Very large compass with 2 large, steel caliper inserts to make a spherical caliper. Combination brass and steel sector-type joint with brass rivet and 2 steel cheekpieces. Two holes in 1 cheekpiece for insertion of a turnkey used in tightening the joint. Brass arms with steel wing screwed into 1 arm and sliding through other arm. All friction screws are steel with turning heads. The screw of the wing has a hand cut wing nut.
