Definition of "circumferentor" []

• An instrument used to measure horizontal angles, consisting of a brass circle and an index, all of one piece. (noun)

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• "Employed by the Board of Ordnance, William Roy began mapping the Highlands in 1747, pushing a surveyor's wheel and using a simple kind of theodolite called a circumferentor."
• "A circumferentor is, according to the OED: Surveying."
• "The ravines are deep, and the sides of the hills are covered with the same stone, of which a pile was erected on the summit of the head to mark the spot where the circumferentor was placed."