Personal, business, and legal letters; manuscripts including prose, poetry, and diaries; and documents including deeds, receipts, invoices, and account books. The 18th century materials focus on the personal and business correspondence of Calvin, Jotham, and Martin Gay, sons of Ebenezer Gay who were engaged in shipping between New England and the Maritime Provinces. There are occasional letters of Jotham and Martin referring to the American Revolution. The Otis family correspondence of the 18th century, likewise, is of a purely routine and personal nature. There are only four letters of Col. James Otis, and only two of his son, James. Gay and Otis family interests intertwine during the 19th century with the marriage of Mary Allyne Otis to Ebenezer Gay, who are among the chief correspondents of this century, along with their children including Sidney Howard Gay and Winckworth Allan Gay. The Otis correspondence centers around business, real estate, and personal interests of Mary A. Otis Gay's brothers John, Joseph, and William Otis.