Baldwin Calculator

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In 1875 Frank S. Baldwin of St. Louis patented a pinwheel calculating machine. He manufactured a few of these machines, but they did not sell well. Baldwin went on to take out a number of other patents. By 1901 he had moved to Newark, New Jersey, where he designed an improved pinwheel machine. He obtained a patent the following year. This is an early example of that machine.
The lever-set, non-printing machine has eight rings at the front that rotate forward to release pins and enter numbers. A zeroing bar for the rings is at the front, and an operating crank to the right. The crank turns clockwise for addition and multiplication and counterclockwise for subtraction and division. Behind the rings is a movable carriage with a row of 16 result windows and, behind this, a second row of nine windows for the revolution register. Both these registers have zeroing cranks. Both also have a thin metal rod below them that moves to serve as a decimal marker.
Pulling forward a lever on the left allows one to shift the carriage. A bell rings when the result changes sign (negative to positive or positive to negative). The entire machine sits in a wooden case with a missing lid.
Compare MA.311954.
A mark stamped on the front reads: No 50.
The donor dated this machine to 1902.
Accession file.
Frank S. Baldwin, “Calculating-Machine,” U.S. Patent 706375, August 5, 1902.
Currently not on view
date made
Baldwin, Frank S.
place made
United States: New Jersey, Newark
Physical Description
metal (overall material)
wood (overall material)
overall: 14.3 cm x 26.5 cm x 19.5 cm; 5 5/8 in x 10 7/16 in x 7 11/16 in
ID Number
catalog number
accession number
maker number
Credit Line
Gift of Monroe Calculating Machine Company
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History


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