bow compass with steel caliper points

This caliper is essential a bow compass whose removable drawing points have been replaced by steel caliper points. The inserts are secured by ornamental butterfly-head screws. The caliper points can be set for measuring outside dimensions or turned to measure inside dimensions. One caliper point is marked with two dots. The leg of the compass there is marked "I."

The bow is held in place on one leg by a pierced, scrolling wing nut. It passes through a slot in the other arm and is fixed to a set opening with a trefoil-headed screw. The bow is divided on one side from 3-22, with 4 subdivisions per number. On the other side it is divided 20-90, with subdivisions every 1 unit. The latter scale does not correspond with degrees that the compass is open. The former scale does not correspond with inches separating the caliper points. Both scales are quite worn.