The Library is the room which constituted the headquarters of Washington, the manager of a great estate. His personal correspondence, official letters, the daily entries in his diary and his accounts were all written at the desk in this room. The desk was purchased by the President in Philadelphia before he retired. The original thermometer barometers hang at either side of the desk. the mahogany case, the globe and a pair of the General's spectacles are original. Washington books and other that belonged to members of his immediate family are grouped in the first of the four built-in bookcases. Of the books in the other cases many duplicate volumes that were owned by Washington.