bow compasses
Webster's Dictionary (GCIDE)
Compasses \Com"pass*es\, n., pl. An instrument for describing circles, measuring figures, etc., consisting of two, or (rarely) more, pointed branches, or legs, usually joined at the top by a rivet on which they move. [1913 Webster]
Note: The compasses for drawing circles have adjustable pen points, pencil points, etc.; those used for measuring without adjustable points are generally called dividers. See Dividers. [1913 Webster]
Bow compasses. See Bow-compass.
Caliber compasses, Caliper compasses. See Calipers.
Proportional, Triangular, etc., compasses. See under Proportional, etc. [1913 Webster]