed the conditions with a transmitter that allows
a very high percentage of the current to flow into the wires, and a
comparatively insensitive receiver. The result is a "loud-speaking
telephone"--not a novelty, for Edison invented one as long ago as
1877--which is capable of reproducing speech in a wonderfully powerful
fashion.

M. Germain, with the help of special tubular receivers, has actually
sent messages through a line having the same resistance as that of the
London-Paris line, so audibly that the words could be heard fifteen
yards from the receiver in the open air!




The Telephone

WIRELESS TELEPHONY.


In days when wireless telegraphy is occupying such a great deal of the
world's attention, it is not likely to cause much astonishment in the
reader to learn that wireless transmission of _speech_ over
considerable distances is an accomplished fact. We have already
mentioned (see "Wireless Telegraphy") that by means of parallel
systems of wires Sir William Preece bridged a large air-gap, and
induced in the one sounds imparted to the other.

Since then two other methods have been introduced; and as a preface to
the mention of the first we may say a few words about Graham Bell's
_Photophone_.

In this instrument _light_ is made to do the work of a metal
connection between speaker and listener. Professor Bell, in arranging
the Photophone, used a mouthpiece as in his electric telephone, but
instead of a diaphragm working in front of a magnet to set up electric
impulses along a wire he employed a mirror of very thin glass,
silvered on one side. The effect of sound on this mirror was to cause
rapid alterations of its shape from concave to convex, and consequent
variations of its reflecting power. A strong beam of light was
concentrated on the centre of the mirror through a lens, and reflected
by the mirror at an angle through another lens in the direction of the
receiving instrument. The receiver consisted of a parabolic reflector
to catch the rays and focus them on a selenium cell connected by an
electric circuit with an ordinary telephone earpiece.

On delivering a message into the mouthpiece the speaker would, by
agitating the mirror, send a succession of light waves of varying
intensity towards the distant selenium cell. Selenium has the peculiar
property of offering less resistance to electrical currents when light
is thrown upon it than when it is in darkness: and the more intense is
the light the less is the obstruction it affords. The light-waves from
the mirror, therefore, constantly alter its capacity as a conductor,
allowing currents to pass through the telephone with varying power.

In this way Professor Bell bridged 800 yards of space; over which he
sent, besides articulate words, musical notes, using for the latter
purpose a revolving perforated disc to interrupt a constant beam of
light a certain number of times per second. As the speed of the disc
increased the rate of the light-flashes increased also, and produced
in the selenium cell the same number of passages to the electric
current, converted into a musical note by the receiver. So that by
means of mechanical apparatus a "playful sunbeam" could literally be
compelled to play a tune.

From the Photophone we pass to another method of sound transmission by
light, with which is connected the name of Mr. Hammond V. Hayes of
Boston, Massachusetts. It is embodied in the Radiophone, or the
Ray-speaker, for it makes strong rays of light carry the human voice.

Luminous bodies give off heat. As the light increases, so as a general
rule does the heat also. At present we are unable to create strong
light without having recourse to heat to help us, since we do not know
how to cause other vibrations of sufficient rapidity to yield the
sensation of light. But we can produce heat directly, and heat will
set atoms in motion, and the ether too, giving us light, but taking as
reward a great deal of the energy exerted. Now, the electric arc of a
searchlight produces a large amount of light _and_ heat. The light is
felt by the eye at a distance of many miles, but the body is not
sensitive enough to be aware of the heat emanating from the same
source. Mr. Hayes has, however, found the heat accompanying a
searchlight beam quite sufficient to affect a mechanical "nerve" in a
far-away telephone receiver.

The transmitting apparatus is a searchlight, through the back of which
run four pairs of wires connected with a telephone mouthpiece after
passing through a switch and resistance-box or regulator. The receiver
is a concave mirror, in the focus of which is a tapering glass bulb,
half filled with carbonised filament very sensitive to heat. The
tapering end of the bulb projects through the back of the mirror into
an ear tube.

If a message is to be transmitted the would-be speaker turns his
searchlight in the direction of the person with whom he wishes to
converse, and makes the proper signals. On seeing them the other
presents his mirror to the beam and listens.

The speaker's voice takes control of the searchlight beam. The louder
the sound the more brilliantly glows the electric arc; the stronger
becomes the beam, the greater is the amount of heat passed on to the
mirror and gathered on the sensitive bulb. The filament inside
expands. The tapering point communicates the fact to the earpiece.

This operation being repeated many times a second the earpiece fills
with sound, in which all the modulations of the far-distant voice are
easily distinguishable.

Two sets of the apparatus above described are necessary for a
conversation, the functions of the searchlight and the bulb not being
reversible. But inasmuch as all large steamers carry searchlights the
necessary installation may be completed at a small expense. Mr. Hayes'
invention promises to be a rival to wireless telegraphy over
comparatively short distances. It can be relied upon in all weathers,
and is a fast method of communication. Like the photophone it
illustrates the inter-relationship of the phenomena of Sound, Light,
and Heat, and the readiness with which they may be combined to attain
an end.

Next we turn from air to earth, and to the consideration of the work
of Mr. A. F. Collins of Philadelphia. This electrician merely makes
use of the currents flowing in all directions through the earth, and
those excited by an electric battery connected with earth. The outfit
requisite for sending wireless spoken messages consists of a couple of
convenient stands, as many storage batteries, sets of coils, and
receiving and transmitting instruments.

The action of the transmitter is to send from the battery a series of
currents through the coils, which transmit them, greatly intensified,
to the earth by means of a wire connected with a buried wire-screen.
The electric disturbances set up in the earth travel in all
directions, and strike a similar screen buried beneath the receiving
instrument, where the currents affect the delicate diaphragm of the
telephone earpiece.

The system is, in fact, upon all fours with Mr. Marconi's, the
distinguishing feature being that the ether of the atmosphere is used
in the latter case, that of the earth in the former. The intensity
coils are common to both; the buried screens are the counterpart of
the aërial kites or balloons; the telephone transmitter corresponds to
the telegraphic transmitting key; the earpiece to the coherer and
relay. No doubt in time Mr. Collins will "tune" his instruments, so
obtaining below ground the same sympathetic electric vibrations which
Mr. Marconi, Professor Lodge, or others have employed to clothe their
aërial messages in secrecy.




THE PHONOGRAPH.


Even if Thomas Edison had not done wonders with electric lighting,
telephones, electric torpedoes, new processes for separating iron from
its ore, telegraphy, animated photography, and other things too
numerous to mention, he would still have made for himself an enduring
name as the inventor of the Phonograph. He has fitly been called the
"Wizard of the West" from his genius for conjuring up out of what
would appear to the multitude most unpromising materials startling
scientific marvels, among which none is more truly wizard-like than
the instrument that is as receptive of sound as the human ear, and of
illimitable reproducing power. By virtue of its elfishly human
characteristic, articulate speech, it occupies, and always will
occupy, a very high position as a mechanical wonder. When listening to
a telephone we are aware of the fact that the sounds are immediate
reproductions of a living person's voice, speaking at the moment and
at a definite distance from us; but the phonographic utterances are
those of a voice perhaps stilled for ever, and the difference adds
romance to the speaking machine.

The Phonograph was born in 1876. As we may imagine, its appearance
created a stir. A contributor to the _Times_ wrote in 1877: "Not many
weeks have passed since we were startled by the announcement that we
could converse audibly with each other, although hundreds of miles
apart, by means of so many miles of wire with a little electric magnet
at each end.

"Another wonder is now promised us--an invention purely mechanical in
its nature, by means of which words spoken by the human voice can be,
so to speak, stored up and reproduced at will over and over again
hundreds, it may be thousands, of times. What will be thought of a
piece of mechanism by means of which a message of any length can be
spoken on to a plate of metal--that plate sent by post to any part of
the world and the message absolutely respoken in the very voice of the
sender, purely by mechanical agency? What, too, shall be said of a
mere machine, by means of which the old familiar voice of one who is
no longer with us on earth can be heard speaking to us in the very
tones and measure to which our ears were once accustomed?"

The first Edison machine was the climax of research in the realm of
sound. As long ago as 1856 a Mr. Leo Scott made an instrument which
received the formidable name of Phonautograph, on account of its
capacity to register mechanically the vibrations set up in the
atmosphere by the human voice or by musical instruments. A large metal
cone like the mouth of an ear-trumpet had stretched across its smaller
end a membrane, to which was attached a very delicate tracing-point
working on the surface of a revolving cylinder covered with blackened
paper. Any sound entering the trumpet agitated the membrane, which in
turn moved the stylus and produced a line on the cylinder
corresponding to the vibration. Scott's apparatus could only record.
It was, so to speak, the first half of the phonograph. Edison, twenty
years later, added the active half. His machine, as briefly described
in the _Times_, was simple; so very simple that many scientists must
have wondered how they failed to invent it themselves.

A metal cylinder grooved with a continuous square-section thread of
many turns to the inch was mounted horizontally on a long axle cut at
one end with a screw-thread of the same "pitch" as that on the
cylinder. The axle, working in upright supports, and furnished with a
heavy flywheel to render the rate of revolution fairly uniform, was
turned by a handle. Over the grooved cylinder was stretched a thin
sheet of tinfoil, and on this rested lightly a steel tracing-point,
mounted at the end of a spring and separated from a vibrating
diaphragm by a small pad of rubber tubing. A large mouthpiece to
concentrate sound on to the diaphragm completed the apparatus.

To make a record with this machine the cylinder was moved along until
the tracing-point touched one extremity of the foil. The person
speaking into the mouthpiece turned the handle to bring a fresh
surface of foil continuously under the point, which, owing to the
thread on the axle and the groove on the cylinder being of the same
pitch, was always over the groove, and burnished the foil down into it
to a greater or less depth according to the strength of the impulses
received from the diaphragm.

[Illustration: _A unique group of Phonographs. 1. The oldest
phonograph in existence, now in South Kensington Museum. 2. Tinfoil
instrument. 3. A cheaper form of the same. 4. A "spectacle-form"
graphophone. 5. An exactly similar instrument, half-size scale. 6. A
doll fitted with phonograph._]

The record being finished, the point was lifted off the foil, the
cylinder turned back to its original position, and the point allowed
to run again over the depressions it had made in the metal sheet. The
latter now became the active part, imparting to the air by means of
the diaphragm vibrations similar in duration and quality to those that
affected it when the record was being made.

It is interesting to notice that the phonograph principle was
originally employed by Edison as a telephone "relay." His attention
had been drawn to the telephone recently produced by Graham Bell, and
to the evil effects of current leakage in long lines. He saw that the
amount of current wasted increased out of proportion to the length of
the lines--even more than in the proportion of the squares of their
lengths--and he hoped that a great saving of current would be effected
if a long line were divided into sections and the sound vibrations
were passed from one to the other by mechanical means. He used as the
connecting link between two sections a strip of moistened paper, which
a needle, attached to a receiver, indented with minute depressions,
that handed on the message to another telephone. The phonograph
proper, as a recording machine, was an after-thought.

Edison's first apparatus, besides being heavy and clumsy, had in
practice faults which made it fall short of the description given in
the _Times_. Its tone was harsh. The records, so far from enduring a
thousand repetitions, were worn out by a dozen. To these defects must
be added a considerable difficulty in adjusting a record made on one
machine to the cylinder of another machine.

Edison, being busy with his telephone and electric lamp work, put
aside the phonograph for a time. Graham Bell, his brother, Chichester
Bell, and Charles Sumner Tainter, developed and improved his crude
ideas. They introduced the Graphophone, using easily removable
cylinder records. For the tinfoil was substituted a thin coating of a
special wax preparation on light paper cylinders. Clockwork-driven
motors replaced the hand motion, and the new machines were altogether
more handy and effective. As soon as he had time Edison again entered
the field. He conceived the solid wax cylinder, and patented a small
shaving apparatus by means of which a record could be pared away and a
fresh surface be presented for a new record.

The phonograph or graphophone of to-day is a familiar enough sight;
but inasmuch as our readers may be less intimately acquainted with its
construction and action than with its effects, a few words will now be
added about its most striking features.

In the first place, the record remains stationary while the trumpet,
diaphragm and stylus pass over it. The reverse was the case with the
tinfoil instrument.

The record is cut by means of a tiny sapphire point having a circular
concave end very sharp at the edges, to gouge minute depressions into
the wax. The point is agitated by a delicate combination of weights
and levers connecting it with a diaphragm of French glass 1/140 inch
thick. The reproducing point is a sapphire ball of a diameter equal to
that of the gouge. It passes over the depressions, falling into them
in turn and communicating its movements to a diaphragm, and so
tenderly does it treat the records that a hundred repetitions do not
inflict noticeable damage.

It is a curious instance of the manner in which man unconsciously
copies nature that the parts of the reproducing attachment of a
phonograph contains parts corresponding in function exactly to those
bones of the ear known as the Hammer, Anvil, and Stirrup.

To understand the inner working of the phonograph the reader must be
acquainted with the theory of sound. All sound is the result of
impulses transmitted by a moving body usually reaching the ear through
the medium of the air. The quantity of the sound, or loudness, depends
on the violence of the impulse; the tone, or note, on the number of
impulses in a given time (usually fixed as one second); and the
quality, or _timbre_, as musicians say, on the existence of minor
vibrations within the main ones.

If we were to examine the surface of a phonograph record (or
phonogram) under a powerful magnifying glass we should see a series
of scoops cut by the gouge in the wax, some longer and deeper than
others, long and short, deep and shallow, alternating and recurring in
regular groups. The depth, length, and grouping of the cuts decides
the nature of the resultant note when the reproducing sapphire point
passes over the record--at a rate of about ten inches a second.

The study of a tracing made on properly prepared paper by a point
agitated by a diaphragm would enable us to understand easily the cause
of that mysterious variation in _timbre_ which betrays at once what
kind of instrument has emitted a note of known pitch. For instance,
let us take middle C, which is the result of a certain number of
atmospheric blows per second on the drum of the ear. The same note may
come from a piano, a violin, a banjo, a man's larynx, an organ, or a
cornet; but we at once detect its source. It is scarcely imaginable
that a piano and a cornet should be mistaken for one another. Now, if
the tracing instrument had been at work while the notes were made
successively it would have recorded a wavy line, each wave of exactly
the same _length_ as its fellows, but varying in its _outline_
according to the character of the note's origin. We should notice that
the waves were themselves wavy in section, being jagged like the teeth
of a saw, and that the small secondary waves differed in size.

The minor waves are the harmonics of the main note. Some musical
instruments are richer in these harmonics than others. The fact that
these delicate variations are recorded as minute indentations in the
wax and reproduced is a striking proof of the phonograph's mechanical
perfection.

Furthermore, the phonograph registers not only these composite notes,
but also chords or simultaneous combinations of notes, each of which
may proceed from a different instrument. In its action it here
resembles a man who by constant practice is able to add up the pounds,
shillings, and pence columns in his ledger at the same time, one wave
system overlapping and blending with another.

The phonograph is not equally sympathetic with all classes of sounds.
Banjo duets make good records, but the guitar gives a poor result.
Similarly, the cornet is peculiarly effective, but the bass drum
disappointing. The deep chest notes of a man come from the trumpet
with startling truth, but the top notes on which the soprano prides
herself are often sadly "tinny." The phonograph, therefore, even in
its most perfect form is not the equal of the exquisitely sensitive
human ear; and this may partially be accounted for by the fact that
the diaphragm in both recorder and reproducer has its own fundamental
note which is not in harmony with all other notes, whereas the ear,
like the eye, adapts itself to any vibration.

Yet the phonograph has an almost limitless répertoire. It can justly
be claimed for it that it is many musical instruments rolled into one.
It will reproduce clearly and faithfully an orchestra, an
instrumental soloist, the words of a singer, a stump orator, or a
stage favourite. Consequently we find it every where--at
entertainments, in the drawing-room, and even tempting us at the
railway station or other places of public resort to part with our
superfluous pence. At the London Hippodrome it discourses to audiences
of several thousand persons, and in the nursery it delights the
possessors of ingeniously-constructed dolls which, on a button being
pressed and concealed machinery being brought into action, repeat some
well-known childish melody.

It must not be supposed that the phonograph is nothing more than a
superior kind of scientific toy. More serious duties than those of
mere entertainment have been found for it.

At the last Presidential Election in the States the phonograph was
often called upon to harangue large meetings in the interests of the
rival candidates, who were perhaps at the time wearing out their
voices hundreds of miles away with the same words.

Since the pronunciation of a foreign language is acquired by constant
imitation of sounds, the phonograph, instructed by an expert, has been
used to repeat words and phrases to a class of students until the
difficulties they contain have been thoroughly mastered. The sight of
such a class hanging on the lips--or more properly the trumpet--of a
phonograph gifted with the true Parisian accent may be common enough
in the future.

As a mechanical secretary and substitute for the shorthand writer the
phonograph has certainly passed the experimental stage. Its daily use
by some of the largest business establishments in the world testify to
its value in commercial life. Many firms, especially American, have
invested heavily in establishing phonograph establishments to save
labour and final expense. The manager, on arriving at his office in
the morning, reads his letters, and as the contents of each is
mastered, dictates an answer to a phonograph cylinder which is
presently removed to the typewriting room, where an assistant, placing
it upon her phonograph and fixing the tubes to her ears, types what is
required. It is interesting to learn that at Ottawa, the seat of the
Canadian Government, phonographs are used for reporting the
parliamentary proceedings and debates.

There is therefore a prospect that, though the talking-machine may
lose its novelty as an entertainer, its practical usefulness will be
largely increased. And while considering the future of the instrument,
the thought suggests itself whether we shall be taking full advantage
of Mr. Edison's notable invention if we neglect to make records of all
kinds of intelligible sounds which have more than a passing interest.
If the records were made in an imperishable substance they might
remain effective for centuries, due care being taken of them in
special depositories owned by the nation. To understand what their
value would be to future generations we have only to imagine ourselves
listening to the long-stilled thunder of Earl Chatham, to the golden
eloquence of Burke, or the passionate declamations of Mrs. Siddons.
And in the narrower circle of family interests how valuable a part of
family heirlooms would be the phonograms containing a vocal message to
posterity from Grandfather this, or Great-aunt that, whose portraits
in the drawing-room album do little more than call attention to the
changes in dress since the time when their subjects faced the camera!

_Record-Making and Manufacture._--Phonographic records are of two
shapes, the cylindrical and the flat, the latter cut with a volute
groove continuously diminishing in diameter from the circumference to
the centre. Flat records are used in the Gramophone--a reproducing
machine only. Their manufacture is effected by first of all making a
record on a sheet of zinc coated with a very thin film of wax, from
which the sharp steel point moved by the recording diaphragm removes
small portions, baring the zinc underneath. The plate is then flooded
with an acid solution, which eats into the bared patches, but does not
affect the parts still covered with wax. The etching complete, the wax
is removed entirely, and a cast or electrotype _negative_ record made
from the zinc plate. The indentations of the original are in this
represented by excrescences of like size; and when the negative block
is pressed hard down on to a properly prepared disc of vulcanite or
celluloid, the latter is indented in a manner that reproduces exactly
the tones received on the "master" record.

Cylindrical records are made in two ways, by moulding or by copying.
The second process is extremely simple. The "master" cylinder is
placed on a machine which also rotates a blank cylinder at a short
distance from and parallel to the first. Over the "master" record
passes a reproducing point, which is connected by delicate levers to a
cutting point resting on the "blank," so that every movement of the
one produces a corresponding movement of the other.

This method, though accurate in its results, is comparatively slow.
The _moulding_ process is therefore becoming the more general of the
two. Edison has recently introduced a most beautiful process for
obtaining negative moulds from wax positives. Owing to its shape, a
zinc cylinder could not be treated like a flat disc, as, the negative
made, it could not be detached without cutting. Edison, therefore,
with characteristic perseverance, sought a way of electrotyping the
wax, which, being a non-conductor of electricity, would not receive a
deposit of metal. The problem was how to deposit on it.

Any one who has seen a Crookes' tube such as is used for X-ray work
may have noticed on the glass a black deposit which arises from the
flinging off from the negative pole of minute particles of platinum.
Edison took advantage of this repellent action; and by enclosing his
wax records in a vacuum between two gold poles was able to coat them
with an infinitesimally thin skin of pure gold, on which silver or
nickel could be easily deposited. The deposit being sufficiently thick
the wax was melted out and the surface of the electrotype carefully
cleaned. To make castings it was necessary only to pour in wax, which
on cooling would shrink sufficiently to be withdrawn. The delicacy of
the process may be deduced from the fact that some of the sibilants,
or hissing sounds of the voice, are computed to be represented by
depressions less than a millionth of an inch in depth, and yet they
are most distinctly reproduced! Cylinder records are made in two
sizes, 2-1/2 and 5 inches in diameter respectively. The larger size
gives the most satisfactory renderings, as the indentations are on a
larger scale and therefore less worn by the reproducing point. One
hundred turns to the inch is the standard pitch of the thread; but in
some records the number is doubled.

Phonographs, Graphophones, and Gramophones are manufactured almost
entirely in America, where large factories, equipped with most perfect
plant and tools, work day and night to cope with the orders that flow
in freely from all sides. One factory alone turns out a thousand
machines a day, ranging in value from a few shillings to forty pounds
each. Records are made in England on a large scale; and now that the
Edison-Bell firm has introduced the unbreakable celluloid form their
price will decrease. By means of the Edison electrotyping process a
customer can change his record without changing his cylinder. He takes
the cylinder to the factory, where it is heated, placed in the mould,
and subjected to great pressure which drives the soft celluloid into
the mould depressions; and behold! in a few moments "Auld Lang Syne"
has become "Home, Sweet Home," or whatever air is desired. Thus
altering records is very little more difficult than getting a fresh
book at the circulating library.


THE PHOTOGRAPHOPHONE.

This instrument is a phonograph working entirely by means of light and
electricity.

The flame of an electric lamp is brought under the influence of sound
vibrations which cause its brilliancy to vary at every alteration of
pitch or quality.

The light of the flame is concentrated through a lens on to a
travelling photographic sensitive film, which, on development in the
ordinary way, is found to be covered with dark and bright stripes
proportionate in tone to the strength of the light at different
moments. The film is then passed between a lamp and a selenium plate
connected with an electric circuit and a telephone. The resistance of
the selenium to the current varies according to the power of the light
thrown upon it. When a dark portion of the film intercepts the light
of the lamp the selenium plate offers high resistance; when the light
finds its way through a clear part of the film the resistance weakens.
Thus the telephone is submitted to a series of changes affecting the
"receiver." As in the making of the record speech-vibrations affect
light, and the light affects a sensitive film; so in its reproduction
the film affects a sensitive selenium plate, giving back to a
telephone exactly what it received from the sound vibrations.

One great advantage of Mr. Ruhmer's method is that from a single film
any number of records can be printed by photography; another, that, as
with the Telegraphone (see below), the same film passed before a
series of lamps successively is able to operate a corresponding number
of telephones.

The inventor is not content with his success. He hopes to record not
merely sounds but even pictures by means of light and a selenium
plate.


THE TELEPHONOGRAPH.

Having dealt with the phonograph and the telephone separately, we may
briefly consider one or two ingenious combinations of the two
instruments. The word Telephonograph signifies an apparatus for
recording sounds sent from a distance. It takes the place of the human
listener at the telephone receiver.

Let us suppose that a Reading subscriber wishes to converse along the
wires with a friend in London, but that on ringing up his number he
discovers that the friend is absent from his home or office. He is
left with the alternative of either waiting till his friend returns,
which may cause a serious loss of time, or of dictating his message, a
slow and laborious process. This with the ordinary telephonic
apparatus. But if the London friend be the possessor of a
Telephonograph, the person answering the call-bell can, if desired to
do so, switch the wires into connection with it and start the
machinery; and in a very short time the message will be stored up for
reproduction when the absent friend returns.

The Telephonograph is the invention of Mr. J. E. O. Kumberg. The
message is spoken into the telephone transmitter in the ordinary way,
and the vibrations set up by the voice are caused to act upon a
recording stylus by the impact of the sound waves at the further end
of the wires. In this manner a phonogram is produced on the wax
cylinder in the house or office of the person addressed, and it may be
read off at leisure. A very sensitive transmitter is employed, and if
desired the apparatus can be so arranged that by means of a
double-channel tube the words spoken are simultaneously conveyed to
the telephone and to an ordinary phonograph, which insures that a
record shall be kept of any message sent.

The _Telegraphone_, produced by Mr. Valdemar Poulsen, performs the
same functions as the telephonograph, but differs from it in being
entirely electrical. It contains no waxen cylinder, no cutting-point;
their places are taken respectively by a steel wire wound on a
cylindrical drum (each turn carefully insulated from its neighbours)
and by a very small electro-magnet, which has two delicate points that
pass along the wire, one on either side, resting lightly upon it.

As the drum rotates, the whole of the wire passes gradually between
the two points, into which a series of electric shocks is sent by the
action of the speaker's voice at the further end of the wires. The
shocks magnetise the portion of steel wire which acts as a temporary
bridge between the two points. At the close of three and a half
minutes the magnet has worked from one end of the wire coil to the
other; it is then automatically lifted and carried back to the
starting-point in readiness for reproduction of the sounds. This is
accomplished by disconnecting the telegraphone from the telephone
wires and switching it on to an ordinary telephonic earpiece or
receiver. As soon as the cylinder commences to revolve a second time,
the magnet is influenced by the series of magnetic "fields" in the
wires, and as often as it touches a magnetised spot imparts an impulse
to the diaphragm of the receiver, which vibrates at the rate and with
the same force as the vibrations originally set up in the distant
transmitter. The result is a clear and accurate reproduction of the
message, even though hours and even days may have elapsed since its
arrival.

As the magnetic effects on the wire coil retain their power for a
considerable period, the message may be reproduced many times. As soon
as the wire-covered drum is required for fresh impressions, the old
one is wiped out by passing a permanent magnet along the wire to
neutralise the magnetism of the last message.

Mr. Poulsen has made an instrument of a different type to be employed
for the reception of an unusually lengthy communication. Instead of a
wire coil on a cylinder, a ribbon of very thin flat steel spring is
wound from one reel on to another across the poles of _two_
electro-magnets, which touch the lower side only of the strip. The
first magnet is traversed by a continuous current to efface the
previous record; the second magnetises the strip in obedience to
impulses from the telephone wires. The message complete, the strip is
run back, and the magnets connected with receivers, which give out
loud and intelligent speech as the strip again traverses them. The
Poulsen machine makes the transmission of the same message
simultaneously through several telephones an easy matter, as the strip
can be passed over a series of electro-magnets each connected with a
telephone.




THE TELAUTOGRAPH.


It is a curious experience to watch for the first time the movements
of a tiny Telautograph pen as it works behind a glass window in a
japanned case. The pen, though connected only with two delicate wires,
appears instinct with human reason. It writes in a flowing hand, just
as a man writes. At the end of a word it crosses the t's and dots the
i's. At the end of a line it dips itself in an inkpot. It punctuates
its sentences correctly. It illustrates its words with sketches. It
uses shorthand as readily as longhand. It can form letters of all
shapes and sizes.

And yet there is no visible reason why it should do what it does. The
japanned case hides the guiding agency, whatever it may be. Our ears
cannot detect any mechanical motion. The writing seems at first sight
as mysterious as that which appeared on the wall to warn King
Belshazzar.

In reality it is the outcome of a vast amount of patience and
mechanical ingenuity culminating in a wonderful instrument called the
Telautograph. The Telautograph is so named because by its aid we can
send our autographs, _i.e._ our own particular handwriting,
electrically over an indefinite length of wire, as easily as a
telegraph clerk transmits messages in the Morse alphabet. Whatever
the human hand does on one telautograph at one end of the wires, that
will be reproduced by a similar machine at the other end, though the
latter be hundreds of miles away.

[Illustration: _By kind permission of The Telautograph Co._

_The Telautograph. The upper portion is the Receiver, the lower (with
cover removed) is the Transmitter._]

The instrument stands about eighteen inches high, and its base is as
many inches square. It falls into two parts, the receiver and the
transmitter. The receiver is vertical and forms the upright and back
portion of the telautograph. At one side of it hangs an ordinary
telephone attachment. The transmitter, a sloping desk placed
conveniently for the hand, is the front and horizontal portion. The
receiver of one station is connected with the transmitter of another
station; there being ordinarily no direct communication between the
two parts of the same instrument.

An attempt will be made to explain, with the help of a simple diagram,
the manner in which the telautograph performs its duties.

These duties are threefold. In the first place, it must reproduce
whatever is written on the transmitter. Secondly, it must reproduce
only what is _written_, not all the movements of the hand. Thirdly, it
must supply the recording pen with fresh paper to write on, and with
fresh ink to write with.

In our diagram we must imagine that all the coverings of the
telautograph have been cleared away to lay bare the most essential
parts of the mechanism. For the sake of simplicity not all the coils,
wires, and magnets having functions of their own are represented, and
the drawing is not to scale. But what is shown will enable the reader
to grasp the general principles which work the machine.

Turning first of all to the transmitter, we have P, a little platform
hinged at the back end, and moving up and down very slightly in front,
according as pressure is put on to or taken off it by the pencil.
Across it a roll of paper is shifted by means of the lever S, which
has other uses as well. To the right of P is an electric bell-push, E,
and on the left K, another small button.

The pencil is at the junction of two small bars CC', which are hinged
at their other end to the levers AA'. Any motion of the pencil is
transmitted by CC' to AA', and by them to the arms LL', the
extremities of which, two very small brushes ZZ', sweep along the
quadrants RR'. This is the first point to observe, that the position
of the pencil decides on which sections of the quadrants these little
brushes rest, and consequently how much current is to be sent to the
distant station. The quadrants are known technically as rheostats, or
current-controllers. Each quadrant is divided into 496 parts,
separated from each other by insulating materials, so that current can
pass from one to the other only by means of some connecting wire. In
our illustration only thirteen divisions are given, for the sake of
clearness. The dark lines represent the insulation. WW' are the very
fine wire loops connecting each division of the quadrant with its
neighbours. If then a current from the battery B enters the rheostat
at division 1 it will have to pass through all these wires before it
can reach division 13. The current always enters at 1, but the point
of departure from the rheostat depends entirely upon the position of
the brushes Z or Z'. If Z happens to be on No. 6 the current will pass
through five loops of wire, along the arm L, and so through the main
wire to the receiving station; if on No. 13, through twelve loops.

[Illustration: THE TELAUTOGRAPH]

Before going any further we must have clear ideas on the subject of
electrical resistance, upon which the whole system of the telautograph
is built up. Electricity resembles water in its objection to flow
through small passages. It is much harder to pump water through a
half-inch pipe than through a one-inch pipe, and the longer the pipe
is, whatever its bore, the more work is required. So then, two things
affect resistance--_size_ of pipe or wire, and _length_ of pipe or
wire.

The wires WW' are very fine, and offer very high resistance to a
current; so high that by the time the current from battery B has
passed through all the wire loops only one-fifteenth or less of the
original force is left to traverse the long-distance wire.

The rheostats act independently of one another. As the pencil moves
over the transmitting paper, a succession of currents of varying
intensity is sent off by each rheostat to the receiving station.

The receiver, to which we must now pay attention, has two arms DD',
and two rods FF', corresponding in size with AA' and CC' of the
transmitter. The arms DD' are moved up and down by the coils TT' which
turn on centres in circular spaces at the bend of the magnets MM'. The
position of these coils relatively to the magnets depend on the
strength of the currents coming from the transmitting station. Each
coil strains at a small spiral spring until it has reached the
position in which its electric force is balanced by the retarding
influence of the spring. One of the cleverest things in the
telautograph is the adjustment of these coils so that they shall
follow faithfully the motions of the rods LL' in the transmitter.

[Illustration: _By kind permission of_] [_The Telautograph Co._

_An example of the work done by the Telautograph. The upper sketch
shows a design drawn on the transmitter; the lower is the same design
as reproduced by the receiving instrument, many miles distant._]

We are now able to trace the actions of sending a message. The sender
first presses the button E to call the attention of some one at the
receiving station to the fact that a message is coming, either on the
telephone or on the paper. It should be remarked, by-the-bye, that the
same wires serve for both telephone and telautograph, the unhooking of
the telephone throwing the telautograph out of connection for the
time.

He then presses the lever S towards the left, bringing his transmitter
into connection with the distant receiver, and also moving a fresh
length of paper on to the platform P. With his pencil he writes his
message, pressing firmly on the paper, so that the platform may bear
down against an electric contact, X. As the pencil moves about the
paper the arms CC' are constantly changing their angles, and the
brushes ZZ' are passing along the segments of the rheostats.

Currents flow in varying intensity away to the coils TT' and work the
arms DD', the wires FF', and the pen, a tiny glass tube.

In the perfectly regulated telautograph the arms AA' and the arms DD'
will move in unison, and consequently the position of the pen must be
the same from moment to moment as that of the pencil.

Mr. Foster Ritchie, the clever inventor of this telautograph, had to
provide for many things besides mere slavish imitation of movement. As
has been stated above, the pen must record only those movements of the
pencil which are essential. Evidently, if while the pencil returns to
dot an _i_ a long line were registered by the pen corresponding to the
path of the pencil, confusion would soon ensue on the receiver; and
instead of a neatly-written message we should have an illegible and
puzzling maze of lines. Mr. Ritchie has therefore taken ingenious
precautions against any such mishap. The platen P on being depressed
by the pencil touches a contact, X, which closes an electric circuit
through the long-distance wires and excites a magnet at the receiving
end. That attracts a little arm and breaks another circuit, allowing
the bar Y to fall close to the paper. The wires FF' and the pen are
now able to rest on the paper and trace characters. But as soon as the
platen P rises, on the removal of the pencil from the transmitting
paper, the contact at X is broken, the magnet at the receiver ceases
to act, the arm it attracted falls back and sets up a circuit which
causes the bar to spring up again and lift the pen. So that unless
you are actually pressing the paper with your pencil, the pen is not
marking, though it may be moving.

As soon as a line is finished a fresh surface of paper is required at
both ends. The operator pushes the lever S sideways, and effects the
change mechanically at his end. At the same time a circuit is formed
which excites certain magnets at the receiver and causes the shifting
forward there also of the paper, and also breaks the _writing_
current, so that the pen returns for a moment to its normal position
of rest in the inkpot.

It may be asked: If the wires are passing currents to work the writing
apparatus, how can they simultaneously affect the lifting-bar, Y? The
answer is that currents of two different kinds are used, a direct
current for writing, a vibratory current for depressing the
lifting-bar. The _direct_ current passes from the battery B through
the rheostats RR' along the wires, through the coils working the arms
DD' and into the earth at the far end; but the _vibratory_ current,
changing its direction many times a second and so neutralising itself,
passes up one wire and back down the other through the lifting-bar
connection without interfering with the direct current.

The message finished, the operator depresses with the point of his
pencil the little push-key, K, and connects his receiver with the
distant transmitter in readiness for an answer.

The working speed of the telautograph is that of the writer. If
shorthand be employed, messages can be transmitted at the rate of over
100 words per minute. As regards the range of transmission, successful
tests have been made by the postal authorities between Paris and
London, and also between Paris and Lyons. In the latter case the
messages were sent from Paris to Lyons and back directly to Paris, the
lines being connected at Lyons, to give a total distance of over 650
miles. There is no reason why much greater length of line should not
be employed.

The telautograph in its earlier and imperfect form was the work of
Professor Elisha Gray, who invented the telephone almost
simultaneously with Professor Graham Bell. His telautograph worked on
what is known as the step-by-step principle, and was defective in that
its speed was very limited. If the operator wrote too fast the
receiving pen lagged behind the transmitting pencil, and confusion
resulted. Accordingly this method, though ingenious, was abandoned,
and Mr. Ritchie in his experiments looked about for some preferable
system, which should be simpler and at the same time much speedier in
its action. After four years of hard work he has brought the rheostat
system, explained above, to a pitch of perfection which will be at
once appreciated by any one who has seen the writing done by the
instrument.

The advantages of the Telautograph over the ordinary telegraphy may be
briefly summed up as follows:--

Anybody who can write can use it; the need of skilled operators is
abolished.

A record is automatically kept of every message sent.

The person to whom the message is sent need not be present at the
receiver. He will find the message written out on his return.

The instrument is silent and so insures secrecy. An ordinary telegraph
may be read by sound; but not the telautograph.

It is impossible to tap the wires unless, as is most unlikely, the
intercepting party has an instrument in exact accord with the
transmitter.

It can be used on the same wires as the ordinary telephone, and since
a telephone is combined with it, the subscriber has a double means of
communication. For some items of business the telephone may be used as
preferable; but in certain cases, the telautograph. A telephone
message may be heard by other subscribers; it is impossible to prove
the authenticity of such a message unless witnesses have been present
at the transmitting end; and the message itself may be misunderstood
by reason of bad articulation. But the telautograph preserves secrecy
while preventing any misunderstanding. Anything written by it is for
all practical purposes as valid as a letter.

We must not forget its extreme usefulness for transmitting sketches. A
very simple diagram often explains a thing better than pages of
letter-press. The telautograph may help in the detection of criminals,
a pictorial presentment of whom can by its means be despatched all
over the country in a very short time. And in warfare an instrument
flashing back from the advance-guard plans of the country and of the
enemy's positions might on occasion prove of the greatest importance.




MODERN ARTILLERY.


The vast subject of artillery in its modern form, including under this
head for convenience' sake not only heavy ordnance but machine-guns
and small-arms, can of necessity only be dealt with most briefly in
this chapter.

It may therefore be well to take a general survey and to define
beforehand any words or phrases which are used technically in
describing the various operations.

The employment of firearms dates from a long-distant past, and it is
interesting to note that many an improvement introduced during the
last century is but the revival of a former invention which only lack
of accuracy in tools and appliances had hitherto prevented from being
brought into practical usage.

So far back as 1498 the art of _rifling_ cannon in straight grooves
was known, and a British patent was taken out in 1635 by Rotsipan. The
grooves were first made spiral or screwed by Koster of Birmingham
about 1620. Berlin possesses a rifled cannon with thirteen grooves
dated 1664. But the first recorded uses of such weapons in actual
warfare was during Louis Napoleon's Italian campaign in 1859, and two
years later by General James of the United States Army.

The system of _breech-loading_, again, is as old as the sixteenth
century, and we find a British patent of 1741; while the first United
States patent was given in 1811 for a flint-lock weapon.

_Magazine_ guns of American production appeared in 1849 and 1860, but
these were really an adaptation of the old matchlock revolvers, said
to belong to the period 1480-1500. There is one in the Tower of London
credited to the fifteenth century, and a British patent of 1718
describes a well-constructed revolver carried on a tripod and of the
dimensions of a modern machine-gun. The inventor gravely explains that
he has provided round chambers for round bullets to shoot Christians,
and square chambers with square missiles for use against the Turks!

The word "ordnance" is applied to heavy guns of all kinds, and
includes guns mounted on fortresses, naval guns, siege artillery, and
that for use in the field. These guns are all mounted on stands or
carriages, and may be divided into three classes:--

     (i.) _Cannon_, or heavy guns.

     (ii.) _Howitzers_, for field, mountain, or siege use, which are
     lighter and shorter than cannon, and designed to throw hollow
     projectiles with comparatively small charges.

     (iii.) _Mortars_, for throwing shells at a great elevation.

The modern long-range guns and improved howitzers have, however,
virtually superseded mortars. _Machine-guns_ of various forms are
comparatively small and light, transportable by hand, and filling a
place between cannon and small-arms, the latter term embracing the
soldier's personal armament of rifle and pistol or revolver, which are
carried in the hand.

A group of guns of the like design are generally given the name of
their first inventor, or the place of manufacture: such as the
Armstrong gun, the Vickers-Maxim, the Martini-Henry rifle, or the
Enfield.

The indifferent use of several expressions in describing the same
weapon is, however, rather confusing. One particular gun may be thus
referred to:--by its _weight_ in tons or cwt., as "the 35-ton gun"; by
the weight of its _projectile_, as "a 68-pounder"; by its _calibre_,
that is, size of bore, as "the 4-inch gun." Of these the heavier
breech-loading (B.-L.) and quick-firing (Q.-F.) guns are generally
known by the size of bore; small Q.-F.'s, field-guns, &c., by the
weight of projectile. It is therefore desirable to enter these
particulars together when making any list of service ordnance for
future reference.

No individual gun, whether large or small, is a single whole, but
consists of several pieces fastened together by many clever devices.

The principal parts of a cannon are:--

     (1) The _chase_, or main tube into which the projectile is
     loaded; terminating at one end in the muzzle.

     (2) The _breech-piece_, consisting of (_a_) the chamber, which
     is bored out for a larger diameter than the chase to contain
     the firing-charge. (_b_) The _breech-plug_, which is closed
     before the charge is exploded and screwed tightly into place,
     sealing every aperture by means of a special device called the
     "obturator," in order to prevent any gases passing out round it
     instead of helping to force the projectile forwards towards the
     muzzle.

The whole length of inside tube is termed the _barrel_, as in a
machine-gun, rifle, or sporting-piece, but in the two latter weapons
the breech-opening is closed by sliding or springing back the
breech-block or bolt into firing position.

Old weapons as a rule were smooth-bored (S.-B.), firing a round
missile between which and the barrel a considerable amount of the
gases generated by the explosion escaped and caused loss of power,
this escape of gas being known as _windage_.

In all modern weapons we use conical projectiles, fitted near the base
with a soft copper driving-band, the diameter of which is somewhat
larger than that of the bore of the gun, and cut a number of spiral
grooves in the barrel. The enormous pressure generated by the
explosion of the charge forces the projectile down the bore of the gun
and out of the muzzle. The body of the projectile, made of steel or
iron, being smaller in diameter than the bore, easily passes through,
but the driving-band being of greater diameter, and being composed of
soft copper, can only pass down the bore with the projectile by
flowing into the grooves, thus preventing any escape of gas, and being
forced to follow their twist. It therefore rotates rapidly upon its
own longitudinal axis while passing down the barrel, and on leaving
the muzzle two kinds of velocity have been imparted to it;--first, a
velocity of motion through the air; secondly, a velocity of rotation
round its axis which causes it to fly steadily onward in the required
direction, _i.e._ a prolongation of the axis of the gun. Thus extreme
velocity and penetrating power, as well as correctness of aim, are
acquired.

