AMCO Adding Machine
Physical Object
2019.07.02.01
The AMCO is a single-axis multi-column adding machine with a setting mechanism operated directly by finger pressure on rotary metal discs. Each setting disc has a series of projecting tabs numbered from 1 to 9, with complements from 8 to 0 for subtraction. The finger is placed on the required tab and drawn down to the shelf at the front, advancing the register at the top of the machine by the corresponding number of places. The short vertical tabs in front of the discs operate a locking mechanism to prevent overthrow on reaching the bottom of the stroke. The setting discs drive the register through a ratchet mechanism, and return to their home position when released.