Johnston Adding Machine, Model A11

Johnston Adding Machine, Model A11

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This gray mechanical 10-key adding machine was manufactured by Johnston Adding Machine Company of California. It is a model A11 Adder with 10 white number keys and 6 red function keys. The machine could add, subtract, and multiply as well as print a paper tape. Its cover is hinged and opens to reveal the calculating mechanisms, the ribbon and platen for printing, and a red knob for advancing the printing paper. Stamped on a metal plate located on the inside right rear is the serial # 11766A11.
Johnston Adding Machine Company was acquired by the Marchant Calculating Machine Company in 1957. The Johnston plant was engaged to produce and distribute the Marchant 10-key adding machine.
See also: 1979.3084.128 Advertisement for Marchant's new adding machine.
1979.3084.023 -.025 Marchant Board of Directors Minutes of Meetings.
Currently not on view
Object Name
adding machine
date made
ca 1956
Johnston Adding Machine Company
Physical Description
metal (overall material)
plastic (overall, keys material)
overall: 19.5 cm x 22.5 cm x 35.5 cm; 7 11/16 in x 8 27/32 in x 13 31/32 in
ID Number
model number
accession number
catalog number
Credit Line
Ernest Eldon Jorgenson
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
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