The path of a projectile through the air is called its _trajectory_,
and if uninterrupted its flight would continue on indefinitely in a
perfectly straight line. But immediately a shot has been hurled from
the gun by the explosion in its rear two other natural forces begin to
act upon it:--

Gravitation, which tends to bring it to earth.

Air-resistance, which gradually checks its speed.

(Theoretically, a bullet dropped perpendicularly from the muzzle of a
perfectly horizontal rifle would reach the ground at the same moment
as another bullet fired from the muzzle horizontally, the action of
gravity being the same in both cases.)

Its direct, even course is therefore deflected till it forms a curve,
and sooner or later it returns to earth, still retaining a part of its
velocity. To counteract the attraction of gravity the shot is thrown
upwards by elevating the muzzle, care being taken to direct the gun's
action to the same height above the object as the force of gravitation
would draw the projectile down during the time of flight. The gunner
is enabled to give the proper inclination to his piece by means of the
_sights_; one of these, near the muzzle, being generally fixed, while
that next the breech is adjustable by sliding up an upright bar which
is so graduated that the proper _elevation_ for any required range is
given.

The greater the velocity the flatter is the trajectory, and the more
dangerous to the enemy. Assuming the average height of a man to be six
feet, all the distance intervening between the point where a bullet
has dropped to within six feet of the earth, and the point where it
actually strikes is dangerous to any one in that interval, which is
called the "danger zone." A higher initial velocity is gained by using
stronger firing charges, and a more extended flight by making the
projectile longer in proportion to its diameter. The reason why a
shell from a cannon travels further than a rifle bullet, both having
the same muzzle velocity, is easily explained.

A rifle bullet is, let us assume, three times as long as it is thick;
a cannon shell the same. If the shell have ten times the diameter of
the bullet, its "nose" will have 10 × 10 = 100 times the area of the
bullet's nose; but its _mass_ will be 10 × 10 × 10 = 1000 times that of
the bullet.

In other words, when two bodies are proportional in all their
dimensions their air-resistance varies as the square of their
diameters, but their mass and consequently their momentum varies as
the _cube_ of their diameters. The shell therefore starts with a great
advantage over the bullet, and may be compared to a "crew" of cyclists
on a multicycle all cutting the same path through the air; whereas the
bullet resembles a single rider, who has to overcome as much
air-resistance as the front man of the "crew" but has not the weight
of other riders behind to help him.

As regards the effect of rifling, it is to keep the bullet from
turning head over heels as it flies through the air, and to maintain
it always point forwards. Every boy knows that a top "sleeps" best
when it is spinning fast. Its horizontal rotation overcomes a tendency
to vertical movement towards the ground. In like manner a rifle
bullet, spinning vertically, overcomes an inclination of its atoms to
move out of their horizontal path. Professor John Perry, F.R.S., has
illustrated this gyroscopic effect, as it is called, of a whirling
body with a heavy flywheel in a case, held by a man standing on a
pivoted table. However much the man may try to turn the top from its
original direction he will fail as long as its velocity of rotation is
high. He may move the top relatively to his body, but the table will
turn so as to keep the centre line of the top always pointing in the
same direction.


RIFLES.

Up to the middle of last century our soldiers were armed with the
flint-lock musket known as "Brown Bess," a smooth-bore barrel 3/4-inch
in diameter, thirty-nine inches long, weighing with its bayonet over
eleven pounds. The round leaden bullet weighed an ounce, and had to be
wrapped in a "patch" or bit of oily rag to make it fit the barrel and
prevent windage; it was then pushed home with a ramrod on to the
powder-charge, which was ignited by a spark passing from the flint
into a priming of powder. How little its accuracy of aim could be
depended upon, however, is proved by the word of command when
advancing upon an enemy, "Wait till you see the whites of their eyes,
boys, before you fire!"

In the year 1680 each troop of Life Guards was supplied with eight
rifled carbines, a modest allowance, possibly intended to be used
merely by those acting as scouts. After this we hear nothing of them
until in 1800 the 95th Regiment received a 20-bore muzzle-loading
rifle, exchanged about 1835 for the Brunswick rifle firing a spherical
bullet, an improvement that more than doubled its effective range. The
companies so armed became known as the Rifle Brigade. At last, in
1842, the old flint-lock was superseded for the whole army by the
original percussion musket, a smooth-bore whose charge was exploded by
a percussion cap made of copper. [That this copper had some commercial
value was shown by the rush of "roughs" to Aldershot and elsewhere
upon a field-day to collect the split fragments which strewed the
ground after the troops had withdrawn.]

Soon afterward the barrel was rifled and an elongated bullet brought
into use. This missile was pointed in front, and had a hollowed base
so contrived that it expanded immediately the pressure of exploding
gases was brought to bear on it, and thus filled up the grooves,
preventing any windage. The one adopted by our army in the year 1852
was the production of M. Minié, a Frenchman, though an expanding
bullet of English invention had been brought forward several years
before.

Meanwhile the Prussians had their famous needle-gun, a breech-loading
rifled weapon fired by a needle attached to a sliding bolt; as the
bolt is shot forward the needle pierces the charge and ignites the
fulminate by friction. This rifle was used in the Prusso-Austrian war
of 1866 some twenty years after its first inception, and the French
promptly countered it by arming their troops with the Chassepôt rifle,
an improved edition of the same principle. A piece which could be
charged and fired in any position from five to seven times as fast as
the muzzle-loader, which the soldier had to load standing, naturally
caused a revolution in the infantry armament of other nations.

The English Government, as usual the last to make a change, decided in
1864 upon using breech-loading rifles. Till a more perfect weapon
could be obtained the Enfields were at a small outlay converted into
breech-loaders after the plans of Mr. Snider, and were henceforward
known as Snider-Enfields. Eventually--as the result of open
competition--the Martini-Henry rifle was produced by combining Henry's
system of rifling with Martini's mechanism for breech-loading. This
weapon had seven grooves with one turn in twenty-two inches, and
weighed with bayonet 10 lb. 4 oz. It fired with great accuracy, the
trajectory having a rise of only eight feet at considerable distances,
so that the bullet would not pass over the head of a cavalry man.
Twenty rounds could be fired in fifty-three seconds.

Now in the latter years of the century all these weapons have been
superseded by magazine rifles, _i.e._ rifles which can be fired
several times without recourse to the ammunition pouch. They differ
from the revolver in having only one firing chamber, into which the
cartridges are one by one brought by a simple action of the breech
mechanism, which also extracts the empty cartridge-case. The bore of
these rifles is smaller and the rifling sharper; they therefore shoot
straighter and harder than the large bore, and owing to the use of new
explosives the recoil is less.

The French _Lebel_ magazine rifle was the pioneer of all now used by
European nations, though a somewhat similar weapon was familiar to the
Americans since 1849, being first used during the Civil War. The Henry
rifle, as it was called, afterwards became the Winchester.

The German army rifle is the _Mauser_, so familiar to us in the hands
of the Boers during the South African War--loading five cartridges at
once in a case or "clip" which falls out when emptied. The same rifle
has been adopted by Turkey, and was used by the Spaniards in the late
Spanish-American War.

The Austrian _Mannlicher_, adopted by several continental nations, and
the Krag-Jorgensen now used in the north of Europe and as the United
States army weapon, resemble the Mauser in most particulars. Each of
these loads the magazine in one movement with a clip.

The _Hotchkiss_ magazine rifle has its magazine in the stock, holding
five extra cartridges pushed successively into loading position by a
spiral spring.

Our forces are now armed principally with the _Lee-Enfield_, which is
taking the place of the _Lee-Metford_ issued a few years ago. These
are small-bore rifles of .303 inch calibre, having a detachable box,
which is loaded with ten cartridges (Lee-Metford eight) passed up in
turn by a spring into the breech, whence, when the bolt is closed,
they are pushed into the firing-chamber. The empty case is ejected by
pulling back the bolt, and at the same time another cartridge is
pressed up from the magazine and the whole process repeated. When the
cut-off is used the rifle may be loaded and fired singly, be the
magazine full or empty.

The Lee-Enfield has five grooves (Lee-Metford ten), making one
complete turn from right to left in every ten inches. It weighs 9 lb.
4 oz., and the barrel is 30.197 inches long. The range averages 3500
yards.

We are now falling into line with other powers by adopting the "clip"
form instead of the box for loading. The sealed pattern of the new
service weapon is thus provided, and has also been made somewhat
lighter and shorter while preserving the same velocity.

We are promised an even more rapid firing rifle than any of these, one
in which the recoil is used to work the breech and lock so that it is
a veritable automatic gun. Indeed, several continental nations have
made trial of such weapons and reported favourably upon them. One
lately tried in Italy works by means of gas generated by the explosion
passing through a small hole to move a piston-rod. It is claimed that
the magazine can hold as many as fifty cartridges and fire up to
thirty rounds a minute; but the barrel became so hot after doing this
that the trial had to be stopped.

The principal result of automatic action would probably be excessive
waste of cartridges by wild firing in the excitement of an engagement.
It is to-day as true as formerly that it takes on the average a man's
weight of lead to kill him in battle.

To our neighbours across the Channel the credit also belongs of
introducing _smokeless powder_, now universally used; that of the
Lee-Metford being "cordite." To prevent the bullets flattening on
impact they are coated with a hard metal such as nickel and its
alloys. If the nose is soft, or split beforehand, a terribly enlarged
and lacerated wound is produced; so the Geneva Convention humanely
prohibited the use of such missiles in warfare.

Before quitting this part of our subject it is as well to add a few
words about _pistols_.

These have passed through much the same process of evolution as the
rifle, and have now culminated in the many-shotted _revolver_.

During the period 1480-1500 the match-lock revolver is said to have
been brought into use; and one attributed to this date may be seen in
the Tower of London.

Two hundred years ago, Richards, a London gunsmith, converted the
ancient wheel-lock into the flint-lock; he also rifled his barrel and
loaded it at the breech. The Richards weapon was double-barrelled, and
unscrewed for loading at the point where the powder-chamber ended; the
ball was placed in this chamber in close contact with the powder, and
the barrel rescrewed. The bullet being a soft leaden ball, was forced,
when the charge was fired, through the rifled barrel with great
accuracy of aim.

The percussion cap did not oust the flint-lock till less than a
century ago, when many single-barrelled pistols, such as the famous
Derringer, were produced; these in their turn were replaced by the
revolver which _Colt_ introduced in 1836-1850. Smith and Wesson in the
early sixties improved upon it by a device for extracting the empty
cartridges automatically. Livermore and Russell of the United States
invented the "clip," containing several cartridges; but the equally
well-known _Winchester_ has its cartridges arranged in a tube below
the barrel, whence a helical spring feeds them to the breech as fast
as they are needed.

At the present time each War Department has its own special service
weapon. The German _Mauser_ magazine-pistol for officer's use fires
ten shots in ten seconds, a slight pressure of the trigger setting the
full machinery in motion; the pressure of gas at each explosion does
all the rest of the work--extracts and ejects the cartridge case,
cocks the hammer, and presses springs which reload and close the
weapon, all in a fraction of a second. The _Mannlicher_ is of the same
automatic type, but its barrel moves to the front, leaving space for a
fresh cartridge to come up from the magazine below, while in the
Mauser the breech moves to the rear during recoil. The range is half a
mile. The cartridges are made up in sets of ten in a case, which can
be inserted in one movement.


MACHINE-GUNS.

Intermediate between hand-borne weapons and artillery, and partaking
of the nature of both, come the machine-guns firing small projectiles
with extraordinary rapidity.

Since the United States made trial of Dr. Gatling's miniature battery
in the Civil War (1862-1865), invention has been busy evolving more
and more perfect types, till the most modern machine-gun is a marvel
of ingenuity and effectiveness.

The _Gatling_ machine-gun, which has been much improved in late years
by the Accles system of "feed," and is not yet completely out of date,
consists of a circular series of ten barrels--each with its own
lock--mounted on a central shaft and revolved by a suitable gear. The
cartridges are successively fed by automatic actions into the barrels,
and the hammers are so arranged that the entire operation of loading,
closing the breech, firing and withdrawing the empty cartridge-cases
(which is known as their "longitudinal reciprocating motion") is
carried on while the locks are kept in constant revolution, along with
the barrels and breech, by means of a hand-crank. One man places a
feed-case filled with cartridges into the hopper, another turns the
crank. As the gun is rotated the cartridges drop one by one from the
feed-cases into the grooves of the carrier, and its lock loads and
fires each in turn. While the gun revolves further the lock, drawing
back, extracts and drops the empty case; it is then ready for the next
cartridge.

In action five cartridges are always going through some process of
loading, while five empty shells are in different stages of ejection.
The latest type, fitted with an electro-motor, will fire at the _rate_
of one thousand rounds per minute, and eighty rounds have actually
been fired within ten seconds! It is not, however, safe to work these
machine-guns so fast, as the cartridges are apt to be occasionally
pulled through unfired and then explode among the men's legs. The
automatic guns, on the contrary, as they only work by the explosion,
are free from any risk of such accidents.

The feed-drums contain 104 cartridges, and can be replaced almost
instantly. One drumful can be discharged in 5-1/4 seconds. The
small-sized Gatling has a drum-feed of 400 cartridges in sixteen
sections of twenty-five each passed up without interruption.

The gun is mounted for use so that it can be pointed at any angle, and
through a wide lateral range, without moving the carriage.

_The Gardner._--The Gatling, as originally made, was for a time
superseded by the _Gardner_, which differed from it in having the
barrels (four or fewer in number) fixed in the same horizontal plane.
This was worked by a rotatory handle on the side of the gun. The
cartridges slid down a feed-case in a column to the barrel, where they
were fired by a spring acting on a hammer.

_The Nordenfelt._--Mr. Nordenfelt's machine-gun follows this
precedent; its barrels--10, 5, 4, 2, or 1 in number--also being
arranged horizontally in a strong, rigid frame. Each barrel has its
own breech-plug, striker, spring, and extractor, and each fires
independently of the rest, so that all are not out of action together.
The gun has a swivelled mount easily elevated and trained, and the
steel frames take up the force of the discharge. In rapid firing one
gunner can work the firing-handle while another lays and alters the
direction. The firing is operated by a lever working backwards and
forwards by hand, and the gun can be discharged at the rate of 600
rounds per minute.

_The Hotchkiss._--The Hotchkiss gun, or revolving cannon, is on a
fresh system, that of intermittent rotation of the barrels without any
rotation of breech or mechanism. There is only one loading piston, one
spring striker, and one extractor for all the barrels. The shock of
discharge is received against a massive fixed breech, which
distributes it to the whole body.

Like the _Nordenfelt_, however, it can be dismounted and put together
again without the need of tools. The above pattern throws 1 lb.
projectiles.

_The Maxim._--Differing from all these comes the _Maxim_ gun, so much
in evidence now with both land and sea service. It is made up of two
portions:--

     (1) _Fixed_: a barrel-casing, which is also a water-jacket, and
     breech-casing.

     (2) _Recoiling_: a barrel and two side plates which carry lock
     and crank.

This recoiling portion works inside the fixed.

The gun is supplied with ammunition by a belt holding 250 cartridges
passing through a feed-block on the top. Its mechanism is worked
_automatically_; first by the explosion of the charge, which causes
the barrel to recoil backwards and extends a strong spring which, on
reasserting itself, carries it forwards again. The recoiling part
moves back about an inch, and this recoil is utilised by bringing
into play mechanism which extracts the empty cartridge-case, and on
the spring carrying the barrel forward again moves a fresh one into
position. Under the barrel casing is the ejector tube through which
the empty cartridge-cases are ejected from the gun.

The rate of fire of the Maxim gun is 600 rounds per minute. Deliberate
fire means about 70 rounds per minute; rapid fire will explode 450
rounds in the same time. As the barrel becomes very hot in use the
barrel-casing contains seven pints of water to keep it cool. About
2000 rounds can be fired at short intervals; but in continuous firing
the water boils after some 600 rounds, and needs replenishing after
about 1000. A valved tube allows steam, but not water to escape.

The operator works this gun by pressing a firing-lever or button.
After starting the machine he merely sits behind the shield, which
protects him from the enemy, directing it, as it keeps on firing
automatically so long as the bands of cartridges are supplied and a
finger held on the trigger or button. By setting free a couple of
levers with his left hand, and pressing his shoulder against the
padded shoulder-piece, he is able to elevate or depress, or train the
barrel horizontally, without in any way interfering with the hail of
missiles.

We use two sizes, one with .45 bore for the Navy, which takes an
all-lead bullet weighing 480 grains, and the other with .303 bore, the
ordinary nickel-coated rifle bullet for the Army. But as the Maxim
gun can be adapted to every rifle-calibre ammunition it is patronised
by all governments.

The gun itself weighs 56 lbs., and is mounted for use in various ways:
on a tripod, a field stand, or a field carriage with wheels. This
carriage has sixteen boxes of ammunition, each containing a belt of
250 cartridges, making 4000 rounds altogether. Its total weight is
about half a ton, so that it can be drawn by one horse, and it is
built for the roughest cross-country work. A little machine, which can
be fixed to the wheel, recharges the belts with cartridges by the
working of a handle.

For ships the Maxim is usually mounted on the ordinary naval cone
mount, or it can be clamped to the bulwark of the deck or the military
"top" on the mast.

But there is a most ingenious form of parapet mounting, known as the
garrison mount, which turns the Maxim into a "disappearing gun," and
can be used equally well for fortress walls or improvised
entrenchments. The gun is placed over two little wheels on which it
can be run along by means of a handle pushed behind in something the
fashion of a lawn-mower. Arrived at its destination, the handle, which
is really a rack, is turned downwards, and on twisting one of the
wheels the gun climbs it by means of a pinion-cog till it points over
the wall, to which hooks at the end of two projecting bars firmly fix
it, the broadened end of the handle being held by its weight to the
ground. It is locked while in use, but a few turns of the wheel cause
it to sink out of sight in as many seconds.

The rifle-calibre guns may also be used as very light horse artillery
to accompany cavalry by being mounted on a "galloping carriage" drawn
by a couple of horses, and with two seats for the operators. The
carriage conveys 3000 rounds, and the steel-plated seats turn up and
form shields during action.

It is interesting to notice that an extra light form of the gun is
made which may be carried strapped on an infantryman's back and fired
from a tripod. Two of these mounted on a double tricycle can be
propelled at a good pace along a fairly level road, and the riders
dismounting have, in a few moments, a valuable little battery at their
disposal.

The _Pom-pom_, of which we have heard so much in the late war, is a
large edition of the Maxim automatic system with some differences in
the system. Its calibre is 1-1/2 inches. Instead of bullets it emits
explosive shells 1 lb. in weight, fitted with percussion fuses which
burst them into about twelve or fourteen pieces. The effective range
is up to 2000 yards, and it will carry to 4000 yards. An improved
_Pom-pom_ recently brought out hurls a 1-1/4 lb. shell with effect at
a mark 3000 yards away, and as far as 6000 yards before its energy is
entirely exhausted. The muzzle velocity of this weapon is 2350 feet a
second as against the 1800 feet of the older pattern. They both fire
300 rounds a minute.

The _Colt_ automatic gun is an American invention whose automatic
action is due to explosion of the charge, not to recoil. The force by
which the motions of firing, extracting, and loading are performed is
derived from the powder-gases, a portion of which--passing through a
small vent in the muzzle--acts by means of a lever on the mechanism of
the gun.

This is also in two parts: (_a_) _barrel_, attached to (_b_)
breech-casing, in which gear for charging, firing, and ejecting is
contained. The barrel, made of a strong alloy of nickel, has its
cartridges fed in by means of belts coiled in boxes attached to the
breech-casing, the boxes moving with the latter so that the movements
of the gun do not affect it. These boxes contain 250 cartridges each
and are easily replaced.

The feed-belt is inserted, and the lever thrown down and moved
backward--once by hand--as far as it will go; this opens the breech
and passes the first cartridge from the belt to the carrier. The lever
is then released and the spring causes it to fly forward, close the
vent, and transfer the cartridge from the carrier to the barrel, also
compressing the mainspring and opening and closing the breech.

On pulling the trigger the shot is fired, and after the bullet has
passed the little vent, but is not yet out of the muzzle, the force of
the expanding gas, acting through the vent on the piston, sets a
gas-lever in operation which acts on the breech mechanism, opens
breech, ejects cartridge-case, and feeds another cartridge into the
carrier. The gas-lever returning forces the cartridge home in the
barrel and closes and locks the breech.

The hammer of the gun acts as the piston of an air-pump, forcing a
strong jet of air into the chamber, and through the barrel, thus
removing all unburnt powder, and thoroughly cleansing it. The metal
employed is strong enough to resist the heaviest charge of
nitro-powder, and the accuracy of its aim is not disturbed by the
vibrations of rapid fire. It does not heat fast, so has no need of a
water-jacket, any surplus heat being removed by a system of radiation.

The bore is made of any rifle calibre for any small-arm ammunition,
and is fitted with a safety-lock. For our own pieces we use the
Lee-Metford cartridges. Four hundred shots per minute can be fired.

The gun consists altogether of ninety-four pieces, but the
working-pieces, _i.e._ those only which need be separated for
cleaning, &c., when in the hands of the artilleryman, are less than
twenty. It can be handled in action by one man, the operation
resembling that of firing a pistol.

The machine weighs 40 lbs., and for use by cavalry or infantry can be
mounted on the _Dundonald Galloping Carriage_. The ammunition-box,
containing 2000 rounds ready for use, carries the gun on its upper
side, and is mounted on a strong steel axle. A pole with a slotted end
is inserted into a revolving funnel on the bend of the shaft, the
limbering-up being completed by an automatic bolt and plug.

The gun-carriage itself is of steel, with hickory wheels and hickory
and steel shafts, detachable at will. The simple harness suits any
saddled cavalry horse, and the shafts work in sockets behind the
rider's legs. Its whole weight with full load of ammunition is under
four hundredweight.


HEAVY ORDNANCE.

As with rifles and the smaller forms of artillery, so also with heavy
ordnance, the changes and improvements within the last fifty years
have been greater than those made during the course of all the
previous centuries.

These changes have affected alike not only the materials from which a
weapon is manufactured, the relative size of calibre and length of
bore, the fashion of mounting and firing, but also the form and weight
of the projectile, the velocity with which it is thrown, and even the
substances used in expelling it from the gun.

Compare for a moment the old cast-iron muzzle-loaders, stubby of
stature, which Wellington's bronzed veterans served with round cannon
balls, well packed in greasy clouts to make them fit tight, or with
shell and grape shot, throughout the hard-fought day of Waterloo, from
a distance which the chroniclers measure by _paces_, so near stood the
opposing ranks to one another.

Or stand in imagination upon one of Nelson's stately men-o'-war and
watch the grimy guns' crews, eight or ten to each, straining on the
ropes. See the still smoking piece hauled inboard, its bore swabbed
out to clean and cool it, then recharged by the muzzle; home go
powder, wad, and the castor full of balls or the chain shot to
splinter the enemy's masts, rammed well down ere the gun is again run
out through the port-hole. Now the gunner snatches the flaming
lintstock and, signal given, applies it to the powder grains sprinkled
in the touch-hole. A salvo of fifty starboard guns goes off in one
terrific broadside, crashing across the Frenchman's decks at such
close quarters that in two or three places they are set on fire by the
burning wads. Next comes a cry of "Boarders!" and the ships are
grappled as the boarding-party scrambles over the bulwarks to the
enemy's deck, a brisk musket-fire from the crowded rigging protecting
their advance; meanwhile the larboard guns, with their simultaneous
discharge, are greeting a new adversary.

Such was war a century ago. Compare with it the late South African
Campaign where the range of guns was estimated in _miles_, and after a
combat lasting from morn to eve, the British general could report: "I
do not think we have seen a gun or a Boer all day."

The days of hand-to-hand fighting have passed, the mêlée in the ranks
may be seen no more; in a few years the bayonet may be relegated to
the limbo of the coat-of-mail or the cast-iron culverin. Yet the
modern battle-scene bristles with the most death-dealing weapons which
the ingenuity of man has ever constructed. The hand-drawn machine-gun
discharges in a couple of minutes as many missiles as a regiment of
Wellington's infantry, with a speed and precision undreamt of by him.
The quick-firing long-range naval guns now in vogue could annihilate a
fleet or destroy a port without approaching close enough to catch a
glimpse of the personnel of their opponents. The deadly torpedo guards
our waterways more effectually than a squadron of ships.

All resources of civilisation have been drawn upon, every triumph of
engineering secured, to forge such weapons as shall strike the hardest
and destroy the most pitilessly. But strange and unexpected the
result! Where we counted our battle-slain by thousands we now mourn
over the death of hundreds; where whole regiments were mown down our
ambulances gather wounded in scattered units. Here is the bright side
of modern war.

The muzzle-loading gun has had its day, a very long day and a
successful one. Again and again it has reasserted itself and ousted
its rivals, but at last all difficulties of construction have been
surmounted and the breech-loader has "come to stay."

However, our services still contain a large number of muzzle-loading
guns, many of them built at quite a recent period, and adapted as far
as possible to modern requirements. So to these we will first turn our
attention.

The earliest guns were made of cast-iron, but this being prone to
burst with a large charge, bronze, brass, and other tougher materials
were for a long time employed. Most elaborately chased and ornamented
specimens of these old weapons are to be seen in the Tower, and many
other collections.

In the utilitarian days of the past century cheapness and speed in
manufacture were more sought after than show. Iron was worked in many
new ways to resist the pressure of explosion.

Armstrong of Elswick conceived the idea of building up a barrel of
_coiled_ iron by joining a series of short welded cylinders together,
and closing them by a solid forged breech-piece. Over all, again,
wrought-iron coils were shrunk. Subsequently he tried a solid
forged-iron barrel bored out to form a tube. Neither make proving very
satisfactory, steel tubes were next used, but were too expensive and
uncertain at that stage of manufacture. Again coiled iron was called
into requisition, and Mr. Frazer of the Royal Gun Factory introduced a
system of double and triple coils which was found very successful,
especially when a thin steel inner tube was substituted for the iron
one (1869).

All these weapons were rifled, so that there was of necessity a
corresponding difference in the projectile employed. Conical shells
being used, studs were now placed on the body of the shell to fit into
the rifling grooves, which were made few in number and deeply cut.
This was apt to weaken the bore of the gun; but on the other hand
many studs to fit into several shallow grooves weakened the cover of
the shells.

Various modifications were tried, and finally a gas-check which
expands into the grooves was placed at the base of the shell.

The muzzle-loader having thus been turned into a very efficient modern
weapon the next problem to be solved was how to throw a projectile
with sufficient force to penetrate the iron and steel armour-plates
then being generally applied to war-ships. "Build larger guns" was the
conclusion arrived at, and presently the arsenals of the Powers were
turning out mammoth weapons up to 100 tons, and even 110 tons in
weight with a calibre of 16 inches and more for their huge shells.
Then was the mighty 35-ton "Woolwich Infant" born (1872), and its
younger but still bigger brothers, 81 tons, 16-inch bore, followed by
the Elswick 100-ton giants, some of which were mounted on our defences
in the Mediterranean. But the fearful concussion of such enormous guns
when fixed in action on board ship injured the superstruction, and
even destroyed the boats, and the great improvements made in steel
both for guns and armour soon led to a fresh revolution. Henceforward
instead of mounting a few very heavy guns we have preferred to trust
to the weight of metal projected by an increased number of smaller
size, but much higher velocity. And these guns are the quick-firing
breech-loaders.

The heaviest of our up-to-date ordnance is of moderate calibre, the
largest breech-loaders being 12-inch, 10-inch, and 9.2-inch guns. But
the elaborateness of its manufacture is such that one big gun takes
nearly as long to "build up" as the ship for which it is destined.
Each weapon has to pass through about sixteen different processes:--

     (1) The solid (or hollow) ingot is _forged_.

     (2) _Annealed_, to get rid of strains.

     (3) It is placed horizontally on a lathe and _rough-turned_.

     (4) _Rough-bored_ in a lathe.

     (5) _Hardened._ Heated to a high temperature and plunged, while
     hot, into a bath of rape oil kept cold by a water-bath. It
     cools slowly for seven to eight hours, being moved about at
     intervals by a crane. This makes the steel more elastic and
     tenacious.

     (6) _Annealed_, _i.e._ reheated to 900° Fahr. and slowly
     cooled. Siemens' pyrometer is used in these operations.

     (7) _Tested_ by pieces cut off.

     (8) _Turned_ and _bored_ for the second time.

     (9) Carefully turned again for _shrinkage_. Outer coil expanded
     till large enough to fit easily over inner. Inside, set up
     vertically in a pit, has outside lowered on to it, water and
     gas being applied to make all shrink evenly. Other projections,
     hoops, rings, &c., also shrunk on.

     (10) Finish--_bored_ and _chambered_.

     (11) _Broached_, or very fine bored, perhaps _lapped_ with lead
     and emery.

     (12) _Rifled_ horizontally in a machine.

     (13) Prepared for breech fittings.

     (14) Taken to the Proof Butts for trial.

     (15) Drilled for sockets, sights, &c. Lined and engraved.
     Breech fittings, locks, electric firing gear, &c., added. Small
     adjustments made by filing.

     (16) _Browned_ or _painted_.

When worn the bore can be lined with a new steel tube.

These lengthy operations completed, our gun has still to be _mounted_
upon its field-carriage, naval cone, or disappearing mounting, any of
which are complicated and delicately-adjusted pieces of mechanism, the
product of much time and labour, which we have no space here to
describe.

Some account of the principal parts of these guns has already been
given, but the method by which the breech is closed remains to be
dealt with.

It will be noticed that though guns now barely reach half the weight
of the monster muzzle-loaders, they are even more effective. Thus the
46-ton (12-inch) gun hurls an 850-lb. projectile with a velocity of
2750 foot-seconds, and uses a comparatively small charge. The famous
"81-ton" needed a very big charge for its 1700-lb. shell, and had
little more than half the velocity and no such power of penetration.
This change has been brought about by using a slower-burning explosive
very powerful in its effects; enlarging the chamber to give it
sufficient air space, and lengthening the chase of the gun so that
every particle of the powder-gas may be brought into action before
the shot leaves the muzzle. This system and the substitution of steel
for the many layers of welded iron, makes our modern guns long and
slim in comparison with the older ones.

To resist the pressure of the explosion against the breech end, a
tightly-fitting breech-plug must be employed. The most modern and
ingenious is the Welin plug, invented by a Swedish engineer. The
ordinary interrupted screw breech-plug has three parts of its
circumference plane and the other three parts "threaded," or grooved,
to screw into corresponding grooves in the breech; thus only half of
the circumference is engaged by the screw. Mr. Welin has cut steps on
the plug, three of which would be threaded to one plane segment, each
locking with its counterpart in the breech. In this case there are
three segments engaged to each one left plane, and the strength of the
screw is almost irresistible. The plug, which is hinged at the side,
has therefore been shortened by one-third, and is light enough to
swing clear with one touch of the handwheel that first rotates and
unlocks it.

The method of firing is this: The projectile lifted (by hydraulic
power on a ship) into the loading tray is swung to the mouth of the
breech and pushed into the bore. A driving-band attached near its base
is so notched at the edges that it jams the shell closely and prevents
it slipping back if loaded at a high angle of elevation. The powder
charge being placed in the chamber the breech-plug is now swung-to and
turned till it locks close. The vent-axial or inner part of this
breech-plug (next to the charge), which is called from its shape the
"mushroom-head," encloses between its head and the screw-plug the de
Bange obturator, a flat canvas pad of many layers soaked with mutton
fat tightly packed between discs of tin. When the charge explodes, the
mushroom-head--forced back upon the pad--compresses it till its edges
bulge against the tube and prevent any escape of gas breechwards.

The electric spark which fires the charge is passed in from outside by
means of a minute and ingenious apparatus fitted into a little vent or
tube in the mushroom-head. As the electric circuit cannot be completed
till the breech-plug is screwed quite home there is now no more fear
of a premature explosion than of double loading. If the electric gear
is disordered the gun can be fired equally well and safely by a
percussion tube.

This description is of a typical large gun, and may be applied to all
calibres and also to the larger quick-firers. The mechanism as the
breech is swung open again withdraws the empty cartridge. So valuable
has de Bange's obturator proved, however, that guns up to the 6-inch
calibre now have the powder charge thrown into the chamber in bags,
thus saving the weight of the metal tubes hitherto necessary.

Of course several types of breech-loading guns are used in the
Service, but the above are the most modern.

The favourite mode of construction at the present time is the
wire-wound barrel, the building up of which is completed by covering
the many layers of wire with an outer tube or jacket expanded by heat
before it is slipped on in order that it may fit closely when cold. A
previous make, without wire, is strengthened by rings or hoops also
shrunk on hot.

The quick-firers proper are of many sizes, 8-inch, 7.5-inch, 6-inch,
4.7-inch, 4-inch, and 3-inch (12-pounders). The naval type is as a
rule longer and lighter than those made for the rough usage of field
campaigning and have a much greater range. There are also smaller
quick-firers, 3-pounders and 6-pounders with bore something over
1-inch and 2-inch (Nordenfelt, Hotchkiss, Vickers-Maxim). Some of the
high velocity 12-pounders being employed as garrison guns along with
6-inch and 4.7-inch, and the large calibre howitzers.

We still use howitzer batteries of 5-inch bore in the field and in the
siege-train, all being short, rifled, breech-loading weapons, as they
throw a heavy shell with smallish charges at a high angle of
elevation, but cover a relatively short distance. A new pattern of
8-inch calibre is now under consideration.

It is interesting to contrast the potencies of some of these guns, all
of which use cordite charges.

  +----------+---------------+-----------+----------------+-----------+
  |Calibre.  |    Charge.    |Weight of  |Muzzle Velocity |Number of  |
  |          |               |  Shot.    |      in        |Rounds per |
  |          |               |           | Foot Seconds.  |  Minute.  |
  +----------+---------------+-----------+----------------+-----------+
  | 12 inch  |207 lbs.       | 850 lbs.  |     2750       |    1      |
  |  8  "    | 52  "         | 210  "    |     2750       |    5      |
  |  6  "    | 25  "         | 100  "    |     2775       |    8      |
  |4.7  "    |  9  "         |  45  "    |     2600       |   12      |
  |  3  "    |  2 lbs. 9 oz. |12.5  "    |     2600       |   20      |
  +----------+---------------+-----------+----------------+-----------+

[Illustration: _The Simms armour-clad motor-car for coast defence.
Maxim guns and Pom-pom in action._]

In the armament of our fine Navy guns are roughly distributed as
follows:--81-ton, 13-1/2-inch, and superseded patterns of machine-guns
such as Gatling's, Gardner's, and Nordenfelt's, besides a few
surviving muzzle-loaders, &c., are carried only by the oldest
battleships.

The first-class battleships are chiefly supplied with four 12-inch
guns in barbettes, twelve 6-inch as secondary batteries, and a number
of smaller quick-firers on the upper decks and in the fighting tops,
also for use in the boats, to which are added several Maxims.

The first-class cruisers have 9.2 as their largest calibre, with a
lessened proportion of 6-inch, &c. Some of the newest bear only 7-1/2
or 6-inch guns as their heaviest ordnance; like the second-class
cruisers which, however, add several 4.7's between these and their
small quick-firers.

Vessels of inferior size usually carry nothing more powerful than the
4.7.

All are now armed with torpedo tubes.

These same useful little quick-firers and machine-guns have been the
lethal weapons which made the armoured trains so formidable. Indeed,
there seems no limit to their value both for offence and defence, for
the battle chariot of the ancient Briton has its modern successor in
the Simms' motor war car lately exhibited at the Crystal Palace. This
armour-plated movable fort is intended primarily for coast defence,
but can work off beaten tracks over almost any sort of country. It is
propelled at the rate of nine miles an hour by a 16-horse-power
motor, carrying all its own fuel, two pom-poms, two small Maxims, and
10,000 rounds of ammunition, besides the necessary complement of men
and searchlights for night use, &c., &c.

The searchlight, by the way, has taken the place of all former
inventions thrown from guns, such as ground-light balls, or parachute
lights with a time-fuse which burst in the air and remained suspended,
betraying the enemy's proceedings.

In like manner the linked chain and "double-headed" shot, the
"canister"--iron balls packed in thin iron or tin cylinders which
would travel about 350 yards--the "carcasses" filled with inflammable
composition for firing ships and villages, are as much out of date as
the solid round shot or cannon-ball. Young Shrapnell's invention a
century ago of the form of shell that bears his name, a number of
balls arranged in a case containing also a small bursting-charge fired
either by percussion or by a time-fuse, has practically replaced them
all. Thrown with great precision of aim its effective range is now up
to 5000 yards. A 15-pounder shrapnell shell, for instance, contains
192 bullets, and covers several hundred yards with the scattered
missiles flying with extreme velocity.

Common shell, from 2-1/2 to 3 calibres long, contains an explosive
only. Another variety is segment shell, made of pieces built up in a
ring with a bursting charge in the centre which presently shatters
it.

The Palliser shell has a marvellous penetrating power when used
against iron plates. But, _mirabile dictu!_ experiments tried within
the past few months prove that a soft cap added externally enables a
projectile to pierce with ease armour which had previously defied
every attack.


EXPLOSIVES.

Half a century ago gunpowder was still the one driving power which
started the projectile on its flight. It is composed of some 75 parts
of saltpetre or nitrate of potash, 15 parts of carefully prepared
charcoal, and 10 parts of sulphur. This composition imprisons a large
amount of oxygen for combustion and is found to act most successfully
when formed into rather large prismatic grains.

On the abolition of the old flint-lock its place was taken by a
detonating substance enclosed in a copper cap, and some time later
inventors came forward with new and more powerful explosives to
supersede the use of gunpowder.

By treating cotton with nitric and sulphuric acid reaction
_gun-cotton_ was produced; and a year later glycerine treated in the
same manner became known to commerce as _nitro-glycerine_. This liquid
form being inconvenient to handle, some inert granular substance such
as infusorial earth was used to absorb the nitro-glycerine, and
_dynamite_ was the result.

The explosion of gun-cotton was found to be too sudden and rapid for
rifles or cannon; it was liable to burst the piece instead of blowing
out the charge. In order to lessen the rapidity of its ignition
ordinary cotton was mixed with it, or its threads were twisted round
some inert substance.

When repeating-rifles and machine-guns came into general use a
smokeless powder became necessary. Such powders as a rule contain
nitro-cellulose (gun-cotton) or nitro-glycerine, or both. These are
combined into a plastic, gluey composition, which is then made up into
sticks or pellets of various shapes, and usually of large size to
lessen the extreme rapidity of their combustion. Substances such as
tan, paraffin, starch, bran, peat, &c., &c., and many mineral salts,
are used in forming low explosives from high ones.

To secure complete combustion some of the larger pellets are made with
a central hole, or even pierced by many holes, so that the fire
penetrates the entire mass and carries off all its explosive
qualities.

Our _cordite_ consists of nitro-glycerine dissolving di-nitro
cellulose by the acid of a volatile solvent and a mineral jelly or
oil. This compound is semi-fluid, and being passed like macaroni
through round holes in a metal plate it forms strings or cords of
varying size according to the diameter of the holes. Hence the name,
cordite.

Many experiments in search of more powerful explosives resulted in an
almost universal adoption of picric acid as the base. This acid is
itself produced by the action of nitric acid upon carbolic acid, and
each nation has its own fashion of preparing it for artillery.

The French began with _mélinite_ in 1885, this being a mixture of
picric acid and gun-cotton.

The composition of _lyddite_ (named from its place of manufacture,
Lydd, in Kent) is a jealously-guarded British secret. This substance
was first used in 5-inch howitzers during the late Soudan campaign,
playing a part in the bombardment of Omdurman. The effect of the
50-lb. lyddite shells upon the South African kopjes is described as
astounding. When the yellow cloud had cleared away trees were seen
uprooted, rocks pulverised, the very face of the earth had changed.

Several attempts have been made to utilise dynamite for shells, some
of the guns employing compressed air as their motive power. The United
States some years ago went to great expense in setting up for this
purpose heavy pneumatic plant, which has recently been disposed of as
too cumbrous. Dudley's "Aërial Torpedo" gun discharged a 13-lb. shell
containing explosive gelatine, gun-cotton, and fulminate of mercury by
igniting the small cordite charge in a parallel tube, through a vent
in which the partially cooled gases acted on the projectile in the
barrel. This was rotated in the air by inclined blades on a tailpiece,
as the barrel could not be rifled for fear of the heat set up by
friction. Some guns actuated on much the same principle are said to
have been used with effect in the Hispano-American war. Mr. Hudson
Maxim with his explosive "maximite" claims to throw half a ton of
dynamite about a mile, and a one-ton shell to half that distance.

But even these inventors are outstripped by Professor Birkeland, who
undertakes to hurl a projectile weighing two tons from an iron tube
coiled with copper wire down which an electric current is passed; thus
doing away entirely with the need of a firing-charge.


IN THE GUN FACTORY.

Let us pay a visit to one of our gun factories and get some idea of
the multiform activities necessary to the turning out complete of a
single piece of ordnance or a complicated machine-gun. We enter the
enormous workshop, glazed as to roof and sides, full of the varied
buzz and whirr and clank of the machinery. Up and down the long bays
stand row upon row of lathes, turning, milling, polishing, boring,
rifling--all moving automatically, and with a precision which leaves
nothing to be desired. The silent attendants seem to have nothing in
their own hands, they simply watch that the cutting does not go too
far, and with a touch of the guiding handles regulate the pace or
occasionally insert a fresh tool. The bits used in these processes are
self-cleaning, so the machinery is never clogged; and on the ground
lie little heaps of brass chips cut away by the minute milling tools;
or in other places it is bestrewn with shavings of brass and steel
which great chisels peel off as easily as a carpenter shaves a deal
board.

