Books in Browsing: Science - Earth/Agricultural/Farming (sorted alphabetically)
- Old Fashioned Flowers, and other out-of-door studies Maurice Maeterlinck
- Old Mines of Southern California Harold W. Fairbanks and William H. Storms
- Old Red Sandstone; or, New Walks in an Old Field Hugh Miller
- One Hundred Proofs That the Earth Is Not a Globe William Carpenter
- One Thousand Questions in California Agriculture Answered Edward J. Wickson
- On Naval Timber and Arboriculture Patrick Matthew
- On The Affinities of Leptarctus primus of Leidy Jacob Lawson Wortman
- On the cattle plague: or, Contagious typhus in horned cattle. Its history, origin, description, and treatment Honoré Bourguignon
- On the improved beet root, as winter food for cattle Pinder Simpson
- On the Red Chalk of England Thomas Wiltshire
- Orchids James O'Brien
- Organic Gardener's Composting Steve Solomon
- Origin of Cultivated Plants Alphonse de Candolle
- Ornithosauria H. G. Seeley
- Our Domestic Birds: Elementary Lessons in Aviculture John H. Robinson
- Our Humble Helpers: Familiar Talks on the Domestic Animals Jean-Henri Fabre
- Our national forests : a short popular account of the work of the United States Forest service on the national forests Richard H. D. Boerker
- Our Sentimental Garden Egerton Castle and Agnes Castle
- Outlines of the Earth's History: A Popular Study in Physiography Nathaniel Southgate Shaler
- Paper Shell Pecans Keystone Pecan Company
- Paradisi in sole paradisus terrestris, or, A garden of all sorts of pleasant flowers which our English ayre will permitt to be noursed vp John Parkinson
- Parsons on the Rose Samuel Browne Parsons
- peaches of New York U. P. Hedrick
- Peanut Plant: Its Cultivation And Uses B. W. Jones
- Pearls & Parasites Sir A. E. Shipley