Wooden Box Model Comptometer

This key-driven non-printing adding machine has eight columns of metal keys, with nine keys in each column. It indicates totals with as many as nine digits. It is the sixth of eight production models made by American inventor and entrepreneur Dorr E. Felt of Chicago as he began his work with key-driven adding machines in 1886 and 1887.
The keys in each column are stamped with the numbers from 1 to 9, with the digits colored black. The key stems pass through the key tops and there is a spring around each key stem. The stems become progressively longer as the digits get larger. No complementary digits are indicated, and the key tops are flat and entirely of metal. 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 right side of the machine. The base is covered with green felt. Metal and paper tags are stored with object.
The machine is marked on a metal tag screwed to the top in back of the keyboard: D.E.FELT MFR (/) PAT’S PENDING. A metal tag stored with the machine reads: 2. There is no serial number
According to the accession journal of Felt & Tarrant Manufacturing Company, received from the successor firm of Victor Comptometer Corporation, this was the sixth of the first eight marketable Comptometers built by Felt with the help of R. F. Foster in the fall of 1886. It was secured by Felt & Tarrant from Mr. Foster in 1938.
Felt & Tarrant, 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
cloth (overall material)
cherry wood (overall material)
metal (overall material)
overall: 12.9 cm x 19.2 cm x 36 cm; 5 3/32 in x 7 9/16 in x 14 3/16 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 Victor Comptometer Corporation
Additional Media

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