Correspondence, diaries, essays, research notes, photographs, and other papers, relating chiefly to Tuttle's astronomical, historical, and genealogical research; togeher with records (1859-1893) of the Prince Society, historians' organization based in Boston, consisting mainly of correspondence relating to membership and sale of publications, bills, receipts, and membership files. Includes historical correspondence pertaining to Tuttle's work on Captains John Mason and Francis Champerowne and genealogical correspondence with members of the Tuttle, Merrow, and related families. Other correspondents include John Ward Dean and other historians.