Comptometer Study Model 520 Series (?) Adding Machine Section

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This is a model of a section of a Comptometer. It has a single column of white plastic numeral keys. Alternate keys are concave (odd digits) and flat (even digits). Left of the number keys are two red keys. One is marked: UNIVERSAL (/) KEY (/) DRIVE. The other is marked: INDIVIDUAL (/) KEY (/) DRIVE. The section of a metal case under the keys is painted brown. The mechanism is steel. The model has no numeral wheels, no zeroing lever, no base, and no cover.
During the late 1920s, J. A. V. Turck of Felt & Tarrant Manufacturing Company worked on inventing an adding machine that could either be driven by striking individual keys (have an individual key drive, in his language), or by setting keys and then driving them simultaneously (having a universal key drive, in his language). This object relates to that effort. Comptometers had traditionally used individual key drive.
U.S. Patent 1869872, granted August 2, 1932.
Felt & Tarrant, Accession Journal, #134, 135, 136, 150.
Currently not on view
date made
ca 1927
Felt & Tarrant Manufacturing Company
place made
United States: Illinois, Chicago
Physical Description
steel (overall material)
plastic (overall material)
overall: 14.5 cm x 7.2 cm x 31 cm; 5 23/32 in x 2 27/32 in x 12 7/32 in
ID Number
catalog number
accession number
Credit Line
Gift of Victor Comptometer Corporation
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History


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