The papers consist of logs, 1748 to 1771, letter and order books, 1757 to 1771, sailing and fighting instructions, 1747 to 1778, and notes and personal papers, 1759 to 1780. There are also some of Clements's charts in the Department of Navigation and Astronomy

Administrative / biographical background
Between 1748 and 1749 Clements served in the East Indies in the Syren. He was in the Unicorn firstly in the Mediterranean and later in the Western Squadron, from 1755, when he became a lieutenant, until 1757, when he was promoted to captain and given command of the London buss In 1758 he was posted into the Actaeon in home waters and from 1759 to 1763 he commanded the Pallas , at first under Admiral Hawke (q.v.) in the Channel and later in the Mediterranean. He was at Portsmouth in the Dorsetshire in 1770 and in the Channel in the Vengeance in 1778. He became a rear-admiral in 1790.