This collection consists almost entirely of letters, mostly written by Jefferson, to various people. The largest portion of the letters are from Jefferson to Louis Hue Girardin concerning the latter's work in completing The history of Virginia: from its first settlement to the present day, Volume 4 . Of particular interest is Jefferson's notes on his colleges' role in that history, including the plot to establish a dictator of Virginia. The letters to Girardin also include discussions of plants, the building of the University of Virginia, and books.

This is primarily a collection of letters and manuscripts sent to Wistar by prominent men who were among his many correspondents. These documents reflect his broad interests, including botany, paleontology, medicine, the American Philosophical Society, and André Michaux's plans for exploring the Missouri.

These papers include diaries (1777-1782), expense books (1794-1804), notebooks, a commonplace book, drafts of essays, excerpts from minutes of Friends' Monthly Meeting, Tortola (1741-1761), newspaper clippings, sketches, and correspondence. Also included are letters and papers of Mrs. Thornton.

Catherine Wistar Bache (1805-1886) was the point of connection between two of Philadelphia's most illustrious families of the late eighteenth century. Daughter of the physician Caspar Wistar, in November 1797 she married Dr. William Bache, who was the son of Richard Bache and the grandson of Benjamin Franklin. Primarily letters to Mrs. Bache (wife of Dr. William Bache) of Philadelphia, from Mrs. David Hosack (nee Mary Eddy), Mrs. Elizabeth Trist, and Mary Jones. The letters are personal and concern family life, activities of husbands, etc., with many references to Caspar Wistar, There are comments on diseases, education (at William and Mary College), war, and politics. References are also made to the deaths of Richard Bache and Caspar Wistar, and to Benjamin Franklin's Stockado (a musical instrument).

Transcripts and photocopies of Correia de Serra correspondence, made by Richard B. Davis for "The Abbé Correa in America," APS Transactions 45, 2 (1955). Seven mss. letters are also included.

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