Pins and Levers
Baldwin’s commercial pinwheel calculator
Other pinwheel calculator manufacturers had eclipsed Baldwin before he brought his own pinwheel calculator to market.
Pins and Levers
Frank Baldwin’s 1872 “pinwheel” calculator design was the first significant advance since the 1820 Thomas Arithmometer. Zero to nine teeth protruded from a thin “pinwheel” gear, depending on the position of a lever set by the operator. The number of protruding pins determined the digit entered by turning the gear. Additional gears in a row allowed multi-digit numbers. Other manufacturers copied Baldwin and eclipsed his tiny production.
Baldwin patent drawing
This was Baldwin’s first mechanism for changing the number of gear teeth to represent different numbers, but he did not market it aggressively.
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Felix Arithmometer
This device is based on the original 1873 Odhner “pinwheel” design. Odhner was a Swedish immigrant who lived in Russia. The “Felix” name of this model refers to first head of the Soviet secret police Felix Dzerzhinsky, who started production of these devices in 1924 as a way employing young people during revolutionary times. Over the course of the 20th century, millions of Arithmometers were sold worldwide by several different manufacturers.
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