Here an enormous steel ingot, forged solid, heated again and again in
a huge furnace and beaten by steam-hammers, or pressed by hydraulic
power between each heating till it is brought to the desired size and
shape, is having its centre bored through by a special drill which
takes out a solid core. This operation is termed "trepanning," and is
applied to guns not exceeding eight inches; those of larger calibre
being rough-bored on a lathe, and mandrils placed in them during the
subsequent forgings. The tremendous heat generated during the boring
processes--we may recall how Benjamin Thompson made water boil by the
experimental boring of a cannon--is kept down by streams of soapy
water continually pumped through and over the metal. We notice this
flow of lubricating fluid in all directions, from oil dropping slowly
on to the small brass-milling machines to this fountain-play of water
which makes a pleasant undertone amidst the jangle of the machines.
But these machines are less noisy than we anticipated; in their actual
working they emit scarcely the slightest sound. What strikes us more
than the supreme exactness with which each does its portion of the
work, is the great deliberateness of its proceeding. All the hurry and
bustle is above us, caused by the driving-bands from the engine, which
keeps the whole machinery of the shed in motion. Suddenly, with harsh
creakings, a great overhead crane comes jarring along the bay, drops a
chain, grips up a gun-barrel, and, handling this mass of many tons'
weight as easily as we should lift a walking-stick, swings it off to
undergo another process of manufacture.

We pass on to the next lathe where a still larger forging is being
turned externally, supported on specially devised running gear, many
different cutters acting upon it at the same time, so that it is
gradually assuming the tapering, banded appearance familiar to us in
the completed state.

We turn, fairly bewildered, from one stage of manufacture to another.
Here is a gun whose bore is being "chambered" to the size necessary
for containing the firing charge. Further along we examine a more
finished weapon in process of preparation to receive the breech-plug
and other fittings. Still another we notice which has been
"fine-bored" to a beautifully smooth surface but is being improved yet
more by "lapping" with lead and emery powder.

In the next shed a marvellous machine is rifling the interior of a
barrel with a dexterity absolutely uncanny, for the tool which does
the rifling has to be rotated in order to give the proper "twist" at
the same moment as it is advancing lengthwise down the bore. The
grooves are not made simultaneously but as a rule one at a time, the
distance between them being kept by measurements on a prepared disc.

Now we have reached the apparatus for the wire-wound guns, a principle
representing the _ne plus ultra_ of strength and durability hitherto
evolved. The rough-bored gun is placed upon a lathe which revolves
slowly, drawing on to it from a reel mounted at one side a continuous
layer of steel ribbon about a quarter of an inch wide. On a 12-inch
gun there is wound some 117 miles of this wire! fourteen layers of it
at the muzzle end and seventy-five at the breech end. Heavy weights
regulate the tension of the wire, which varies for each layer, the
outermost being at the lowest tension, which will resist a pressure of
over 100 tons to the square inch.

We next enter the division in which the gun cradles and mounts are
prepared, where we see some of the heaviest work carried out by
electric dynamos, the workman sitting on a raised platform to keep
careful watch over his business.

Passing through this with interested but cursory inspection of the
cone mountings for quick-firing naval guns, some ingenious elevating
and training gear and a field carriage whose hydraulic buffers merit
closer examination, we come to the shell department where all kinds of
projectiles are manufactured. Shrapnel in its various forms,
armour-piercing shells, forged steel or cast-iron, and small brass
cartridges for the machine-guns may be found here; and the beautifully
delicate workmanship of the fuse arrangements attracts our admiration.
But we may not linger; the plant for the machine-guns themselves claim
our attention.

Owing to the complexity and minute mechanism of these weapons almost a
hundred different machines are needed, some of the milling machines
taking a large selection of cutters upon one spindle. Indeed, in many
parts of the works one notices the men changing their tools for others
of different size or application. Some of the boring machines work two
barrels at the same time, others can drill three barrels or polish a
couple simultaneously. But there are hundreds of minute operations
which need to be done separately, down to the boring of screw holes
and cutting the groove on a screw-head. Many labourers are employed
upon the lock alone. And every portion is gauged correctly to the most
infinitesimal fraction, being turned out by the thousand, that every
separate item may be interchangeable among weapons of the same make.

Look at the barrel which came grey and dull from its first turning now
as it is dealt with changing into bright silver. Here it is adjusted
upon the hydraulic rifling machine which will prepare it to carry the
small-arm bullet (.303 inch). That one of larger calibre is rifled to
fire a small shell. Further on, the barrels and their jackets are
being fitted together and the different parts assembled and screwed
up. We have not time to follow the perfect implement to its mounting,
nor to do more than glance at those howitzers and the breech mechanism
of the 6-inch quick-firers near which our guide indicates piles of
flat cases to keep the de Bange obturators from warping while out of
use. For the afternoon is waning and the foundry still unvisited.

To reach it we pass through the smith's shop and pause awhile to watch
a supply of spanners being roughly stamped by an immense machine out
of metal plates and having their edges tidied off before they can be
further perfected. A steam-hammer is busily engaged in driving
mandrils of increasing size through the centre of a red-hot forging.
The heat from the forges is tremendous, and though it is tempered by a
spray of falling water we are glad to escape into the next shed.

Here we find skilled workmen carefully preparing moulds by taking in
sand the exact impression of a wooden dummy. Fortunately we arrive
just as a series of casts deeply sunk in the ground are about to be
made. Two brawny labourers bear forward an enormous iron crucible,
red-hot from the furnace, filled with seething liquid--manganese
bronze, we are told--which, when an iron bar is dipped into it, throws
up tongues of beautiful greenish-golden flame. The smith stirs and
clears off the scum as coolly as a cook skims her broth! Now it is
ready, the crucible is again lifted and its contents poured into a
large funnel from which it flows into the moulds beneath and fills
them to the level of the floor. At each one a helper armed with an
iron bar takes his stand and stirs again to work up all dross and
air-bubbles to the surface before the metal sets--a scene worthy of a
painter's brush.

And so we leave them.




DIRIGIBLE TORPEDOES.


The history of warlike inventions is the history of a continual
see-saw between the discovery of a new means of defence and the
discovery of a fresh means of attack. At one time a shield is devised
to repel a javelin; at another a machine to hurl the javelin with
increased violence against the shield; then the shield is reinforced
by complete coats of mail, and so on. The ball of invention has rolled
steadily on into our own times, gathering size as it rolls, and
bringing more and more startling revolutions in the art of war. To-day
it is a battle between the forces of nature, controllable by man in
the shape of "high explosives," and the resisting power of metals
tempered to extreme toughness.

At present it looks as if, on the sea at least, the attack were
stronger than the defence. Our warships may be cased in the hardest
metal several inches thick until they become floating forts, almost
impregnable to the heaviest shells. They may be provided with terrible
engines able to give blow for blow, and be manned with the stoutest
hearts in the world. And yet, were a sea-fight in progress, a blow,
crushing and resistless, might at any time come upon the vessel from a
quarter whence, even though suspected, its coming might escape
notice--below the waterline. Were it possible to case an ironclad from
deck to keel in foot-thick plating, the metal would crumple like a
biscuit-box under the terrible impact of the torpedo.

This destructive weapon is an object of awe not so much from what it
has done as from what it can do. The instances of a torpedo shivering
a vessel in actual warfare are but few. Yet its moral effect must be
immense. Even though it may miss its mark, the very fact of its
possible presence will, especially at night-time, tend to keep the
commanding minds of a fleet very much on the stretch, and to destroy
their efficiency. A torpedo knows no half measures. It is either
entirely successful or utterly useless. Its construction entails great
expense, but inasmuch as it can, if directed aright, send a million of
the enemy's money and a regiment of men to the bottom, the discharge
of a torpedo is, after all, but the setting of a sprat to catch a
whale.

The aim of inventors has been to endow the dirigible torpedo, fit for
use in the open sea, with such qualities that when once launched on
its murderous course it can pursue its course in the required
direction without external help. The difficulties to be overcome in
arriving at a serviceable weapon have been very great owing to the
complexity of the problem. A torpedo cannot be fired through water
like a cannon shell through air. Water, though yielding, is
incompressible, and offers to a moving body a resistance increasing
with the speed of that body. Therefore the torpedo must contain its
own motive power and its own steering apparatus, and be in effect a
miniature submarine vessel complete in itself. To be out of sight and
danger it must travel beneath the surface and yet not sink to the
bottom; to be effective it must possess great speed, a considerable
sphere of action, and be able to counteract any chance currents it may
meet on its way.

Among purely automobile torpedoes the Whitehead is easily first. After
thirty years it still holds the lead for open sea work. It is a very
marvel of ingenious adaptation of means to an end, and as it has
fulfilled most successfully the conditions set forth above for an
effective projectile it will be interesting to examine in some detail
this most valuable weapon.

In 1873 one Captain Lupuis of the Austrian navy experimented with a
small fireship which he directed along the surface of the sea by means
of ropes and guiding lines. This fireship was to be loaded with
explosives which should ignite immediately on coming into collision
with the vessel aimed at. The Austrian Government declared his scheme
unworkable in its crude form, and the Captain looked about for some
one to help him throw what he felt to be a sound idea into a practical
shape. He found the man he wanted in Mr. Whitehead, who was at that
time manager of an engineering establishment at Fiume. Mr. Whitehead
fell in enthusiastically with his proposition, at once discarded the
complicated system of guiding ropes, and set to work to solve the
problem on his own lines. At the end of two years, during which he
worked in secret, aided only by a trusted mechanic and a boy, his son,
he constructed the first torpedo of the type that bears his name. It
was made of steel, was fourteen inches in diameter, weighed 300 lbs.,
and carried eighteen pounds of dynamite as explosive charge. But its
powers were limited. It could attain a rate of but six knots an hour
under favourable conditions, and then for a short distance only. Its
conduct was uncertain. Sometimes it would run along the surface, at
others make plunges for the bottom. However, the British Government,
recognising the importance of Mr. Whitehead's work, encouraged him to
perfect his instrument, and paid him a large sum for the patent
rights. Pattern succeeded pattern, until comparative perfection was
reached.

Described briefly, the Whitehead torpedo is cigar-shaped, blunt-nosed
and tapering gradually towards the tail, so following the lines of a
fish. Its length is twelve times its diameter, which varies in
different patterns from fourteen to nineteen inches. At the fore end
is the striker, and at the tail are a couple of three-bladed screws
working on one shaft in opposite directions, to economise power and
obviate any tendency of the torpedo to travel in a curve; and two sets
of rudders, the one horizontal, the other vertical. The latest form of
the torpedo has a speed of twenty-nine knots and a range of over a
thousand yards.

The torpedo is divided into five compartments by watertight steel
bulkheads. At the front is the _explosive head_, containing wet
gun-cotton, or some other explosive. The "war head," as it is called,
is detachable, and for practice purposes its place is taken by a
dummy-head filled with wood to make the balance correct.

Next comes the _air chamber_, filled with highly-compressed air to
drive the engines; after it the _balance chamber_, containing the
apparatus for keeping the torpedo at its proper depth; then the
_engine-room_; and, last of all, the _buoyancy chamber_, which is
air-tight and prevents the torpedo from sinking at the end of its run.

To examine the compartments in order:--

In the very front of the torpedo is the pistol and primer-charge for
igniting the gun-cotton. Especial care has been taken over this part
of the mechanism, to prevent the torpedo being as dangerous to friends
as to foes. The pistol consists of a steel plug sliding in a metal
tube, at the back end of which is the fulminating charge. Until the
plug is driven right in against this charge there can be no explosion.
Three precautions are taken against this happening prematurely. In the
first place, there is on the forward end of the plug a thread cut, up
which a screw-fan travels as soon as it strikes the water. Until the
torpedo has run forty-five feet the fan has not reached the end of its
travel, and the plug consequently cannot be driven home. Even when the
plug is quite free only a heavy blow will drive it in, as a little
copper pin has to be sheared through by the impact. And before the
screw can unwind at all, a safety-pin must be withdrawn at the moment
of firing. So that a torpedo is harmless until it has passed outside
the zone of danger to the discharging vessel.

The detonating charge is thirty-eight grains of fulminate of mercury,
and the primer-charge consists of six one-ounce discs of dry
gun-cotton contained in a copper cylinder, the front end of which is
connected with the striker-tube of the pistol. The fulminate, on
receiving a blow, expands 2500 times, giving a violent shock to the
gun-cotton discs, which in turn explode and impart a shock to the main
charge, 200 lbs. of gun-cotton.

The _air chamber_ is made of the finest compressed steel, or of
phosphor-bronze, a third of an inch thick. When ready for action this
chamber has to bear a pressure of 1350 lbs. to the square inch. So
severe is the compression that in the largest-sized torpedoes the air
in this chamber weighs no less than 63 lbs. The air is forced in by
very powerful pumps of a special design. Aft of this chamber is that
containing the stop-valve and steering-gear. The stop-valve is a
species of air-tap sealing the air chamber until the torpedo is to be
discharged. The valve is so arranged that it is impossible to insert
the torpedo into the firing-tube before the valve has been opened,
and so brought the air chamber into communication with the
starting-valve, which does not admit air to the engines till after the
projectile has left the tube.

The _steering apparatus_ is undoubtedly the most ingenious of the many
clever contrivances packed into a Whitehead torpedo. Its function is
to keep the torpedo on an even keel at a depth determined before the
discharge. This is effected by means of two agencies, a swinging
weight, and a valve which is driven in by water pressure as the
torpedo sinks. When the torpedo points head downwards the weight
swings forward, and by means of connecting levers brings the
horizontal rudders up. As the torpedo rises the weight becomes
vertical and the rudder horizontal. This device only insures that the
torpedo shall travel horizontally. The valve makes it keep its proper
depth by working in conjunction with the pendulum. The principle,
which is too complicated for full description, is, put briefly, a
tendency of the valve to correct the pendulum whenever the latter
swings too far. Lest the pendulum should be violently shaken by the
discharge there is a special controlling gear which keeps the rudders
fixed until the torpedo has proceeded a certain distance, when the
steering mechanism is released. The steering-gear does not work
directly on the rudder. Mr. Whitehead found in his earlier experiments
that the pull exerted by the weight and valve was not sufficient to
move the rudders against the pressure of the screws. He therefore
introduced a beautiful little auxiliary engine, called the
servo-motor, which is to the torpedo what the steam steering-gear is
to a ship. The servo-motor, situated in the _engine-room_, is only
four inches long, but the power it exerts by means of compressed air
is so great that a pressure of half an ounce exerted by the
steering-gear produces a pull of 160 lbs. on the rudders.

The engines consist of three single-action cylinders, their cranks
working at an angle of 120° to one another, so that there is no "dead"
or stopping point in their action. They are very small, but, thanks to
the huge pressure in the air chamber, develop nearly thirty-one
horse-power. Lest they should "race," or revolve too quickly, while
passing from the tube to the water and do themselves serious damage,
they are provided with a "delay action valve," which is opened by the
impact of the torpedo against the water. Further, lest the air should
be admitted to the cylinders at a very high pressure gradually
decreasing to zero, a "reducing valve" or governor is added to keep
the engines running at a constant speed.

Whitehead torpedoes are fired from tubes above or below the waterline.
Deck tubes have the advantage of being more easily aimed, but when
loaded they are a source of danger, as any stray bullet or shell from
an enemy's ship might explode the torpedo with dire results. There is
therefore an increasing preference for submerged tubes. An ingenious
device is used for aiming the torpedo, which makes allowances for the
speed of the ship from which it is fired, the speed of the ship aimed
at, and the speed of the torpedo itself. When the moment for firing
arrives, the officer in charge presses an electric button, which sets
in motion an electric magnet fixed to the side of the tube. The magnet
releases a heavy ball which falls and turns the "firing rod."
Compressed air or a powder discharge is brought to bear on the rear
end of the torpedo, which, if submerged, darts out from the vessel's
side along a guiding bar, from which it is released at both ends
simultaneously, thus avoiding the great deflection towards the stern
which would occur were a broadside torpedo not held at the nose till
the tail is clear. This guiding apparatus enables a torpedo to leave
the side of a vessel travelling at high speed almost at right angles
to the vessel's path.

It will be easily understood that a Whitehead torpedo is a costly
projectile, and that its value--£500 or more--makes the authorities
very careful of its welfare. During practice with "blank" torpedoes a
"Holmes light" is attached. This light is a canister full of calcium
phosphide to which water penetrates through numerous holes, causing
gas to be thrown off and rise to the surface, where, on meeting with
the oxygen of the air, it bursts into flame and gives off dense
volumes of heavy smoke, disclosing the position of the torpedo by
night or day.

At Portsmouth are storehouses containing upwards of a thousand
torpedoes. Every torpedo is at intervals taken to pieces, examined,
tested, and put together again after full particulars have been taken
down on paper. Each steel "baby" is kept bright and clean, coated
with a thin layer of oil, lest a single spot of rust should mar its
beauty. An interesting passage from Lieutenant G. E. Armstrong's book
on "Torpedoes and Torpedo Vessels" will illustrate the scrupulous
exactness observed in all things relating to the torpedo depôts: "As
an example of the care with which the stores are kept it may be
mentioned that a particular tiny pattern of brass screw which forms
part of the torpedo's mechanism and which is valued at about
twopence-halfpenny per gross, is never allowed to be a single number
wrong. On one occasion, when the stocktaking took place, it was found
that instead of 5000 little screws being accounted for by the man who
was told off to count them, there were only 4997. Several foolscap
letters were written and exchanged over these three small screws,
though their value was not more than a small fraction of a farthing."

The classic instance of the effectiveness of this type of torpedo is
the battle of the Yalu, fought between the Japanese and Chinese fleets
in 1894. The Japanese had been pounding their adversaries for hours
with their big guns without producing decisive results. So they
determined upon a torpedo attack, which was delivered early in the
morning under cover of darkness, and resulted in the destruction of a
cruiser, the _Ting Yuen_. The next night a second incursion of the
Japanese destroyers wrecked another cruiser, the _Lai Yuen_, which
sunk within five minutes of being struck; sank the _Wei Yuen_, an old
wooden vessel used as a training-school; and blew a large steam
launch out of the water on to an adjacent wharf. These hits "below the
belt" were too much for the Chinese, who soon afterwards surrendered
to their more scientific and better equipped foes.

If a general naval war broke out to-day most nations would undoubtedly
pin their faith to the Whitehead torpedo for use in the open sea, now
that its accuracy has been largely increased by the gyroscope, a heavy
flywheel attachment revolving rapidly at right angles to the path of
the torpedo, and rendering a change of direction almost impossible.

For harbour defence the Brennan or its American rival, the
Sims-Edison, might be employed. They are both torpedoes dirigible from
a fixed base by means of connecting wires. The presence of these wires
constitutes an obstacle to their being of service in a fleet action.

The Brennan is used by our naval authorities. It is the invention of a
Melbourne watchmaker. Being a comparatively poor man, Mr. Brennan
applied to the Colonial Government for grants to aid him in the
manufacture and development of his torpedo, and he was supplied with
sufficient money to perfect it. In 1881 he was requested by our
Admiralty to bring his invention to England, where it was experimented
upon, and pronounced so efficient for harbour and creek defence that
at the advice of the Royal Engineers Mr. Brennan was paid large sums
for his patents and services.

The Brennan torpedo derives its motive power from a very powerful
engine on shore, capable of developing 100 horse-power, with which it
is connected by stout piano wires. One end of these wires is wound on
two reels inside the torpedo, each working a screw; the other end is
attached to two winding drums driven at high velocity by the engine on
shore. As the drums wind in the wire the reels in the torpedo revolve;
consequently, the harder the torpedo is pulled back the faster it
moves forward, liked a trained trotting mare. The steering of the
torpedo is effected by alterations in the relative speeds of the
drums, and consequently of the screws. The drums run loose on the
engine axle, and are thrown in or out of gear by means of a
friction-brake, so that their speed can be regulated without altering
the pace of the engines. Any increase in the speed of one drum causes
a corresponding decrease in the speed of the other. The torpedo can be
steered easily to right or left within an arc of forty degrees on each
side of straight ahead; but when once launched it cannot be retrieved
except by means of a boat. Its path is marked by a Holmes light,
described above. It has a 200-lb. gun-cotton charge, and is fitted
with an apparatus for maintaining a proper depth very similar to that
used in the Whitehead torpedo.

The Sims-Edison torpedo differs from the Brennan in its greater
obedience to orders and in its motive power being electrically
transmitted through a single connecting cable. It is over thirty feet
in length and two feet in diameter. Attached to the torpedo proper by
rods is a large copper float, furnished with balls to show the
operator the path of the torpedo. The torpedo itself is in four parts:
the explosive head; the magazine of electric cables, which is paid out
as the torpedo travels; the motor room; and the compartment containing
the steering-gear. The projectile has a high speed and long
range--over four thousand yards. It can twist and turn in any
direction, and, if need be, be called to heel. Like the Brennan, it
has the disadvantage of a long trailing wire, which could easily
become entangled; and it might be put out of action by any damage
inflicted on its float by the enemy's guns. But it is likely to prove
a very effective harbour-guard if brought to the test.

In passing to the Orling-Armstrong torpedo we enter the latest phase
of torpedo construction. Seeing the disadvantages arising from wires,
electricians have sought a means of controlling torpedoes without any
tangible connection. Wireless telegraphy showed that such a means was
not beyond the bounds of possibility. Mr. Axel Orling, a Swede,
working in concert with Mr. J. T. Armstrong, has lately proved that a
torpedo can be steered by waves of energy transmitted along rays of
light, or perhaps it would be more correct to say along shafts of a
form of X-rays.

Mr. Orling claims for his torpedo that it is capable of a speed of
twenty-two knots or more an hour; that it can be called to heel, and
steered to right or left at will; that as long as it is in sight it is
controllable by rays invisible to the enemy; that not merely one, but
a number of torpedoes can be directed by the same beams of light;
that, as it is submerged, it would, even if detected, be a bad mark
for the enemy's guns.

The torpedo carries a shaft which projects above the water, and bears
on its upper end a white disc to receive the rays and transmit them to
internal motors to be transmuted into driving power. The rod also
carries at night an electric light, shaded on the enemy's side, but
rendering the whereabouts of the torpedo very visible to the steerer.

Mr. Orling's torpedo acts throughout in a cruelly calculating manner.
Before its attack a ship would derive small advantage from a crinoline
of steel netting; for the large torpedo conceals in its head a smaller
torpedo, which, as soon as the netting is struck, darts out and blasts
an opening through which its longer brother, after a momentary delay,
can easily follow. The netting penetrated, the torpedo has yet to
strike twice before exploding. On the first impact, a pin, projecting
from the nose, is driven in to reverse the engines, and at the same
time a certain nut commences to travel along a screw. The nut having
worked its way to the end of the thread, the head of the torpedo fills
slowly through a valve, giving it a downward slant in front. The
engines are again reversed and the nut again travels, this time
bringing the head of the torpedo up, so as to strike the vessel at a
very effective angle from below.

This torpedo has passed beyond the experimental stage. It is reported
that by command of the Swedish Government, to whom Mr. Orling offered
his invention, and of the King, who takes a keen interest in the ideas
of his young countryman, a number of experiments were some time ago
carried out in the Swedish rivers. Torpedoes were sent 2-1/2 miles,
directed as desired, and made to rise or sink--all this without any
tangible connection. The Government was sufficiently satisfied with
the result to take up the patents, as furnishing a cheap means of
defending their coasts.

Mr. Orling has described what he imagines would happen in case of an
attack on a position protected by his ingenious creations. "Suppose
that I had twelve torpedoes hidden away under ten feet of water in a
convenient little cove, and that I was directed to annihilate a
hostile fleet just appearing above the horizon. Before me, on a little
table perhaps, I should have my apparatus; twelve buttons would be
under my fingers. Against each button there would be a description of
the torpedo to which it was connected; it would tell me its power of
destruction, and the power of its machinery, and for what distance it
would go. On each button, also, would be indicated the time that I
must press it to release the torpedoes. Well now, I perceive a large
vessel in the van of the approaching fleet. I put my fingers on the
button which is connected with my largest and most formidable weapon.
I press the button--perhaps for twelve seconds. The torpedo is pushed
forward from its fastenings by a special spring, a small pin is
extracted from it, and immediately the motive machinery is set in
motion, and underneath the water goes my little agent of destruction,
and there is nothing to tell the ship of its doom. I place my hand on
another button, and according to the time I press it I steer the
torpedo; the rudder answers to the rays, and the rays answer to the
will of my mind."[2]

     [2] _Pearson's Magazine._

If this torpedo acts fully up to its author's expectations, naval
warfare, at least as at present conducted, will be impossible. There
appears to be no reason why this torpedo should not be worked from
shipboard; and we cannot imagine that hostile ships possessing such
truly infernal machines would care to approach within miles of one
another, especially if the submarine be reinforced by the aërial
torpedo, different patterns of which are in course of construction by
Mr. Orling and Major Unge, a brother Swede. The Orling type will be
worked by the new rays, strong enough to project it through space.
Major Unge's will depend for its motive power upon a succession of
impulses obtained by the ignition of a slow-burning gas, passing
through a turbine in the rear of the torpedo. The inventor hopes for a
range of at least six miles.

What defence would be possible against such missiles? Liable to be
shattered from below, or shivered from above, the warship will be
placed at an ever-increasing disadvantage. Its size will only render
it an easier mark; its strength, bought at the expense of weight, will
be but the means of insuring a quicker descent to the sea's bottom. Is
it not probable that sea-fights will become more and more matters of a
few terrible, quickly-delivered blows? Human inventions will hold the
balance more and more evenly between nations of unequal size, first on
sea, then on land, until at last, as we may hope, even the hottest
heads and bravest hearts will shrink from courting what will be less
war than sheer annihilation, and war, man's worst enemy, will be
itself annihilated.




SUBMARINE BOATS.


The introduction of torpedoes for use against an enemy's ships below
the waterline has led by natural stages to the evolution of a vessel
which may approach unsuspected close enough to the object of attack to
discharge its missile effectively. Before the searchlight was adopted
a night surprise gave due concealment to small craft; but now that the
gloom of midnight can be in an instant flooded with the brilliance of
day a more subtle mode of attack becomes necessary.

Hence the genesis of the submarine or submersible boat, so constructed
as to disappear beneath the sea at a safe distance from the doomed
ship, and when its torpedo has been sped to retrace its invisible
course until outside the radius of destruction.

To this end many so-called submarine boats have been invented and
experimented with during recent years. The idea is an ancient one
revived, as indeed are the large proportion of our boasted modern
discoveries.

Aristotle describes a vessel of this kind (a diving-bell rather than a
boat, however), used in the siege of Tyre more than two thousand years
ago; and also refers to the divers being provided with an air-tube,
"like the trunk of an elephant," by means of which they drew a fresh
supply of air from above the surface--a contrivance adopted in more
than one of our modern submarines. Alexander the Great is said to have
employed divers in warfare; Pliny speaks of an ingenious diving
apparatus, and Bacon refers to air-tubes used by divers. We even find
traces of weapons of offence being employed. Calluvius is credited
with the invention of a submarine gun for projecting Greek fire.

The Bishop of Upsala in the sixteenth century gives a somewhat
elaborate description of certain leather skiffs or boats used to
scuttle ships by attacking them from beneath, two of which he claims
to have personally examined. In 1629 we read that the Barbary corsairs
fixed submarine torpedoes to the enemy's keel by means of divers.

As early as 1579 an English gunner named William Bourne patented a
submarine boat of his own invention fitted with leather joints, so
contrived as to be made smaller or larger by the action of screws,
ballasted with water, and having an air-pipe as mast. The Campbell-Ash
submarine tried in 1885 was on much the same principle.

Cornelius van Drebbel, an ingenious Dutchman who settled in England
before 1600, produced certain submersible vessels and obtained for
them the patronage of two kings. He claims to have discovered a means
of re-oxygenating the foul air and so enabling his craft to remain a
long time below water; whether this was done by chemical treatment,
compressed air, or by surface tubes no record remains. Drebbel's
success was such that he was allowed to experiment in the Thames, and
James I. accompanied him on one of his sub-aquatic journeys. In 1626
Charles I. gave him an order to make "boates to go under water," as
well as "water mines, water petards," &c., presumably for the campaign
against France, but we do not hear of these weapons of destruction
being actually used upon this occasion.

[Illustration: _The "Holland" Submarine Boat._]

These early craft seem to have been generally moved by oars working in
air-tight leather sockets; but one constructed at Rotterdam about 1654
was furnished with a paddle-wheel.

Coming now nearer to our own times, we find that an American called
Bushnell had a like inspiration in 1773, when he invented his famous
"Turtles," small, upright boats in which one man could sit, submerge
himself by means of leather bottles with the mouths projecting
outside, propel himself with a small set of oars and steer with an
elementary rudder. An unsuccessful attempt was made to blow up the
English fleet with one of these "Turtles" carrying a torpedo, but the
current proved too strong, and the missile exploded at a harmless
distance, the operator being finally rescued from an unpremeditated
sea-trip! Bushnell was the author of the removable safety-keel now
uniformly adopted.

Soon afterwards another New Englander took up the running, Fulton--one
of the cleverest and least appreciated engineers of the early years
of the nineteenth century. His _Nautilus_, built in the French
dockyards, was in many respects the pattern for our own modern
submarines. The cigar-shaped copper hull, supported by iron ribs, was
twenty-four feet four inches long, with a greatest diameter of seven
feet. Propulsion came from a wheel, rotated by a hand winch, in the
centre of the stern; forward was a small conning-tower, and the boat
was steered by a rudder. There was a detachable keel below; and fitted
into groves on the top were a collapsible mast and sail for use on the
surface of the water. An anchor was also carried externally. In spite
of the imperfect materials at his disposal Fulton had much success. At
Brest he took a crew of three men twenty-five feet down, and on
another day blew up an old hulk. In the Seine two men went down for
twenty minutes and steered back to their starting-point under water.
He also put in air at high pressure and remained submerged for hours.
But France, England, and his own country in turn rejected his
invention; and, completely discouraged, he bent his energies to
designing boat engines instead.

In 1821 Captain Johnson, also an American, made a submersible vessel
100 feet long, designed to fetch Napoleon from St. Helena, travelling
for the most part upon the surface. This expedition never came off.

Two later inventions, by Castera and Payerne, in 1827 and 1846
respectively, were intended for more peaceful objects. Being
furnished with diving-chambers, the occupants could retrieve things
from the bottom of the sea; Castera providing his boat with an
air-tube to the surface.

Bauer, another inventor, lived for some years in England under the
patronage of Prince Albert, who supplied him with funds for his
experiments. With Brunel's help he built a vessel which was
indiscreetly modified by the naval authorities, and finally sank and
drowned its crew. Going then to Russia he constructed sundry
submarines for the navy; but was in the end thrown over, and, like
Fulton, had to turn himself to other employment.

The fact is that up to this period the cry for a practical submarine
to use in warfare had not yet arisen, or these inventions would have
met with a far different reception. Within the last half century all
has changed. America and France now rival each other in construction,
while the other nations of Europe look on with intelligent interest,
and in turn make their contributions towards solving the problem of
under-wave propulsion.

America led the way during the Civil War blockades in 1864, when the
_Housatonic_ was sunk in Charleston harbour, and damage done to other
ships. But these experimental torpedo-boats were clumsy contrivances
compared with their modern successors, for they could only carry their
destructive weapon at the end of a spar projecting from the bows--to
be exploded upon contact with the obstacle, and probably involve the
aggressor in a common ruin. So nothing more was done till the
perfecting of the Whitehead torpedo (see Dirigible Torpedoes) gave the
required impetus to fresh enterprise.

France, experimenting in the same direction, produced in 1889 Goubet's
submarine, patent of a private inventor, who has also been patronised
by other navies. These are very small boats, the first, 16-1/2 feet
long, carrying a crew of two or three men. _Goubet No. 2_, built in
1899, is 26-1/4 feet long, composed of several layers of gun-metal
united by strong screw-bolts, and so able to resist very great
pressure. They are egg-or spindle-shaped, supplied with compressed
air, able to sink and rise by rearrangement of water-ballast.
Reservoirs in the hull are gradually filled for submersion with water,
which is easily expelled when it is desired to rise again. If this
system goes wrong a false keel of thirty-six hundredweight can be
detached and the boat springs up to the surface. The propulsive force
is electricity, which works the driving-screw at the rear, and the
automobile torpedo is discharged from its tube by compressed air.

"By the aid of an optical tube, which a pneumatic telescopic apparatus
enables the operator to thrust above the surface and pull down in a
moment, the captain of the _Goubet_ can, when near the surface, see
what is going on all round him. This telescope has a system of prisms
and lenses which cause the image of the sea-surface to be deflected
down to the eye of the observer below.

"Fresh air for the crew is provided by reservoirs of oxygen, and
accumulations of foul air can be expelled by means of a small pump.
Enough fresh air can be compressed into the reservoirs to last the
crew for a week or more."

The _Gymnote_, laid down in 1898, is more than double the size of the
_Goubet_; it is cigar-shaped, 29 feet long by 6 feet diameter, with a
displacement of thirty tons. The motive power is also electricity
stored in accumulators for use during submersion, and the speed
expected--but not realised--was to be ten knots.

Five years later this type was improved upon in the _Gustave Zédé_,
the largest submarine ever yet designed. This boat, built of
phosphor-bronze, with a single screw, measures 131 feet in length and
has a displacement of 266 tons; she can contain a crew of nine
officers and men, carries three torpedoes--though with one torpedo
tube instead of two--has a lightly armoured conning-tower, and is said
to give a surface speed of thirteen knots and to make eight knots when
submerged. At a trial of her powers made in the presence of M.
Lockroy, Minister of Marine, she affixed an unloaded torpedo to the
battleship _Magenta_ and got away unobserved. The whole performance of
the boat on that occasion was declared to be most successful. But its
cost proved excessive considering the small radius of action
obtainable, and a smaller vessel of the same type, the _Morse_ (118 ×
9 feet), is now the official size for that particular class.

In 1896 a competition was held and won by the submersible _Narval_ of
M. Laubeuf, a craft shaped much like the ordinary torpedo-boat. On the
surface or awash the _Narval_ works by means of a Brulé engine burning
oil fuel to heat its boilers; but when submerged for attack with
funnel shut down is driven by electric accumulators. She displaces 100
odd tons and is provided with four Dzewiecki torpedo tubes. Her radius
of action, steaming awash, is calculated at some 250 miles, or seventy
miles when proceeding under water at five knots an hour. This is the
parent of another class of boats designed for offensive tactics, while
the _Morse_ type is adapted chiefly for coast and harbour defence. The
French navy includes altogether thirty submarine craft, though several
of these are only projected at present, and none have yet been put to
the practical tests of actual warfare--the torpedoes used in
experimenting being, of course, blank.

Meanwhile in America experiments have also been proceeding since 1887,
when Mr. Holland of New York produced the vessel that bears his name.
This, considerably modified, has now been adopted as model by our Navy
Department, which is building some half-dozen on very similar lines.
Though it is not easy to get any definite particulars concerning
French submarines Americans are less reticent, and we have graphic
accounts of the _Holland_ and her offspring from those who have
visited her.

These vessels, though cigar-shaped liked most others, in some respects
resemble the _Narval_, being intended for long runs on the surface,
when they burn oil in a four-cylinder gasolene engine of 160
horse-power. Under water they are propelled by an electric waterproof
motor of seventy horse-power, and proceed at a pace of seven knots per
hour. There is a superstructure for deck, with a funnel for the engine
and a small conning-tower protected by 4-inch armour. The armament
carried comprises five 18-inch Whitehead torpedoes, 11 feet 8 inches
long. One hundred and twenty tons is the displacement, including tank
capacity for 850 gallons of gasolene; the full length is 63 feet 4
inches, with a beam of 11 feet 9 inches.

[Illustration: _An interior view of the "Holland." The large pendulum
on the right actuates mechanism to keep the Submarine at the required
depth below the surface._]

The original Holland boat is thus described by an adventurous
correspondent who took a trip in her[3]: "The _Holland_ is fifty-three
feet long, and in its widest part it is 10-1/4 feet in diameter. It
has a displacement of seventy-four tons, and what is called a reserve
buoyancy of 2-1/2 tons which tends to make it come to the surface.

     [3] _Pearson's Magazine._

"The frames of the boat are exact circles of steel. They are set a
little more than a foot apart. They diminish gradually in diameter
from the centre of the boat to the bow and stern. On the top of the
boat a flat superstructure is built to afford a walking platform, and
under this are spaces for exhaust pipes and for the external outfit of
the boat, such as ropes and a small anchor. The steel plates which
cover the frame are from one-half to three-eighths of an inch in
thickness.

"From what may be called the centre of the boat a turret extends
upwards through the superstructure for about eighteen inches. It is
two feet in diameter, and is the only means of entrance to the boat.
It is the place from which the boat is operated. At the stern is an
ordinary three-bladed propeller and an ordinary rudder, and in
addition there are two horizontal rudders--"diving-rudders" they are
called--which look like the feet of a duck spread out behind as it
swims along the water.

"From the bow two-thirds of the way to the stern there is a flooring,
beneath which are the storage batteries, the tank for the gasolene,
and the tanks which are filled with water for submerging; in the last
one-third of the boat the flooring drops away, and the space is
occupied by the propelling machinery.

"There are about a dozen openings in the boat, the chief being three
Kingston valves, by means of which the submerging tanks are filled or
emptied. Others admit water to pressure gauges, which regulate or show
the depth of the vessel under water. There are twelve deadlights in
the top and sides of the craft. To remain under water the boat must be
kept in motion, unless an anchor is used.

"It can be steered to the surface by the diving rudders, or sent
flying to the top through emptying the storage tanks. If it strikes
bottom, or gets stuck in the mud, it can blow itself loose by means of
its compressed air. It cannot be sunk unless pierced above the
flooring. It has a speed capacity of from eight to ten knots either
on the surface or under water.

"It can go 1500 miles on the surface without renewing its supply of
gasolene. It can go fully forty knots under water without coming to
the surface, and there is enough compressed air in the tanks to supply
a crew with fresh air for thirty hours, if the air is not used for any
other purpose, such as emptying the submerging tanks. It can dive to a
depth of twenty feet in eight seconds.

"The interior is simply packed with machinery. As you climb down the
turret you are confronted with it at once. There is a diminutive
compass which must be avoided carefully by the feet. A pressure gauge
is directly in front of the operator's eye as he stands in position.
There are speaking-tubes to various parts of the boat, and a
signal-bell to the engine-room.

"As the operator's hands hang by his sides, he touches a wheel on the
port side, by turning which he steers the little vessel, and one on
the starboard side, by turning which he controls the diving machinery.
After the top is clamped down the operator can look out through
plate-glass windows, about one inch wide and three inches long, which
encircle the turret.

"So long as the boat is running on the surface these are valuable,
giving a complete view of the surroundings if the water is smooth.
After the boat goes beneath the surface, these windows are useless; it
is impossible to see through the water. Steering must be done by
compass; until recently considered an impossible task in a submarine
boat. A tiny electric light in the turret shows the operator the
direction in which he is going, and reveals the markings on the depth
gauges. If the boat should pass under an object, such as a ship, a
perceptible shadow would be noticed through the deadlights, but that
is all. The ability to see fishes swimming about in the water is a
pleasant fiction.

"The only clear space in the body of the boat is directly in front of
the bench on which the man in the turret is standing. It is where the
eighteen-inch torpedo-tube, and the eight and five-eighths inch aërial
gun are loaded.

"Along the sides of this open space are six compressed-air tanks,
containing thirty cubic feet of air at a pressure of 2000 lbs. to a
square inch. Near by is a smaller tank, containing three cubic feet of
air at a fifty pounds pressure. A still smaller tank contains two
cubic feet of air at a ten pounds pressure. These smaller tanks supply
the compressed air which, with the smokeless powder, is used in
discharging the projectiles from the boat.

"Directly behind the turret, up against the roof on the port side, is
the little engine by which the vessel is steered; it is worked by
compressed air. Fastened to the roof on the starboard side is the
diving-engine, with discs that look as large as dinner-plates stood on
end. These discs are diaphragms on which the water-pressure exerts an
influence, counteracting certain springs which are set to keep the
diving rudders at a given pitch, and thus insuring an immersion of an
exact depth during a run.

"At one side is a cubic steel box--the air compressor; and directly in
the centre of this part of the boat is a long pendulum, just as there
is in the ordinary torpedo, which, by swinging backwards and forwards
as the boat dives and rises, checks a tendency to go too far down, or
to come up at too sharp an angle. On the floor are the levers which,
when raised and moved in certain directions, fill or empty the
submerging tanks. On every hand are valves and wheels and pipes in
such apparent confusion as to turn a layman's head.

"There are also pumps in the boat, a ventilating apparatus, and a
sounding contrivance, by means of which the channel is picked out when
running under water. This sounding contrivance consists of a heavy
weight attached to a piano wire passing from a reel out through a
stuffing-box in the bottom. There are also valves which release fresh
air to the crew, although in ordinary runs of from one-half to one
hour this is not necessary, the fresh air received from the various
exhausts in the boat being sufficient to supply all necessities in
that length of time."

Another submersible of somewhat different design is the production of
the Swedish inventor, Mr. Nordenfelt. This boat is 9-1/2 metres in
length, and has a displacement of sixty tons. Like the _Goubet_ it
sinks only in a horizontal position, while the _Holland_ plunges
downward at a slight angle. On the surface a steam-engine of 100
horse-power propels it, and when the funnel is closed down and the
vessel submerges itself, the screws are still driven by superheated
steam from the large reservoir of water boiling at high pressure which
maintains a constant supply, three circulation pumps keeping this in
touch with the boiler. The plunge is accomplished by means of two
protected screws, and when they cease to move the reserve buoyancy of
the boat brings it back to the surface. It is steered by a rudder
which a pendulum regulates. The most modern of these boats is of
English manufacture, built at Barrow, and tried in Southampton Water.

The vessels hitherto described should be termed submersible rather
than submarine, as they are designed to usually proceed on the
surface, and submerge themselves only for action when in sight of the
enemy.

American ingenuity has produced an absolutely unique craft to which
the name submarine may with real appropriateness be applied, for,
sinking in water 100 feet deep, it can remain below and run upon three
wheels along the bottom of the sea. This is the _Argonaut_, invented
by Mr. Simon Lake of Baltimore, and its main portion consists of a
steel framework of cylindrical form which is surmounted by a flat,
hollow steel deck. During submersion the deck is filled with water and
thus saved from being crushed by outside pressure as well as helping
to sink the craft.

When moving on the surface it has the appearance of an ordinary ship,
with its two light masts, a small conning-tower on which is the
steering-wheel, bowsprit, ventilators, a derrick, suction-pump, and
two anchors. A gasolene engine of special design is used for both
surface and submerged cruising under ordinary circumstances, but in
time of war storage batteries are available. An electric dynamo
supplies light to the whole interior, including a 4000 candle-power
searchlight in the extreme bow which illuminates the pathway while
under water.

