Haines Calculating Machine Patent Model

Haines, William M. · 1849

This patent model for an adder with a single digit mechanical carry has a wooden base and a circular metal mechanism. At the center is a brass disc that has 100 holes around the outside. Around it is a slightly elevated stationary ring, with the numbers from 1 to 9 engraved around it, representing 10, 20, etc, through 90. Between each of these numbers, smaller digits from 1 up to 9 are engraved. There is a stop at 0.