What’s small, made of plastic, has less than ten moving parts, is fun to play with… would you immediately cry “a calculating device”?
And yet – a calculating device it is, the Kes-Add Pocket Adder, manufactured by the Kesling Pocket Adder Company of St. Louis, Missouri. “An Adding Machine”, says the box to prevent any confusion, “Not a Toy!”
This device is simple and lightweight; and the ivory-colored plastic is surprisingly elegant, avoiding the “cheap” look typical of many old plastics.
The Kes-Add has no Reset option; to zero it before a calculation you must turn each wheel to the zero position, by placing the stylus in the hole next to the “X” and rotating until the X is hidden. Now you can add and subtract numbers by turning the wheels with the stylus, Clockwise for addition, Counterclockwise for subtraction, one digit at a time.
Here are two pages from the fanfold instruction leaflet.
This calculator was invented and produced by Elmer G. Kesling of Bloomfield, Missouri. I talked to his nephew, and learned that Elmer was a dentist and also a prolific inventor; he has patents to his name in areas as diverse as dentures, surgical instruments, gardening tools, automotive systems, and calculation devices. In fact, he won a big lawsuit against General Motors for a gear shift system patent they’d infringed on (and used in their cars). You can read about this David and Goliath story here. Turns out that Dr. Kesling was an indomitable inventor and tinkerer – my king of guy!
All this may seem unusual for a dentist, but not in the Kesling family. I learned that dentist-inventors were plentiful in that family back then – the nephew named three others in the same generation besides Elmer!
Exhibit provenance:
Another nice find on eBay.
More info: A wealth of information can be found on Jaap Scherphuis’s site.