Comptometer Model B, 1/20 Fraction

This full-keyboard non-printing adding machine has a metal top and mechanism, eight columns of color-coded octagonal plastic keys with complementary digits indicated, and a zeroing crank on the right side. The second column of keys from the right has only one key in it. The keys are alternately concave (odd digits) and flat (even digits). Nine rows of number wheels in front of the keyboard indicate the result. The second number wheel from the right has only zeros and ones on it. The sides and base of the machine are missing. It is marked on a metal tag screwed to the top at the back: TRADE COMPTOMETER MARK. The last patent date on the tag is: AUG.9.04.
This is a forerunner of the Model C Comptometer for British currency (MA*323652).
Felt & Tarrant, Accession Journal 1991.3107.06.
Currently not on view
Object Name
adding machine
date made
Felt & Tarrant Manufacturing Company
Physical Description
wood (overall material)
metal (overall material)
plastic (overall material)
overall: 14.5 cm x 24 cm x 36 cm; 5 23/32 in x 9 7/16 in x 14 3/16 in
place made
United States: Illinois, Chicago
ID Number
catalog number
accession number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Victor Comptometer Corporation
Additional Media

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