Baldwin Calculating Engine

Baldwin, Frank S. · 1875

This is the U.S. Patent Office model for a printing pinwheel calculating machine patented by Frank S. Baldwin of St. Louis, Mo., in 1875. The machine has a brass base, two open brass pieces on each side that form a frame, and a brass, steel, and wooden mechanism. A cylindrical drum mounted horizontally on the frame is 11.5 cm. (4-1/2”) in diameter and 5 cm. (2”) in height.