These are primarily letters, with some receipts for medical services rendered included. They relate to the general social and intellectural life of Philadelphia and to publications on medical topics. Many of the letters are introductions to Europeans when Pennock first visited there. Letters dated post-1867 are to relatives and colleagues (?).

Letters and papers relating to Sparks's research on Benjamin Franklin and the publication of an edition of the latter's writings. There are also extracts from Sparks's journal, 1831-1841, relating to his Franklin researches.

These selected papers include correspondence concerning Franklin, Franklin's descendants, and Franklin's papers, extracts from Philadelphia newspapers on Franklin, papers used in Sparks' biography, miscellaneous entries in his diary (1830-1854) relating to his search for Franklin manuscripts, and his preparation of an edition of Franklin's writings. Correspondents include Henry Stevens, Jr.; Henry Stevens, Sr.; Benjamin Vaughan; Petty Vaughan; James Mease; H. D. Gilpin; J. Francis Fisher; Franklin Bache; and others.

Personal and professional correspondence of the chemist Robert Hare, including drafts of letters to editors of journals on such varied topics as fish guano, slaughterhouses, paper money, and the meaning of the term "Yankee annexations." The collection originally contained over 300 scrolls, since disbound, which contained drafts of letters, essays, and lectures, composed by Hare on ordinary sheets of paper, then pasted end to end, and rolled up. The essay and lecture topics include: chemistry, storms, slavery, currency, fire-fighting, capital punishment, railroads, the Smithsonian Institution, Michael Faraday, religion and Spiritualism, riots in Philadelphia, epidemics, underwater blasting, and Ralph W. Emerson; there is some verse. The collection also contains an account book of Hare and his wife, 1806-1829 (180 pp.; B/H22#3); a volume by Hare on Cyclones (tornadoes), n.d. (ca. 60 pp.; B/H22#4); and Samuel Powel, Jr.'s "Short notes on a course of antiquities at Rome... under M. Byre Antiquarian," 1764. (60 pp.).

The Thomas Jefferson papers contain a large number of correspondence both to and from Jefferson, as well as various other material related to American Revolutionary War and Early Republic. Includes correspondence with Patrick Henry, Charles Willson Peale, Richard Henry Lee, Horatio Gates, David Rittenhouse, Robert Patterson

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).