On the boat being stopped and the order given to submerge, the crew
first throw out sounding lines to make sure of the depth. They then
close down external openings, and retreat into the boat through the
conning-tower, within which the helmsman takes his stand, continuing
to steer as easily as when outside. The valves which fill the deck and
submersion tanks are opened, and the _Argonaut_ drops gently to the
floor of the ocean. The two apparent masts are in reality 3-inch iron
pipes which rise thirty feet or more above the deck, and so long as no
greater depth is attained, they supply the occupants with fresh air
and let exhausted gases escape, but close automatically when the water
reaches their top.

Once upon the bottom of the sea this versatile submarine begins its
journey as a tricycle. It is furnished with a driving-wheel on either
side, each of which is 6-1/2 feet in diameter and weighs 5000 lbs.;
and is guided by a third wheel weighing 2000 lbs. journalled in the
rudder. On a hard bottom or against a strong tide the wheels are most
effective owing to their weight, but in passing through soft sand or
mud the screw propeller pushes the boat along, the driving-wheels
running "loose." In this way she can travel through even waist-deep
mud, the screw working more strongly than on the surface, because it
has such a weight of water to help it, and she moves more easily
uphill.

In construction the _Argonaut_ is shaped something like a huge cigar,
her strong steel frames, spaced twenty inches apart, being clad with
steel plates 3/8-inch thick double riveted over them. Great strength
is necessary to resist the pressure of superincumbent water, which at
a depth of 100 feet amounts to 44 lbs. per square inch.

Originally she was built 36 feet long, but was subsequently lengthened
by some 20 odd feet, and has 9 feet beam. She weighs fifty-seven tons
when submerged. A false section of keel, 4000 lbs. in weight, can on
emergency be instantly released from inside; and two downhaul weights,
each of 1000 lbs., are used as an extra precaution for safety when
sinking in deep water.

The interior is divided into various compartments, the living quarters
consisting of the cabin, galley, operating chamber and engine-room.
There are also a division containing stores and telephone, the
intermediate, and the divers' room. The "operating" room contains the
levers, handwheels, and other mechanism by which the boat's movements
are governed. A water gauge shows her exact depth below the surface; a
dial on either side indicates any inclination from the horizontal.
Certain levers open the valves which admit water to the ballast-tanks
in the hold; another releases the false keel; there is a cyclometer to
register the wheel travelling, and other gauges mark the pressure of
steam, speed of engines, &c.

A compass in the conning-tower enables the navigator to steer a true
course whether above or below the surface. This conning-tower, only
six feet high, rises above the centre of the living quarters, and is
of steel with small windows in the upper part. Encircling it to about
three-quarters of its height is a reservoir for gasolene, which feeds
into a smaller tank within the boat for consumption. The compressed
air is stored in two Mannesmann steel reservoirs which have been
tested to a pressure of 4000 lbs. per square inch. This renews the
air-supply for the crew when the _Argonaut_ is long below, and also
enables the diving operations to be carried on.

The maximum speed at which the _Argonaut_ travels submerged is five
knots an hour, and when she has arrived at her destination--say a
sunken coal steamer--the working party pass into the "intermediate"
chamber, whose air-tight doors are then closed. A current of
compressed air is then turned on until the air is equal in pressure to
that in the divers' room. The doors of this close over india rubber to
be air and water-tight; one communicates with the "intermediate," the
other is a trap which opens downwards into the sea. Through three
windows in the prow those remaining in the room can watch operations
outside within a radius varying according to the clearness of the
water. The divers assume their suits, to the helmets of which a
telephone is attached, so arranged that they are able to talk to each
other as well as to those in the boat. They are also provided with
electric lamps, and a brilliant flood of light streams upon them from
the bows of the vessel. The derrick can be used with ease under water,
and the powerful suction-pump will "retrieve" coal from a submerged
vessel into a barge above at the rate of sixty tons per hour.

It will thus be seen how valuable a boat of this kind may be for
salvage operations, as well as for surveying the bottom of harbours,
river mouths, sea coasts, and so on. In war time it can lay or examine
submarine mines for harbour defence, or, if employed offensively, can
enter the enemy's harbour with no chance of detection, and there
destroy his mines or blow up his ships with perfect impunity.

To return the _Argonaut_ to the surface it is only necessary to force
compressed air into the space below the deck and the four tanks in the
hold. Her buoyancy being thus gradually restored she rises slowly and
steadily till she is again afloat upon the water, and steams for land.

We have now glanced briefly at some of the most interesting
attempts--out of many dozens--to produce a practicable submarine
vessel in bygone days; and have inquired more closely into the
construction of several modern designs; among these the _Holland_ has
received especial attention, as that is the model adopted by our
Admiralty, and our own new boats only differ in detail from their
American prototype. But before quitting this subject it will be well
to consider what is required from the navigating engineer, and how far
present invention has supplied the demand.

[Illustration: _The "Holland" Submarine in the last stages of
submersion._]

The perfect submarine of fiction was introduced by Jules Verne, whose
_Nautilus_ remains a masterpiece of scientific imagination. This
marvellous vessel ploughed the seas with equal power and safety,
whether on the surface or deeply sunk beneath the waves, bearing the
pressure of many atmospheres. It would rest upon the ocean floor while
its inmates, clad in diving suits, issued forth to stroll amid aquatic
forests and scale marine mountains. It gathered fabulous treasures
from pearl beds and sunken galleons; and could ram and sink an
offending ship a thousand times its size without dinting or loosening
a plate on its own hull. No weather deflected its compass, no movement
disturbed its equilibrium. Its crew followed peacefully and cheerfully
in their spacious cabins a daily round of duties which electric power
and automatic gear reduced to a minimum. Save for the misadventure of
a shortened air-supply when exploring the Polar pack, and the clash of
human passions, Captain Nemo's guests would have voyaged in a
floating paradise.

Compare with this entrancing creation the most practical vessels of
actual experiment. They are small, blind craft, groping their way
perilously when below the surface, the steel and electrical machinery
sadly interfering with any trustworthy working of their compass, and
the best form of periscope hitherto introduced forming a very
imperfect substitute for ordinary vision.

Their speed, never very fast upon the surface, is reduced by
submersion to that of the oldest and slowest gunboats. Their radius of
action is also circumscribed--that is, they cannot carry supplies
sufficient to go a long distance, deal with a hostile fleet, and then
return to headquarters without replenishment.

Furthermore, there arise the nice questions of buoyancy combined with
stability when afloat, of sinking quickly out of sight, and of keeping
a correct balance under water. The equilibrium of such small vessels
navigating between the surface and the bottom is extremely sensitive;
even the movements to and fro of the crew are enough to imperil them.
To meet this difficulty the big water-ballast tanks, engines and
accumulators are necessarily arranged at the bottom of the hull, and a
pendulum working a helm automatically is introduced to keep it
longitudinally stable.

To sink the boat, which is done by changing the angle of the
propeller in the _Goubet_ and some others, and by means of horizontal
rudders and vanes in the _Nordenfelt_ and _Holland_, it must first be
most accurately balanced, bow and stern exactly in trim. Then the boat
must be put into precise equilibrium with the water--_i.e._ must weigh
just the amount of water displaced. For this its specific gravity must
be nearly the same as that of the water (whether salt or fresh), and a
small accident might upset all calculations. Collision, even with a
large fish, could destroy the steering-gear, and a dent in the side
would also tend to plunge it at once to destruction.

Did it escape these dangers and succeed in steering an accurate course
to its goal, we have up to now little practical proof that the mere
act of discharging its torpedo--though the weight of the missile is
intended to be automatically replaced immediately it drops from the
tube--may not suffice to send the vessel either to bottom or top of
the sea. In the latter case it would be within the danger zone of its
alarmed enemy and at his mercy, its slow speed (even if uninjured)
leaving it little chance of successful flight.

But whatever the final result, one thing is certain, that--untried as
it is--the possible contingency of a submarine attack is likely to
shake the _morale_ of an aggressive fleet.

"When the first submarine torpedo-boat goes into action," says Mr.
Holland, "she will bring us face to face with the most perplexing
problem ever met in warfare. She will present the unique spectacle,
when used in attack, of a weapon against which there is no defence....
You can send nothing against the submarine boat, not even itself....
You cannot see under water, hence you cannot fight under water. Hence
you cannot defend yourself against an attack under water except by
running away."

This inventor is, however, an enthusiast about the future awaiting the
submarine as a social factor. His boat has been tested by long voyages
on and below water with complete success. The _Argonaut_ also upon one
occasion travelled a thousand miles with five persons, and proved
herself "habitable, seaworthy, and under perfect control."

Mr. Holland confidently anticipates in the near future a Channel
service of submerged boats run by automatic steering-gear upon cables
stretched from coast to coast, and eloquently sums up its advantages.

The passage would be always practicable, for ordinary interruptions
such as fog and storms cannot affect the sea depths.

An even temperature would prevail summer and winter, the well-warmed
and lighted boats being also free from smoke and spray.

No nauseating smells would proceed from the evenly-working electric
engines. No motion cause sea-sickness, no collision be apprehended--as
each line would run on its own cable, and at its own specified depth,
a telephone keeping it in communication with shore.

In like manner a service might be plied over lake bottoms, or across
the bed of wide rivers whose surface is bound in ice. Such is the
submarine boat as hitherto conceived for peace or war--a daring
project for the coming generation to justify.




ANIMATED PICTURES.


Has it ever occurred to the reader to ask himself why rain appears to
fall in streaks though it arrives at earth in drops? Or why the
glowing end of a charred stick produces fiery lines if waved about in
the darkness? Common sense tells us the drop and the burning point
cannot _be_ in two places at one and the same time. And yet apparently
we are able to see both in many positions simultaneously.

This seeming paradox is due to "persistence of vision," a phenomenon
that has attracted the notice of scientific men for many centuries.
Persistence may be briefly explained thus:--

The eye is extremely sensitive to light, and will, as is proved by the
visibility of the electric spark, lasting for less than the millionth
part of a second, _receive_ impressions with marvellous rapidity.

But it cannot get rid of these impressions at the same speed. The
duration of a visual impression has been calculated as one-tenth to
one-twenty-first of a second. The electric spark, therefore, appears
to last much longer than it really does.

Hence it is obvious that if a series of impressions follow one another
more rapidly than the eye can free itself of them, the impressions
will overlap, and one of four results will follow.

     (_a_) _Apparently uninterrupted presence_ of an image if the
     same image be repeatedly represented.

     (_b_) _Confusion_, if the images be all different and
     disconnected.

     (_c_) _Combination_, if the images of two or a very few objects
     be presented in regular rotation.

     (_d_) _Motion_, if the objects be similar in all but one part,
     which occupies a slightly different portion in each
     presentation.

In connection with (_c_) an interesting story is told of Sir J.
Herschel by Charles Babbage:--[4]

     [4] Quoted from Mr. Henry V. Hopwood's "Living Pictures," to
     which book the author is indebted for much of his information
     in this chapter.

"One day Herschel, sitting with me after dinner, amusing himself by
spinning a pear upon the table, suddenly asked whether I could show
him the two sides of a shilling at the same moment. I took out of my
pocket a shilling, and holding it up before the looking-glass, pointed
out my method. 'No,' said my friend, 'that won't do;' then spinning my
shilling upon the table, he pointed out his method of seeing both
sides at once. The next day I mentioned the anecdote to the late Dr.
Fitton, who a few days after brought me a beautiful illustration of
the principle. It consisted of a round disc of card suspended between
two pieces of sewing silk. These threads being held between the finger
and thumb of each hand, were then made to turn quickly, when the disc
of card, of course, revolved also. Upon one side of this disc of card
was painted a bird, upon the other side an empty bird-cage. On turning
the thread rapidly the bird appeared to have got inside the cage. We
soon made numerous applications, as a rat on one side and a trap on
the other, &c. It was shown to Captain Kater, Dr. Wollaston, and many
of our friends, and was, after the lapse of a short time, forgotten.
Some months after, during dinner at the Royal Society Club, Sir Joseph
Banks being in the chair, I heard Mr. Barrow, then secretary to the
Admiralty, talking very loudly about a wonderful invention of Dr.
Paris, the object of which I could not quite understand. It was called
the Thaumatrope, and was said to be sold at the Royal Institution, in
Albemarle Street. Suspecting that it had some connection with our
unnamed toy I went next morning and purchased for seven shillings and
sixpence a thaumatrope, which I afterwards sent down to Slough to the
late Lady Herschel. It was precisely the thing which her son and Dr.
Fitton had contributed to invent, which amused all their friends for a
time, and had then been forgotten."

The _thaumatrope_, then, did nothing more than illustrate the power of
the eye to weld together a couple of alternating impressions. The toys
to which we shall next pass represent the same principle working in a
different direction towards the production of the living picture.

Now, when we see a man running (to take an instance) we see the _same_
body and the same legs continuously, but in different positions, which
merge insensibly the one into the other. No method of reproducing that
impression of motion is possible if only _one_ drawing, diagram, or
photograph be employed.

A man represented with as many legs as a centipede would not give us
any impression of running or movement; and a blur showing the
positions taken successively by his legs would be equally futile.
Therefore we are driven back to a _series_ of pictures, slightly
different from one another; and in order that the pictures may not be
blurred a screen must be interposed before the eye while the change
from picture to picture is made. The shorter the period of change, and
the greater the number of pictures presented to illustrate a single
motion, the more realistic is the effect. These are the general
principles which have to be observed in all mechanism for the
production of an illusory effect of motion. The persistence of vision
has led to the invention of many optical toys, the names of which, in
common with the names of most apparatus connected with the living
picture, are remarkable for their length. Of these toys we will select
three for special notice.

In 1833 Plateau of Ghent invented the _phenakistoscope_, "the thing
that gives one a false impression of reality"--to interpret this
formidable word. The phenakistoscope is a disc of card or metal round
the edge of which are drawn a succession of pictures showing a man or
animal in progressive positions. Between every two pictures a narrow
slit is cut. The disc is mounted on an axle and revolved before a
mirror, so that a person looking through the slits see one picture
after another reflected in the mirror.

The _zoetrope_, or Wheel of Life, which appeared first in 1860, is a
modification of the same idea. In this instrument the pictures are
arranged on the inner side of a hollow cylinder revolving on a
vertical axis, its sides being perforated with slits above the
pictures. As the slit in both cases caused distortion M. Reynaud, a
Frenchman, produced in 1877 the _praxinoscope_, which differed from
the zoetrope in that the pictures were not seen directly through
slits, but were reflected by mirrors set half-way between the pictures
and the axis of the cylinder, a mirror for every picture. Only at the
moment when the mirror is at right angles to the line of sight would
the picture be visible. M. Reynaud also devised a special lantern for
projecting praxinoscope pictures on to a screen.

These and other somewhat similar contrivances, though ingenious, had
very distinct limitations. They depended for their success upon the
inventiveness and accuracy of the artist, who was confined in his
choice of subject; and could, owing to the construction of the
apparatus, only represent a small series of actions, indefinitely
repeated by the machine. And as a complete action had to be crowded
into a few pictures, the changes of position were necessarily abrupt.

To make the living picture a success two things were needed; some
method of securing a very rapid series of many pictures, and a machine
for reproducing the series, whatever its length. The method was found
in photography, with the advance of which the living picture's
progress is so closely related, that it will be worth while to notice
briefly the various improvements of photographic processes. The
old-fashioned Daguerreotype process, discovered in 1839, required an
exposure of half-an-hour. The introduction of wet collodion reduced
this tax on a sitter's patience to ten seconds. In 1878 the dry plate
process had still further shortened the exposure to one second; and
since that date the silver-salt emulsions used in photography have had
their sensitiveness to light so much increased, that clear pictures
can now be made in one-thousandth of a second, a period minute enough
to arrest the most rapid movements of animals.

By 1878, therefore, instantaneous photography was ready to aid the
living picture. Previously to that year series of photographs had been
taken from posed models, without however extending the choice of
subjects to any great extent. But between 1870 and 1880 two men, Marey
and Muybridge, began work with the camera on the movements of horses.
Marey endeavoured to produce a series of pictures round the edge of
one plate with a single lens and repeated exposures.[5] Muybridge, on
the other hand, used a series of cameras. He erected a long white
background parallel to which were stationed the cameras at equal
distances. The shutters of the cameras were connected to threads laid
across the interval between the background and the cameras in such a
manner that a horse driven along the track snapped them at regular
intervals, and brought about successive exposures. Muybridge's method
was carried on by Anschütz, a German, who in 1899 brought out his
electrical Tachyscope, or "quick-seer." Having secured his negatives
he printed off transparent positives on glass, and arranged these last
round the circumference of a large disc rotating in front of a screen,
having in it a hole the size of the transparencies. As each picture
came opposite the hole a Geissler tube was momentarily lit up behind
it by electrical contact, giving a fleeting view of one phase of a
horse's motion.

     [5] A very interesting article in the May, 1902, issue of
     _Pearson's Magazine_ deals with the latest work of Professor
     Marey in the field of the photographic representation of the
     movements of men, birds, and quadrupeds.

The introduction of the ribbon film in or about 1888 opened much
greater possibilities to the living picture than would ever have
existed had the glass plate been retained. It was now comparatively
easy to take a long series of pictures; and accordingly we find
Messrs. Friese-Greene and Evans exhibiting in 1890 a camera capable of
securing three hundred exposures in half a minute, or ten per second.


The next apparatus to be specially mentioned is Edison's Kinetoscope,
which he first exhibited in England in 1894. As early as 1887 Mr.
Edison had tried to produce animated pictures in a manner analogous to
the making of a sound-record on a phonograph (see p. 56). He wrapped
round a cylinder a sheet of sensitized celluloid which was covered,
after numerous exposures, by a spiral line of tiny negatives. The
positives made from these were illuminated in turn by flashes of
electric light. This method was, however, entirely abandoned in the
perfected kinetoscope, an instrument for viewing pictures the size of
a postage stamp, carried on a continuously moving celluloid film
between the eye of the observer and a small electric lamp. The
pictures passed the point of inspection at the rate of forty-six per
second (a rate hitherto never approached), and as each picture was
properly centred a slit in a rapidly revolving shutter made it visible
for a very small fraction of a second. Holes punched at regular
intervals along each side of the film engaged with studs on a wheel,
and insured a regular motion of the pictures. This principle of a
perforated film has been used by nearly all subsequent manufacturers
of animatographs.

To secure forty-six negatives per second Edison invented a special
exposure device. Each negative would have but one-forty-sixth of a
second to itself, and that must include the time during which the
fresh surface of film was being brought into position before the lens.
He therefore introduced an intermittent gearing, which jerked the
film forwards forty-six times per second, but allowed it to remain
stationary for nine-tenths of the period allotted to each picture.
During the time of movement the lens was covered by the shutter. This
principle of exposure has also been largely adopted by other
inventors. By its means weak negatives are avoided, while pictures
projected on to a screen gain greatly in brilliancy and steadiness.

The capabilities of a long flexible film-band having been shown by
Edison, he was not long without imitators. Phantoscopes, Bioscopes,
Photoscopes, and many other instruments followed in quick succession.
In 1895 Messrs. Lumière scored a great success with their
Cinematograph, which they exhibited at Marseilles and Paris; throwing
the living picture as we now know it on to a screen for a large
company to see. This camera-lantern opens the era of commercial
animated-photography. The number of patents taken out since 1895 in
connection with living-picture machines is sufficient proof that
inventors have either found in this particular branch of photography a
peculiar fascination, or have anticipated from it a substantial
profit.

A company known as the Mutoscope and Biograph Company has been formed
for the sole object of working the manufacture and exhibition of the
living picture on a great commercial scale. The present company is
American, but there are subsidiary allied companies in many parts of
the world, including the British Isles, France, Italy, Belgium,
Germany, Austria, India, Australia, South Africa. The part that the
company has played in the development of animated photography will be
easily understood from the short account that follows.

The company controls three machines, the Mutograph, or camera for
making negatives; the Biograph, or lantern for throwing pictures on to
the screen; and the Mutoscope, a familiar apparatus in which the same
pictures may be seen in a different fashion on the payment of a penny.

Externally the Mutograph is remarkable for its size, which makes it a
giant of its kind. The complete apparatus weighs, with its
accumulators, several hundreds of pounds. It takes a very large
picture, as animatograph pictures go--two by two-and-a-half inches,
which, besides giving increased detail, require less severe
magnification than is usual with other films. The camera can make up
to a hundred exposures per second, in which time _twenty-two_ feet of
film will have passed before the lens.

The film is so heavy that were it arrested bodily during each exposure
and then jerked forward again, it might be injured. The mechanism of
the mutograph, driven at regular speed, by an electric motor, has been
so arranged as to halt only that part of the film which is being
exposed, the rest moving forward continuously. The exposed portion,
together with the next surface, which has accumulated in a loop
behind it, is dragged on by two rollers that are in contact with the
film during part only of their revolutions. Thus the jerky motion is
confined to but a few inches of the film, and even at the highest
speeds the camera is peculiarly free from vibration.

An exposed mutograph film is wound for development round a skeleton
reel, three feet in diameter and seven long, which rotates in a
shallow trough containing the developing solution. Development
complete, the reel is lifted from its supports and suspended over a
succession of other troughs for washing, fixing, and final washing.
When dry the negative film is passed through a special printing frame
in contact with another film, which receives the positive image for
the biograph. The difficulty of handling such films will be
appreciated to a certain extent even by those whose experience is
confined to the snaky behaviour of a short Kodak reel during
development.

The Mutoscope Company's organisation is as perfect as its machinery.
It has representatives in all parts of the world. Wherever stirring
events are taking place, whether in peace or war, a mutograph operator
will soon be on the spot with his heavy apparatus to secure pictures
for world-wide exhibition. It need hardly be said that great
obstacles, human and physical, have often to be overcome before a film
can be exposed; and considerable personal danger encountered. We read
that an operator, despatched to Cuba during the Spanish-American War
was left three days and nights without food or water to guard his
precious instruments, the party that had landed him having suddenly
put to sea on sighting a Spanish cruiser. Another is reported to have
had a narrow escape from being captured at sea by the Spaniards after
a hot chase. It is also on record that a mutograph set up in Atlantic
City to take a procession of fire-engines was charged and shattered by
one of the engines; that the operators were flung into the crowd: and
that nevertheless the box containing the exposed films was uninjured,
and on development yielded a very sensational series of pictures
lasting to the moment of collision.

The Mutoscope Company owns several thousand series of views, none
probably more valuable than those of his Holiness the Pope, who
graciously gave Mr. W. K. Dickson five special sittings, during which
no less than 17,000 negatives were made, each one of great interest to
millions of people throughout the world.

The company spares neither time nor money in its endeavour to supply
the public with what will prove acceptable. A year's output runs into
a couple of hundred miles of film. As much as 700 feet is sometimes
expended on a single series, which may be worth anything up to £1000.

The energy displayed by the operators is often marvellous. To take
instances. The Derby of 1898 was run at 3.20 P.M. At ten o'clock the
race was run again by Biograph on the great sheet at the Palace
Theatre. On the home-coming of Lord Kitchener from the Soudan
Campaign, a series of photographs was taken at Dover in the afternoon
and exhibited the same evening! Or again, to consider a wider sphere
of action, the Jubilee Procession of 1897 was watched in New York ten
days after the event; two days later in Chicago; and in three more the
films were attracting large audiences in San Francisco, 5000 miles
from the actual scene of the procession!

One may easily weary of a series of single views passed slowly through
a magic-lantern at a lecture or entertainment. But when the Biograph
is flashing its records at lightning speed there is no cause for
dullness. It is impossible to escape from the fascination of
_movement_. A single photograph gives the impression of mere
resemblance to the original; but a series, each reinforcing the
signification of the last, breathes life into the dead image, and
deludes us into the belief that we see, not the representation of a
thing, but the thing itself. The bill of fare provided by the Biograph
Company is varied enough to suit the most fastidious taste. Now it is
the great Naval Review off Spithead, or President Faure shooting
pheasants on his preserves near Paris. A moment's pause and then the
magnificent Falls of Niagara foam across the sheet; Maxim guns fire
harmlessly; panoramic scenes taken from locomotives running at high
velocity unfold themselves to the delighted spectators, who feel as if
they really were speeding over open country, among towering rocks, or
plunging into the darkness of a tunnel. Here is an express approaching
with all the quiver and fuss of real motion, so faithfully rendered
that it seems as if a catastrophe were imminent; when, snap! we are
transported a hundred miles to watch it glide into a station. The
doors open, passengers step out and shake hands with friends, porters
bustle about after luggage, doors are slammed again, the guard waves
his flag, and the carriages move slowly out of the picture. Then our
attention is switched away to the 10-inch disappearing gun, landing
and firing at Sandy Hook. And next, as though to show that nothing is
beneath the notice of the biograph, we are perhaps introduced to a
family of small pigs feeding from a trough with porcine earnestness
and want of manners.

It must not be thought that the Living Picture caters for mere
entertainment only. It serves some very practical and useful ends. By
its aid the movements of machinery and the human muscles may be
studied in detail, to aid a mechanical or medical education. It
furnishes art schools with all the poses of a living model. Less
serious pursuits, such as dancing, boxing, wrestling and all athletic
sports and exercise, will find a use for it. As an advertising medium
it stands unrivalled, and we shall owe it a deep debt of gratitude if
it ultimately supplants the flaring posters that disfigure our towns
and desecrate our landscapes. Not so long since, the directors of the
Norddeutscher-Lloyd Steamship Company hired the biograph at the
Palace Theatre, London, to demonstrate to anybody who cared to witness
a very interesting exhibition that their line of vessels should always
be used for a journey between England and America.

The Living Picture has even been impressed into the service of the
British Empire to promote emigration to the Colonies. Three years ago
Mr. Freer exhibited at the Imperial Institute and in other places in
England a series of films representing the 1897 harvest in Manitoba.
Would-be emigrants were able to satisfy themselves that the great
Canadian plains were fruitful not only on paper. For could they not
see with their own eyes the stately procession of automatic "binders"
reaping, binding, and delivering sheaves of wheat, and puffing engines
threshing out the grain ready for market? A far preferable method this
to the bogus descriptions of land companies such as lured poor
Chuzzlewit and Mark Tapley into the deadly swamps of "Eden."

Again, what more calculated to recruit boys for our warships than the
fine Polytechnic exhibition known as "Our Navy"? What words, spoken or
printed, could have the effect of a series of vivid scenes truthfully
rendered, of drills on board ship, the manning and firing of big guns,
the limbering-up of smaller guns, the discharge of torpedoes, the
headlong rush of the "destroyers"?

The Mutoscope, to which reference has been made above, may be found in
most places of public entertainment, in refreshment bars, on piers,
in exhibitions, on promenades. A penny dropped into a slot releases a
handle, the turning of which brings a series of pictures under
inspection. The pictures, enlarged from mutograph films, are mounted
in consecutive order round a cylinder, standing out like the leaves of
a book. When the cylinder is revolved by means of the handle the
picture cards are snapped past the eye, giving an effect similar to
the lifelike projections on a biograph screen. From 900 to 1000
pictures are mounted on a cylinder.

The advantages of the mutoscope--its convenient size, its simplicity,
and the ease with which its contents may be changed to illustrate the
topics and events of the day--have made the animated photograph
extremely popular. It does for vision what the phonograph does for
sound. In a short time we shall doubtless be provided with handy
machines combining the two functions and giving us double value for
our penny.

The real importance and value of animated photography will be more
easily estimated a few years hence than to-day, when it is still more
or less of a novelty. The multiplication of illustrated newspapers and
magazines points to a general desire for pictorial matter to help down
the daily, weekly, or monthly budget of news, even if the
illustrations be imaginative products of Fleet Street rather than
faithful to fact. The reliable living picture (we expect the
"set-scene") which "holds up a mirror to nature," will be a companion
rather than a rival of journalism, following hard on the description
in print of an event that has taken place under the eye of the
recording camera. The zest with which we have watched during the last
two years biographic views of the embarkation and disembarkation of
troops, of the transport of big guns through drifts and difficult
country, and of the other circumstances of war, is largely due to the
descriptions we have already read of the things that we see on the
screen. And, on the other hand, the impression left by a series of
animated views will dwell in our memories long after the contents of
the newspaper columns have become confused and jumbled. It is
therefore especially to be hoped that photographic records will be
kept of historic events, such as the Jubilee, the Queen's Funeral,
King Edward's Coronation, so that future generations may, by the
turning of a handle, be brought face to face with the great doings of
a bygone age.




THE GREAT PARIS TELESCOPE


A telescope so powerful that it brings the moon apparently to within
thirty-five miles of the earth; so long that many a cricketer could
not throw a ball from one end of it to the other; so heavy that it
would by itself make a respectable load for a goods train; so
expensive that astronomically-inclined millionaires might well
hesitate to order a similar one for their private use.

Such is the huge Paris telescope that in 1900 delighted thousands of
visitors in the French Exposition, where, among the many wonderful
sights to be seen on all sides, it probably attracted more notice than
any other exhibit. This triumph of scientific engineering and dogged
perseverance in the face of great difficulties owes its being to a
suggestion made in 1894 to a group of French astronomers by M.
Deloncle. He proposed to bring astronomy to the front at the coming
Exposition, and to effect this by building a refracting telescope that
in size and power should completely eclipse all existing instruments
and add a new chapter to the "story of the heavens."

To the mind unversed in astronomy the telescope appeals by the
magnitude of its dimensions, in the same way as do the Forth Bridge,
the Eiffel Tower, the Big Wheel, the statue of Liberty near New York
harbour, the Pyramids, and most human-made "biggest on records."

At the time of M. Deloncle's proposal the largest refracting telescope
was the Yerkes' at William's Bay, Wisconsin, with an object-glass
forty inches in diameter; and next to it the 36-inch Lick instrument
on Mount Hamilton, California, built by Messrs. Alvan Clark of
Cambridgeport, Massachusetts. Among reflecting telescopes the prior
place is still held by Lord Rosse's, set up on the lawn of Birr Castle
half a century ago. Its speculum, or mirror, weighing three tons, lies
at the lower end of a tube six feet across and sixty feet long. This
huge reflector, being mounted in meridian, moves only in a vertical
direction. A refracting telescope is one of the ordinary pocket type,
having an object-lens at one end and an eyepiece at the other. A
reflector, on the other hand, has no object-lens, its place being
taken by a mirror that gathers the rays entering the tube and reflects
them back into the eyepiece, which is situated nearer the mouth end of
the tube than the mirror itself.

Each system has its peculiar disadvantages. In reflectors the image is
more or less distorted by "spherical aberration." In refractors the
image is approximately perfect in shape, but liable to "chromatic
aberration," a phenomenon especially noticeable in cheap telescopes
and field-glasses, which often show objects fringed with some of the
colours of the spectrum. This defect arises from the different
refrangibility of different light rays. Thus, violet rays come to a
focus at a shorter distance from the lens than red rays, and when one
set is in focus to the eye the other must be out of focus. In
carefully-made and expensive instruments compound lenses are used,
which by the employment of different kinds of glass bring all the
colours to practically the same focus, and so do away with chromatic
aberration.

To reduce colour troubles to a _minimum_ M. Deloncle proposed that the
object-lens should have a focal distance of about two hundred feet,
since a long focus is more easily corrected than a short one, and a
diameter of over fifty-nine inches. The need for so huge a lens arises
out of the optical principles of a refractor. The rays from an
object--a star, for instance--strike the object-glass at the near end,
and are bent by it into a converging beam, till they all meet at the
focus. Behind the focus they again separate, and are caught by the
eyepiece, which reduces them to a parallel beam small enough to enter
the pupil. We thus see that though the unaided eye gathers only the
few rays that fall directly from the object on to the pupil, when
helped by the telescope it receives the concentrated rays falling on
the whole area of the object-glass; and it would be sensible of a
greatly increased brightness had not this light to be redistributed
over the image, which is the object magnified by the eyepiece.
Assuming the aperture of the pupil to be one-tenth of an inch, and
the object to be magnified a hundred times, the object-lens should
have a hundred times the diameter of the pupil to render the image as
bright as the object itself. If the lens be five instead of ten inches
across, a great loss of light results, as in the high powers of a
microscope, and the image loses in distinctness what it gains in size.

As M. Deloncle meant his telescope to beat all records in respect of
magnification, he had no choice but to make a lens that should give
proportionate illumination, and itself be of unprecedented size.

At first M. Deloncle met with considerable opposition and ridicule.
Such a scheme as his was declared to be beyond accomplishment. But in
spite of many prophecies of ultimate failure he set to work,
entrusting the construction of the various portions of his colossal
telescope to well-tried experts. To M. Gautier was given the task of
making all the mechanical parts of the apparatus; to M. Mantois the
casting of the giant lenses; to M. Despret the casting of the huge
mirror, to which reference will be made immediately.

The first difficulty to be encountered arose from the sheer size of
the instrument. It was evidently impossible to mount such a leviathan
in the ordinary way. A tube, 180 feet long, could not be made rigid
enough to move about and yet permit careful observation of the stars.
Even supposing that it were satisfactorily mounted on an "equatorial
foot" like smaller glasses, how could it be protected from wind and
weather? To cover it, a mighty dome, two hundred feet or more in
diameter, would be required; a dome exceeding by over seventy feet the
cupola of St. Peter's, Rome; and this dome must revolve easily on its
base at a pace of about fifty feet an hour, so that the telescope
might follow the motion of the heavenly bodies.

The constructors therefore decided to abandon any idea of making a
telescope that could be moved about and pointed in any desired
direction. The alternative course open to them was to fix the
telescope itself rigidly in position, and to bring the stars within
its field by means of a mirror mounted on a massive iron frame--the
two together technically called a siderostat. The mirror and its
support would be driven by clockwork at the proper sidereal rate. The
siderostat principle had been employed as early as the eighteenth
century, and perfected in recent years by Léon Foucault, so that in
having recourse to it the builders of the telescope were not
committing themselves to any untried device.

In days when the handling of masses of iron, and the erection of huge
metal constructions have become matters of everyday engineering life,
no peculiar difficulty presented itself in connection with the
metal-work of the telescope. The greatest possible care was of course
observed in every particular. All joints and bearings were adjusted
with an extraordinary accuracy; and all the cylindrical moving parts
of the siderostat verified till they did not vary from perfect
cylindricity by so much as one twenty-five-thousandth of an inch!

The tube of the telescope, 180 feet long, consisted of twenty-four
sections, fifty-nine inches in diameter, bolted together and supported
on seven massive iron pillars. It weighed twenty-one tons. The
siderostat, twenty-seven feet high, and as many in length, weighed
forty-five tons. The lower portion, which was fixed firmly on a bed of
concrete, had on the top a tank filled with quicksilver, in which the
mirror and its frame floated. The quicksilver supported nine-tenths of
the weight, the rest being taken by the levers used to move the
mirror. Though the total weight of the mirror and frame was thirteen
tons, the quicksilver offered so little resistance that a pull of a
few pounds sufficed to rotate the entire mass.

The real romance of the construction of this huge telescope centres on
the making of the lenses and mirror. First-class lenses for all
photographic and optical purposes command a very high price on account
of the care and labour that has to be expended on their production;
the value of the glass being trifling by comparison. Few, if any,
trades require greater mechanical skill than that of lensmaking; the
larger the lens the greater the difficulties it presents, first in the
casting, then in the grinding, last of all in the polishing. The
presence of a single air-bubble in the molten glass, the slightest
irregularity of surface in the polishing may utterly destroy the
value of a lens otherwise worth several thousands of pounds.

[Illustration: _Reproduced by the permission of Proprietors of
"Knowledge."_

_General view, of the Great Paris Telescope, showing the eye-end. The
tube is 180 feet long, and 59 inches in diameter. It weighs 21 tons._]

The object-glass of the great telescope was cast by M. Mantois, famous
as the manufacturer of large lenses. The glass used was boiled and
reboiled many times to get rid of all bubbles. Then it was run into a
mould and allowed to cool very gradually. A whole month elapsed before
the breaking of a mould, when the lens often proved to be cracked on
the surface, owing to the exterior having cooled faster than the
interior and parted company with it. At last, however, a perfect cast
resulted.

M. Despret undertook the even more formidable task of casting the
mirror at his works at Jeumont, North France. A special furnace and
oven, capable of containing over fifteen tons of molten glass, had to
be constructed. The mirror, 6-1/2 feet in diameter and eleven inches
thick, absorbed 3-3/4 tons of liquid glass; and so great was the
difficulty of cooling it gradually, that out of the twenty casts
eighteen were failures.

The rough lenses and mirror having been ground to approximate
correctness in the ordinary way, there arose the question of
polishing, which is generally done by one of the most sensitive and
perfect instruments existing-the human hand. In this case, owing to
the enormous size of the objects to be treated, hand work would not
do. The mere hot touch of a workman would raise on the glass a tiny
protuberance, which would be worn level with the rest of the surface
by the polisher, and on the cooling of the part would leave a
depression, only 1-75,000 of an inch deep, perhaps, but sufficient to
produce distortion, and require that the lens should be ground down
again, and the whole surface polished afresh.

M. Gautier therefore polished by machinery. It proved a very difficult
process altogether, on account of frictional heating, the rise of
temperature in the polishing room, and the presence of dust. To insure
success it was found necessary to warm all the polishing machinery,
and to keep it at a fixed temperature.

At the end of almost a year the polishing was finished, after the
lenses and mirror had been subjected to the most searching tests, able
to detect irregularities not exceeding 1-250,000 of an inch. M.
Gautier applied to the mirror M. Foucault's test, which is worth
mentioning. A point of light thrown by the mirror is focused through a
telescope. The eyepiece is then moved inwards and outwards so as to
throw the point out of focus. If the point becomes a luminous circle
surrounded by concentric rings, the surface throwing the light point
is perfectly plane or smooth. If, however, a pushing-in shows a
vertical flattening of the point, and a pulling-out a horizontal
flattening, that part is concave; if the reverse happens, convexity is
the cause.

For the removal of the mirror from Jeumont to Paris a special train
was engaged, and precautions were taken rivalling those by which
travelling Royalty is guarded. The train ran at night without
stopping, and at a constant pace, so that the vibration of the glass
atoms might not vary. On arriving at Paris, the mirror was transferred
to a ponderous waggon, and escorted by a body of men to the Exposition
buildings. The huge object-lens received equally careful treatment.

The telescope was housed at the Exhibition in a long gallery pointing
due north and south, the siderostat at the north end. At the other,
the eyepiece, end, a large amphitheatre accommodated the public
assembled to watch the projection of stellar or lunar images on to a
screen thirty feet high, while a lecturer explained what was visible
from time to time. The images of the sun and moon as they appeared at
the primary focus in the eyepiece measured from twenty-one to
twenty-two inches in diameter, and the screen projections were
magnified from these about thirty times superficially.

The eyepiece section consisted of a short tube, of the same breadth as
the main tube, resting on four wheels that travelled along rails.
Special gearing moved this truck-like construction backwards and
forwards to bring a sharp focus into the eyepiece or on to a
photographic plate. Focusing was thus easy enough when once the
desired object came in view; but the observer being unable to control
the siderostat, 250 feet distant, had to telephone directions to an
assistant stationed near the mirror whenever he wished to examine an
object not in the field of vision.

By the courtesy of the proprietors of the _Strand_ _Magazine_ we are
allowed to quote M. Deloncle's own words describing his emotions on
his first view through the giant telescope:--

"As is invariably the case, whenever an innovation that sets at nought
old-established theories is brought forward, the prophecies of failure
were many and loud, and I had more than a suspicion that my success
would cause less satisfaction to others than to myself. Better than
any one else I myself was cognisant of the unpropitious conditions in
which my instrument had to work. The proximity of the river, the dust
raised by hundreds of thousands of trampling feet, the trepidation of
the soil, the working of the machinery, the changes of temperature,
the glare from the thousands of electric lamps in close
proximity--each of these circumstances, and many others of a more
technical nature, which it would be tedious to enumerate, but which
were no less important, would have been more than sufficient to make
any astronomer despair of success even in observatories where all the
surroundings are chosen with the utmost care.

"In regions pure of calm and serene air large new instruments take
months, more often years, to regulate properly.

"In spite of everything, however, I still felt confident. Our
calculations had been gone over again and again, and I could see
nothing that in my opinion warranted the worst apprehensions of my
kind critics.

"It was with ill-restrained impatience that I waited for the first
night when the moon should show herself in a suitable position for
being observed; but the night arrived in due course.

"Everything was in readiness. The movable portion of the roof of the
building had been slid back, and the mirror of the siderostat stood
bared to the sky.

"In the dark, square chamber at the other end of the instrument, 200
feet away, into which the eyepiece of the instrument opened, I had
taken my station with two or three friends. An attendant at the
telephone stood waiting at my elbow to transmit my orders to his
colleague in charge of the levers that regulated the siderostat and
its mirror.

"The moon had risen now, and her silvery glory shone and sparkled in
the mirror.

"'A right declension,' I ordered.

"The telephone bell rang in reply. 'Slowly, still slower; now to the
left--enough; again a right declension--slower; stop now--very, very
slowly.'

"On the ground-glass before our eyes the moon's image crept up from
one corner until it had overspread the glass completely. And there we
stood in the centre of Paris, examining the surface of our satellite
with all its craters and valleys and bleak desolation.

"I had won the day."




PHOTOGRAPHING THE INVISIBLE.


Most of us are able to recognise when we see them shadowgraphs taken
by the aid of the now famous X-rays. They generally represent some
part of the structure of men, beasts, birds, or fishes. Very dark
patches show the position of the bones, large and small; lighter
patches the more solid muscles clinging to the bony framework; and
outside these again are shadowy tracts corresponding to the thinnest
and most transparent portions of the fleshy envelope.

In an age fruitful as this in scientific marvels, it often takes some
considerable time for the public to grasp the full importance of a
fresh discovery. But when, in 1896, it was announced that Professor
Röntgen of Würzburg had actually taken photographs of the internal
organs of still living creatures, and penetrated metal and other
opaque substances with a new kind of ray, great interest was
manifested throughout the civilised world. On the one hand the "new
photography" seemed to upset popular ideas of opacity; on the other it
savoured strongly of the black art, and, by its easy excursions
through the human body, seemed likely to revolutionise medical and
surgical methods. At first many strange ideas about the X-rays got
afloat, attributing to them powers which would have surprised even
their modest discoverer. It was also thought that the records were
made in a camera after the ordinary manner of photography, but as a
matter of fact Röntgen used neither lens nor camera, the operation
being similar to that of casting a shadow on a wall by means of a
lamp. In X-radiography a specially constructed electrically-lit glass
tube takes the place of the lamp, and for the wall is substituted a
sensitised plate. The object to be radiographed is merely inserted
between them, its various parts offering varying resistance to the
rays, so that the plate is affected unequally, and after exposure may
be developed and printed from it the usual way. Photographs obtained
by using X-rays are therefore properly called shadowgraphs or
skiagraphs.

