bow-compass \bow"-com`pass\, n.; pl. bow-compasses.
   1. an arcograph.
      1913 webster

   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.
      1913 webster

   3. a pair of compasses, with a bow or arched plate riveted to
      one of the legs, and passing through the other.
      1913 webster
see also:
bow-compasses