The Calcumeter

The Calcumeter is a cogged-wheel dial adder that was operated by using a stylus (or a sharpish pencil would do). There were a number of different models running from 5 dials (as shown) all the way up to 12. Sometime around 1908 a reset mechanism was added. It is made of steel and brass and is approximately 6.25" L x 2" W in size. On the top edge are two folding legs that allow this to be placed at a maximum 45 degree angle when set on a desk top.

The model pictured is one of the earliest models. Its 5 dials have what is known as a stored-energy carry, which simply means that one full rotation of a dial automatically moves the dial to the left by one. There is no reset mechanism on this model so you reset it by starting at the far right and successively moving each dial to zero, a tedious task at best.

A more in-depth write-up about the Calcumeter can be found at https://americanstationer.wordpress.com/2013/04/08/the-calcumeter/.