Circumferentor, 1771-1781.

This circumferentor was made by James Search of London. Circumferentors (with a full circle scale) and graphometers (with a half-circle scale) were widely used throughout the 17th and 18th centuries for angle measurement. A joint on the support allowed for both vertical and horizontal use. The inscription/ trademark is printed on the box lid: 'Mathematical/ Philosophical and Optical/ INSTRUMENTS/ Made and Repaird in the best Manner/ At the Globe in Crown Court, St Ann's Soho,/ London/ BY/ James Search, Instrument Maker'.