Correspondence of Joseph Priestley, scientist, Unitarian minister, and republican theorist. The collection includes 41 letters written to John Vaughan, 1791-1800, 5 letters to other correspondents, and manuscripts and photostats of 68 items in the Municipal Library, Warrington, England, on theological issues, the internal development of the United States, the French Revolution and its aftermath, Unitarianism, science, his publications, and American Philosophical Society.