In astronomy, a surveyor's compass is used to measure an arc of the horizon from a southern point to an intersection on the horizon made by a vertical circle that passes through an object in the sky. This particular one belonged to Epaphras Hoyt, the uncle of Edward Hitchcock, who encouraged his nephew in his enthusiasm for astronomy. The two published a paper together in the Journal of the American Academy of Arts and Sciences, although only in Hoyt's name.