Comptometer Model F

This full-keyboard non-printing adding machine represents the successful adoption of mechanical aids to computation by American scientists. It was one of several computing devices owned by the meteorologist Daniel Draper. Draper used Comptometers in his work at the New York Meteorological Observatory from about 1886. He acquired this machine in 1914 or later.

The machine has a metal case painted brown and a metal mechanism, with eight columns of octagonal, color-coded plastic keys. Complementary digits are indicated on the keys. Keys for odd digits are concave, and those for even digits are flat. The length of the key stems increases going from front to back. There are subtraction levers, numbered decimal markers in front of the keys, and nine windows to show the result in front of the decimal markers. A zeroing handle is on the right side. The machine fits on a wooden stand and has a metal cover painted black.

The machine has serial number F58074. It is marked on a metal plaque screwed to the back of the machine: TRADE COMPTOMETER MARK (/) PAT'D [. . .] (/) Felt & Tarrant Mfg. Co. (/) CHICAGO. It is also marked there with several patent dates, the last of which is; SEP.15.14. It is marked on the front of the metal cover: COMPTOMETER (Pronounced like Thermometer) (/) FELT & TARRANT MFG. CO. (/) CHICAGO. U.S.A. (/) Adds - Divides (/) Multiplies - Subtracts

Reference:

P. A. Kidwell, “American Scientists and Calculating Machines: From Novelty to Commonplace,” Annals of the History of Computing, 12, 1990, pp. 31-40.

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