Comptometer, Wooden Box Model

By the 1880s, American business and government used reams of figures to track how they were doing. The Comptometer, invented in Chicago by Dorr E. Felt in the mid-1880s, was one of the first machines that sold successfully to help with this work. This key-driven machine is one of the first eight Felt built for customers. It has eight columns of metal keys with nine keys in each column. The keys are stamped with the digits from 1 to 9. The case is of cherry, with a metal plate at the front. Nine windows in this metal plate reveal digits on nine number wheels that indicate the total. A zeroing lever and knob are on the left side of the machine.
This particular Comptometer was used for many years by Joseph S. McCoy, Actuary of the U.S. Treasury. Felt and his associates would greatly improve the machine, and sell it successfully throughout much of the world.
U.S. Patent 366945, (Application July 6, 1887, granted July 19, 1887); U.S. Patent 371496 (application March, 1887, granted October 11, 1887).
Accession Journal 1991.3107.06.
J. A. V. Turck, Origin of Modern Calculating Machines, Chicago: Western Society of Engineers, 1921.
Currently not on view
Object Name
adding machine
date made
Felt, Dorr E.
Physical Description
cherry wood (overall material)
metal (overall material)
overall: 15 cm x 19.6 cm x 37.7 cm; 5 29/32 in x 7 23/32 in x 14 27/32 in
place made
United States: Illinois, Chicago
ID Number
catalog number
accession number
Science & Mathematics
Adding Machines
See more items in
Medicine and Science: Mathematics
Adding Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Dorr E. Felt

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