These are records of the United States Exploring Expedition under the command of Lieutenant Charles Wilkes, and include letters, journals, ship's logs, and records of court martials.

This ship's log consists of a vertical-turned brass rod with a slot in the top for a pulley or fulcrum which is missing. A pair of shorter rods support between them a pivoted brass quadrant which is scaled but not numbered. The base is scaled radially from the axis of the quadrant. Inscribed "Porters A Conno(e)r" on the base. Paper on underside label marked "Porter Constant Log." (Robert P. Multhauf, "Catalogue of Instruments and Models," 1961).