Demonstration model of single digit carry mechanism from Schickard calculator
1 x 8 1/2 x 4 3/4 in.
Object is a hand-made demonstration model comprising two digit wheels and a carry (?) mechanism between them. The frame is of balsa (?) wood. The rotating parts are of wood on wood axles. A small spring is formed of a paper clip or similar wire. Hand-written on the back in pencil: "Paul Van Deusen / John Mcnally"