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, Baldwin went on to invent other calculating machines, most notably those manufactured by the Monroe Calculating Machine Company.
This non-printing machine has eight rings at the front that may be rotated forward to release pins and enter numbers. The zeroing bar for the rings is at the front and the 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 a second row of nine windows for the revolution register behind this. Both of these registers have zeroing cranks and thin metal rods below them that move to serve as decimal markers. Lifting a metal hook on the left allows one to shift the carriage. The entire machine sits in a wooden case with lid with handle.
A mark scratched on the front of the machine reads: 150. The museum number assigned by the Museum of the Peaceful Arts is: 27-94. A metal tag on the lid of the machine reads: BALDWIN (/) CALCULATOR (/) 150 (/) PAT. AUG. 5. 1902. Another metal tag in the same place reads: THE SPECTATOR CO (/) AGENTS (/) 95 WILLIAM ST. (/) NEW YORK.
This example is from the collection of L. Leland Locke and was once in on deposit at the Museums of the Peaceful Arts in New York City.
The Spectator Company of New York sold Baldwin’s calculator from at least 1903 through at least 1907. Their advertisements boasted of the reliability of the machine and its American manufacture. It cost $250.
Compare MA.307384.
Frank S. Baldwin, “Calculating-Machine,” U.S. Patent 706375, August 5, 1902.
Advertisement, The Spectator, vol. 76 #3 (Feb 1, 1904), p. 66.
Currently not on view
date made
ca 1905
The Spectator Company
Baldwin, Frank S.
place made
United States: New Jersey, Newark
place distributed
United States: New York, New York
Physical Description
metal (overall material)
wood (overall material)
rubber (overall material)
overall: 19 cm x 29.8 cm x 21.5 cm; 7 15/32 in x 11 23/32 in x 8 15/32 in
ID Number
catalog number
accession number
Credit Line
Gift of L. Leland Locke
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History