Circumferentor, 1771-1781

Circumferentor, 1771-1781.
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 tradecard on the box lid reads: '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'.
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