The discovery that has made Professor Röntgen famous is, like many
great discoveries, based upon the labours of other men in the same
field. Geissler, whose vacuum tubes are so well known for their
striking colour effects, had already noticed that electric discharges
sent through very much rarefied air or gases produced beautiful glows.
Sir William Crookes, following the same line of research, and reducing
with a Sprengel air-pump the internal pressure of the tubes to
1/100000 of an atmosphere, found that a luminous glow streamed from
the cathode, or negative pole, in a straight line, heating and
rendering phosphorescent anything that it met. Crookes regarded the
glow as composed of "radiant matter," and explained its existence as
follows. The airy particles inside the tube, being few in number, are
able to move about with far greater freedom than in the tightly packed
atmosphere outside the tube. A particle, on reaching the cathode, is
repelled violently by it in a straight line, to "bombard" another
particle, the walls of the tube, or any object set up in its path, the
sudden arrest of motion being converted into light and heat.

By means of special tubes he proved that the "radiant matter" could
turn little vanes, and that the flow continued even when the terminals
of the shocking-coil were _outside_ the glass, thus meeting the
contention of Puluj that the radiant matter was nothing more than
small particles of platinum torn from the terminals. He also showed
that, when intercepted, radiant matter cast a shadow, the intercepting
object receiving the energy of the bombardment; but that when the
obstruction was removed the hitherto sheltered part of the glass wall
of the tube glowed with a brighter phosphorescence than the part which
had become "tired" by prolonged bombardment. Experiments further
revealed the fact that the shaft of "Cathode rays" could be deflected
by a magnet from their course, and that they affected an ordinary
photographic plate exposed to them.

In 1894 Lenard, a Hungarian, and pupil of the famous Hertz, fitted a
Crookes' tube with a "window" of aluminium in its side replacing a
part of the glass, and saw that the course of the rays could be
traced through the outside air. From this it was evident that
something else than matter must be present in the shaft of energy sent
from the negative terminal of the tube, as there was no direct
communication between the interior and the exterior of the tube to
account for the external phosphorescence. Whatever was the nature of
the rays he succeeded in making them penetrate and impress themselves
on a sensitised plate enclosed in a metal box.

Then in 1896 came Röntgen's great discovery that the rays from a
Crookes' tube, after traversing the _glass_, could pierce opaque
matter. He covered the tube with thick cardboard, but found that it
would still cast the shadows of books, cards, wood, metals, the human
hand, &c., on to a photographic plate even at the distance of some
feet. The rays would also pass through the wood, metal, or bones in
course of time; but certain bodies, notably metals, offered a much
greater resistance than others, such as wood, leather, and paper.
Professor Röntgen crowned his efforts by showing that a skeleton could
be "shadow-graphed" while its owner was still alive.

Naturally everybody wished to know not only what the rays could do,
but what they were. Röntgen, not being able to identify them with any
known rays, took refuge in the algebraical symbol of the unknown
quantity and dubbed them X-rays. He discovered this much, however,
that they were invisible to the eye under ordinary conditions; that
they travelled in straight lines only, passing through a prism, water,
or other refracting bodies without turning aside from their path; and
that a magnet exerted no power over them. This last fact was
sufficient of itself to prevent their confusion with the radiant
matter "cathode rays" of the tube. Röntgen thought, nevertheless, that
they might be the cathode rays transmuted in some manner by their
passage through the glass, so as to resemble in their motion
sound-waves, _i.e._ moving straight forward and not swaying from side
to side in a series of zig-zags. The existence of such ether waves had
for some time before been suspected by Lord Kelvin.

Other authorities have other theories. We may mention the view that X
represents the ultra-violet rays of the spectrum, caused by vibrations
of such extreme rapidity as to be imperceptible to the human eye, just
as sounds of extremely high pitch are inaudible to the ear. This
theory is to a certain extent upheld by the behaviour of the
photographic plate, which is least affected by the colours of the
spectrum at the red end and most by those at the violet end. A
photographer is able to use red or orange light in his dark room
because his plates cannot "see" them, though he can; whereas the
reverse would be the case with X-rays. This ultra-violet theory claims
for X-rays a rate of ether vibration of trillions of waves per
second.

An alternative theory is to relegate the rays to the gap in the scale
of ether-waves between heatwaves and light-waves. But this does not
explain any more satisfactorily than the other the peculiar phenomenon
of non-refraction.

The apparatus employed in X-photography consists of a Crookes' tube of
a special type, a powerful shocking or induction coil, a fluorescent
screen and photographic plates and appliances for developing, &c.,
besides a supply of high-pressure electricity derived from the main, a
small dynamo or batteries.

A Crookes' tube is four to five inches in diameter, globular in its
middle portion, but tapering away towards each end. Through one
extremity is led a platinum wire, terminating in a saucer-shaped
platinum plate an inch or so across. At the focus of this, the
negative terminal, is fixed a platinum plate at an angle to the path
of the rays so as to deflect them through the side of the tube. The
positive terminal penetrates the glass at one side. The tube contains,
as we have seen, a very tiny residue of air. If this were entirely
exhausted the action of the tube would cease; so that some tubes are
so arranged that when rarefaction becomes too high the passage of an
electrical current through small bars of chemicals, whose ends project
through the sides of the tube, liberates gas from the bars in
sufficient quantity to render the tube active again.

When the Ruhmkorff induction coil is joined to the electric circuit a
series of violent discharges of great rapidity occur between the tube
terminals, resembling in their power the discharge of a Leyden jar,
though for want of a dense atmosphere the brilliant spark has been
replaced by a glow and brush-light in the tube. The coil is of large
dimensions, capable of passing a spark across an air-gap of ten to
twelve inches. It will perhaps increase the reader's respect for
X-rays to learn that a coil of proper size contains upwards of
thirteen miles of wire; though indeed this quantity is nothing in
comparison with the 150 miles wound on the huge inductorium formerly
exhibited at the London Polytechnic.

If we were invited to an X-ray demonstration we should find the
operator and his apparatus in a darkened room. He turns on the current
and the darkness is broken by a velvety glow surrounding the negative
terminal, which gradually extends until the whole tube becomes clothed
in a green phosphorescence. A sharply-defined line athwart the tube
separates the shadowed part behind the receiving plate at the negative
focus--now intensely hot--from that on which the reflected rays fall
directly.

One of us is now invited to extend a hand close to the tube. The
operator then holds on the near side of the hand his fluorescent
screen, which is nothing more than a framework supporting a paper
smeared on one side with platino-cyanide of barium, a chemical that,
in common with several others, was discovered by Salvioni of Perugia
to be sensitive to the rays and able to make them visible to the human
eye. The value of the screen to the X-radiographer is that of the
ground-glass plate to the ordinary photographer, as it allows him to
see exactly what things are before the sensitised plate is brought
into position, and in fact largely obviates the necessity for making a
permanent record.

The screen shows clearly and in full detail all the bones of the
hand--so clearly that one is almost irresistibly drawn to peep behind
to see if a real hand is there. One of us now extends an arm and the
screen shows us the _ulna_ and the _radius_ working round each other,
now both visible, now one obscuring the other. On presenting the body
to the course of the rays a remarkable shadow is cast on to the
screen. The spinal column and the ribs; the action of the heart and
lungs are seen quite distinctly. A deep breath causes the movement of
a dark mass--the liver. There is no privacy in presence of the rays.
The enlarged heart, the diseased lung, the ulcerated liver betrays
itself at once. In a second of time the phosphorescent screen reveals
what might baulk medical examination for months.

If a photographic slide containing a dry-plate be substituted for the
focusing-screen, the rays soon penetrate any covering in which the
plate may be wrapped to protect it from ordinary light rays. The
process of taking a shadowgraph may therefore be conducted in broad
daylight, which is under certain conditions a great advantage, though
the sensitiveness of plates exposed to Röntgen rays entails special
care being taken of them when they are not in use. In the early days
of X-radiography an exposure of some minutes was necessary to secure a
negative, but now, thanks to the improvements in the tubes, a few
seconds is often sufficient.

The discovery of the X-rays is a great discovery, because it has done
much to promote the noblest possible cause, the alleviation of human
suffering. Not everybody will appreciate a more rapid mode of
telegraphy, or a new method of spinning yarn, but the dullest
intellect will give due credit to a scientific process that helps to
save life and limb. Who among us is not liable to break an arm or leg,
or suffer from internal injuries invisible to the eye? Who among us
therefore should not be thankful on reflecting that, in event of such
a mishap, the X-rays will be at hand to show just what the trouble is,
how to deal with it, and how far the healing advances day by day? The
X-ray apparatus is now as necessary for the proper equipment of a
hospital as a camera for that of a photographic studio.

It is especially welcome in the hospitals which accompany an army into
the field. Since May 1896 many a wounded soldier has had reason to
bless the patient work that led to the discovery at Würzburg. The
Greek war, the war in Cuba, the Tirah campaign, the Egyptian campaign,
and the war in South Africa, have given a quick succession of fine
opportunities for putting the new photography to the test. There is
now small excuse for the useless and agonising probings that once
added to the dangers and horrors of the military hospital. Even if the
X-ray equipment, by reason of its weight, cannot conveniently be kept
at the front of a rapidly moving army, it can be set up in the
"advanced" or "base" hospitals, whither the wounded are sent after a
first rough dressing of their injuries. The medical staff there
subject their patients to the searching rays, are able to record the
exact position of a bullet or shell-fragment, and the damage it has
done; and by promptly removing the intruder to greatly lessen its
power to harm.

The Röntgen ray has added to the surgeon's armoury a powerful weapon.
Its possibilities are not yet fully known, but there can be no doubt
that it marks a new epoch in surgical work. And for this reason
Professor Röntgen deserves to rank with Harvey, the discoverer of the
blood's circulation; with Jenner, the father of vaccination; and with
Sir James Young Simpson, the first doctor to use chloroform as an
anæsthetic.


PHOTOGRAPHY IN THE DARK.

Strange as it seems to take photographs with invisible rays, it is
still stranger to be able to affect sensitised plates without
apparently the presence of any kind of rays.

Professor W. J. Russell, Vice-President of the Royal Society of
London, has discovered that many substances have the power of
impressing their outlines automatically on a sensitive film, if the
substance be placed in a dark cupboard in contact with, or very close
to a dry-plate.

After some hours, or it may be days, development of the plate will
reveal a distinct impression of the body in question. Dr. Russell
experimented with wood, metal, leaves, drawings, printed matter, lace.
Zinc proved to be an unusually active agent. A plate of the metal,
highly polished and then ruled with patterns, had at the end of a few
days imparted a record of every scratch and mark to the plate. And not
only will zinc impress itself, but it affects substances which are not
themselves active, throwing shadowgraphs on to the plate. This was
demonstrated with samples of lace, laid between a plate and a small
sheet of bright zinc; also with a skeleton leaf. It is curious that
while the interposition of thin films of celluloid, gutta-percha,
vegetable parchment, and gold-beater's skin--all inactive--between the
zinc and the plate has no obstructive effect, a plate of thin glass
counteracts the action of the zinc. Besides zinc, nickel, aluminium,
pewter, lead, and tin among the metals influence a sensitised plate.
Another totally different substance, printer's ink, has a similar
power; or at least some printer's ink, for Professor Russell found
that different samples varied greatly in their effects. What is
especially curious, the printed matter on _both sides_ of a piece of
newspaper appeared on the plate, and that the effect proceeded from
the ink and not from any rays passing from beyond it is proved by the
fact that the type came out _dark_ in the development, whereas if it
had been a case of shadowgraphy, the ink by intercepting rays would
have produced _white_ letters. Professor Russell has also shown that
modern writing ink is incapable of producing an impression unaided,
but that on the other hand paper written on a hundred years ago or a
printed book centuries old will, with the help of zinc, yield a
picture in which even faded and uncertain characters appear quite
distinctly. This opens the way to a practical use of the discovery, in
the deciphering of old and partly obliterated manuscripts.

A very interesting experiment may be made with that useful
possession--a five-pound note. Place the note printed side next to the
plate, and the printing appears dark; but insert the note between a
zinc sheet and the plate, its back being this time towards the
sensitised surface, and the printing appears _white_; and the zinc,
after contact with the printed side, will itself yield a picture of
the inscription as though it had absorbed some virtue from the note!

As explanation of this paradoxical dark photography--or whatever it
is--two theories may be advanced. The one--favoured by Professor
Russell--is that all "active" substances give off _vapours_ able to
act on a photographic plate. In support of this may be urged the fact
that the interposition of glass prevents the making of dark pictures.
But on the other hand it must be remembered that celluloid and
sheet-gelatine, also air-tight substances, are able to store up light
and to give it out again. It is well known among photographers that to
allow sunlight to fall on the inside of a camera is apt to have a
"fogging" effect on a plate that is exposed in the camera afterwards,
though the greatest care be taken to keep all external light from the
plate. But here the glass again presents a difficulty, for if this
were a case of reflected light, glass would evidently be _less_
obstructive than opaque vegetable parchment or gutta-percha.




SOLAR MOTORS.


One day George Stephenson and a friend stood watching a train drawn by
one of his locomotives.

"What moves that train?" asked Stephenson.

"The engine," replied his friend.

"And what moves the engine?"

"The steam."

"And what produces the steam?"

"Coal."

"And what produces coal?"

This last query nonplussed his friend, and Stephenson himself replied,
"The sun."

The "bottled sunshine" that drove the locomotive was stored up
millions of years ago in the dense forests then covering the face of
the globe. Every day vegetation was built by the sunbeams, and in the
course of ages this growth was crushed into fossil form by the
pressure of high-piled rock and débris. To-day we cast "black
diamonds" into our grates and furnaces, to call out the warmth and
power that is a legacy from a period long prior to the advent of
fire-loving man, often forgetful of its real source.

We see the influence of the sun more directly in the motions of wind
and water. Had not the sun's action deposited snow and rain on the
uplands of the world, there would be no roaring waterfall, no rushing
torrent, no smooth-flowing stream. But for the sun heating the
atmosphere unequally, there would not be that rushing of cool air to
replace hot which we know as wind.

We press Sol into our service when we burn fuel; our wind-mills and
water-mills make him our slave. Of late years many prophets have
arisen to warn us that we must not be too lavish of our coal; that the
time is not so far distant, reckoning by centuries, when the
coal-seams of the world will be worked out and leave our descendants
destitute of what plays so important a part in modern life. Now,
though waste is unpardonable, and the care for posterity praiseworthy,
there really seems to be no good reason why we should alarm ourselves
about the welfare of the people of the far future. Even if coal fails,
the winds and the rivers will be there, and the huge unharnessed
energy of the tides, and the sun himself is ready to answer appeals
for help, if rightly shaped. He does not demand the prayers of Persian
fire-worshippers, but rather the scientific gathering of his good
gifts.

Place your hand on a roof lying square to the summer sun, and you will
find it too hot for the touch. Concentrate a beam of sunshine through
a small burning-glass. How fierce is the small glowing focal spot that
makes us draw our hands suddenly away! Suppose now a large glass many
feet across bending several square yards of sun rays to a point, and
at that point a boiler. The boiler would develop steam, and the steam
might be led into cylinders and forced to drudge for us.

Do many of us realise the enormous energy of a hot summer's day? The
heat falling in the tropics on a single square foot of the earth's
surface has been estimated as the equivalent of one-third of a
horse-power. The force of Niagara itself would on this basis be
matched by the sunshine streaming on to a square mile or so. A
steamship might be propelled by the heat that scorches its decks.

For many centuries inventors have tried to utilise this huge waste
power. We all know how, according to the story, Archimedes burnt up
the Roman ships besieging his native town, Syracuse, by concentrating
on them the sun heat cast from hundreds of mirrors. This story is less
probable than interesting as a proof that the ancients were aware of
the sun's power. The first genuine solar machine was the work of
Ericsson, the builder of the _Monitor_. He focused sun heat on a
boiler, which gave the equivalent of one horse-power for every hundred
square feet of mirrors employed. This was not what engineers would
call a "high efficiency," a great deal of heat being wasted, but it
led the way to further improvements.

In America, especially in the dry, arid regions, where fuel is scarce
and the sun shines pitilessly day after day, all the year round,
sun-catchers of various types have been erected and worked
successfully. Dr. William Calver, of Washington, has built in the
barren wastes of Arizona huge frames of mirrors, travelling on
circular rails, so that they may be brought to face the sun at all
hours between sunrise and sunset. Dr. Calver employs no less than 1600
mirrors. As each of these mirrors develops 10-15 degrees of heat it is
obvious, after an appeal to simple arithmetic, that the united efforts
of these reflectors should produce the tremendous temperature
16,000-24,000 degrees, which, expressed comparatively, means the
paltry 90 degrees in the shade beneath which we grow restive
multiplied hundreds of times. Hitherto the greatest known heat had
been that of the arc of the electric lamp, in which the incandescent
particles between pole and pole attain 6000 degrees Fahrenheit.

The combined effect of the burning mirrors is irresistible. They can,
we are told, in a few moments reduce Russian iron to the consistency
of warmed wax, though it mocks the heat of many blast-furnaces. They
will bake bricks twenty times as rapidly as any kiln, and the bricks
produced are not the friable blocks which a mason chips easily with
his trowel, but bodies so hard as to scratch case-hardened steel.

There are at work in California sun-motors of another design. The
reader must imagine a huge conical lamp-shade turned over on to its
smaller end, its inner surface lined with nearly 1800 mirrors 2 feet
long and 3 inches broad, the whole supported on a light iron
framework, and he will have a good idea of the apparatus used on the
Pasadena ostrich farm. The machine is arranged _in meridian_, that is,
at right angles to the path of the sun, which it follows all day long
by the agency of clockwork. In the focus of the mirrors is a boiler,
13 feet 6 inches long, coated with black, heat-absorbing substances.
This boiler holds over 100 gallons of water, and being fed
automatically will raise steam untended all the day through. The steam
is led by pipes to an engine working a pump, capable of delivering
1400 gallons per minute.

The cheapness of the apparatus in proportion to its utility is so
marked that, in regions where sunshine is almost perpetual, the solar
motor will in time become as common as are windmills and factory
chimneys elsewhere. If the heat falling on a few square yards of
mirror lifts nearly 100,000 gallons of water an hour, there is indeed
hope for the Sahara, the Persian Desert, Arabia, Mongolia, Mexico,
Australia. That is to say, if the water under the earth be in these
parts as plentiful as the sunshine above it. The effect of water on
the most unpromising soil is marvellous. Already in Algeria the French
have reclaimed thousands of square miles by scientific irrigation. In
Australia huge artesian wells have made habitable for man and beast
millions of acres that were before desert.

It is only a just retribution that the sun should be harnessed and
compelled to draw water for tracts to which he has so long denied it.
The sun-motor is only just entering on its useful career, and at
present we can but dream of the great effects it may have on future
civilisation. Yet its principle is so simple, so scientific, and so
obvious, that it is easy to imagine it at no far distant date a
dangerous rival to King Coal himself. To quarry coal from the bowels
of the earth and transform it into heat, is to traverse two sides of a
triangle, the third being to use the sunshine of the passing hour.




LIQUID AIR.


Among common phenomena few are more interesting than the changes
undergone by the substance called water. Its usual form is a liquid.
Under the influence of frost it becomes hard as iron, brittle as
glass. At the touch of fire it passes into unsubstantial vapour.

This transformation illustrates the great principle that the form of
every substance in the universe is a question of heat. A metal
transported from the earth to the sun would first melt and then
vaporise; while what we here know only as vapours would in the moon
turn into liquids.

We notice that, as regards bulk, the most striking change is from
liquid to gaseous form. In steam the atoms and molecules of water are
endowed with enormous repulsive vigour. Each atom suddenly shows a
huge distaste for the company of its neighbours, drives them off, and
endeavours to occupy the largest possible amount of private space.

Now, though we are accustomed to see water-atoms thus stirred into an
activity which gives us the giant steam as servant, it has probably
fallen to the lot of but few of us to encounter certain gaseous
substances so utterly deprived of their self-assertiveness as to
collapse into a liquid mass, in which shape they are quite strangers
to us. What gaseous body do we know better than the air we breathe?
and what should we less expect to be reducible to the consistency of
water? Yet science has lately brought prominently into notice that
strange child of pressure and cold, Liquid Air; of which great things
are prophesied, and about which many strange facts may be told.

Very likely our readers have sometimes noticed a porter uncoupling the
air-tube between two railway carriages. He first turns off the tap at
each end of the tube, and then by a twist disconnects a joint in the
centre. At the moment of disconnection what appears to be a small
cloud of steam issues from the joint. This is, however, the result of
cold, not heat, the tube being full of highly-compressed air, which by
its sudden expansion develops cold sufficient to freeze any particles
of moisture in the surrounding air.

Keep this in mind, and also what happens when you inflate your
cycle-tyre. The air-pump grows hotter and hotter as inflation
proceeds: until at last, if of metal, it becomes uncomfortably warm.
The heat is caused by the forcing together of air-molecules, and
inasmuch as all force produces heat, your strength is transformed into
warmth.

In these two operations, compression and expansion, we have the key to
the creation of liquid air--the great power, as some say, of
to-morrow.

[Illustration: _By kind permission of The Liquid Air Co._

_A view of the Liquid Air Co.'s factory at Pimlico. On the left are
the three compressors, squeezing the air at pressures of 90, 500 and
2,200 lbs. to the square inch respectively. On the right is the
reservoir in which the liquid is stored._]

Suppose we take a volume of air and squeeze it into 1/100 of its
original space. The combativeness of the air-atoms is immensely
increased. They pound each other frantically, and become very hot in
the process. Now, by cooling the vessel in which they are, we rob them
of their energy. They become quiet, but they are much closer than
before. Then imagine that all of a sudden we let them loose again. The
life is gone out of them, their heat has departed, and on separating
they shiver grievously. In other words, the heat contained by the
1/100 volume is suddenly compelled to "spread itself thin" over the
whole volume: result--intense cold. And if this air be brought to bear
upon a second vessel filled likewise with compressed air, the cold
will be even more intense, until at last the air-atoms lose all their
strength and collapse into a liquid.

Liquid air is no new thing. Who first made it is uncertain. The credit
has been claimed for several people, among them Olzewski, a Pole, and
Pictet, a Swiss. As a mere laboratory experiment the manufacture of
liquid air in small quantities has been known for twenty years or
more. The earlier process was one of terrific compression alone,
actually forcing the air molecules by sheer strength into such close
contact that their antagonism to one another was temporarily overcome.
So expensive was the process that the first ounce of liquid air is
estimated to have cost over £600!

In order to make liquid air an article of commerce the most important
condition was a wholesale decrease in cost of production. In 1857 C.
W. Siemens took out a patent for making the liquid on what is known as
the regenerative principle, whereby the compressed air is chilled by
expanding a part of it. Professor Dewar--a scientist well known for
his researches in the field of liquid gases--had in 1892 produced
liquid air by a modification of the principle at comparatively small
cost; and other inventors have since then still further reduced the
expense, until at the present day there appears to be a prospect of
liquid air becoming cheap enough to prove a dangerous rival to steam
and electricity.

A company, known as the Liquid Air, Power and Automobile Company, has
established large plants in America and England for the manufacture of
the liquid on a commercial scale. The writer paid a visit to their
depot in Gillingham Street, London, where he was shown the process by
Mr. Hans Knudsen, the inventor of much of the machinery there used.
The reader will doubtless like to learn the "plain, unvarnished truth"
about the creation of this peculiar liquid, and to hear of the freaks
in which it indulges--if indeed those may be called freaks which are
but obedience to the unchanging laws of Nature.

On entering the factory the first thing that strikes the eye and ear
is the monstrous fifty horse-power gas-engine, pounding away with an
energy that shakes the whole building. From its ponderous flywheels
great leather belts pass to the compressors, three in number, by which
the air, drawn from outside the building through special purifiers, is
subjected to an increasing pressure. Three dials on the wall show
exactly what is going on inside the compressors. The first stands at
90 lbs. to the square inch, the second at 500, and the third at 2200,
or rather less than a ton pressure on the area of a penny! The pistons
of the low-pressure compressor is ten inches in diameter, but that of
the high pressure only two inches, or 1/25 of the area, so great is
the resistance to be overcome in the last stage of compression.

Now, if the cycle-pump heats our hands, it will be easily understood
that the temperature of the compressors is very high. They are
water-jacketed like the cylinders of a gas-engine, so that a
circulating stream of cold water may absorb some of the heat. The
compressed air is passed through spiral tubes winding through large
tanks of water which fairly boils from the fierceness of the heat of
compression.

When the air has been sufficiently cooled it is allowed to pass into a
small chamber, expanding as it goes, and from the small into a larger
chamber, where the cold of expansion becomes so acute that the
air-molecules collapse into liquid, which collects in a special
receptacle. Arrangements are made whereby any vapour rising from the
liquid passes through a space outside the expansion chambers, so that
it helps to cool the incoming air and is not wasted.

The liquid-air tank is inside a great wooden case, carefully protected
from the heat of the atmosphere by non-conducting substances. A tap
being turned, a rush of vapour shoots out, soon followed by a clear,
bluish liquid, which is the air we breathe in a fresh guise.

A quantity of it is collected in a saucepan. It simmers at first, and
presently boils like water on a fire. The air-heat is _by comparison_
so great that the liquid cannot resist it, and strives to regain its
former condition.

You may dip your finger into the saucepan--if you withdraw it again
quickly--without hurt. The cushion of air that your finger takes in
with it protects you against harm--for a moment. But if you held it in
the liquid for a couple of seconds you would be minus a digit. Pour a
little over your coat sleeve. It flows harmlessly to the ground, where
it suddenly expands into a cloud of chilly vapour.

Put some in a test tube and cork it up. The cork soon flies out with a
report--the pressure of the boiling air drives it. Now watch the
boiling process. The nitrogen being more volatile--as it boils at a
lower temperature than oxygen--passes off first, leaving the pure,
blue oxygen. The temperature of this liquid is over 312 degrees below
zero (as far below the temperature of the air we breathe as the
temperature of molten lead is above it!). A tumbler of liquid oxygen
dipped into water is soon covered with a coating of ice, which can be
detached from the tumbler and itself used as a cup to hold the liquid.
If a bit of steel wire be now twisted round a lighted match and the
whole dipped into the cup, the steel flares fiercely and fuses into
small pellets; which means that an operation requiring 3000 degrees
Fahrenheit has been accomplished in a liquid 300 degrees below zero!

Liquid air has curious effects upon certain substances. It makes iron
so brittle that a ladle immersed for a few moments may be crushed in
the hands; but, curiously enough, it has a toughening effect on copper
and brass. Meat, eggs, fruit, and all bodies containing water become
hard as steel and as breakable as glass. Mercury is by it congealed to
the consistency of iron; even alcohol, that can brave the utmost
Arctic cold, succumbs to it. The writer was present when some
thermometers, manufactured by Messrs. Negretti and Zambra, were tested
with liquid air. The spirit in the tubes rapidly descended to 250
degrees below zero, then sank slowly, and at about 260 degrees froze
and burst the bulb. The measuring of such extreme temperatures is a
very difficult matter in consequence of the inability of spirit to
withstand them, and special apparatus, registering cold by the
shrinkage of metal, must be used for testing some liquid gases,
notably liquid hydrogen, which is so much colder than liquid air that
it actually freezes it into a solid ice form!

For handling and transporting liquid gases glass receptacles with a
double skin from which all air has been exhausted are employed. The
surrounding vacuum is so perfect an insulator that a "Dewar bulb" full
of liquid air scarcely cools the hand, though the intervening space is
less than an inch. This fact is hard to square with the assertion of
scientific men that our atmosphere extends but a hundred or two miles
from the earth's surface, and that the recesses of space are a vacuum.
If it were so, how would heat reach us from the sun, ninety-two
millions of miles away?

One use at least for liquid air is sufficiently obvious. As a
refrigerating agent it is unequalled. Bulk for bulk its effect is of
course far greater than that of ice; and it has this advantage over
other freezing compounds, that whereas slow freezing has a destructive
effect upon the tissues of meat and fruit, the instantaneous action of
liquid air has no bad results when the thing frozen is thawed out
again. The Liquid Air Company therefore proposes erecting depôts at
large ports for supplying ships, to preserve the food, cool the cabins
in the tropics, and, we hope, to alleviate some of the horrors of the
stokehold.

Liquid air is already used in medical and surgical science. In surgery
it is substituted for anæsthetics, deadening any part of the body on
which an operation has to be performed. In fever hospitals, too, its
cooling influence will be welcomed; and liquid oxygen takes the places
of compressed oxygen for reviving the flickering flame of life. It
will also prove invaluable for divers and submarine boats.

In combination with oil and charcoal liquid air, under the name of
"oxyliquit," becomes a powerful blasting agent. Cartridges of paper
filled with the oil and charcoal are provided with a firing primer.
When everything is ready for the blasting the cartridges are dropped
into a vessel full of liquid air, saturated, placed in position, and
exploded. Mr. Knudsen assured the writer that oxyliquit is twice as
powerful as nitro-glycerine, and its cost but one-third of that of the
other explosive. It is also safer to handle, for in case of a misfire
the cartridge becomes harmless in a few minutes, after the liquid air
has evaporated.

But the greatest use will be found for liquid air when it exerts its
force less violently. It is the result of power; its condition is
abnormal; and its return to its ordinary state is accompanied by a
great development of energy. If it be placed in a closed vessel it is
capable of exerting a pressure of 12,000 lbs. to the square inch. Its
return to atmospheric condition may be regulated by exposing it more
or less to the heat of the atmosphere. So long as it remains liquid
it represents so much _stored force_, like the electricity stored in
accumulators. The Liquid Air Company have at their Gillingham Street
depôt a neat little motor car worked by liquid air. A copper
reservoir, carefully protected, is filled with the liquid, which is by
mechanical means squirted into coils, in which it rapidly expands, and
from them passes to the cylinders. A charge of eighteen gallons will
move the car forty miles at an average pace of twelve miles an hour,
without any of the noise, dirt, smell, or vapour inseparable from the
employment of steam or petroleum. The speed of the car is regulated by
the amount of liquid injected into the expansion coils.

We now come to the question of cost--the unromantic balance in which
new discoveries are weighed and many found wanting. The storage of
liquid air is feasible for long periods. (A large vacuum bulb filled
and exposed to the atmosphere had some of the liquid still
unevaporated at the end of twenty-two days.) But will it be too costly
for ordinary practical purposes now served by steam and electricity?
The managers of the Liquid Air Company, while deprecating extravagant
prophecies about the future of their commodity, are nevertheless
confident that it has "come to stay." With the small 50 horse-power
plant its production costs upwards of one shilling a gallon, but with
much larger plant of 1000 horse-power they calculate that the expenses
will be covered and a profit left if they retail it at but one penny
the gallon. This great reduction in cost arises from the economising
of "waste energy." In the first place the power of expansion previous
to the liquefaction of the compressed air will be utilised to work
motors. Secondly, the heat of the cooling tanks will be turned to
account, and even the "exhaust" of a motor would be cold enough for
ordinary refrigerating. It is, of course, impossible to get more out
of a thing than has been put into it; and liquid air will therefore
not develop even as much power as was required to form it. But its
handiness and cleanliness strongly recommend it for many purposes, as
we have seen; and as soon as it is turned out in large quantities new
uses will be found for it. Perhaps the day will come when liquid-air
motors will replace the petrol car, and in every village we shall see
hung out the sign, "Liquid air sold here." As the French say, "_Qui
vivra verra_."




HORSELESS CARRIAGES.


A body of enterprising Manchester merchants, in the year 1754, put on
the road a "flying coach," which, according to their special
advertisement, would, "however incredible it may appear, actually,
barring accidents, arrive in London in four and a half days after
leaving Manchester." According to the Lord Chancellor of the time such
swift travelling was considered dangerous as well as wonderful--the
condition of the roads might well make it so--and also injurious to
health. "I was gravely advised," he says, "to stay a day in York on my
journey between Edinburgh and London, as several passengers who had
gone through without stopping had died of apoplexy from the rapidity
of the motion."

As the coach took a fortnight to pass from the Scotch to the English
capital, at an average pace of between three and four miles an hour,
it is probable that the Chancellor's advisers would be very seriously
indisposed by the mere sight of a motor-car whirling along in its
attendant cloud of dust, could they be resuscitated for the purpose.
And we, on the other hand, should prefer to get out and walk to
"flying" at the safe speed of their mail coaches.

[Illustration: _By kind permission of The Speedwell Motor Co._

_M. Serpollet on the "Easter Egg," which at Nice covered a kilometre
in the record time of 29-4/5 secs. (over 75 miles per hour). This car
is run with steam._]

The improvement of highroads, and road-making generally, accelerated
the rate of posting. In the first quarter of the nineteenth century an
average of ten or even twelve miles an hour was maintained on the Bath
Road. But that pace was considered inadequate when the era of the
"iron horse" commenced, and the decay of stage-driving followed hard
upon the growth of railways. What should have been the natural
successor of the stage-coach was driven from the road by ill-advised
legislation, which gave the railroads a monopoly of swift transport,
which has but lately been removed.

The history of the steam-coach, steam-carriage, automobile,
motor-car--to give it its successive names--is in a manner unique,
showing as it does, instead of steady development of a practical means
of locomotion, a sudden and decisive check to an invention worthy of
far better treatment than it received. The compiler of even a short
survey of the automobile's career is obliged to divide his account
into two main portions, linked together by a few solitary engineering
achievements.

The first period (1800-1836), will, without any desire to arrogate for
England more than her due or to belittle the efforts of any other
nations, be termed the English period, since in it England took the
lead, and produced by far the greatest number of steam-carriages. The
second (1870 to the present day) may, with equal justice, be styled
the Continental period, as witnessing the great developments made in
automobilism by French, German, Belgian, and American engineers:
England, for reasons that will be presently noticed, being until quite
recently too heavily handicapped to take a part in the advance.

_Historical._--It is impossible to discover who made the first
self-moving carriage. In the sixteenth century one Johann Haustach, a
Nuremberg watchmaker, produced a vehicle that derived its motive power
from coiled springs, and was in fact a large edition of our modern
clockwork toys. About the same time the Dutch, and among them
especially one Simon Stevin, fitted carriages with sails, and there
are records of a steam-carriage as early as the same century.

But the first practical, and at least semi-successful, automobile
driven by internal force was undoubtedly that of a Frenchman, Nicholas
Joseph Cugnot, who justly merits the title of father of automobilism.
His machine, which is to-day one of the most treasured exhibits in the
Paris Museum of Arts and Crafts, consisted of a large carriage, having
in front a pivoted platform bearing the machinery, and resting on a
solid wheel, which propelled as well as steered the vehicle. The
boiler, of stout riveted copper plates, had below it an enclosed
furnace, from which the flames passed upwards through the water
through a funnel. A couple of cylinders, provided with a simple
reversing gear, worked a ratchet that communicated motion to the
driving-wheel. This carriage did not travel beyond a very slow walking
pace, and Cugnot therefore added certain improvements, after which
(1770) it reached the still very moderate speed of four miles an hour,
and distinguished itself by charging and knocking down a wall, a feat
that is said to have for a time deterred engineers from developing a
seemingly dangerous mode of progression.

Ten years later Dallery built a steam car, and ran it in the streets
of Amiens--we are not told with what success; and before any further
advance had been made with the automobile the French Revolution put a
stop to all inventions of a peaceful character among our neighbours.

In England, however, steam had already been recognised as the coming
power. Richard Trevethick, afterwards to become famous as a railroad
engineer, built a steam motor in 1802, and actually drove it from
Cambourne to Plymouth, a distance of ninety miles. But instead of
following up this success, he forsook steam-carriages for the
construction of locomotives, leaving his idea to be expanded by other
men, who were convinced that a vehicle which could be driven over
existing roads was preferable to one that was helpless when separated
from smooth metal rails. Between the years 1800 and 1836 many steam
vehicles for road traffic appeared from time to time, some, such as
David Gordon's (propelled by metal legs pressing upon the ground),
strangely unpractical, but the majority showing a steady improvement
in mechanical design.

As it will be impossible, without writing a small book, to name all
the English constructors of this period, we must rest content with the
mention of the leading pioneers of the new locomotion.

Sir Goldsworthy Gurney, an eminent chemist, did for mechanical road
propulsion what George Stephenson was doing for railway development.
He boldly spent large sums on experimental vehicles, which took the
form of six-wheeled coaches. The earliest of these were fitted with
legs as well as driving-wheels, since he thought that in difficult
country wheels alone would not have sufficient grip. (A similar
fallacy was responsible for the cogged wheels on the first railways.)
But in the later types legs were abandoned as unnecessary. His coaches
easily climbed the steepest hills round London, including Highgate
Hill, though a thoughtful mathematician had proved by calculations
that a steam-carriage, so far from mounting a gradient, could not,
without violating all natural laws, so much as move itself on the
level!

Having satisfied himself of their power, Gurney took his coaches
further afield. In 1829 was published the first account of a motor
trip made by him and three companions through Reading, Devizes, and
Melksham. The pace was, we read, at first only about six miles an
hour, including stoppages. They drove very carefully to avoid injury
to the persons or feelings of the country folk; but at Melksham, where
a fair was in progress, they had to face a shower of stones, hurled by
a crowd of roughs at the instigation of some coaching postilions, who
feared losing their livelihood if the new method of locomotion became
general. Two of the tourists were severely hurt, and Gurney was
obliged to take shelter in a brewery, where constables guarded his
coach. On the return journey the party timed their movements so as to
pass through Melksham while the inhabitants were all safely in bed.

The coach ran most satisfactorily, improving every mile. "Our pace was
so rapid," wrote one of the company, "that the horses of the mail-cart
which accompanied us were hard put to it to keep up with us. At the
foot of Devizes Hill we met a coach and another vehicle, which stopped
to see us mount this hill, an extremely steep one. We ascended it at a
rapid rate. The coach and passengers, delighted at this unexpected
sight, honoured us with shouts of applause."

In 1830 Messrs. Ogle and Summers completely beat the road record on a
vehicle fitted with a tubular boiler. This car, put through its trials
before a Special Commission of the House of Commons, attained the
astonishing speed of 35 miles an hour on the level, and mounted a hill
near Southampton at 24-1/2 miles an hour. It worked at a boiler
pressure of 250 lbs. to the square inch, and though not hung on
springs, ran 800 miles without a breakdown. This performance appears
all the more extraordinary when we remember the roads of that day were
not generally as good as they are now, and that in the previous year
Stephenson's "Rocket," running on rails, had not reached a higher
velocity.

The report of the Parliamentary Commission on horseless carriages was
most favourable. It urged that the steam-driven car was swifter and
lighter than the mail-coaches; better able to climb and descend hills;
safer; more economical; and less injurious to the roads; and, in
conclusion, that the heavy charges levied at the toll-gates (often
twenty times those on horse vehicles) were nothing short of
iniquitous.

As a result of this report, motor services, inaugurated by Walter
Hancock, Braithwayte, and others, commenced between Paddington and the
Bank, London and Greenwich, London and Windsor, London and Stratford.
Already, in 1829, Sir Charles Dance had a steam-coach running between
Cheltenham and Gloucester. In four months it ran 3500 miles and
carried 3000 passengers, traversing the nine miles in three-quarters
of an hour; although narrow-minded landowners placed ridges of stone
eighteen inches deep on the road by way of protest.

The most ambitious service of all was that between London and
Birmingham, established in 1833 by Dr. Church. The rolling-stock
consisted of a single very much decorated coach.

The success of the road-steamer seemed now assured, when a cloud
appeared on the horizon. It had already been too successful. The
railway companies were up in arms. They saw plainly that if once the
roads were covered with vehicles able to transport the public at low
fares quickly from door to door on existing thoroughfares, the
construction of expensive railroads would be seriously hindered, if
not altogether stopped. So, taking advantage of two motor accidents,
the companies appealed to Parliament--full of horse-loving squires and
manufacturers, who scented profit in the railways--and though
scientific opinion ran strongly in favour of the steam-coach, a law
was passed in 1836 which rendered the steamers harmless by robbing
them of their speed. The fiat went forth that in future _every road
locomotive should be preceded at a distance of a hundred yards by a
man on foot carrying a red flag to warn passengers of its approach_.
This law marks the end of the first period of automobilism as far as
England is concerned. At one blow it crippled a great industry,
deprived the community of a very valuable means of transport, and
crushed the energies of many clever inventors who would soon, if we
may judge by the rapid advances already made in construction, have
brought the steam-carriage to a high pitch of perfection. In the very
year in which they were suppressed the steam services had proved their
efficiency and safety. Hancock's London service alone traversed 4200
miles without serious accident, and was so popular that the coaches
were generally crowded. It is therefore hard to believe that these
vehicles did not supply a public want, or that they were regarded by
those who used them as in any way inferior to horse-drawn coaches.
Yet ignorant prejudice drove them off the road for sixty years; and
to-day it surprises many Englishmen to learn that what is generally
considered a novel method of travelling was already fairly well
developed in the time of their grandfathers.

_Second Period_ (1870 onwards).--To follow the further development of
the automobile we must cross the Channel once again. French invention
had not been idle while Gurney and Hancock were building their
coaches. In 1835 M. Dietz established a service between Versailles and
Paris, and the same year M. D'Asda carried out some successful trials
of his steam "diligence" under the eyes of Royalty. But we find that
for the next thirty-five years the steam-carriage was not much
improved, owing to want of capital among its French admirers. No
Gurney appeared, ready to spend his thousands in experimenting; also,
though the law left road locomotion unrestricted, the railways offered
a determined opposition to a possibly dangerous rival. So that, on the
whole, road transport by steam fared badly till after the terrible
Franco-Prussian war, when inventors again took courage. M. Bollée, of
Mans, built in 1873 a car, "l'Obéissante," which ran from Mans to
Paris; and became the subject of allusions in popular songs and plays,
while its name was held up as an example to the Paris ladies. Three
years later he constructed a steam omnibus to carry fifty persons, and
in 1878 exhibited a car that journeyed at the rate of eighteen miles
an hour from Paris to Vienna, where it aroused great admiration.

