The circumferentor (or surveyor’s compass) was the basic tool of any surveyor during the period. These instruments were produced in brass and wood and were made both in England as well as the Colonies. Typically, Mid-Atlantic examples were constructed of brass.

The instrument operates the same as a pocket compass but is larger in size. A pair of sights are located on the North-South axis of the compass. Circumferentors were typically mounted on three-legged staff (tripod) and rotated on ball and socket joint.