|a Du Ponceau was a Philadelphia lawyer who arrived in Portsmouth, N.H., from France in 1777, achieved early prominence as an aide to von Steuben, and as secretary to Robert Livingston, Secretary of Foreign Affairs for the Congress in 1781. Du Ponceau was admitted to the Philadelphia Bar in 1785 where his familiarity with both American and European law brought him an important practice. His intellectual interests included both history and linguistics and he published extensively in both fields. He was a member and officer of both the American Philosophical Society and the Historical Society of Pennsylvania.
A group of incoming letters relate to law, linguistics, and, less importantly, history, 1781-1827. Among the correspondents are James Fenimore Cooper and John Sergeant on law, George W. Featherstonhaugh, Albert Gallatin, and John Pickering on linguistics, and Jared Sparks on history. The second group consists of Du Ponceau's correspondence and notes, including notes on silk culture, 1820s, copies of the legal opinions of Bushrod Washington, and papers dealing with constitutional questions in Alabama, 1831-1833. Also present in this group are autobiographical letters, 1836-1844, addressed to Robert Walsh and others. The third group contains Du Ponceau's letter books, 1792-1801, 1803-1814, 1820-1842; legal precedents, 1784-1798, 1801-1830; letters, 1818-1843, from John Pickering, the Boston lawyer and judge who shared Du Ponceau's interest in linguistics.
Du Ponceau's notes and abstracts concerning the origin of the American Philosophical Society, taken from the minutes of the Junto, the American Society for Promoting Useful Knowledge, the American Philosophical Society, and from the Jared Sparks edition of the Works of Benjamin Franklin.
The transcriptions of letters sent to Du Ponceau, prepared by Job R. Tyson, a Vice-President of the Historical Society of Pennsylvania, were to be used for a memorial biography of Du Ponceau, prepared after his death in 1844. Tyson's selection reflects a strong bias toward military and political figures including DeWitt Clinton, James Kent, John Marshall, James Madison, and James Monroe.