After the year 1880 French engineers divided their attention between
the heavy motor omnibus and light vehicles for pleasure parties. In
1884 MM. Bouton and Trépardoux, working conjointly with the Comte de
Dion, produced a steam-driven tricycle, and in 1887 M. Serpollet
followed suit with another, fitted with the peculiar form of steam
generator that bears his name. Then came in 1890 a very important
innovation, which has made automobilism what it now is. Gottlieb
Daimler, a German engineer, introduced the _petrol gas-motor_. Its
comparative lightness and simplicity at once stamped it as the thing
for which makers were waiting. Petrol-driven vehicles were soon abroad
in considerable numbers and varieties, but they did not attract public
attention to any great extent until, in 1894, M. Pierre Giffard, an
editor of the _Petit Journal_, organised a motor race from Paris to
Rouen. The proprietors of the paper offered handsome prizes to the
successful competitors. There were ten starters, some on steam, others
on petrol cars. The race showed that, so far as stability went,
Daimler's engine was the equal of the steam cylinder. The next year
another race of a more ambitious character was held, the course being
from Paris to Bordeaux and back. Subscriptions for prizes flowed in
freely. Serpollet, de Dion, and Bollée prepared steam cars that should
win back for steam its lost supremacy, while the petrol faction
secretly built motors of a strength to relegate steam once and for all
to a back place. Electricity, too, made a bid unsuccessfully for the
prize in the Jeantaud car, a special train being engaged in advance to
distribute charged accumulators over the route. The steamers broke
down soon after the start, so that the petrol cars "walked over" and
won a most decisive victory.

The interest roused in the race led the Comte de Dion to found the
Automobile Club of France, which drew together all the enthusiastic
admirers of the new locomotion. Automobilism now became a sport, a
craze. The French, with their fine straight roads, and a not too
deeply ingrained love of horseflesh, gladly welcomed the flying car,
despite its noisy and malodorous properties.

Orders flowed in so freely that the motor makers could not keep pace
with the demand, or promise delivery within eighteen months. Rich men
were therefore obliged to pay double prices if they could find any one
willing to sell--a state of things that remains unto this day with
certain makes of French cars. Poorer folks contented themselves with
De Dion motor tricycles, which showed up so well in the 1896
Paris-Marseilles race; or with the neat little three-wheeled cars of
M. Bollée. Motor racing became the topic of the hour. Journals were
started for the sole purpose of recording the doings of motorists; and
few newspapers of any popularity omitted a special column of motor
news. Successive contests on the highroads at increasing speeds
attracted increased interest. The black-goggled, fur-clad _chauffeur_
who carried off the prizes found himself a hero.

In short, the hold which automobilism has over our neighbours may be
gauged from the fact that in 1901 it was estimated that nearly a
thousand motor cars assembled to see the sport on the Longchamps
Course (the scene of that ultra-"horsey" event, the Grand Prix), and
the real interest of the meet did not centre round horses of flesh and
blood.

The French have not a monopoly of devotion to automobilism. The speedy
motor car is too much in accord with the bustling spirit of the age;
its delights too easily appreciated to be confined to one country.
Allowing France the first place, America, Germany, and Belgium are not
far behind in their addiction to the "sport," and even in Britain,
partially freed since 1896 from the red-flag tyranny, thanks to the
efforts of Sir David Salomons, there are most visible signs that the
era of the horse is beginning its end.


TYPES OF CAR.

Automobiles may be classified according to the purpose they serve,
according to their size and weight, or according to their motive
power. We will first review them under the latter head.

_A. Petrol._--The petrol motor, suitable alike for large cars of 40
to 60 horse-power and for the small bicycle weighing 70 lbs. or so, at
present undoubtedly occupies the first place in popular estimation on
account of its comparative simplicity, which more than compensates
certain defects that affect persons off the vehicle more than those on
it--smell and noise.

The chief feature of the internal explosion motor is that at one
operation it converts fuel directly into energy, by exploding it
inside a cylinder. It is herein more economical than steam, which
loses power while passing from the boiler to the driving-gear.

Petrol cycles and small cars have usually only one cylinder, but large
vehicles carry two, three, and sometimes four cylinders. Four and more
avoid that bugbear of rotary motion, "dead points," during which the
momentum of the machinery alone is doing work; and for that reason the
engines of racing cars are often quadrupled.

For the sake of simplicity we will describe the working of a single
cylinder, leaving the reader to imagine it acting alone or in concert
with others as he pleases.

In the first place the fuel, petrol, is a very inflammable
distillation of petroleum: so ready to ignite that it must be most
rigorously guarded from naked lights; so quick to evaporate that the
receptacles containing it, if not quite airtight, will soon render it
"stale" and unprofitable for motor driving.

The engine, to mention its most important parts, consists of a
single-action cylinder (giving a thrust one way only); a heavy
flywheel revolving in an airtight circular case, and connected to the
piston by a hinged rod which converts the reciprocating movement of
the piston into a rotary movement of the crank-shaft built in with the
wheel; inlet and outlet valves; a carburettor for generating petrol
gas, and a device to ignite the gas-and-air mixture in the cylinder.

The action of the engine is as follows: as the piston moves outwards
in its first stroke it sucks through the inlet valve a quantity of
mixed air and gas, the proportions of which are regulated by special
taps. The stroke ended, the piston returns, compressing the mixture
and rendering it more combustible. Just as the piston commences its
second outward stroke an electric spark passed through the mixture
mechanically ignites it, and creates an explosion, which drives the
piston violently forwards. The second return forces the burnt gas
through the exhaust-valve, which is lifted by cog-gear once in every
two revolutions of the crank, into the "silencer." The cycle of
operations is then repeated.

We see that during three-quarters of the "cycle"--the suction,
compression, and expulsion--the work is performed entirely by the
flywheel. It follows that a single-cylinder motor, to work at all,
must rotate the wheel at a high rate. Once stopped, it can be
restarted only by the action of the handle or pedals; a task often so
unpleasant and laborious that the driver of a car, when he comes to
rest for a short time only, disconnects his motor from the
driving-gear and lets it throb away idly beneath him.

The means of igniting the gas in the cylinders may be either a Bunsen
burner or an electric spark. Tube ignition is generally considered
inferior to electrical because it does not permit "timing" of the
explosion. Large cars are often fitted with both systems, so as to
have one in reserve should the other break down.

Electrical ignition is most commonly produced by the aid of an
intensity coil, which consists of an inner core of coarse insulated
wire, called the primary coil; and an outer, or secondary coil, of
very fine wire. A current passes at intervals, timed by a cam on the
exhaust-valve gear working a make-and-break contact blade, from an
accumulator through the primary coil, exciting by induction a current
of much greater intensity in the secondary. The secondary is connected
to a "sparking plug," which screws into the end of the cylinder, and
carries two platinum points about 1/32 of an inch apart. The secondary
current leaps this little gap in the circuit, and the spark, being
intensely hot, fires the compressed gas. Instead of accumulators a
small dynamo, driven by the motor, is sometimes used to produce the
primary current.

By moving a small lever, known as the "advancing lever," the driver
can control the time of explosion relatively to the compression of the
gas, and raise or lower the speed of the motor.

The strokes of the petrol-driven cylinder are very rapid, varying from
1000 to 3000 a minute. The heat of very frequent explosions would soon
make the cylinder too hot to work were not measures adopted to keep it
cool. Small cylinders, such as are carried on motor cycles, are
sufficiently cooled by a number of radiating ribs cast in a piece with
the cylinder itself; but for large machines a water jacket or tank
surrounding the cylinder is a necessity. Water is circulated through
the jacket by means of a small centrifugal pump working off the
driving gear, and through a coil of pipes fixed in the front of the
car to catch the draught of progression. So long as the jacket and
tubes are full of water the temperature of the cylinder cannot rise
above boiling point.

Motion is transmitted from the motor to the driving-wheels by
intermediate gear, which in cycles may be only a leather band or
couple of cogs, but in cars is more or less complicated. Under the
body of the car, running usually across it, is the countershaft,
fitted at each end with a small cog which drives a chain passing also
over much larger cogs fixed to the driving-wheels. The countershaft
engages with the cylinder mechanism by a "friction-clutch," a couple
of circular faces which can be pressed against one another by a lever.
To start his car the driver allows the motor to obtain a considerable
momentum, and then, using the friction lever, brings more and more
stress on to the countershaft until the friction-clutch overcomes the
inertia of the car and produces movement.

Gearing suitable for level stretches would not be sufficiently
powerful for hills: the motor would slow and probably stop from want
of momentum. A car is therefore fitted with changing gears, which give
two or three speeds, the lower for ascents, the higher for the level:
and on declines the friction-clutch can be released, allowing the car
to "coast."

_B. Steam Cars._--Though the petrol car has come to the front of late
years it still has a powerful rival in the steam car. Inventors have
made strenuous efforts to provide steam-engines light enough to be
suitable for small pleasure cars. At present the Locomobile (American)
and Serpollet (French) systems are increasing their popularity. The
Locomobile, the cost of which (about £120) contrasts favourably with
that of even the cheaper petrol cars, has a small multitubular boiler
wound on the outside with two or three layers of piano wire, to render
it safe at high pressures. As the boiler is placed under the seat it
is only fit and proper that it should have a large margin of safety.
The fuel, petrol, is passed through a specially designed burner,
pierced with hundreds of fine holes arranged in circles round air
inlets. The feed-supply to the burner is governed by a spring valve,
which cuts off the petrol automatically as soon as the steam in the
boiler reaches a certain pressure. The locomobile runs very evenly and
smoothly, and with very little noise, a welcome change after the very
audible explosion motor.

The Serpollet system is a peculiar method of generating steam. The
boiler is merely a long coil of tubing, into which a small jet of
water is squirted by a pump at every stroke of the cylinders. The
steam is generated and used in a moment, and the speed of the machine
is regulated by the amount of water thrown by the pumps. By an
ingenious device the fuel supply is controlled in combination with the
water supply, so that there may not be any undue waste in the burner.

_C. Electricity._--Of electric cars there are many patterns, but at
present they are not commercially so practical as the other two types.
The great drawbacks to electrically-driven cars are the weight of the
accumulators (which often scale nearly as much as all the rest of the
vehicle), and the difficulty of getting them recharged when exhausted.
We might add to these the rapidity with which the accumulators become
worn out, and the consequent expense of renewal. T. A. Edison is
reported at work on an accumulator which will surpass all hitherto
constructed, having a much longer life, and weighing very much less,
power for power. The longest continuous run ever made with
electricity, 187 miles at Chicago, compares badly with the feat of a
petrol car which on November 23, 1900, travelled a thousand miles on
the Crystal Palace track in 48 hours 24 minutes, without a single
stop. Successful attempts have been made by MM. Pieper and Jenatsky to
combine the petrol and electric systems, by an arrangement which
instead of wasting power in the cylinders when less speed is required,
throws into action electric dynamos to store up energy, convertible,
when needed, into motive power by reversing the dynamo into a motor.
But the simple electric car will not be a universal favourite until
either accumulators are so light that a very large store of
electricity can be carried without inconvenient addition of weight, or
until charging stations are erected all over the country at distances
of fifty miles or so apart.

Whether steam will eventually get the upper hand of the petrol engine
is at present uncertain. The steam car has the advantage over the
gas-engine car in ease of starting, the delicate regulation of power,
facility of reversing, absence of vibration, noise and smell, and
freedom from complicated gears. On the other hand the petrol car has
no boiler to get out of order or burst, no troublesome gauges
requiring constant attention, and there is small difficulty about a
supply of fuel. Petrol sufficient to give motive power for hundreds of
miles can be carried if need be; and as long as there is petrol on
board the car is ready for work at a moment's notice. Judging by the
number of the various types of vehicles actually at work we should
say that while steam is best for heavy traction, the gas-engine is
most often employed on pleasure cars.

[Illustration: _By kind permission of The Liquid Air Co._

_This graceful little motor-car is driven by Liquid Air. It makes
absolutely no smell or noise._]

_D. Liquid Air_ will also have to be reckoned with as a motive power.
At present it is only on its probation; but the writer has good
authority for stating that before these words appear in print there
will be on the roads a car driven by liquid air, and able to turn off
eighty miles in the hour.

_Manufacture._--As the English were the pioneers of the steam car, so
are the Germans and French the chief manufacturers of the petrol car.
While the hands of English manufacturers were tied by shortsighted
legislation, continental nations were inventing and controlling
valuable patents, so that even now our manufacturers are greatly
handicapped. Large numbers of petrol cars are imported annually from
France, Germany, and Belgium. Steam cars come chiefly from America and
France. The former country sent us nearly 2000 vehicles in 1901. There
are signs, however, that English engineers mean to make a determined
effort to recover lost ground; and it is satisfactory to learn that in
heavy steam vehicles, such as are turned out by Thorneycroft and Co.,
this country holds the lead. We will hope that in a few years we shall
be exporters in turn.

Having glanced at the history and nature of the various types of car,
it will be interesting to turn to a consideration of their travelling
capacities. As we have seen, a steam omnibus attained, in 1830, a
speed of no less than thirty-five miles an hour on what we should call
bad roads. It is therefore to be expected that on good modern roads
the latest types of car would be able to eclipse the records of
seventy years ago. That such has indeed been the case is evident when
we examine the performances of cars in races organised as tests of
speed. France, with its straight, beautifully-kept, military roads, is
the country _par excellence_ for the _chauffeur_. One has only to
glance at the map to see how the main highways conform to Euclid's
dictum that a straight line is the shortest distance between any two
points, _e.g._ between Rouen and Dieppe, where a park of artillery,
well posted, could rake the road either way for miles.

The growth of speed in the French races is remarkable. In 1894 the
winning car ran at a mean velocity of thirteen miles an hour; in 1895,
of fifteen. The year 1898 witnessed a great advance to twenty-three
miles, and the next year to thirty miles. But all these speeds paled
before that of the Paris to Bordeaux race of 1901, in which the
winner, M. Fournier, traversed the distance of 327-1/2 miles at a rate
of 53-3/4 miles per hour! The famous Sud express, running between the
same cities, and considered the fastest long-distance express in the
world, was beaten by a full hour. It is interesting to note that in
the same races a motor bicycle, a Werner, weighing 80 lbs. or less,
successfully accomplished the course at an average rate of nearly
thirty miles an hour. The motor-car, after waiting seventy years, had
had its revenge on the railways.

This was not the only occasion on which an express service showed up
badly against its nimble rival of the roads. In June, 1901, the French
and German authorities forgot old animosities in a common enthusiasm
for the automobile, and organised a race between Paris and Berlin. It
was to be a big affair, in which the cars of all nations should fight
for the speed championship. Every possible precaution was taken to
insure the safety of the competitors and the spectators. Flags of
various colours and placards marked out the course, which lay through
Rheims, Luxembourg, Coblentz, Frankfurt, Eisenach, Leipsic, and
Potsdam to the German capital. About fifty towns and large villages
were "neutralised"--that is to say, the competitors had to consume a
certain time in traversing them. At the entrance to each neutralised
zone a "control" was established. As soon as a competitor arrived, he
must slow down, and a card on which was written the time of his
arrival was handed to a "pilot," who cycled in front of the car to the
other "control" at the farther end of the zone, from which, when the
proper time had elapsed, the car was dismissed. Among other rules
were: that no car should be pushed or pulled during the race by any
one else than the passengers; that at the end of the day only a
certain time should be allowed for cleaning and repairs; and that a
limited number of persons, varying with the size of the car, should
be permitted to handle it during that period.

A small army of automobile club representatives, besides thousands of
police and soldiers, were distributed along the course to restrain the
crowds of spectators. It was absolutely imperative that for vehicles
propelled at a rate of from 50 to 60 miles an hour a clear path should
be kept.

At dawn, on July 27th, 109 racing machines assembled at the Fort de
Champigny, outside Paris, in readiness to start for Berlin. Just
before half-past three, the first competitor received the signal; two
minutes later the second; and then at short intervals for three hours
the remaining 107, among whom was one lady, Mme. de Gast. At least
20,000 persons were present, even at that early hour, to give the
racers a hearty farewell, and demonstrate the interest attaching in
France to all things connected with automobilism.

Great excitement prevailed in Paris during the three days of the race.
Every few minutes telegrams arrived from posts on the route telling
how the competitors fared. The news showed that during the first stage
at least a hard fight for the leading place was in progress. The
French cracks, Fournier, Charron, De Knyff, Farman, and Girardot
pressed hard on Hourgières, No. 2 at the starting-point. Fournier soon
secured the lead, and those who remembered his remarkable driving in
the Paris-Bordeaux race at once selected him as the winner.
Aix-la-Chapelle, 283 miles from Paris and the end of the first
stage, was reached in 6 hours 28 minutes. Fournier first, De Knyff
second by six minutes.

[Illustration: _By kind permission of The Liquid Air Co._

_Diagram of the Liquid Air Motor-Car, showing A, reservoir of liquid
air; B, pipes in which the liquid is transformed into atmospheric air
under great pressure; C, cylinders for driving the rear wheels by
means of chain-gear._]

On the 28th the racing became furious. Several accidents occurred.
Edge, driving the only English car, wrecked his machine on a culvert,
the sharp curve of which flung the car into the air and broke its
springs. Another ruined his chances by running over and killing a boy.
But Fournier, Antony, De Knyff, and Girardot managed to avoid mishaps
for that day, and covered the ground at a tremendous pace. At
Düsseldorf Girardot won the lead from Fournier, to lose it again
shortly. Antony, driving at a reckless speed, gained ground all day,
and arrived a close second at Hanover, the halting-place, after a run
averaging, in spite of bad roads and dangerous corners, no less than
54 miles an hour!

The _chauffeur_ in such a race must indeed be a man of iron nerves.
Through the great black goggles which shelter his face from the
dust-laden hurricane set up by the speed he travels at he must keep a
perpetual, piercingly keen watch. Though travelling at express speed,
there are no signals to help him; he must be his own signalman as well
as driver. He must mark every loose stone on the road, every
inequality, every sudden rise or depression; he must calculate the
curves at the corners and judge whether his mechanician, hanging out
on the inward side, will enable a car to round a turn without
slackening speed. His calculations and decisions must be made in the
fraction of a second, for a moment's hesitation might be disaster. His
driving must be furious and not reckless; the timid _chauffeur_ will
never win, the careless one will probably lose. His head must be cool
although the car leaps beneath him like a wild thing, and the wind
lashes his face. At least one well-tried driver found the mere mental
strain too great to bear, and retired from the contest; and we may be
sure that few of the competitors slept much during the nights of the
race.

At four o'clock on the 29th Fournier started on the third stage, which
witnessed another bout of fast travelling. It was now a struggle
between him and Antony for first place. The pace rose at times to
eighty miles an hour, a speed at which our fastest expresses seldom
travel. Such a speed means huge risks, for stopping, even with the
powerful brakes fitted to the large cars, would be a matter of a
hundred yards or more. Not far from Hanover Antony met with an
accident--Girardot now held second place; and Fournier finished an
easy first. All along the route crowds had cheered him, and hurled
bouquets into the car, and wished him good speed; but in Berlin the
assembled populace went nearly frantic at his appearance. Fournier was
overwhelmed with flowers, laurel wreaths, and other offerings; dukes,
duchesses, and the great people of the land pressed for presentations;
he was the hero of the hour.

Thus ended what may be termed a peaceful invasion of Germany by the
French. Among other things it had shown that over an immense stretch
of country, over roads in places bad as only German roads can be, the
automobile was able to maintain an average speed superior to that of
the express trains running between Paris and Berlin; also that, in
spite of the large number of cars employed in the race, the accidents
to the public were a negligible quantity. It should be mentioned that
the actual time occupied by Fournier was 16 hours 5 minutes; that out
of the 109 starters 47 reached Berlin; and that Osmont on a motor
cycle finished only 3 hours and 10 minutes behind the winner.

In England such racing would be undesirable and impossible, owing to
the crookedness of our roads. It would certainly not be permissible so
long as the 12 miles an hour limit is observed. At the present time an
agitation is on foot against this restriction, which, though
reasonable enough among traffic and in towns, appears unjustifiable in
open country. To help to convince the magisterial mind of the ease
with which a car can be stopped, and therefore of its safety even at
comparatively high speeds, trials were held on January 2, 1902, in
Welbeck Park. The results showed that a car travelling at 13 miles an
hour could be stopped dead in 4 yards; at 18 miles in 7 yards; at 20
miles in 13 yards; or in less than half the distance required to pull
up a horse-vehicle driven at similar speeds.

_Uses._--Ninety-five per cent of motors, at least in England, are
attached to pleasure vehicles, cycles, voiturettes, and large cars. On
account of the costliness of cars motorists are far less numerous than
cyclists; but those people whose means enable them to indulge in
automobilism find it extremely fascinating. Caricaturists have
presented to us in plenty the gloomier incidents of motoring--the
broken chain, the burst tyre, the "something gone wrong." It requires
personal experience to understand how lightly these mishaps weigh
against the exhilaration of movement, the rapid change of scene, the
sensation of control over power which can whirl one along tirelessly
at a pace altogether beyond the capacities of horseflesh. If proof
were wanted of the motor car's popularity it will be seen in the
unconventional dress of the _chauffeur_. The breeze set up by his
rapid rush is such as would penetrate ordinary clothing; he dons
cumbrous fur cloaks. The dust is all-pervading at times; he swathes
himself in dust-proof overalls, and mounts large goggles edged with
velvet, while a cap of semi-nautical cut tightly drawn down over neck
and ears serves to protect those portions of his anatomy. The
general effect is peculiarly unpicturesque; but even the most
artistically-minded driver is ready to sacrifice appearances to
comfort and the proper enjoyment of his car.

In England the great grievance of motorists arises from the speed
limit imposed by law. To restrict a powerful car to twelve miles an
hour is like confining a thoroughbred to the paces of a broken-down
cab horse. Careless driving is unpardonable, but its occasional
existence scarcely justifies the intolerant attitude of the law
towards motorists in general. It must, however, be granted in justice
to the police that the _chauffeur_, from constant transgression of the
law, becomes a bad judge of speed, and often travels at a far greater
velocity than he is willing to admit.

The convenience of the motor car for many purposes is immense,
especially for cross-country journeys, which may be made from door to
door without the monotony or indirectness of railway travel. It bears
the doctor swiftly on his rounds. It carries the business man from his
country house to his office. It delivers goods for the merchant;
parcels for the post office.

In the warfare of the future, too, it will play its part, whether to
drag heavy ordnance and stores, or to move commanding officers from
point to point, or perform errands of mercy among the wounded. By the
courtesy of the Locomobile Company we are permitted to append the
testimony of Captain R. S. Walker, R.E., to the usefulness of a car
during the great Boer War.

"Several months ago I noticed a locomobile car at Cape Town, and being
struck with its simplicity and neatness, bought it and took it up
country with me, with a view to making some tests with it over bad
roads, &c. Its first trip was over a rough course round Pretoria,
especially chosen to find out defects before taking it into regular
use. Naturally, as the machine was not designed for this class of
work, there were several. In about a month these had all been found
out and remedied, and the car was in constant use, taking stores, &c.,
round the towns and forts. It also performed some very useful work in
visiting out-stations, where searchlights were either installed or
wanted, and in this way visited nearly all the bigger towns in the
Transvaal. It was possible to go round all the likely positions for a
searchlight in one day at every station, which frequently meant
considerably over fifty miles of most indifferent roads--more than a
single horse could have been expected to do--and the car generally
carried two persons on these occasions. The car was also used as a
tender to a searchlight plant, on a gun-carriage and limber, being
utilised to fetch gasolene, carbons, water, &c., &c., and also to run
the dynamo for charging the accumulators used for sparking, thus
saving running the gasolene motor for this purpose. To do this the
trail of the carriage, on which was the dynamo, was lowered on to the
ground, the back of the car was pulled up, one wheel being supported
on the dynamo pulley and the other clear of the ground, and two bolts
were passed through the balance-gear to join it. On one occasion the
car ran a 30 c.m. searchlight for an hour, driving a dynamo in this
way. In consequence of this a trailer has been made to carry a dynamo
and projector for searchlighting in the field, but so far this has
not been so used. The trailer hooks into an eye, passing just behind
the balance-gear. A Maxim, Colt, or small ammunition cart, &c., could
be attached to this same eye.

"Undoubtedly the best piece of work done by the car so far was its
trial trip with the trailer, when it blew up the mines at Klein Nek.
These mines were laid some eight months previously, and had never been
looked to in the interval. There had been several bad storms, the
Boers and cattle had been frequently through the Nek, it had been on
fire, and finally it was shelled with lyddite. The mines, eighteen in
number, were found to be intact except two, which presumably had been
fired off by the heat of the veldt fire. All the insulation was burnt
off the wires, and the battery was useless. It had been anticipated
that a dynamo exploder would be inadequate to fire these mines, so a
250 volt two h.p. motor, which happened to be in Pretoria, weighing
about three or four hundredweight, was placed on the trailer; a
quarter of a mile of insulated cable, some testing gear, the kits of
three men and their rations for three days, with a case of gasolene
for the car, were also carried on the car and trailer, and the whole
left Pretoria one morning and trekked to Rietfontein. Two of us were
mounted, the third drove the car. At Rietfontein we halted for the
night, and started next morning with an escort through Commando Nek,
round the north of the Magaliesburg, to near Klein Nek, where the road
had to be left, and the car taken across country through bush veldt.
At the bottom the going was pretty easy; only a few bushes had to be
charged down, and the grass, &c., rather wound itself around the
wheels and chain. As the rise became steeper the stones became very
large, and the car had to be taken along very gingerly to prevent
breaking the wheels. A halt was made about a quarter of a mile from
the top of the Nek, where the mines were. These were reconnoitered,
and the wire, &c., was picked up; that portion which was useless was
placed on top of the charges, and the remainder taken to the car. The
dynamo was slid off the trailer, the car backed against it; one wheel
was raised slightly and placed against the dynamo pulley, which was
held up to it by a man using his rifle as a lever; the other wheel was
on the ground with a stone under it. The balance gear being free, the
dynamo was excited without the other wheel moving, and the load being
on for a very short time (that is, from the time of touching lead on
dynamo terminal to firing of the mine) no harm could come to the car.
When all the leads had been joined to the dynamo the car was started,
and after a short time, when it was judged to have excited, the second
terminal was touched, a bang and clouds of dust resulted, and the
Klein Nek Minefield had ceased to exist. The day was extremely hot,
and the work had not been light, so the tea, made with water drawn
direct from the boiler, which we were able to serve round to the main
body of our escort was much appreciated, and washed down the surplus
rations we dispensed with to accommodate the battery and wire, which
we could not leave behind for the enemy.

"On the return journey we found this extra load too much for the car,
and had great difficulty getting up to Commando Nek, frequently having
to stop to get up steam, so these materials were left at the first
blockhouse, and the journey home continued in comfort.

"A second night at Rietfontein gave us a rest after our labour, and
the third afternoon saw us on our way back to Pretoria. As luck would
have it, a sandstorm overtook the car, which had a lively time of it.
The storm began by blowing the sole occupant's hat off, so, the two
mounted men being a long way behind, he shut off steam and chased his
hat. In the meantime the wind increased, and the car sailed off 'on
its own,' and was only just caught in time to save a smash. Luckily
the gale was in the right direction, for the fire was blown out, and
it was impossible to light a match in the open. The car sailed into a
poort on the outskirts of Pretoria, got a tow from a friendly cart
through it, and then steamed home after the fire had been relit.

"The load carried on this occasion (without the battery, &c.) must
have been at least five hundredweight besides the driver, which,
considering the car is designed to carry two on ordinary roads, and
that these roads were by no means ordinary, was no mean feat. The car,
as ordinarily equipped for trekking, carries the following: Blankets,
waterproof sheets, &c., for two men; four planks for crossing ditches,
bogs, stones, &c.; all necessary tools and spare parts, a day's supply
of gasolene, a couple of telephones, and one mile of wire. In
addition, on the trailer, if used for searchlighting: One 30 c.m.
projector, one automatic lamp for projector, one dynamo (100 volts 20
ampères), two short lengths of wire, two pairs of carbons, tools, &c.
This trailer would normally be carried with the baggage, and only
picked up by the car when wanted as a light; that is, as a rule, after
arriving in camp, when a good many other things could be left behind."

Perhaps the most useful work in store for the motor is to help relieve
the congestion of our large towns and to restore to the country some
of its lost prosperity. There is no stronger inducement to make people
live in the country than rapid and safe means of locomotion, whether
public or private. At present the slow and congested suburban train
services on some sides of London consume as much time as would suffice
a motor car to cover twice or three times the distance. We must
welcome any form of travel which will tend to restore the balance
between country and town by enabling the worker to live far from his
work. The gain to the health of the nation arising from more even
distribution of population would be inestimable.

A world's tour is among the latest projects in automobilism. On April
29, 1902, Dr. Lehwess and nine friends started from Hyde Park Corner
for a nine months' tour on three vehicles, the largest of them a
luxuriously appointed 24 horse-power caravan, built to accommodate
four persons. Their route lies through France, Germany, Russia,
Siberia, China, Japan, and the United States.




HIGH-SPEED RAILWAYS.


A century ago a long journey was considered an exploit, and an exploit
to be carried through as quickly as possible on account of the dangers
of the road and the generally uncomfortable conditions of travel.
To-day, though our express speed is many times greater than that of
the lumbering coaches, our carriages comparatively luxurious, the risk
practically nil, the same wish lurks in the breast of ninety-nine out
of a hundred railway passengers--to spend the shortest time in the
train that the time-table permits of. Time differences that to our
grandfathers would have appeared trifling are now matters of
sufficient importance to make rival railway companies anxious to clip
a few minutes off a 100-mile "run" simply because their passengers
appreciate a few minutes' less confinement to the cars.

During the last fifty years the highest express speeds have not
materially altered. The Great Western Company in its early days ran
trains from Paddington to Slough, 18 miles, in 15-1/2 minutes, or at
an average pace of 69-1/2 miles an hour.

On turning to the present regular express services of the world we
find America heading the list with a 50-mile run between Atlantic City
and Camden, covered at the average speed of 68 miles an hour; Britain
second with a 33-mile run between Forfar and Perth at 59 miles; and
France a good third with an hourly average of rather more than 58
miles between Les Aubrais and S. Pierre des Corps. These runs are
longer than that on the Great Western Railway referred to above (which
now occupies twenty-four minutes), but their average velocity is less.
What is the cause of this decrease of speed? Not want of power in
modern engines; at times our trains attain a rate of 80 miles an hour,
and in America a mile has been turned off in the astonishing time of
thirty-two seconds. We should rather seek it in the need for economy
and in the physical limitations imposed by the present system of
plate-laying and railroad engineering. An average speed of ninety
miles an hour would, as things now stand, be too wasteful of coal and
too injurious to the rolling-stock to yield profit to the proprietors
of a line; and, except in certain districts, would prove perilous for
the passengers. Before our services can be much improved the steam
locomotive must be supplanted by some other application of motive
power, and the metals be laid in a manner which will make special
provision for extreme speed.

Since rapid transit is as much a matter of commercial importance as of
mere personal convenience it must not be supposed that an average of
50 miles an hour will continue to meet the needs of travellers.
Already practical experiments have been made with two systems that
promise us an ordinary speed of 100 miles an hour and an express speed
considerably higher.

One of these, the monorail or single-rail system, will be employed on
a railroad projected between Manchester and Liverpool. At present
passengers between these two cities--the first to be connected by a
railroad of any kind--enjoy the choice of three rival services
covering 34-1/2 miles in three-quarters of an hour. An eminent
engineer, Mr. F. B. Behr, now wishes to add a fourth of unprecedented
swiftness. Parliamentary powers have been secured for a line starting
from Deansgate, Manchester, and terminating behind the pro-Cathedral
in Liverpool, on which single cars will run every ten minutes at a
velocity of 110 miles an hour.

A monorail track presents a rather curious appearance. The ordinary
parallel metals are replaced by a single rail carried on the summit of
A-shaped trestles, the legs of which are firmly bolted to sleepers. A
monorail car is divided lengthwise by a gap that allows it to hang
half on either side of the trestles and clear them as it moves. The
double flanged wheels to carry and drive the car are placed at the
apex of the gap. As the "centre of gravity" is below the rail the car
cannot turn over, even when travelling round a sharp curve.

The first railway built on this system was constructed by M. Charles
Lartigue, a French engineer, in Algeria, a district where an ordinary
two-rail track is often blocked by severe sand-storms. He derived the
idea of balancing trucks over an elevated rail from caravans of camels
laden on each flank with large bags. The camel, or rather its legs,
was transformed by the engineer's eye into iron trestles, while its
burden became a car. A line built as a result of this observation, and
supplied with mules as tractive power, has for many years played an
important part in the esparto-grass trade of Algeria.

In 1886 Mr. Behr decided that by applying steam to M. Lartigue's
system he could make it successful as a means of transporting
passengers and goods. He accordingly set up in Tothill Fields,
Westminster, on the site of the new Roman Catholic Cathedral, a
miniature railway which during nine months of use showed that the
monorail would be practical for heavy traffic, safe, and more cheaply
maintained than the ordinary double-metal railway. The train travelled
easily round very sharp curves and climbed unusually steep gradients
without slipping.

Mr. Behr was encouraged to construct a monorail in Kerry, between
Listowel, a country town famous for its butter, and Ballybunion, a
seaside resort of increasing popularity. The line, opened on the 28th
of February 1888, has worked most satisfactorily ever since, without
injury to a single employé or passenger.

On each side of the trestles, two feet below the apex, run two
guide-rails, against which press small wheels attached to the
carriages to prevent undue oscillation and "tipping" round curves. At
the three stations there are, instead of points, turn-tables or
switches on to which the train runs for transference to sidings.

Road traffic crosses the rail on drawbridges, which are very easily
worked, and which automatically set signals against the train. The
bridges are in two portions and act on the principle of the Tower
Bridge, each half falling from a perpendicular position towards the
centre, where the ends rest on the rail, specially strengthened at
that spot to carry the extra weight. The locomotive is a twin affair;
has two boilers, two funnels, two fireboxes; can draw 240 tons on the
level at fifteen miles an hour, and when running light travels a mile
in two minutes. The carriages, 18 feet long and carrying twelve
passengers on each side, are divided longitudinally into two parts.
Trucks too are used, mainly for the transport of sand--of which each
carries three tons--from Ballybunion to Listowel: and in the centre of
each train is a queer-looking vehicle serving as a bridge for any one
who may wish to cross from one side of the rail to the other.

Several lines on the pattern of the Ballybunion-Listowel have been
erected in different countries. Mr. Behr was not satisfied with his
first success, however, and determined to develop the monorail in the
direction of fast travelling, which he thought would be most easily
attained on a trestle-track. In 1893 he startled engineers by
proposing a Lightning-Express service, to transport passengers at a
velocity of 120 miles an hour. But the project seemed too ideal to
tempt money from the pockets of financiers, and Mr. Behr soon saw that
if a high-speed railway after his own heart were constructed it must
be at his own expense. He had sufficient faith in his scheme to spend
£40,000 on an experimental track at the Brussels Exhibition of 1897.
The exhibition was in two parts, connected by an electric railway, the
one at the capital, the other at Tervueren, seven miles away. Mr. Behr
built his line at Tervueren.

The greatest difficulty he encountered in its construction arose from
the opposition of landowners, mostly small peasant proprietors, who
were anxious to make advantageous terms before they would hear of the
rail passing through their lands. Until he had concluded two hundred
separate contracts, by most of which the peasants benefited, his
platelayers could not get to work. Apart from this opposition the
conditions were not favourable. He was obliged to bridge no less than
ten roads; and the contour of the country necessitated steep
gradients, sharp curves, long cuttings and embankments, the last of
which, owing to a wet summer, could not be trusted to stand quite
firm. The track was doubled for three miles, passing at each end round
a curve of 1600 feet radius.

The rail ran about four feet above the track on trestles bolted down
to steel sleepers resting on ordinary ballast. The carriage--Mr. Behr
used but one on this line--weighed 68 tons, was 59 feet long and 11
feet wide, and could accommodate one hundred persons. It was
handsomely fitted up, and had specially-shaped seats which neutralised
the effect of rounding curves, and ended fore and aft in a point, to
overcome the wind-resistance in front and the air-suction behind.
Sixteen pairs of wheels on the under side of the carriage engaged with
the two pairs of guide rails flanking the trestles, and eight large
double-flanged wheels, 4-1/2 feet in diameter, carried the weight of
the vehicle. The inner four of these wheels were driven by as many
powerful electric motors contained, along with the guiding mechanism,
in the lower part of the car. The motors picked up current from the
centre rail and from another steel rail laid along the sleepers on
porcelain insulators.

The top speed attained was about ninety miles an hour. On the close of
the Exhibition special experiments were made at the request of the
Belgian, French, and Russian Governments, with results that proved
that the Behr system deserved a trial on a much larger scale.

The engineer accordingly approached the British Government with a Bill
for the construction of a high-speed line between Liverpool and
Manchester. A Committee of the House of Commons rejected the Bill on
representations of the Salford Corporation. The Committee had to
admit, nevertheless, that the evidence called was mainly in favour of
the system; and, the plans of the rail having been altered to meet
certain objections, Parliamentary consent was obtained to commence
operations when the necessary capital had been subscribed. In a few
years the great seaport and the great cotton town will probably be
within a few minutes' run of each other.

A question that naturally arises in the mind of the reader is this:
could the cars, when travelling at 110 miles an hour, be arrested
quickly enough to avoid an accident if anything got on the line?

The Westinghouse air-brake has a retarding force of three miles a
second. It would therefore arrest a train travelling at 110 miles per
hour in 37 seconds, or 995 yards. Mr. Behr proposes to reinforce the
Westinghouse with an electric brake, composed of magnets 18 inches
long, exerting on the guide rails by means of current generated by the
reversed motors an attractive force of 200 lbs. per square inch. One
great advantage of this brake is that its efficiency is greatest when
the speed of the train is highest and when it is most needed. The
united brakes are expected to stop the car in half the distance of the
Westinghouse alone; but they would not both be applied except in
emergencies. Under ordinary conditions the slowing of a car would take
place only at the termini, where the line ascends gradients into the
stations. There would, however, be small chance of collisions, the
railway being securely fenced off throughout its entire length, and
free from level crossings, drawbridges and points. Furthermore, each
train would be its own signalman. Suppose the total 34-1/2 miles
divided into "block" lengths of 7 miles. On leaving a terminus the
train sets a danger signal behind it; at 7 miles it sets another, and
at 14 miles releases the first signal. So that the driver of a car
would have at least 7 miles to slow down in after seeing the signals
against him. In case of fog he would consult a miniature signal in his
cabin working electrically in unison with the large semaphores.

The Manchester-Liverpool rail will be reserved for express traffic
only. Mr. Behr does not believe in mixing speeds, and considers it one
of the advantages of his system that slow cars and waggons of the
ordinary two-rail type cannot be run on the monorail; because if they
could managers might be tempted to place them there.

A train will consist of a single vehicle for forty, fifty, or seventy
passengers, as the occasion requires. It is calculated that an average
of twelve passengers at one penny per mile would pay all the expenses
of running a car.

Mr. Behr maintains that monorails can be constructed far more cheaply
than the two-rail, because they permit sharper curves, and thereby
save a lot of cutting and embankment; and also because the monorail
itself, when trestles and rail are specially strengthened, can serve
as its own bridge across roads, valleys and rivers.

Though the single-rail has come to the front of late, it must not be
supposed that the two-rail track is for ever doomed to moderate speeds
only. German engineers have built an electric two-rail military line
between Berlin and Zossen, seventeen miles long, over which cars have
been run at a hundred miles an hour. The line has very gradual curves,
and in this respect is inferior to the more sinuous monorail. Its
chief virtue is the method of applying motive power--a method common
to both systems.

The steam locomotive creates its own motive force, and as long as it
has fuel and water can act independently. The electric locomotive, on
the other hand, receives its power through metallic conductors from
some central station. Should the current fail all the traffic on the
line is suspended. So far the advantage rests with the steamer. But
as regards economy the superiority of the current is obvious. In
the electric systems under consideration--the monorail and
Berlin-Zossen--there is less weight per passenger to be shifted, since
a comparatively light motor supersedes the heavy locomotive. The cars
running singly, bridges and track are subjected to less strain, and
cost less to keep in repair. But the greatest saving of all is made in
fuel. A steam locomotive uses coal wastefully, sending a lot of latent
power up the funnel in the shape of half-expanded steam. Want of space
prevents the designer from fitting to a moving engine the more
economical machinery to be found in the central power-station of an
electric railway, which may be so situated--by the water-side or near
a pit's mouth--that fuel can be brought to it at a trifling cost. Not
only is the expense of distributing coal over the system avoided, but
the coal itself, by the help of triple and quadruple expansion engines
should yield two or three times as much energy per ton as is developed
in a locomotive furnace.

Many schemes are afoot for the construction of high-speed railways.
The South-Eastern plans a monorail between Cannon Street and Charing
Cross to avoid the delay that at present occurs in passing from one
station to the other. We hear also of a projected railway from London
to Brighton, which will reduce the journey to half-an-hour; and of
another to connect Dover and London. It has even been suggested to
establish monorails on existing tracks for fast passenger traffic, the
expresses passing overhead, the slow and goods trains plodding along
the double metals below.

But the most ambitious programme of all comes from the land of the
Czar. M. Hippolyte Romanoff, a Russian engineer, proposes to unite St.
Petersburg and Moscow by a line that shall cover the intervening 600
miles in three hours--an improvement of ten hours on the present
time-tables. He will use T-shaped supports to carry two rails, one on
each arm, from which the cars are to hang. The line being thus double
will permit the cars--some four hundred in number--to run to and fro
continuously, urged on their way by current picked up from overhead
wires. Each car is to have twelve wheels, four drivers arranged
vertically and eight horizontally, to prevent derailment by gripping
the rail on either side. The stoppage or breakdown of any car will
automatically stop those following by cutting off the current.

