Addometer Model C

This eight-wheeled stylus-operated non-printing adding machine has plastic wheels and a metal frame. The first wheel is red and has eight holes near its edge for adding fractions. The second wheel from the left is white and has 12 holes near its edge for adding inches. The remaining six wheels each have ten holes around the edge. The rightmost is red, the next three are white, and the next two are red. All the wheels are labeled around the outside with digits for use in addition, and around the inside with digits for use in subtraction. A steel stylus and a clearing bar fit into the right side.
The top edge of the instrument has an 11-inch scale of equal parts, divided to sixteenths of an inch. A sales receipt indicates the machine was purchased September 19, 1951, by Frederick Mathesius for $12.95. A second sheet gives operating instructions. The machine is stored in a tan and purple cardboard box. It was made by Reliable Typewriter & Adding Machine Company of Chicago, Illinois.
Typewriter Topics, vol. 66, August, 1927, pp. 36-37 (announced as coming in September - $10.00), Typewriter Topics, vol. 72, June, 1929, p. 29 (cost $15.00); Office Appliances, vol. 87, January, 1948, p. 138, 182 (price $12.95); Office Appliances, vol. 98, Oct., 1953, p. 233 (price $14.95).
Currently not on view
date made
H. & M. Button Company
Reliable Typewriter & Adding Machine Corporation
place made
United States: Illinois, Chicago
place distributed
United States: New York, Rochester
Physical Description
paper (overall material)
plastic (overall material)
metal (overall material)
overall: 1.8 cm x 30.5 cm x 6.5 cm; 23/32 in x 12 in x 2 9/16 in
ID Number
catalog number
accession number
Credit Line
Gift of Douglas E. Evelyn & Martha M. Evelyn
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Adding Machines
Data Source
National Museum of American History


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