Papers, 1795-1846, but mainly correspondence, lecture notes, diagrams, and memoranda, 1818-1828, concerning the junior Symmes's theory of planetary construction. Correspondence with editors, congressmen, military and naval officers, diplomatic representatives of Russia and Great Britain, and academic societies throughout the world attest to his efforts to arouse interest in his theory and to gain support for a scientific polar expedition. Family papers include a few autobiographical notes, one letter from his cousin Anna (“Nancy”) Symmes Harrison (Mrs. William Henry Harrison), two to his brother Peyton, undated fragments written to his wife during his army career, and undated notes for a will. A few letters and notes refer to provisions for use or sale of his three slaves. There are several drafts of military letters (1805) and notes and a newspaper article (1821) pertaining to service of the First Regiment in the War of 1812. Symmes's other correspondents included Eben I. Bell, Lewis Bissell, William B. Champney, Thomas S. Hinde, James McBride, John McLean, Samuel L. Mitchell, Horatio Gates Spafford, and William A. Trimble.

The few papers of the elder Symmes in this volume include an Ohio land agreement to which Symmes, Jonathan Dayton, Israel Ludlow, Arthur St. Clair, and James Wilkinson were principal parties, and a list of mortgages to be sold by Symmes in 1804. A biographical and genealogical account of the judge and his family is embodied in a letter (1846) by John Cleves Short.