Burroughs Sample Calculator, Double 1/12 Fraction

In 1911 the Burroughs Adding Machine Company introduced a key-driven adding machine much like the Comptometer made by Felt & Tarrant Manufacturing Company. The Burroughs calculator, as the new machine was called, performed ordinary decimal arithmetic. Burroughs inventors soon designed special versions of the calculator to solve other problems. This is the model for one of them.
This machine has a green metal plate under the keys and a black metal bottom, but no sides or cover for the numeral wheels. The five columns of octagonal plastic keys have concave keys for odd digits, flat ones for even ones. The rightmost and the middle columns have two keys, for 11 and 12. The other three columns have nine keys, numbered from 1 to 9. The complements of numbers on the keys are also given, with the numbers totaling 11 on the four right columns and 9 on the leftmost. There are four numeral wheels at the front. Two to the right have numbers from 0 to 11, the other two digits from 0 to 9. There is no handle. The numbers in the two rightmost columns add, and carry when the total passes 12. The middle two columns don’t seem to function. and the machine does not function. There are four rubber feet and as a rubber piece around three sides at the base.
A red tag attached to the machine reads: PATENT DEPT (/) #231. A white tag attached to the machine reads: Reference Machine (/) 5 Columns (/) Double 1/12 Fraction (/) DO NOT REMOVE THIS TAG - REFER TO (/) LETTER 12/5/40 - JAS to GWL. A metal tag attached to the object reads: DONATED TO (/) The Smithsonian Institution (/) by (/) Burroughs Corporation.
Objects 1982.0794.47, 1982.0794.48, 1987.0794.49, and 1982.0794.89 are all from Burroughs Patent Department Model 231.
Currently not on view
Object Name
adding machine
date made
ca 1920
Burroughs Adding Machine Company
Physical Description
plastic (overall material)
paper (overall material)
rubber (overall material)
metal (overall material)
overall: 13 cm x 15 cm x 28.2 cm; 5 1/8 in x 5 29/32 in x 11 3/32 in
place made
United States: Michigan, Detroit
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 Burroughs Corporation
Additional Media

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