This calcumeter is marked 89939 79, the former being the serial number and the purpose of the second two digits yet to be established.1 This Calcumeter is later than 1907 or later as it includes the upgraded RESET dial on the right of its input dials which was patented in November of 1907. A chronology of the Calcumeters compiled by Robert Otnes suggests that by 1 Jan 1909 there were “50,000 in use” and in a further year’s time “60,000 in use”.2 Assuming the serial numbers are sequential this suggests a dating of 1912 for this Calcumeter.

The Calcumeter was invented by James J. Walsh of Elizabeth, N.J. He received a patent for it December 17, 1901 (U.S. Patent 689,225). First manufactured by Morse & Walsh Company over 1903–4, by 1906 it was being produced by Herbert North Morse of Trenton and was sold until 1915 and had disappeared by 1920 after being outclassed by machines such as the Lightening Adder. An early rotating gear adder, as with many that would follow it, the Calcumeter utilised a stylus for input.

All dials are reset to zero by spinning the RESET dial fully clockwise, and then fully counterclockwise. The Calcumeter was available in various models with 6 to 12 input dials. Two swivel legs hold the calcumeter at about a 30 degree angle, or can be folded for flat use on the desk.

Whilst some list the Calcumeter as following in the footsteps of the Pascaline it uses a quite different method for storing potential energy in order to affect a carry across its dials. Whilst the Pascaline used a sortoir weight which was progressively lifted until a carry occurred, the Calcumeter achieved this by storing the energy of the turned dials in springs, which were released as the dial moved from 9 to 0 triggering an addition of 1 to the next dial to the left.

The machine is made of steel, nickel, brass and German Silver (an alloy of nickel, copper and zinc), which is reflected in the color variations amongst the various components.

Length - 8 3/4” Width - 2” Height - 3/4”

The mechanism diagrams from the 1901 Calcumeter Patent by James Walsh are shown below:


1 Robert Otnes, The Calcumeter, IEEE Annals of the History of Computing, Vol. 20, No. 1, 1988, p. 68 (↑)

2 ibid. (↑)

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