These letters are principally to his brother John Cleaves Short, on personal, family, and general topics.

This diary is a journal of a trip from Philadelphia by stage to Pittsburgh, then afoot through Franklin, LeBoeuf, and Erie to the Huron River; thence by boat to Detroit, where he remained 26-29 July, when he set out by canoe for Michilimackinac. Included are descriptions of Detroit, plants, animals, springs, Indian mounds, and notes on goitre.

Zaccheus Collins' botanical correspondence, 1805-1827, from the Academy of Natural Sciences, Philadelpha.

These letters, from the Wellcome Historical Medical Society's collections, are on a variety of topics, primarily natural history and medicine.

These letters of American Philosophical Society members and prominent early American scientists were selected from Carson's extra-illustrated draft of "A History of the Medical Department of the University of Pennsylvania" (Philadelphia, 1869).

These papers reflect Isaac Hays' interests and activities in the medical profession and as an editor. His interest in paleontology, especially in the controversy with G. W. Featherstonhaugh, is also represented. There is one separate volume (77 letters) containing correspondence about natural history and naturalists, written to Hays by C. L. Bonaparte, George Ord, Thomas Say, and Charles A. Lesueur. The correspondence in the larger collection, however, contains much material on the American Journal of the Medical Sciences, particularly illuminated in the correspondence with John D. Godman. The I. Minis Hays material consists of letters from doctors, relating to medicine and medical publications and editing, as well as medical organizations. Most significant of the correspondence is that with John Shaw Billings (ca. 60 letters).

There is correspondence concerning geology, botany, natural history, natural selection, evolution, British science and scientists, and other scientific topics. Most of the letters are written by Lyell, with a very few items by others.

George Ord made important contributions as an ornithologist and writer but is also famous for his contempt of fellow ornithologist John James Audubon. Throughout his life he published numerous scientific articles and assisted in completing Alexander Wilson's life's work, American Ornithology; or, The Natural History of the Birds of the United States. Ord also left his mark as a member of the American Philosophical Society and as the president of the Academy of Natural Science of Philadelphia. The George Ord collection consists primarily of outgoing personal correspondence to Charles Waterton ranging from 1831 to 1866 that highlights Ord's professional as well as personal affairs, most notably his hostility toward Audubon. The collection is supplemented by correspondence of Ord's to and from various individuals regarding personal and business matters.