Beam compass made by George Adams (the Younger), Fleet Street, London, 1775-1795.
This beam scale was used for technical drawing tasks such as creating large arcs and bisecting lines or angles. It consists of a mahogany beam inlaid with a boxwood scale of 0 - 33 inches and divided into tenths. The pointer can be finely adjusted by means of a micrometer screw one end. George Adams the Younger made instruments for King George III and the then Prince of Wales (the future King George IV).