This eight-wheeled stylus-operated adding machine has metal wheels and frame. The wheels each have ten holes around the edge. The two rightmost are white, the next three are red, and the next three are white. 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. The machine was made by the Reliable Typewriter & Adding Machine Company of Chicago, Illinois.
The instrument was purchased by Smithsonian curator Audrey B. Davis from Greybird Enterprises in Taneytown, Md., in 1990 for $45.00.
For a related accession, see 2010.0214. For another Addometer, see 1996.0220.01
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). Accession file.
Currently not on view
Object Name
adding machine
date made
ca 1950
Reliable Typewriter & Adding Machine Corporation
Physical Description
metal (overall material)
overall: 1.9 cm x 29.5 cm x 6.1 cm; 3/4 in x 11 5/8 in x 2 3/8 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 Miles Davis

Visitor Comments

11/6/2016 12:01:42 PM
ty thom
Hello. I have a addometer that of course I have no idea how to work. Can you tell me how. Also, researching this meter on the net, I find the one I have is different as to the wheel colors. Mine, left to right is red, white, white, red, red, white, white, red. How is this different from the other units? This one I got was being used in a state engineering/ DOT department. Thank you.
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