This instrument is inscribed with the scale, punched on the circle, '0(5)90(5)0(5)90(5)0', by degrees. It has one pair of fixed sights only and the compas is mising. Circumferentors (with a complete circle scale) and graphometers (with a half circle scale) were widely used through the 17th and 18th centuries for angle measurement. A joint on the support allowed for both vertical and horizontal use.
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