Washington, D.C. August 20, 1819. Three vellum sheets, stab sewn with green silk ties, 14 3/4 x 11 in. (375 x 279 mm). Partially-printed document, signed by James Monroe as President of the United States, and John Quincy Adams as Secretary of State, being an official Letters Patent for Benjamin Wilmer, inventor of "an Instrument for measuring Heights & Distances." Counter-signed by Attorney General William Wirt, as well as Wilmer, at bottom. Second in third sheets comprising autograph patent schedule, signed by Wilmer. Original paper seal and silk ties intact. Creasing from old folds; leaves variously soiled. Elliot, William. A List of Patents Granted by the United States...1790-1820, p. 27

An official Letters Patent for Benjamin Wilmer of Baltimore, signed by President James Monroe and Secretary of State John Quincy Adams. The invention is described in Wilmer's own words as a compound quadrant manufactured from brass, that "may be advantageously used in the surveying of land..." or "In determining distances at sea..."