Centigraph Adder

This nine-key manual non-printing adding machine has an iron case painted black, and nine white number keys arranged in two rows. It adds one digit at a time, up to and including 500. The digits of the result appear in three windows on the face of the machine, which is in the shape of an alarm clock. A zeroing knob is in the center of this face, and the result windows are above the knob. There is no maker’s mark on the machine.

The machine is identified as a Centigraph Adder in the accession file, although it differs from other machines with this name in having nine rather than five keys, in having a case, in the placement of the result windows, and in having paper and plastic rather than plastic key covers. Moreover it has a mechanical carry, unlike the Centigraph described in the patent. Two screws on back allow one to remove front cover. The mechanism appears to be steel, and quite different from A.E.Shattuck’s 1891 patent for the Centigraph.

References:

Arthur E. Shattuck, “Adding-Machine,” U.S. Patent 453,778, June 9, 1891.

Accession File.

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