In the early days of railway history lines were projected in all
directions, regardless of the fact whether they would be of any use or
not. Many of these lines began, where they ended, on paper. And now
that the high-speed question has cropped up, we must not believe that
every projected electric railway will be built, though of the ultimate
prevalence of far higher speeds than we now enjoy there can be no
doubt.

The following is a time-table drawn up on the two-mile-per-minute
basis.

A man leaving London at 10 A.M. would reach--

    Brighton      50 miles away, at 10.25 A.M.
    Portsmouth    60   "      "     10.30 A.M.
    Birmingham   113   "      "     10.57 A.M.
    Leeds        188   "      "     11.34 A.M.
    Liverpool    202   "      "     11.41 A.M.
    Holyhead     262   "      "     12.11 P.M.
    Edinburgh    400   "      "      1.20 P.M.
    Aberdeen     540   "      "      2.30 P.M.

What would become of the records established in the "Race to the
North" and by American "fliers"?

And what about continental travel?

Assuming that the Channel Tunnel is built--perhaps a rather large
assumption--Paris will be at our very doors. A commercial traveller
will step into the lightning express at London, sleep for two hours
and twenty-four minutes and wake, refreshed, to find the blue-smocked
Paris porters bawling in his ear. Or even if we prefer to keep the
"little silver streak" free from subterranean burrows, he will be able
to catch the swift turbine steamers--of which more anon--at Dover,
slip across to Calais in half-an-hour, and be at the French capital
within four hours of quitting London. And if M. Romanoff's standard be
reached, the latest thing in hats despatched from Paris at noon may
be worn in Regent Street before two o'clock.

Such speeds would indeed produce a revolution in travelling comparable
to the substitution of the steam locomotive for the stage coach. As
has been pithily said, the effect of steam was to make the bulk of
population travel, whereas they had never travelled before, but the
effect of the electric railway will be to make those who travel travel
much further and much oftener.




SEA EXPRESSES.


In the year 1836 the _Sirius_, a paddle-wheel vessel, crossed the
Atlantic from Cork Harbour to New York in nineteen days. Contrast with
the first steam-passage from the Old World to the New a return journey
of the _Deutschland_, a North German liner, which in 1900 averaged
over twenty-seven miles an hour between Sandy Hook and Plymouth,
accomplishing the whole distance in the record time of five days seven
hours thirty-eight minutes.

This growth of speed is even more remarkable than might appear from
the mere comparison of figures. A body moving through water is so
retarded by the inertia and friction of the fluid that to quicken its
pace a force quite out of proportion to the increase of velocity must
be exerted. The proportion cannot be reduced to an exact formula, but
under certain conditions the speed and the power required advance in
the ratio of their cubes; that is, to double a given rate of progress
eight times the driving-power is needed; to treble it, twenty-seven
times.

The mechanism of our fast modern vessels is in every way as superior
to that which moved the _Sirius_, as the beautifully-adjusted safety
cycle is to the clumsy "boneshaker" which passed for a wonder among
our grandfathers. A great improvement has also taken place in the art
of building ships on lines calculated to offer least resistance to the
water, and at the same time afford a good carrying capacity. The big
liner, with its knife-edged bow and tapering hull, is by its shape
alone eloquent of the high speed which has earned it the title
of Ocean Greyhound; and as for the fastest craft of all,
torpedo-destroyers, their designers seem to have kept in mind Euclid's
definition of a line--length without breadth. But whatever its shape,
boat or ship may not shake itself free of Nature's laws. Her
restraining hand lies heavy upon it. A single man paddles his
weight-carrying dinghy along easily at four miles an hour; eight men
in the pink of condition, after arduous training, cannot urge their
light, slender, racing shell more than twelve miles in the same time.

To understand how mail boats and "destroyers" attain, despite the
enormous resistance of water, velocities that would shame many a
train-service, we have only to visit the stokeholds and engine-rooms
of our sea expresses and note the many devices of marine engineers by
which fuel is converted into speed.

We enter the stokehold through air-locks, closing one door before we
can open the other, and find ourselves among sweating, grimy men,
stripped to the waist. As though life itself depended upon it they
shovel coal into the rapacious maws of furnaces glowing with a
dazzling glare under the "forced-draught" sent down into the hold by
the fans whirling overhead. The ignited furnace gases on their way to
the outer air surrender a portion of their heat to the water from
which they are separated by a skin of steel. Two kinds of marine
boiler are used--the fire-tube and the water-tube. In fire-tube
boilers the fire passes inside the tubes and the water outside; in
water-tube boilers the reverse is the case, the crown and sides of the
furnace being composed of sheaves of small parallel pipes through
which water circulates. The latter type, as generating steam very
quickly, and being able to bear very high pressures, is most often
found in war vessels of all kinds. The quality sought in boiler
construction is that the heating surface should be very large in
proportion to the quantity of water to be heated. Special coal,
anthracite or Welsh, is used in the navy on account of its great
heating power and freedom from smoke; experiments have also been made
with crude petroleum, or liquid fuel, which can be more quickly put on
board than coal, requires the services of fewer stokers, and may be
stored in odd corners unavailable as coal bunkers.

From the boiler the steam passes to the engine-room, whither we will
follow it. We are now in a bewildering maze of clanking, whirling
machinery; our noses offended by the reek of oil, our ears deafened
by the uproar of the moving metal, our eyes wearied by the efforts to
follow the motions of the cranks and rods.

On either side of us is ranged a series of three or perhaps even four
cylinders, of increasing size. The smallest, known as the
high-pressure cylinder, receives steam direct from the boiler. It
takes in through a slide-valve a supply for a stroke; its piston is
driven from end to end; the piston-rod flies through the cylinder-end
and transmits a rotary motion to a crank by means of a connecting-rod.
The half-expanded steam is then ejected, not into the air as would
happen on a locomotive, but into the next cylinder, which has a larger
piston to compensate the reduction of pressure. Number two served, the
steam does duty a third time in number three, and perhaps yet a fourth
time before it reaches the condensers, where its sudden conversion
into water by cold produces a vacuum suction in the last cylinder of
the series. The secret of a marine engine's strength and economy lies
then in its treatment of the steam, which, like clothes in a numerous
family, is not thought to have served its purpose till it has been
used over and over again.

Reciprocating (_i.e._ cylinder) engines, though brought to a high
pitch of efficiency, have grave disadvantages, the greatest among
which is the annoyance caused by their intense vibration to all
persons in the vessel. A revolving body that is not exactly balanced
runs unequally, and transmits a tremor to anything with which it may
be in contact. Turn a cycle upside down and revolve the driving-wheel
rapidly by means of the pedal. The whole machine soon begins to
tremble violently, and dance up and down on the saddle springs,
because one part of the wheel is heavier than the rest, the mere
weight of the air-valve being sufficient to disturb the balance. Now
consider what happens in the engine-room of high-powered vessels. On
destroyers the screws make 400 revolutions a minute. That is to say,
all the momentum of the pistons, cranks, rods, and valves (weighing
tons), has to be arrested thirteen or fourteen times every second.
However well the moving parts may be balanced, the vibration is felt
from stem to stern of the vessel. Even on luxuriously-appointed
liners, with engines running at a far slower speed, the throbbing of
the screw (_i.e._ engines) is only too noticeable and productive of
discomfort.

We shall be told, perhaps, that vibration is a necessary consequence
of speed. This is true enough of all vehicles, such as railway trains,
motor-cars, cycles, which are shaken by the irregularities of the
unyielding surface over which they run, but does not apply universally
to ships and boats. A sail or oar-propelled craft may be entirely free
from vibration, whatever its speed, as the motions arising from water
are usually slow and deliberate. In fact, water in its calmer moods is
an ideal medium to travel on, and the trouble begins only with the
introduction of steam as motive force.

But even steam may be robbed of its power to annoy us. The
steam-turbine has arrived. It works a screw propeller as smoothly as a
dynamo, and at a speed that no cylinder engine could maintain for a
minute without shaking itself to pieces.

The steam-turbine is most closely connected with the name of the Hon.
Charles Parsons, son of Lord Rosse, the famous astronomer. He was the
first to show, in his speedy little _Turbinia_, the possibilities of
the turbine when applied to steam navigation. The results have been
such as to attract the attention of the whole shipbuilding world.

The principle of the turbine is seen in the ordinary windmill. To an
axle revolving in a stationary bearing are attached vanes which oppose
a current of air, water, or steam, at an angle to its course, and by
it are moved sideways through a circular path. Mr. Parsons' turbine
has of course been specially adapted for the action of steam. It
consists of a cylindrical, air-tight chest, inside which rotates a
drum, fitted round its circumference with rows of curved vanes. The
chest itself has fixed immovably to its inner side a corresponding
number of vane rings, alternating with those on the drum, and so
arranged as to deflect the steam on to the latter at the most
efficient angle. The diameter of the chest and drum is not constant,
but increases towards the exhaust end, in order to give the expanding
and weakening steam a larger leverage as it proceeds.

The steam entering the chest from the boiler at a pressure of some
hundreds of pounds to the square inch strikes the first set of vanes
on the drum, passes them and meets the first set of chest-vanes, is
turned from its course on to the second set of drum-vanes, and so on
to the other end of the chest. Its power arises entirely from its
expansive velocity, which, rather than turn a number of sharp corners,
will, if possible, compel the obstruction to move out of its way. If
that obstruction be from any cause difficult to stir, the steam must
pass round it until its pressure overcomes the inertia. Consequently
the turbine differs from the cylinder engine in this respect, that
steam _can_ pass through and be wasted without doing any work at all,
whereas, unless the gear of a cylinder moves, and power is exerted,
all steam ways are closed, and there is no waste. In practice,
therefore, it is found that a turbine is most effective when running
at high speed.

The first steam-turbines were used to drive dynamos. In 1884 Mr.
Parsons made a turbine in which fifteen wheels of increasing size
moved at the astonishing rate of 300 revolutions per second, and
developed 10 horse-power. In 1888 followed a 120 horse-power turbine,
and in 1892 one of 2000 horse-power, provided with a condenser to
produce suction. So successful were these steam fans for electrical
work, pumping water and ventilating mines, that Mr. Parsons determined
to test them as a means of propelling ships. A small vessel 100 feet
long and 9 feet in beam was fitted with three turbines--high, medium,
and low pressure, of a total 2000 horse-power--a proportion of motive
force to tonnage hitherto not approached. Yet when tried over the test
course the _Turbinia_, as the boat was fitly named, ran in a most
disappointing fashion. The screws revolved _too fast_, producing what
is known as _cavitation_, or the scooping out of the water by the
screws, so that they moved in a partial vacuum and utilised only a
fraction of their force, from lack of anything to "bite" on. This
defect was remedied by employing screws of coarser pitch and larger
blade area, three of which were attached to each of the three
propeller shafts. On a second trial the _Turbinia_ attained 32-3/4
knots over the "measured mile," and later the astonishing speed of
forty miles an hour, or double that of the fast Channel packets. At
the Spithead Review in 1897 one of the most interesting sights was the
little nimble _Turbinia_ rushing up and down the rows of majestic
warships at the rate of an express train.

[Illustration: _H.M.S. Torpedo Destroyer "Viper." This vessel was the
fastest afloat, attaining the enormous speed of 41 miles an hour. The
screws were worked by turbines, giving 11,000 horse-power. She was
wrecked on Alderney during the Naval Manoeuvres of 1901._]

After this success Mr. Parsons erected works at Wallsend-on-Tyne for
the special manufacture of turbines. The Admiralty soon placed with
him an order for a torpedo-destroyer--the _Viper_--of 350 tons; which
on its trial trip exceeded forty-one miles an hour at an estimated
horse-power (11,000) equalling that of our largest battleships. A
sister vessel, the _Cobra_, of like size, proved as speedy.
Misfortune, however, overtook both destroyers. The _Viper_ was wrecked
August 3, 1901, on the coast of Alderney during the autumn naval
manoeuvres, and the _Cobra_ foundered in a severe storm on September
12 of the same year in the North Sea. This double disaster casts no
reflections on the turbine engines; being attributed to fog in the one
case and to structural weakness in the other. The Admiralty has since
ordered another turbine destroyer, and before many years are past we
shall probably see all the great naval powers providing themselves
with like craft to act as the "eyes of the fleet," and travel at even
higher speeds than those of the _Viper_ and _Cobra_.

The turbine has been applied to mercantile as well as warlike
purposes. There is at the present time a turbine-propelled steamer,
the _King Edward_, running in the Clyde on the Fairlie-Campbelltown
route. This vessel, 250 feet long, 30 broad, 18 deep, contains three
turbines. In each the steam is expanded fivefold, so that by the time
it passes into the condensers it occupies 125 times its boiler volume.
(On the _Viper_ the steam entered the turbine through an inlet eight
inches in diameter, and left them by an outlet four feet square.) In
cylinder engines thirty-fold expansion is considered a high ratio;
hence the turbine extracts a great deal more power in proportion from
its steam. As a turbine cannot be reversed, special turbines are
attached to the two outside of the three propeller shafts to drive the
vessel astern. The steamer attained 20-1/2 knots over the "Skelmorlie
mile" in fair and calm weather, with 3500 horse-power produced at the
turbines. The _King Edward_ is thus the fastest by two or three knots
of all the Clyde steamers, as she is the most comfortable. We are
assured that as far as the turbines are concerned it is impossible by
placing the hand upon the steam-chest to tell whether the drum inside
is revolving or not!

Every marine engine is judged by its economy in the consumption of
coal. Except in times of national peril extra speed produced by an
extravagant use of fuel would be severely avoided by all owners and
captains of ships. At low speeds the turbine develops less power than
cylinders from the same amount of steam, but when working at high
velocity it gives at least equal results. A careful record kept by the
managers of the Caledonian Steamship Company compares the _King
Edward_ with the _Duchess of Hamilton_, a paddle steamer of equal
tonnage used on the same route and built by the same firm. The record
shows that though the paddle-boat ran a fraction of a mile further
for every ton of coal burnt in the furnaces, the _King Edward_
averaged two knots an hour faster, a superiority of speed quite out of
proportion to the slight excess of fuel. Were the _Duchess_ driven at
18-1/2 knots instead of 16-1/2 her coal bill would far exceed that of
the turbine.

As an outcome of these first trials the Caledonian Company are
launching a second turbine vessel. Three high-speed turbine yachts are
also on the stocks; one of 700 tons, another of 1500 tons, and a third
of 170 tons. The last, the property of Colonel M'Calmont, is designed
for a speed of twenty-four knots.

Mr. Parsons claims for his system the following advantages: Greatly
increased speed; increased carrying power of coal; economy in coal
consumption; increased facilities for navigating shallow waters;
greater stability of vessels; reduced weight of machinery (the
turbines of the _King Edward_ weigh but one-half of cylinders required
to give the same power); cheapness of attending the machinery; absence
of vibration, lessening wear and tear of the ship's hull and assisting
the accurate training of guns; lowered centre of gravity in the
vessel, and consequent greater safety during times of war.

The inventor has suggested a cruiser of 2800 tons, engined up to
80,000 horse-power, to yield a speed of forty-four knots (about fifty
miles) an hour. Figures such as these suggest that we may be on the
eve of a revolution of ocean travel comparable to that made by the
substitution of steam for wind power. Whether the steam-turbine will
make for increased speed all round, or for greater economy, remains to
be seen; but we may be assured of a higher degree of comfort. We can
easily believe that improvements will follow in this as in other
mechanical contrivances, and that the turbine's efficiency has not yet
reached a maximum; and even if our ocean expresses, naval and
mercantile, do not attain the one-mile-a-minute standard, which is
still regarded as creditable to the fastest methods of land
locomotion, we look forward to a time in the near future when much
higher speeds will prevail, and the tedium of long voyages be greatly
shortened. Already there is talk of a service which shall reduce the
trans-Atlantic journey to three-and-a-half days. The means are at hand
to make it a fact.

     _Note._--In the recently-launched turbine destroyer _Velox_ a
     novel feature is the introduction of ordinary reciprocating
     engines fitted in conjunction with the steam turbines. These
     engines are of triple-compound type, and are coupled direct to
     the main turbines. They take steam from the boilers direct and
     exhaust into the high-pressure turbine. These reciprocating
     engines are for use at cruising speeds. When higher power is
     needed the steam will be admitted to the turbines direct from
     the boilers, and the cylinders be thrown out of gear.




MECHANICAL FLIGHT.


Few, if any, problems have so strongly influenced the imagination and
exercised the ingenuity of mankind as that of aërial navigation. There
is something in our nature that rebels against being condemned to the
condition of "featherless bipeds" when birds, bats, and even minute
insects have the whole realm of air and the wide heavens open to them.
Who has not, like Solomon, pondered upon "the way of a bird in the
air" with feelings of envy and regret that he is chained to earth by
his gross body; contrasting our laboured movements from point to point
of the earth's surface with the easy gliding of the feathered
traveller? The unrealised wish has found expression in legends of
Dædalus, Pegasus, in the "flying carpet" of the fairy tale, and in the
pages of Jules Verne, in which last the adventurous Robur on his
"Clipper of the Clouds" anticipates the future in a most startling
fashion.

Aeromobilism--to use its most modern title--is regarded by the crowd
as the mechanical counterpart of the Philosopher's Stone or the Elixir
of Life; a highly desirable but unattainable thing. At times this
incredulity is transformed by highly-coloured press reports into an
equally unreasonable readiness to believe that the conquest of the air
is completed, followed by a feeling of irritation that facts are not
as they were represented in print.

The proper attitude is of course half-way between these extremes.
Reflection will show us that money, time, and life itself would not
have been freely and ungrudgingly given or risked by many
men--hard-headed, practical men among them--in pursuit of a
Will-o'-the-Wisp, especially in a century when scientific calculation
tends always to calm down any too imaginative scheme. The existing
state of the aërial problem may be compared to that of a railway truck
which an insufficient number of men are trying to move. Ten men may
make no impression on it, though they are putting out all their
strength. Yet the arrival of an eleventh may enable them to overcome
the truck's inertia and move it at an increasing pace.

Every new discovery of the scientific application of power brings us
nearer to the day when the truck will move. We have metals of
wonderful strength in proportion to their weight; pigmy motors
containing the force of giants; a huge fund of mechanical experience
to draw upon; in fact, to paraphrase the Jingo song, "We've got the
things, we've got the men, we've got the money too"--but we haven't
as yet got the machine that can mock the bird like the flying express
mocks the strength and speed of horses.

The reason of this is not far to seek. The difficulties attending the
creation of a successful flying-machine are immense, some unique, not
being found in aquatic and terrestrial locomotion.

In the first place, the airship, flying-machine, aerostat, or whatever
we please to call it, must not merely move, but also lift itself.
Neither a ship nor a locomotive is called upon to do this. Its ability
to lift itself must depend upon either the employment of large
balloons or upon sheer power. In the first case the balloon will, by
reason of its size, be unmanageable in a high wind; in the second
case, a breakdown in the machinery would probably prove fatal.

Even supposing that our aerostat can lift itself successfully, we
encounter the difficulties connected with steering in a medium
traversed by ever-shifting currents of air, which demands of the
helmsman a caution and capacity seldom required on land or water. Add
to these the difficulties of leaving the ground and alighting safely
upon it; and, what is more serious than all, the fact that though
success can be attained only by experiment, experiment is in this case
extremely expensive and risky, any failure often resulting in total
ruin of the machine, and sometimes in loss of life. The list of those
who have perished in the search for the power of flight is a very long
one.

Yet in spite of these obstacles determined attempts have been and are
being made to conquer the air. Men in a position to judge are
confident that the day of conquest is not very far distant, and that
the next generation may be as familiar with aerostats as we with
motor-cars. Speculation as to the future is, however, here less
profitable than a consideration of what has been already done in the
direction of collecting forces for the final victory.

To begin at the beginning, we see that experimenters must be divided
into two great classes: those who pin their faith to airships lighter
than air, _e.g._ Santos Dumont, Zeppelin, Roze; and those who have
small respect for balloons, and see the ideal air-craft in a _machine_
lifted entirely by means of power and surfaces pressing the air after
the manner of a kite. Sir Hiram Maxim and Professor S. P. Langley, Mr.
Lawrence Hargrave, and Mr. Sydney Hollands are eminent members of the
latter cult.

As soon as we get on the topic of steerable balloons the name of Mr.
Santos Dumont looms large. But before dealing with his exploits we may
notice the airship of Count Zeppelin, an ingenious and costly
structure that was tested over Lake Constance in 1900.

The balloon was built in a large wooden shed, 450 by 78 by 66 feet,
that floated on the lake on ninety pontoons. The shed alone cost over
£10,000.

The balloon itself was nearly 400 feet long, with a cylindrical
diameter of 39 feet, except at its ends, which were conical, to offer
as little resistance as possible to the air. Externally it afforded
the appearance of a single-compartment bag, but in reality it was
divided into seventeen parts, each gas-tight, so that an accident to
one part of the fabric should not imperil the whole.

A framework of aluminium rods and rings gave the bag a partial
rigidity.

Its capacity was 12,000 cubic yards of hydrogen gas, which, as our
readers doubtless know, is much lighter though more expensive than
ordinary coal-gas; each inflation costing several hundreds of pounds.

Under the balloon hung two cars of aluminium, the motors and the
screws; and also a great sliding weight of 600 lbs. for altering the
"tip" of the airship; and rudders to steer its course.

On June 30 a great number of scientific men and experts assembled to
witness the behaviour of a balloon which had cost £20,000. For two
days wind prevented a start, but on July 2, at 7.30 P.M., the balloon
emerged from its shed, and at eight o'clock commenced its first
journey, with and against a light easterly wind for a distance of
three and a half miles. A mishap to the steering-gear occurred early
in the trip, and prevented the airship appearing to advantage, but a
landing was effected easily and safely. In the following October the
Count made a second attempt, returning against a wind blowing at three
yards a second, or rather more than six miles an hour.

[Illustration: _The air-ship of M. Santos-Dumont rounding the Eiffel
Tower during its successful run for the Henri Deutsch Prize._]

Owing to lack of funds the fate of the "Great Eastern" has overtaken
the Zeppelin airship--to be broken up, and the parts sold.

The aged Count had demonstrated that a petroleum motor could be used
in the neighbourhood of gas without danger. It was, however, reserved
for a younger man to give a more decided proof of the steerableness of
a balloon.

In 1900 M. Henri Deutsch, a member of the French Aero Club, founded a
prize of £4000, to win which a competitor must start from the Aero
Club Park, near the Seine in Paris, sail to and round the Eiffel
Tower, and be back at the starting-point within a time-limit of
half-an-hour.

M. Santos Dumont, a wealthy and plucky young Brazilian, had,
previously to this offer, made several successful journeys in motor
balloons in the neighbourhood of the Eiffel Tower. He therefore
determined to make a bid for the prize with a specially constructed
balloon "Santos Dumont V." The third unsuccessful attempt ended in
disaster to the airship, which fell on to the houses, but fortunately
without injuring its occupant.

Another balloon--"Santos Dumont VI."--was then built. On Saturday,
October 19th, M. Dumont reached the Tower in nine minutes and
recrossed the starting line in 20-1/2 more minutes, thus complying
with the conditions of the prize with half-a-minute to spare. A
dispute, however, arose as to whether the prize had been actually won,
some of the committee contending that the balloon should have come to
earth within the half-hour, instead of merely passing overhead; but
finally the well-merited prize was awarded to the determined young
aeronaut.

The successful airship was of moderate proportions as compared with
that of Count Zeppelin. The cigar-shaped bag was 112 feet long and 20
feet in diameter, holding 715 cubic yards of gas. M. Dumont showed
originality in furnishing it with a smaller balloon inside, which
could be pumped full of air so as to counteract any leakage in the
external bag and keep it taut. The motor, on which everything
depended, was a four-cylinder petrol-driven engine, furnished with
"water-jackets" to prevent over-heating. The motor turned a large
screw--made of silk and stretched over light frames--200 times a
minute, giving a driving force of 175 lbs. Behind, a rudder directed
the airship, and in front hung down a long rope suspended by one end
that could be drawn towards the centre of the frame to alter the trim
of the ship. The aeronaut stood in a large wicker basket flanked on
either side by bags of sand ballast. The fact that the motor, once
stopped, could only be restarted by coming to earth again added an
element of great uncertainty to all his trips; and on one occasion the
mis-firing of one of the cylinders almost brought about a collision
with the Eiffel Tower.

From Paris M. Dumont went to Monaco at the invitation of the prince of
that principality, and cruised about over the bay in his balloon. His
fresh scheme was to cross to Corsica, but it was brought to an abrupt
conclusion by a leakage of gas, which precipitated balloon and
balloonist into the sea. Dumont was rescued, and at once set about new
projects, including a visit to the Crystal Palace, where he would have
made a series of ascents this summer (1902) but for damage done to the
silk of the gas-bag by its immersion in salt water and the other
vicissitudes it had passed through. Dumont's most important
achievement has been, like that of Count Zeppelin, the application of
the gasolene motor to aeromobilism. In proportion to its size this
form of motor develops a large amount of energy, and its mechanism is
comparatively simple--a matter of great moment to the aeronaut. He has
also shown that under favourable conditions a balloon may be steered
against a head-wind, though not with the certainty that is desirable
before air travel can be pronounced an even moderately simple
undertaking. The fact that many inventors, such as Dr. Barton, M.
Roze, Henri Deutsch, are fitting motors to balloons in the hopes of
solving the aërial problem shows that the airship has still a strong
hold on the minds of men. But on reviewing the successes of such
combinations of lifting and driving power it must be confessed, with
all due respect to M. Dumont, that they are somewhat meagre, and do
not show any great advance.

The question is whether these men are not working on wrong lines, and
whether their utmost endeavours and those of their successors will
ever produce anything more than a very semi-successful craft. Their
efforts appear foredoomed to failure. As Sir Hiram Maxim has observed,
a balloon by its very nature is light and fragile, it is a mere
bubble. If it were possible to construct a motor to develop 100
horse-power for every pound of its weight, it would still be
impossible to navigate a balloon against a wind of more than a certain
strength. The mere energy of the motor would crush the gas-bag against
the pressure of the wind, deform it, and render it unmanageable.
Balloons therefore must be at the mercy of the wind, and obliged to
submit to it under conditions not always in accordance with the wish
of the aeronaut.

Sir Hiram in condemning the airship was ready with a substitute. On
looking round on the patterns of Nature, he concluded that, inasmuch
as all things that fly are heavier than air, the problem of aërial
navigation must be solved by a machine whose natural tendency is to
fall to the ground, and which can be sustained only by the exertion of
great force. Its very weight would enable it to withstand, at least to
a far greater extent than the airship, the varying currents of the
air.

The lifting principle must be analogous to that by which a kite is
suspended. A kite is prevented from rising beyond a certain height by
a string, and the pressure of the wind working against it at an angle
tends to lift it, like a soft wedge continuously driven under it. In
practice it makes no difference whether the kite be stationary in a
wind or towed rapidly through a dead calm; the wedge-like action of
the air remains the same.

Maxim decided upon constructing what was practically a huge compound
kite driven by very powerful motors.

But before setting to work on the machine itself he made some useful
experiments to determine the necessary size of his kites or
aeroplanes, and the force requisite to move them.

He accordingly built a "whirling-table," consisting of a long arm
mounted on a strong pivot at one end, and driven by a 10 horse-power
engine. To the free end, which described a circle of 200 feet in
circumference, he attached small aeroplanes, and by means of delicate
balances discovered that at 40 miles an hour the aeroplane would lift
133 lbs. per horse-power, and at 60 miles per hour every square foot
of surface sustained 8 lbs. weight. He, in common with other
experimenters on the same lines, became aware of the fact that if it
took a certain strain to suspend a stationary weight in the air, _to
advance it rapidly as well as to suspend it took a smaller strain_.
Now, as on sea and land, increased speed means a very rapid increase
in the force required, this is a point in favour of the
flying-machine. Professor Langley found that a brass plate weighing a
pound, when whirled at great speed, was supported in the air by a
pulling pressure of less than one ounce. And, of course, as the speed
increased the plate became more nearly horizontal, offering less
resistance to the air.

It is on this behaviour of the aeroplane that the hopes of Maxim and
others have been based. The swiftly moving aeroplane, coming
constantly on to fresh air, the inertia of which had not been
disturbed, would resemble the skater who can at high speed traverse
ice that would not bear him at rest.

Maxim next turned his attention to the construction of the aeroplanes
and engines. He made a special machine for testing fabrics, to decide
which would be most suitable for stretching over strong frames to form
the planes. The fabric must be light, very strong, and offer small
frictional resistance to the air. The testing-machine was fitted with
a nozzle, through which air was forced at a known pace on to the
substance under trial, which met the air current at a certain angle
and by means of indicators showed the strength of its "lift" or
tendency to rise, and that of its "drift" or tendency to move
horizontally in the direction of the air-current. A piece of tin,
mounted at an angle of one in ten to the air-current, showed a "lift"
of ten times its "drift." This proportion was made the standard.
Experiments conducted on velvet, plush, silk, cotton and woollen goods
proved that the drift of crape was several times that of its lift, but
that fine linen had a lift equal to nine times its drift; while a
sample of Spencer's balloon fabric was as good as tin.

Accordingly he selected this balloon fabric to stretch over light but
strong frames. The stretching of the material was no easy matter, as
uneven tension distorted it; but eventually the aeroplanes were
completed, tight as drumheads.

The large or central plane was 50 feet wide and 40 long; on either
side were auxiliary planes, five pairs; giving a total area of 5400
square feet.

The steam-engine built to give the motive power was perhaps the most
interesting feature of the whole construction. Maxim employed steam in
preference to any other power as being one with which he was most
familiar, and yielding most force in proportion to the weight of the
apparatus. He designed and constructed a pair of high-pressure
compound engines, the high-pressure cylinders 5 inches in diameter,
the low-pressure 8 inches, and both 1 foot stroke. Steam was supplied
to the high-pressure cylinders at 320 lbs. per square inch from a
tubular boiler heated by a gasolene burner so powerful in its action
as to raise the pressure from 100 to 200 lbs. in a minute. The total
weight of the boiler, burner, and engines developing 350 horse-power
was 2000 lbs., or about 6 lbs. per horse-power.

The two screw-propellers driven by the engine measured 17 feet 11
inches in diameter.

The completed flying-machine, weighing 7500 lbs., was mounted on a
railway-truck of 9-foot gauge, in Baldwyn's Park, Kent, not far from
the gun-factories for which Sir Hiram is famous. Outside and parallel
to the 9-foot track was a second track, 35 feet across, with a
reversed rail, so that as soon as the machine should rise from the
inner track long spars furnished with flanged wheels at their
extremities should press against the under side of the outer track and
prevent the machine from rising too far. Dynamometers, or instruments
for measuring strains, were fitted to decide the driving and lifting
power of the screws. Experiments proved that with the engines working
at full power the screw-thrust against the air was 2200 lbs., and the
lifting force of the aeroplanes 10,000 lbs., or 1500 in excess of the
machine's weight.

Everything being ready the machine was fastened to a dynamometer and
steam run up until it strained at its tether with maximum power; when
the moorings were suddenly released and it bounded forward at a
terrific pace, so suddenly that some of the crew were flung violently
down on to the platform. When a speed of 42 miles was reached the
inner wheels left their track, and the outer wheels came into play.
Unfortunately, the long 35-foot axletrees were too weak to bear the
strain, and one of them broke. The upper track gave way, and for the
first time in the history of the world a flying-machine actually left
the ground fully equipped with engines, boiler, fuel, and a crew. The
journey, however, was a short one, for part of the broken track fouled
the screws, snapped a propeller blade and necessitated the shutting
off of the steam, which done, the machine settled to earth, the wheels
sinking into the sward and showing by the absence of any marks that it
had come directly downwards and not run along the surface.

The inventor was prevented by other business, and by the want of a
sufficiently large open space, from continuing his experiments, which
had demonstrated that a large machine heavier than air could be made
to lift itself and move at high speed. Misfortune alone prevented its
true capacities being shown.

Another experimenter on similar lines, but on a less heroic scale than
Sir Hiram Maxim, is Professor S. P. Langley, the secretary of the
Smithsonian Institution, Washington. For sixteen years he has devoted
himself to a persevering course of study of the flying-machine, and
after oft-repeated failures has scored a decided success in his
Aerodrome, which, though only a model, has made considerable flights.
His researches have proved beyond doubt that the amount of energy
required for flight is but one-fiftieth of what was formerly regarded
as a minimum. A French mathematician had proved by figures that a
swallow must develop the power of a horse to maintain its rapid
flight! Professor Langley's aerodrome has told a very different tale,
affording another instance of the truth of the saying that an ounce of
practice is worth a pound of theory.

A bird is nearly one thousand times heavier than the air it displaces.
As a motor it develops huge power for its weight, and consumes a very
large amount of fuel in doing so. An observant naturalist has
calculated that the homely robin devours per diem, in proportion to
its size, what would be to a man a sausage two hundred feet long and
three inches thick! Any one who has watched birds pulling worms out of
the garden lawn and swallowing them wholesale can readily credit this.

Professor Langley therefore concentrated himself on the production of
an extremely light and at the same time powerful machine. Like Maxim,
he turned to steam for motive-power, and by rigid economy of weight
constructed an engine with boilers weighing 5 lbs., cylinders of 26
ozs., and an energy of 1 to 1-1/2 horse-power! Surely a masterpiece of
mechanical workmanship! This he enclosed in a boat-shaped cover which
hung from two pairs of aeroplanes 12-1/2 feet from tip to tip. The
whole apparatus weighed nearly 30 lbs., of which one quarter
represented the machinery. Experiments with smaller aerodromes warned
the Professor that rigidity and balance were the two most difficult
things to attain; also that the starting of the machine on its aerial
course was far from an easy matter.

A soaring bird does not rise straight from the ground, but opens its
wings and runs along the ground until the pressure of the air raises
it sufficiently to give a full stroke of its pinions. Also it rises
_against_ the wind to get the full benefit of its lifting force.
Professor Langley hired a houseboat on the Potomac River, and on the
top of it built an apparatus from which the aerodrome could be
launched into space at high velocity.

On May 6, 1896, after a long wait for propitious weather, the
aerodrome was despatched on a trial trip. It rose in the face of the
wind and travelled for over half a mile at the rate of twenty-five
miles an hour. The water and fuel being then exhausted it settled
lightly on the water and was again launched. Its flight on both
occasions was steady, and limited only by the rapid consumption of its
power-producing elements. The Professor believes that larger machines
would remain in the air for a long period and travel at speeds
hitherto unknown to us.

In both the machines that we have considered the propulsive power was
a screw. No counterpart of it is seen in Nature. This is not a valid
argument against its employment, since no animal is furnished with
driving-wheels, nor does any fish carry a revolving propeller in its
tail. But some inventors are strongly in favour of copying Nature as
regards the employment of wings. Mr. Sydney H. Hollands, an
enthusiastic aeromobilist, has devised an ingenious cylinder-motor so
arranged as to flap a pair of long wings, giving them a much stronger
impulse on the down than on the up stroke. The pectoral muscles of a
bird are reproduced by two strong springs which are extended by the
upward motion of the wings and store up energy for the down-stroke.
Close attention is also being paid to the actual shape of a bird's
wing, which is not flat but hollow on its under side, and at the front
has a slightly downward dip. "Aerocurves" are therefore likely to
supersede the "aeroplane," for Nature would not have built bird's
wings as they are without an object. The theory of the aerocurve's
action is this: that the front of the wing, on striking the air, gives
it a downwards motion, and if the wing were quite flat its rear
portion would strike air already in motion, and therefore less
buoyant. The curvature of a floating bird's wings, which becomes more
and more pronounced towards the rear, counteracts this yielding of the
air by pressing harder upon it as it passes towards their hinder edge.

[Illustration: _M. Santos Dumont's Airship returning to Longchamps
after doubling the Eiffel Tower, October 19, 1901._]

The aerocurve has been used by a very interesting group of
experimenters, those who, putting motors entirely aside, have floated
on wings, and learnt some of the secrets of balancing in the air. For
a man to propel himself by flapping wings moved by legs or arms is
impossible. Sir Hiram Maxim, in addressing the Aeronautical Society,
once said that for a man to successfully imitate a bird his lungs must
weigh 40 lbs., to consume sufficient oxygen, his breast muscles 75
lbs., and his breast bone be extended in front 21 inches. And unless
his total weight were increased his legs must dwindle to the size of
broomsticks, his head to that of an apple! So that for the present we
shall be content to remain as we are!

Dr. Lilienthal, a German, was the first to try scientific
wing-sailing. He became a regular air gymnast, running down the sides
of an artificial mound until the wings lifted him up and enabled him
to float a considerable distance before reaching earth again. His
wings had an area of 160 square feet, or about a foot to every pound
weight. He was killed by the wings collapsing in mid-air. A similar
fate also overtook Mr. Percy Pilcher, who abandoned the initial run
down a sloping surface in favour of being towed on a rope attached to
a fast-moving vehicle. At present Mr. Octave Chanute, of Chicago, is
the most distinguished member of the "gliding" school. He employs,
instead of wings, a species of kite made up of a number of small
aerocurves placed one on the top of another a small distance apart.
These box kites are said to give a great lifting force for their
weight.

These and many other experimenters have had the same object in
view--to learn the laws of equilibrium in the air. Until these are
fully understood the construction of large flying-machines must be
regarded as somewhat premature. Man must walk before he can run, and
balance himself before he can fly.

There is no falling off in the number of aërial machines and schemes
brought from time to time into public notice. We may assure ourselves
that if patient work and experiment can do it the problem of "how to
fly" is not very far from solution at the present moment.

As a sign of the times, the War Office, not usually very ready to
take up a new idea, has interested itself in the airship, and
commissioned Dr. F. A. Barton to construct a dirigible balloon which
combines the two systems of aerostation. Propulsion is effected by six
sets of triple propellers, three on each side. Ascent is brought about
partly by a balloon 180 feet long, containing 156,000 cubic feet of
hydrogen, partly by nine aeroplanes having a total superficial area of
nearly 2000 square feet. The utilisation of these aeroplanes obviates
the necessity to throw out ballast to rise, or to let out gas for a
descent. The airship, being just heavier than air, is raised by the
135 horse-power motors pressing the aeroplanes against the air at the
proper angle. In descent they act as parachutes.

The most original feature of this war balloon is the automatic
water-balance. At each end of the "deck" is a tank holding forty
gallons of water. Two pumps circulate water through these tanks, the
amount sent into a tank being regulated by a heavy pendulum which
turns on the cock leading to the end which may be highest in
proportion as it turns off that leading to the lower end. The idea is
very ingenious, and should work successfully when the time of trial
comes.

Valuable money prizes will be competed for by aeronauts at the coming
World's Fair at St. Louis in 1903. Sir Hiram Maxim has expressed an
intention of spending £20,000 in further experiments and prizes. In
this country, too, certain journals have offered large rewards to any
aeronaut who shall make prescribed journeys in a given time. It has
also been suggested that aeronautical research should be endowed by
the state, since England has nothing to fear more than the flying
machine and the submarine boat, each of which tends to rob her of the
advantages of being an island by exposing her to unexpected and unseen
attacks.

Tennyson, in a fine passage in "Locksley Hall," turns a poetical eye
towards the future. This is what he sees--

    "For I dipt into the future, far as human eye could see,
    Saw the vision of the world and all the wonder that would be,
    Saw the heavens fill with commerce, argosies of magic sail,
    Pilots of the purple twilight dropping down with costly bales,
    Heard the heavens fill with shouting, then there rained a ghostly dew,
    From the nations' airy navies, grappling in the central blue."

Expressed in more prosaic language, the flying-machine will primarily
be used for military purposes. A country cannot spread a metal
umbrella over itself to protect its towns from explosives dropped from
the clouds.

Mail services will be revolutionised. The pleasure aerodrome will take
the place of the yacht and motor-car, affording grand opportunities
for the mountaineer and explorer (if the latter could find anything
new to explore). Then there will also be a direct route to the North
Pole over the top of those terrible icefields that have cost
civilisation so many gallant lives. And possibly the ease of transit
will bring the nations closer together, and produce good-fellowship
and concord among them. It is pleasanter to regard the flying-machine
of the future as a bringer of peace than as a novel means of spreading
death and destruction.




TYPE-SETTING BY MACHINERY.


To the Assyrian brickmakers who, thousands of years ago, used blocks
wherewith to impress on their unbaked bricks hieroglyphics and
symbolical characters, must be attributed the first hesitating step
towards that most marvellous and revolutionary of human
discoveries--the art of printing. Not, however, till the early part of
the fifteenth century did Gutenberg and Coster conceive the brilliant
but simple idea of printing from separate types, which could be set in
different orders and combinations to represent different ideas. For
Englishmen, 1474 deserves to rank with 1815, as in that year a very
Waterloo was won on English soil against the forces of ignorance and
oppression, though the effects of the victory were not at once
evident. Considering the stir made at the time by the appearance of
Caxton's first book at Westminster, it seems strange that an invention
of such importance as the printing-press should have been frowned upon
by those in power, and so discouraged that for nearly two centuries
printing remained an ill-used and unprogressive art, a giant half
strangled in his cradle. Yet as soon as prejudice gave it an open
field, improved methods followed close on one another's heels. To-day
we have in the place of Caxton's rude hand-made press great cylinder
machines capable of absorbing paper by the mile, and grinding out
20,000 impressions an hour as easily as a child can unwind a reel of
cotton.

Side by side with the problem how to produce the greatest possible
number of copies in a given time from one machine, has arisen
another:--how to set up type with a proportionate rapidity. A press
without type is as useless as a chaff-cutter without hay or straw. The
type once assembled, as many casts or stereotypes can be made from it
as there are machines to be worked. But to arrange a large body of
type in a short time brings the printer face to face with the
need of employing the expensive services of a small army of
compositors--unless he can attain his end by some equally efficient
and less costly means. For the last century a struggle has been in
progress between the machine compositor and the human compositor,
mechanical ingenuity against eye and brains. In the last five years
the battle has turned most decidedly in favour of the machine. To-day
there are in existence two wonderful contrivances which enable a man
to set up type six times as fast as he could by hand from a box of
type, with an ease that reminds one of the mythical machine for the
conversion of live pigs into strings of sausages by an uninterrupted
series of movements.

