A pioneer in ethnographic and linguistic studies of the American Indian and one of the most active members of the American Philosophical Society, Peter Stephen Du Ponceau helped to establish the American Philosophical Society's reputation as one of the world's foremost centers for the study of American Indians and their languages. The Peter Stephen Du Ponceau collection consists of correspondence on legal matters, Indian linguistics, silk culture, maritime law, the American Philosophical Society, and various publications of the early nineteenth century. The collection also includes several essays by Du Ponceau, most of which deal with maritime law.

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.