The Kesling Pocket Adder, a.k.a. Kes-Add, a small adding device
Channel: Jaap Scherphuis
Date: 2016-09-14

The Kesling Pocket Adder, or Kes-Add, is a small adding device from the 1950s.
To add a number, you use a stylus to dial in the number on the four dials. To subtract, just dial it in anticlockwise.

To view my collection of mechanical calculators, visit my website:
https://www.jaapsch.net/mechccalc/