Webster’s Revised Unabridged Dictionary · 1913
Bow-compass
Bow′-com′pass (bō′kŭm′pas), n.; pl. Bow-compasses.
1. An arcograph.
2. A small pair of compasses, one leg of which carries a pencil, or a pen, for drawing circles. Its legs are often connected by a bow-shaped spring, instead of by a joint.
3. A pair of compasses, with a bow or arched plate riveted to one of the legs, and passing through the other.