Single-barrelled air pump, late 18th century.

This pump is very similar to the one designed by John Smeaton (1724-1792) in 1750. Smeaton's design had a single barrel and the valves and pistons were carefully designed to allow as much air as posible to be exhausted. George Adams, and later, Edward Nairne and Blunt made pumps to Smeaton's design. It may be that this pump was made by one of these makers.