J. T. Campbell Adding Machine

Campbell, J. T. · 1859

This U.S. Patent Office model for a finger-operated adding machine has four metal wheels set flat into a wooden case with a metal top (the fifth wheel is missing). Around the top edge of each wheel are ten short pins labeled clockwise from 0 to 9. Above each wheel is a round opening in the case. The edge of this opening is also labeled clockwise from 0 to 9. The mechanism linking the wheels is out of order. The patent tag is tied to the machine. It reads: 24.990 (/) J.T. Campbell (/) Adding Mch. (/) Patented August 9, (/) 1859.