These machines are called respectively the Linotype and Monotype.
Roughly described, they are to the compositor what a typewriter is to
a clerk--forming words in obedience to the depression of keys on a
keyboard. But whereas the typewriter merely imprints a single
character on paper, the linotype and monotype cast, deliver, and set
up type from which an indefinite number of impressions can be taken.
They meet the compositor more than half-way, and simplify his labour
while hugely increasing his productiveness.

As far back as 1842 periodicals were mechanically composed by a
machine which is now practically forgotten. Since that time hundreds
of other inventions have been patented, and some scores of different
machines tried, though with small success in most cases; as it was
found that quality of composition was sacrificed to quantity, and that
what at first appeared a short cut to the printing-press was after all
the longest way round, when corrections had all been attended to. A
really economical type-setter must be accurate as well as prolific.
Slipshod work will not pay in the long run.

Such a machine was perfected a few years ago by Ottmar Mergenthaler of
Baltimore, who devised the plan of casting a whole _line of type_. The
Linotype Composing Machine, to give it its full title, produces type
all ready for the presses in "slugs" or lines--hence the name, Lin' o'
type. It deserves at least a short description.

The Linotype occupies about six square feet of floor space, weighs one
ton, and is entirely operated by one man. Its most prominent features
are a sloping magazine at the top to hold the brass matrices, or
dies from which the type is cast, a keyboard controlling the machinery
to drop and collect the dies, and a long lever which restores the dies
to the magazine when done with.

[Illustration: _By kind permission of The Linotype Co._

_The Linotype Machine. By pressing keys on the key-board the operator
causes lines of type to be set up, cast, and arranged on the "galley"
ready for the printers._]

The operator sits facing the keyboard, in which are ninety keys,
variously coloured to distinguish the different kinds of letters. His
hands twinkle over the keys, and the brass dies fly into place. When a
key is depressed a die shoots from the magazine on to a travelling
belt and is whirled off to the assembling-box. Each die is a flat,
oblong brass plate, of a thickness varying with the letter, having a
large V-shaped notch in the top, and the letter cut half-way down on
one of the longer sides. A corresponding letter is stamped on the side
nearest to the operator so that he may see what he is doing and make
needful corrections.

As soon as a word is complete, he touches the "spacing" lever at the
side of the keyboard. The action causes a "space" to be placed against
the last die to separate it from the following word. The operations
are repeated until the tinkle of a bell warns him that, though there
may be room for one or two more letters, the line will not admit
another whole syllable. The line must therefore be "justified," that
is, the spaces between the words increased till the vacant room is
filled in. In hand composition this takes a considerable time, and is
irksome; but at the linotype the operator merely twists a handle and
the wedge-shaped "spaces," placed thin end upwards, are driven up
simultaneously, giving the lateral expansion required to make the line
of the right measure.

A word about the "spaces," or space-bands. Were each a single wedge
the pressure would be on the bottom only of the dies, and their tops,
being able to move slightly, would admit lead between them. To obviate
this a small second wedge, thin end _downwards_, is arranged to slide
on the larger wedge, so that in all positions parallelism is secured.
This smaller wedge is of the same shape as the dies and remains
stationary in line with them, the larger one only moving.

The line of dies being now complete, it is automatically borne off and
pressed into contact with the casting wheel. This wheel, revolving on
its centre, has a slit in it corresponding in length and width to the
size of line required. At first the slit is horizontal, and the dies
fit against it so that the row of sunk letters on the faces are in the
exact position to receive the molten lead, which is squirted through
the slit from behind by an automatic pump, supplied from a metal-pot.
The pot is kept at a proper heat of 550° Fahrenheit by the flames of a
Bunsen burner.

The lead solidifies in an instant, and the "slug" of type is ready for
removal, after its back has been carefully trimmed by a knife. The
wheel revolves for a quarter-turn, bringing the slit into a vertical
position; a punch drives out the "slug," which is slid into the galley
to join its predecessors. The wheel then resumes its former horizontal
position in readiness for another cast.

The assembled dies have for the time done their work and must be
returned to the magazine. The mechanism used to effect this is
peculiarly ingenious.

An arm carrying a ribbed bar descends. The dies are pushed up, leaving
the "spaces" behind to be restored to their proper compartment, till
on a level with the ribbed bar, on to which they are slid by a lateral
movement, the notches of the V-shaped opening in the top side of each
die engaging with the ribs on the bar. The bar then ascends till it is
in line with a longer bar of like section passing over the open top of
the entire magazine. A set of horizontal screw-bars, rotating at high
speed, transfer the dies from the short to the long bar, along which
they move till, as a die comes above its proper division of the
magazine, the arrangement of the teeth allows it to drop. While all
this has been going on, the operator has composed another line of
moulds, which will in turn be transferred to the casting wheel, and
then back to the magazine. So that the three operations of composing,
casting, and sorting moulds are in progress simultaneously in
different parts of the machine; with the result that as many as 20,000
letters can be formed by an expert in the space of an hour, against
the 1500 letters of a skilled hand compositor.

How about corrections? Even a comma too few or too many needs the
whole line cast over again. It is a convincing proof of the difference
in speed between the two methods that a column of type can be
corrected much faster by the machine, handicapped as it is by its
solid "slugs," than by hand. No wonder then that more than 1000
linotypes are to be found in the printing offices of Great Britain.

The Monotype, like the Linotype, aims at speed in composition, but in
its mechanism it differs essentially from the linotype. In the first
place, the apparatus is constructed in two quite separate parts. There
is a keyboard, which may be on the third floor of the printing
offices, and the casting machine, which ceaselessly casts and sets
type in the basement. Yet they are but one whole. The connecting link
is the long strip of paper punched by the keyboard mechanism, and then
transferred to the casting machine to bring about the formation of
type. The keyboard is the servant of man; the casting machine is the
slave of the keyboard.

Secondly, the Monotype casts type, not in blocks or a whole line, but
in separate letters. It is thus a complete type-foundry. Order it to
cast G's and it will turn them out by the thousand till another letter
is required.

Thirdly, by means of the punched paper roll, the same type can be set
up time after time without a second recourse to the keyboard, just as
a tune is ground repeatedly out of a barrel organ.

The keyboard has a formidable appearance. It contains 225 keys,
providing as many characters; also thirty keys to regulate the spacing
of the words. At the back of the machine a roll of paper runs over
rollers and above a row of thirty little punches worked by the keys.
A key being depressed, an opened valve admits air into two cylinders,
each driving a punch. The punches fly up and cut two neat little holes
in the paper. The roll then moves forward for the next letter. At the
end of the word a special lever is used to register a space, and so on
to the end of the line. The operator then consults an automatic
indicator which tells him exactly how much space is left, and how much
too long or too short the line would be if the spaces were of the
normal size. Supposing, for instance, that there are ten spaces, and
that there is one-tenth of an inch to spare. It is obvious that by
extending each space one-hundredth of an inch the vacant room will be
exactly filled. Similarly, if the ten normal spaces would make the
line one-tenth of an inch too _long_, by _decreasing_ the spaces each
one-hundredth inch the line will also be "justified."

[Illustration: _By kind permission of_] [_The Monotype Co._

_The Monotype Casting Machine. A punched paper roll fed through the
top of the machine automatically casts and sets up type in separate
letters._]

But the operator need not trouble his head about calculations of this
kind. His indicator, a vertical cylinder covered with tiny squares, in
each of which are printed two figures, tell him exactly what he has to
do. On pressing a certain key the cylinder revolves and comes to rest
with the tip of a pointer over a square. The operator at once presses
down the keys bearing the numbers printed on that square, confident
that the line will be of the proper length.

As soon as the roll is finished, it is detached from the keyboard and
introduced to the casting machine. Hitherto passive, it now becomes
active. Having been placed in position on the rollers it is slowly
unwound by the machinery. The paper passes over a hollow bar in which
there are as many holes as there were punches in the keyboard, and in
precisely the same position. When a hole in the paper comes over a
hole in the hollow bar air rushes in, and passing through a tube
actuates the type-setting machinery in a certain manner, so as to
bring the desired die into contact with molten lead. The dies are, in
the monotype, all carried in a magazine about three inches square,
which moves backwards or forwards, to right or left, in obedience to
orders from the perforated roll. The dies are arranged in exactly the
same way as the keys on the keyboard. So that, supposing A to have
been stamped on the roll, one of the perforations causes the magazine
to slide one way, while the other shoves it another, until the
combined motions bring the matrix engraved with the A underneath the
small hole through which molten lead is forced. The letter is ejected
and moves sideways through a narrow channel, pushing preceding letters
before it, and the magazine is free for other movements.

At the end of each word a "space" or blank lead is cast, its size
exactly determined by the "justifying" hole belonging to that line.
Word follows word till the line is complete; then a knife-like lever
rises, and the type is propelled into the "galley." Though a slave the
casting machine will not tolerate injustice. Should the compositor
have made a mistake, so that the line is too long or too short,
automatic machinery at once comes into play, and slips the driving
belt from the fixed to the loose pulley, thus stopping the machine
till some one can attend to it. But if the punching has been correctly
done, the machine will work away unattended till, a whole column of
type having been set up, it comes to a standstill.

The advantages of the Monotype are easily seen. In order to save money
a man need not possess the complete apparatus. If he has the keyboard
only he becomes to a certain extent his own compositor, able to set up
the type, as it were by proxy, at any convenient time. He can give his
undivided attention to the keyboard, stop work whenever he likes
without keeping a casting-machine idle, and as soon as his roll is
complete forward it to a central establishment where type is set.
There a single man can superintend the completion of half-a-dozen
men's labours at the keyboard. That means a great reduction of
expense.

In due time he receives back his copy in the shape of set-up type, all
ready to be corrected and transferred to the printing machines. The
type done with, he can melt it down without fear of future regret, for
he knows that the paper roll locked up in his cupboard will do its
work a second time as well as it did the first. Should he need the
same matter re-setting, he has only to send the roll through the post
to the central establishment.

Thanks to Mr. Lanston's invention we may hope for the day when every
parish will be able to do its own printing, or at least set up its own
magazine. The only thing needful will be a monotype keyboard supplied
by an enlightened Parish Council--as soon as the expense appears
justifiable--and kept in the Post Office or Village Institute. The
payment of a small fee will entitle the Squire to punch out his speech
on behalf of the Conservative Candidate, the Schoolmaster to compose
special information for his pupils, the Rector to reduce to print
pamphlets and appeals to charity. And if those of humbler degree think
they can strike eloquence from the keys, they too will of course be
allowed to turn out their ideas literally by the yard.




PHOTOGRAPHY IN COLOURS.


While photography was still in its infancy many people believed that,
a means having been found of impressing the representation of an
object on a sensitised surface, a short time only would have to elapse
before the discovery of some method of registering the colours as well
as the forms of nature.

Photography has during the last forty years passed through some
startling developments, especially as regards speed. Experts, such as
M. Marey, have proved the superiority of the camera over the human eye
in its power to grasp the various phases of animal motion. Even rifle
bullets have been arrested in their lightning flight by the sensitised
plate. But while the camera is a valuable aid to the eye in the matter
of form, the eye still has the advantage so far as colour is
concerned. It is still impossible for a photographer by a simple
process similar to that of making an ordinary black-and-white
negative, to affect a plate in such a manner that from it prints may
be made by a single operation showing objects in their natural
colours. Nor, for the matter of that, does colour photography direct
from nature seem any nearer attainment now than it was in the time of
Daguerre.

There are, however, extant several methods of making colour
photographs in an indirect or roundabout way. These various "dodges"
are, apart from their beautiful results, so extremely ingenious and
interesting that we propose to here examine three of the best known.

The reader must be careful to banish from his mind those _coloured_
photographs so often to be seen in railway carriages and shop windows,
which are purely the result of hand-work and mechanical printing, and
therefore not _colour_ photographs at all.

Before embarking on an explanation of these three methods it will be
necessary to examine briefly the nature of those phenomena on which
all are based--light and colour. The two are really identical, light
is colour and colour is light.

Scientists now agree that the sensation of light arises from the
wave-like movements of that mysterious fluid, the omnipresent ether.
In a beam of white light several rates of wave vibrations exist side
by side. Pass the beam through a prism and the various rapidities are
sorted out into violet, indigo, blue, green, yellow, orange and red,
which are called the pure colours, since if any of them be passed
again through a prism the result is still that colour. Crimson, brown,
&c., the composite colours, would, if subjected to the prism, at once
split up into their component pure colours.

There are several points to be noticed about the relationship of the
seven pure colours. In the first place, though they are all allies in
the task of making white light, there is hostility among them, each
being jealous of the others, and only waiting a chance to show it.
Thus, suppose that we have on a strip of paper squares of the seven
colours, and look at the strip through a piece of red glass we see
only one square--the red--in its natural colour, since that square is
in harmony only with red rays. (Compare the sympathy of a piano with a
note struck on another instrument; if C is struck, say on a violin,
the piano strings producing the corresponding note will sound, but the
other strings will be silent.) The orange square suggests orange, but
the green and blue and violet appear black. Red glass has arrested
their ether vibrations and said "no way here." Green and violet would
serve just the same trick on red or on each other. It is from this
readiness to absorb or stop dissimilar rays that we have the different
colours in a landscape flooded by a common white sunlight. The trees
and grass absorb all but the green rays, which they reflect. The
dandelions and buttercups capture and hold fast all but the yellow
rays. The poppies in the corn send us back red only, and the
cornflowers only blue; but the daisy is more generous and gives up all
the seven. Colour therefore is not a thing that can be touched, any
more than sound, but merely the capacity to affect the retina of the
eye with a certain number of ether vibrations per second, and it makes
no difference whether light is reflected from a substance or refracted
through a substance; a red brick and a piece of red glass have similar
effects on the eye.

This then is the first thing to be clearly grasped, that whenever a
colour has a chance to make prisoners of other colours it will do so.

The second point is rather more intricate, viz. that this imprisonment
is going on even when friendly concord appears to be the order of the
day. Let us endeavour to present this clearly to the reader. Of the
pure colours, violet, green and red--the extremes and the centre--are
sufficient to produce white, because each contains an element of its
neighbours. Violet has a certain amount of indigo, green some yellow,
red some orange; in fact every colour of the spectrum contains a
greater or less degree of several of the others, but not enough to
destroy its own identity. Now, suppose that we have three lanterns
projecting their rays on to the same portion of a white sheet, and
that in front of the first is placed a violet glass, in front of the
second a green glass, in front of the third a red glass. What is the
result? A white light. Why? Because they meet _on equal terms_, and as
no one of them is in a point of advantage no prisoners can be made and
they must work in harmony. Next, turn down the violet lantern, and
green and red produce a yellow, half-way between them; turn down red
and turn up violet, indigo-blue results. All the way through a
compromise is effected.

But supposing that the red and green glasses are put in front of the
_same_ lantern and the white light sent through them--where has the
yellow gone to? only a brownish-black light reaches the screen. The
same thing happens with red and violet or green and violet.

Prisoners have been taken, because one colour has had to _demand
passage_ from the other. Red says to green, "You want your rays to
pass through me, but they shall not." Green retorts, "Very well; but I
myself have already cut off all but green rays, and if they don't pass
you, nothing shall." And the consequence of the quarrel is practical
darkness.

The same phenomenon may be illustrated with blue and yellow. Lights of
these two colours projected simultaneously on to a sheet yield white;
but white light sent through blue and yellow glass _in succession_
produces a green light. Also, blue paint mixed with yellow gives
green. In neither case is there darkness or entire cutting-off of
colour, as in the case of Red + Violet or Green + Red.

The reason is easy to see.

Blue light is a compromise of violet and green; yellow of green and
red. Hence the two coloured lights falling on the screen make a
combination which can be expressed as an addition sum.

    Blue   = green + violet.
    Yellow = green + red.
             --------------------
             green + violet + red = white.

But when light is passed _through_ two coloured glasses in succession,
or reflected from two layers of coloured paints, there are prisoners
to be made.

Blue passes green and violet only.

Yellow passes green and red only.

So violet is captured by yellow, and red by blue, green being free to
pass on its way.

There is, then, a great difference between the _mixing_ of colours,
which evokes any tendency to antagonism, and the _adding_ of colours
under such conditions that they meet on equal terms. The first process
happens, as we have seen, when a ray of light is passed through
colours _in succession_; the second, when lights stream simultaneously
on to an object. A white screen, being capable of reflecting any
colour that falls on to it, will with equal readiness show green, red,
violet, or a combination; but a substance that is in white light red,
or green, or violet will capture any other colour. So that if for the
white screen we substituted a red one, violet or green falling
simultaneously, would yield blackness, because red takes _both_
prisoners; if it were violet, green would be captured, and so on.

From this follows another phenomenon: that whereas projection of two
or more lights may yield white, white cannot result from any mixture
of pigments. A person with a whole boxful of paints could not get
white were he to mix them in an infinitude of different ways; but with
the aid of his lanterns and as many differently coloured glasses the
feat is easy enough.

Any two colours which meet on equal terms to make white are called
_complementary_ colours.

     Thus yellow (= red + green lights) is complementary of violet.

      Thus pink (= red + violet lights) is complementary of green.

      Thus blue (= violet + green lights) is complementary of red.

This does not of course apply to mixture of paints, for complementary
colours must act together, not in antagonism.

If the reader has mastered these preliminary considerations he will
have no difficulty in following out the following processes.

(_a_) _The Joly Process_, invented by Professor Joly of Dublin. A
glass plate is ruled across with fine parallel lines--350 to the inch,
we believe. These lines are filled in alternately with violet, green,
and red matter, every third being violet, green or red as the case may
be. The colour-screen is placed in the camera in front of the
sensitised plate. Upon an exposure being made, all light reflected
from a red object (to select a colour) is allowed to pass through the
red lines, but blocked by all the green and violet lines. So that on
development that part of the negative corresponding to the position of
the red object will be covered with dark lines separated by
transparent belts of twice the breadth. From the negative a positive
is printed, which of course shows transparent lines separated by
opaque belts of twice their breadth. Now, suppose that we take the
colour-screen and place it again in front of the plate in the position
it occupied when the negative was taken, the red lines being opposite
the transparent parts of the positive will be visible, but the green
and violet being blocked by the black deposit behind them will not be
noticeable. So that the object is represented by a number of red
lines, which at a small distance appear to blend into a continuous
whole.

The violet and green affect the plate in a corresponding manner; and
composite colours will affect two sets of lines in varying degrees,
the lights from the two sets blending in the eye. Thus yellow will
obtain passage from both green and red, and when the screen is held up
against the positive, the light streaming through the green and red
lines will blend into yellow in the same manner as they would make
yellow if projected by lanterns on to a screen. The same applies to
all the colours.

The advantage of the Joly process is that in it only one negative has
to be made.

(_b_) _The Ives Process._--Mr. Frederic Eugene Ives, of Philadelphia,
arrives at the same result as Professor Joly, but by an entirely
different means. He takes three negatives of the same object, one
through a violet-blue, another through a green, and a third through a
red screen placed in front of the lens. The red negative is affected
by red rays only; the green by green rays only, and the violet-blue by
violet-blue rays only, in the proper gradations. That is to say, each
negative will have opaque patches wherever the rays of a certain kind
strike it; and the positive printed off will be by consequence
transparent at the same places. By holding the positive made from the
red-screen negative against a piece of red glass, we should see light
only in those parts of the positive which were transparent. Similarly
with the green and violet positives if viewed through glasses of
proper colour. The most ingenious part of Mr. Ives' method is the
apparatus for presenting all three positives (lighted through their
coloured glasses) to the eye simultaneously. When properly adjusted,
so that their various parts exactly coincide, the eye blends the three
together, seeing green, red, or violet separately, or blended in
correct proportions. The Kromoscope, as the viewing apparatus is
termed, contains three mirrors, projecting the reflections from the
positives in a single line. As the three slides are taken
stereoscopically the result gives the impression of solidity as well
as of colour, and is most realistic.

(_c_) _The Sanger Shepherd Process._--This is employed mostly for
lantern transparencies. As in the Ives process, three negatives and
three transparent positives are made. But instead of coloured glasses
being used to give effect to the positives the positives themselves
are dyed, and placed one on the top of another in close contact, so
that the light from the lantern passes through them in succession. We
have therefore now quitted the realms of harmony for that of discord,
in which prisoners are made; and Mr. Shepherd has had to so arrange
matters that in every case the capture of prisoners does not interfere
with the final result, but conduces to it.

In the first place, three negatives are secured through violet, green,
and red screens. Positives are printed by the carbon process on thin
celluloid films. The carbon film contains gelatine and bichromate of
potassium. The light acts on the bichromate in such a way as to render
the gelatine insoluble. The result is that, though in the positives
there is at first no colour, patches of gelatine are left which will
absorb dyes of various colours. The dyeing process requires a large
amount of care and patience.

Now, it would be a mistake to suppose that each positive is dyed in
the colour of the screen through which its negative was taken. A
moment's consideration will show us why.

Let us assume that we are photographing a red object, a flower-pot for
instance. The red negative represents the pot by a dark deposit. The
positive printed off will consequently show clear glass at that spot,
the unaffected gelatine being soluble. So that to dye the plate would
be to make all red _except_ the very part which we require red; and on
holding it up to the light the flower-pot would appear as a white
transparent patch.

How then is the problem to be solved?

Mr. Shepherd's process is based upon an ordered system of
prisoner-taking. Thus, as red in this particular case is wanted it
will be attained by the _other two_ positives (which are placed in
contact with the red positive, so that all three coincide exactly),
robbing white light of all _but_ its red rays.

Now if the other positives were dyed green and violet, what would
happen? They would not produce red, but by robbing white light between
them of red, green, and violet, would produce blackness, and we should
be as far as ever from our object.

The positives are therefore dyed, not in the same colours as the
screens used when the negatives were made, but in their
_complementary_ colours, _i.e._ as explained above, those colours
which added to the colour of the screen would make white.

The red screen negative is therefore dyed (violet + green) = blue. The
green negative (red + violet) = pink. The violet negative (red +
green) = yellow.

To return to our flower-pot. The red-screen positive (dyed blue) is,
as we saw, quite transparent where the pot should be. But behind the
transparent gap are the pink and yellow positives.

White light (= violet + green + red) passes through pink (= violet +
red), and has to surrender all its green rays. The violet and red pass
on and encounter yellow (= green + red), and violet falls a victim to
green, leaving red unmolested.

If the flower-pot had been white all three positives would have
contained clear patches unaffected by the three dyes, and the white
light would have been unobstructed. The gradations and mixtures of
colours are obtained by two of the screens being influenced by the
colour of the object. Thus, if it were crimson, both violet and
red-screen negatives would be affected by the rays reflected by it,
and the green screen negative not at all. Hence the pink positive
would be pink, the yellow clear, and the blue clear.

White light passing through is robbed by pink of green, leaving red +
violet = crimson.


COLOUR PRINTING.

Printing in ink colours is done in a manner very similar to the Sanger
Shepherd lantern slide process. Three blocks are made, by the help of
photography, through violet, green and red screens, and etched away
with acid, like ordinary half-tone black-and-white blocks. The three
blocks have applied to them ink of a complementary colour to the
screen they represent, just as in the Sanger Shepherd process the
positives were dyed. The three inks are laid over one another on the
paper by the blocks, the relieved parts of which (corresponding to the
undissolved gelatine of the Shepherd positives) only take the ink.
White light being reflected through layers of coloured inks is treated
in just the same way as it would be were it transmitted through
coloured glasses, yielding all the colours in approximately correct
gradations.




LIGHTING.


The production of fire by artificial means has been reasonably
regarded as the greatest invention in the history of the human race.
Prior to the day when a man was first able to call heat from the
substances about him the condition of our ancestors must have been
wretched indeed. Raw food was their portion; metals mingled with other
matter mocked their efforts to separate them; the cold of winter drove
them to the recesses of gloomy caverns, where night reigned perpetual.

The production of fire also, of course, entailed the creation of
light, which in its developments has been of an importance second only
to the improved methods of heating. So accustomed are we to our
candles, our lamps, our gas-jets, our electric lights, that it is hard
for us to imagine what an immense effect their sudden and complete
removal would have on our existence. At times, when floods,
explosions, or other accidents cause a temporary stoppage of the gas
or current supply, a town may for a time be plunged into darkness; but
this only for a short period, the distress of which can be alleviated
by recourse to paraffin lamps, or the more homely candle.

The earliest method of illumination was the rough-and-ready one of
kindling a pile of brushwood or logs. The light produced was very
uncertain and feeble, but possibly sufficient for the needs of the
cave-dweller. With the advance of civilisation arose an increasing
necessity for a more steady illuminant, discovered in vegetable oils,
burned in lamps of various designs. Lamps have been found in old
Egyptian and Etruscan tombs constructed thousands of years ago. These
lamps do not differ essentially from those in use to-day, being
reservoirs fitted with a channel to carry a wick.

But probably from the difficulty of procuring oil, lamps fell into
comparative disuse, or rather were almost unknown, in many countries
of Europe as late as the fifteenth century; when the cottage and
baronial hall were alike lit by the blazing torch fixed into an iron
sconce or bracket on the wall.

The rushlight, consisting of a peeled rush, coated by repeated dipping
into a vessel of melted fat, made a feeble effort to dispel the gloom
of long winter evenings. This was succeeded by the tallow and more
scientifically made wax candle, which last still maintains a certain
popularity.

How our grandmothers managed to "keep their eyes" as they worked at
stitching by the light of a couple of candles, whose advent was the
event of the evening, is now a mystery. To-day we feel aggrieved if
our lamps are not of many candle-power, and protest that our sight
will be ruined by what one hundred and fifty years ago would have
seemed a marvel of illumination. In the case of lighting necessity has
been the mother of invention. The tendency of modern life is to turn
night into day. We go to bed late and we get up late; this is perhaps
foolish, but still we do it. And, what is more, we make increasing use
of places, such as basements, underground tunnels, and "tubes," to
which the light of heaven cannot penetrate during any of the daily
twenty-four hours.

The nineteenth century saw a wonderful advance in the science of
illumination. As early as 1804 the famous scientist, Sir Humphrey
Davy, discovered the electric arc, presently to be put to such
universal use. About the same time gas was first manufactured and led
about in pipes. But before electricity for lighting purposes had been
rendered sufficiently cheap the discovery of the huge oil deposits in
Pennsylvania flooded the world with an inexpensive illuminant. As
early as the thirteenth century Marco Polo, the explorer, wrote of a
natural petroleum spring at Baku, on the Caspian Sea: "There is a
fountain of great abundance, inasmuch as a thousand shiploads might be
taken from it at one time. This oil is not good to use with food, but
it is _good to burn_; and is also used to anoint camels that have the
mange. People come from vast distances to fetch it, for in all other
countries there is no oil." His last words have been confuted by the
American oil-fields, yielding many thousands of barrels a day--often
in such quantities that the oil runs to waste for lack of a buyer.

The rivals for pre-eminence in lighting to-day are electricity, coal
gas, petroleum, and acetylene gas. The two former have the advantage
of being easily turned on at will, like water; the third is more
generally available.

The invention of the dynamo by Gramme in 1870 marks the beginning of
an epoch in the history of illumination. With its aid current of such
intensity as to constantly bridge an air-gap between carbon points
could be generated for a fraction of the cost entailed by other
previous methods. Paul Jablochkoff devised in 1876 his "electric
candle"--a couple of parallel carbon rods separated by an insulating
medium that wasted away under the influence of heat at the same rate
as the rods. The "candles" were used with rapidly-alternating
currents, as the positive "pole" wasted twice as quickly as the
negative. During the Paris Exhibition of 1878 visitors to Paris were
delighted by the new method of illumination installed in some of the
principal streets and theatres.

The arc-lamp of to-day, such as we see in our streets, factories, and
railway stations, is a modification of M. Jablochkoff's principle.
Carbon rods are used, but they are pointed towards each other, the
distance between their extremities being kept constant by ingenious
mechanical contrivances. Arc-lamps of all types labour under the
disadvantage of being, by necessity, very powerful; and were they only
available the employment of electric lighting would be greatly
restricted. As it is, we have, thanks to the genius of Mr. Edison, a
means of utilising current in but small quantities to yield a gentler
light. The glow-lamp, as it is called, is so familiar to us that we
ought to know something of its antecedents.

In the arc-lamp the electric circuit is _broken_ at the point where
light is required. In glow or incandescent lamps the current is only
_hindered_ by the interposition of a bad conductor of electricity,
which must also be incombustible. Just as a current of water flows in
less volume as the bore of a pipe is reduced, and requires that
greater pressure shall be exerted to force a constant amount through
the pipe, so is an electric current _choked_ by its conductor being
reduced in size or altered in nature. Edison in 1878 employed as the
current-choker a very fine platinum wire, which, having a melting
temperature of 3450 degrees Fahrenheit, allowed a very white heat to
be generated in it. The wire was enclosed in a glass bulb almost
entirely exhausted of air by a mercury-pump before being sealed. But
it was found that even platinum could not always withstand the heating
effect of a strong current; and accordingly Edison looked about for
some less combustible material. Mr. J. W. Swan of Newcastle-on-Tyne
had already experimented with carbon filaments made from cotton
threads steeped in sulphuric acid. Edison and Swan joined hands to
produce the present well-known lamp, "The Ediswan," the filament of
which is a bamboo fibre, carbonised during the exhaustion of air in
the bulb to one-millionth of an atmosphere pressure by passing the
electric current through it. These bamboo filaments are very elastic
and capable of standing almost any heat.

Glow-lamps are made in all sizes--from tiny globes small enough to top
a tie-pin to powerful lamps of 1000 candle-power. Their independence
of atmospheric air renders them most convenient in places where other
forms of illumination would be dangerous or impossible; _e.g._ in coal
mines, and under water during diving operations. By their aid great
improvements have been effected in the lighting of theatres, which
require a quick switching on and off of light. They have also been
used in connection with minute cameras to explore the recesses of the
human body. In libraries they illuminate without injuring the books.
In living rooms they do not foul the air or blacken the ceiling like
oil or gas burners. The advantages of the "Edison lamp" are, in short,
multitudinous.

Cheapness of current to work them is, of course, a very important
condition of their economy. In some small country villages the
cottages are lit by electricity even in England, but these are
generally within easy reach of water power. Mountainous districts,
such as Norway and Switzerland, with their rushing streams and high
water-falls, are peculiarly suited for electric lighting: the cost of
which is mainly represented by the expense of the generating apparatus
and the motive power.

One of the greatest engineering undertakings in the world is connected
with the manufacture of electric current. Niagara, the "Thunder of the
Waters" as the Indians called it, has been harnessed to produce
electrical energy, convertible at will into motion, heat, or light.
The falls pass all the water overflowing from nearly 100,000 square
miles of lakes, which in turn drain a far larger area of territory.
Upwards of 10,000 cubic yards of water leap over the falls every
second, and are hurled downwards for more than 200 feet, with an
energy of eight or nine million horse-power! In 1886 a company
determined to turn some of this huge force to account. They bought up
land on the American bank, and cut a tunnel 6700 yards long, beginning
a mile and a half above the falls, and terminating below them. Water
drawn from the river thunders into the tunnel through a number of
wheel pits, at the bottom of each of which is a water-turbine
developing 5000 horse-power. The united force of the turbines is said
to approximate 100,000 horse-power; and as if this were but a small
thing, the same Company has obtained concessions to erect plant on the
Canadian bank to double or treble the total power.

So cheaply is current thus produced that the Company is in a position
to supply it at rates which appear small compared with those that
prevail in this country. A farthing will there purchase what would
here cost from ninepence to a shilling. Under such conditions the
electric lamp need fear no competitor.

But in less favoured districts gas and petroleum are again holding up
their heads.

Both coal and oil-gas develop a great amount of heat in proportion to
the light they yield. The hydrogen they contain in large quantities
burns, when pure, with an almost invisible flame, but more hotly than
any other known gas. The particles of carbon also present in the flame
are heated to whiteness by the hydrogen, but they are not sufficient
in number to convert more than a fraction of the heat into light.

A German, Auer von Welsbach, conceived the idea of suspending round
the flame a circular "mantle" of woven cotton steeped in a solution of
certain rare earths (_e.g._ lanthanum, yttrium, zirconium), to arrest
the heat and compel it to produce bright incandescence in the
arresting substance.

With the same gas consumption a Welsbach burner yields seven or more
times the light of an ordinary batswing burner. The light itself is
also of a more pleasant description, being well supplied with the blue
rays of the spectrum.

The mantle is used with other systems than the ordinary gas-jet.
Recently two methods of illumination have been introduced in which the
source of illumination is supplied under pressure.

The high-pressure incandescent gas installations of Mr. William Sugg
supply gas to burners at five or six times the ordinary pressure of
the mains. The effect is to pulverise the gas as it issues from the
nozzle of the burners, and, by rendering it more inflammable, to
increase its heating power until the surrounding mantle glows with a
very brilliant and white light of great penetration. Gas is forced
through the pipes connected with the lamps by hydraulic rams working
gas-pumps, which alternately suck in and expel the gas under a
pressure of twelve inches (_i.e._ a pressure sufficient to maintain a
column of water twelve inches high). The gas under this pressure
passes into a cylinder of a capacity considerably greater than the
capacity of the pumps. This cylinder neutralises the shock of the
rams, when the stroke changes from up-to downstroke, and _vice versâ_.
On the top of the cylinder is fixed a governor consisting of a strong
leathern gas-holder, which has a stroke of about three inches, and
actuates a lever which opens and closes the valve through which the
supply of water to the rams flows, and reduces the flow of the water
when it exceeds ten or twelve inches pressure, according to
circumstances. The gas-holder of the governor is lifted by the
pressure of the gas in the cylinder, which passes through a small
opening from the cylinder to the governor so as not to cause any
sudden rise or fall of the gas-holder. By this means a nearly constant
pressure is maintained; and from the outlet of the cylinder the gas
passes to another governor sufficient to supply the number of lights
the apparatus is designed for, and to maintain the pressure without
variation whether all or a few lamps are in action. For very large
installations steam is used.

Each burner develops 300 candle-power. A double-cylinder steam-engine
working a double pump supplies 300 of these burners, giving a total
lighting-power of 90,000 candles. As compared with the cost of
low-pressure incandescent lighting the high-pressure system is very
economical, being but half as expensive for the same amount of light.

It is largely used in factories and railway stations. It may be seen
on the Tower Bridge, Blackfriars Bridge, Euston Station, and in the
terminus of the Great Central Railway, St. John's Wood.

Perhaps the most formidable rival to the electric arc-lamp for the
lighting of large spaces and buildings is the Kitson Oil Lamp, now so
largely used in America and this country.

The lamp is usually placed on the top of an iron post similar to an
ordinary gas-light standard. At the bottom of the post is a chamber
containing a steel reservoir capable of holding from five to forty
gallons of petroleum. Above the oil is an air-space into which air has
been forced at a pressure of fifty lbs. to the square inch, to act as
an elastic cushion to press the oil into the burners. The oil passes
upwards through an extremely fine tube scarcely thicker than electric
incandescent wires to a pair of cross tubes above the burners. The top
one of these acts as a filter to arrest any foreign matter that finds
its way into the oil; the lower one, in diameter about the size of a
lead-pencil and eight inches long, is immediately above the mantles,
the heat from which vaporises the small quantity of oil in the tube.
The oil-gas then passes through a tiny hole no larger than a
needle-point into an open mixing-tube where sufficient air is drawn in
for supporting combustion. The mixture then travels down to the
mantle, inside which it burns.

An ingenious device has lately been added to the system for
facilitating the lighting of the lamp. At the base of the lamp-post a
small hermetically-closed can containing petroleum ether is placed,
and connected by very fine copper-tubing with a burner under the
vaporising tube. When the lamp is to be lit a small rubber bulb is
squeezed, forcing a quantity of the ether vapour into the burner,
where it is ignited by a platinum wire rendered incandescent by a
current passing from a small accumulator also placed in the lamp-post.
The burner rapidly heats the vaporising tube, and in a few moments
oil-gas is passing into the mantles, where it is ignited by the
burner.

So economical is the system that a light of 1000 candle-power is
produced by the combustion of about half-a-pint of petroleum per hour!
Comparisons are proverbially odious, but in many cases very
instructive. Professor V. B. Lewes thus tabulates the results of
experiments with various illuminants:--

_Cost of 1000 candles per hour._

                                               _s. d._
    Electricity  Per unit, 3-1/2d.
         "       Incandescent,                 1   2
         "       Arc,                          0   3-3/4
    Coal-gas     Flat flame,                   1   6
         "       Incandescent,                 0   2-1/4
         "       " high pressure,              0   1-3/4
    Oil          Lamp (oil at 8d. per gall.),  0   7-1/4
     "           Incandescent lamp,            0   2-1/4
     "           Kitson lamp,                  0   1

Petroleum, therefore, at present comes in a very good first in
England.

The system that we have noticed at some length has been adapted for
lighthouse use, as it gives a light peculiarly fog-piercing. It is
said to approximate most closely to ordinary sunlight, and on that
account has been found very useful for the taking of photographs at
night-time. The portability of the apparatus makes it popular with
contractors; and the fact that its installation requires no tearing up
of the streets is a great recommendation with the long-suffering
public of some of our large towns.

Another very powerful light is produced by burning the gas given off
by carbide of calcium when immersed in water. _Acetylene_ gas, as it
is called, is now widely used in cycle and motor lamps, which emit a
shaft of light sometimes painfully dazzling to those who have to face
it. In Germany the gas is largely employed in village streets; and in
this country it is gaining ground as an illuminant of country houses,
being easy to manufacture--in small gasometers of a few cubic yards
capacity--and economical to burn.

Well supplied as we are with lights, we find, nevertheless, that
savants are constantly in pursuit of an _ideal_ illuminant.

From the sun are borne to us through the ether light waves, heat
waves, magnetic waves, and other waves of which we have as yet but a
dim perception. The waves are commingled, and we are unable to
separate them absolutely. And as soon as we try to copy the sun's
effects as a source of heat or light we find the same difficulty. The
fire that cooks our food gives off a quantity of useless light-waves;
the oil-lamp that brightens one's rooms gives off a quantity of
useless, often obnoxious, heat.

The ideal illuminant and the ideal heating agent must be one in which
the required waves are in a great majority. Unfortunately, even with
our most perfected methods, the production of light is accompanied by
the exertion of a disproportionate amount of wasted energy. In the
ordinary incandescent lamp, to take an instance, only 5 or 6 per cent.
of the energy put into it as electricity results in light. The rest is
dispelled in overcoming the resistance of the filament and agitating
the few air-molecules in the bulb. To this we must add the fact that
the current itself represents but a fraction of the power exerted to
produce it. The following words of Professor Lodge are to the point on
this subject:--

"Look at the furnaces and boilers of a steam-engine driving a group of
dynamos, and estimate the energy expended; and then look at the
incandescent filaments of the lamps excited by them, and estimate how
much of their radiated energy is of real service to the eye. It will
be as the energy of a pitch-pipe to an entire orchestra.

"It is not too much to say that a boy turning a handle could, if his
energy were properly directed, produce quite as much real light as is
produced by all this mass of mechanism and consumption of
material."[6]

     [6] Professor Oliver Lodge, in a lecture to the Ashmolean
     Society, 3rd June 1889.

The most perfect light in nature is probably that of the glow-worm and
firefly--a phosphorescent or "cold" light, illuminating without
combustion owing to the absence of all waves but those of the
requisite frequency. The task before mankind is to imitate the
glow-worm in the production of isolated light-waves.

The nearest approach to its achievement has occurred in the
laboratories of Mr. Nikola Tesla, the famous electrician. By means of
a special oscillator, invented by himself, he has succeeded in
throwing the ether particles into such an intense state of vibration
that they become luminous. In other words, he has created vibrations
of the enormous rapidity of light, and this without the creation of
heat waves to any appreciable extent.

An incandescent lamp, mounted on a powerful coil, is lit _without_
contact by ether waves transmitted from a cable running round the
laboratory, or bulbs and tubes containing highly rarefied gases are
placed between two large plate-terminals arranged on the end walls. As
soon as the bulbs are held in the path of the currents passing through
the ether from plate to plate they become incandescent, shining with a
light which, though weak, is sufficiently strong to take photographs
by with a long exposure. Tesla has also invented what he calls a
"sanitary" light, as he claims for it the germ-killing properties of
sunshine. The lamps are glass tubes several feet long, bent into
spirals or other convolutions, and filled before sealing with a
certain gas. The ends of the glass tube are coated with metal and
provided with hooks to connect the lamp with an electric current. The
gas becomes _luminous_ under the influence of current, but not
strictly incandescent, as there is very little heat engendered. This
means economy in use. The lamps are said to be cheaply manufactured,
but as yet they are not "on the market." We shall hear more of them in
the near future, which will probably witness no more interesting
development than that of lighting.

Before closing this chapter a few words may be said about new heating
methods. Gas stoves are becoming increasingly popular by reason of the
ease with which they can be put in action and made to maintain an even
temperature. But the most up-to-date heating apparatus is undoubtedly
electrical. Utensils of all sorts are fitted with very thin heating
strips (formed by the deposition of precious metals, such as gold,
platinum, &c., on exceedingly thin mica sheets), through which are
passed powerful currents from the mains. The resistance of the strip
converts the electromotive energy of the current into heat, which is
either radiated into the air or into water for cookery, &c.

In all parts of the house the electric current may be made to do work
besides that of lighting. It warms the passages by means of special
radiators--replacing the clumsy coal and "stuffy" gas stove; in the
kitchen it boils, stews, and fries, heats the flat-irons and ovens; in
the breakfast room boils the kettle, keeps the dishes, teapots, and
coffee-pots warm; in the bathroom heats the water; in the smoking-room
replaces matches; in the bedroom electrifies footwarmers, and--last
wonder of all--even makes possible an artificially warm bed-quilt to
heat the chilled limbs of invalids!

The great advantage of electric heating is the freedom from all smell
and smoke that accompanies it. But until current can be provided at
cheaper rates than prevail at present, its employment will be chiefly
restricted to the houses of the wealthy or to large establishments,
such as hotels, where it can be used on a sufficient scale to be
comparatively economical.

                               THE END


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  THE ROMANCE OF MODERN ELECTRICITY


  By EDMUND SELOUS

  THE ROMANCE OF THE ANIMAL WORLD
  THE ROMANCE OF INSECT LIFE


  By AGNES GIBERNE

  THE ROMANCE OF THE MIGHTY DEEP


  SEELEY & Co., LIMITED







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