Circumferentor

A circumferentor is a surveying instrument used for measuring horizontal angles. It consists of a circular or semicircular arc that is graduated in degrees, allowing surveyors to set and read angular measurements accurately. The circumferentor typically features a sighting mechanism, such as a telescope or a sighting wire, to help align with survey points. Historically, circumferentors were used in various surveying applications, including land surveying, mapping, and construction.