Subject areaArtificial intelligence
Also known asLeibniz wheelstepped reckoner drum
The stepped drum is a cylinder with nine teeth of increasing length set along its axis, devised by Gottfried Wilhelm Leibniz in 1672 for his calculating machine.
A small gear slides parallel to the cylinder: depending on where it is moved, one turn of the drum engages from zero to nine teeth, and the matching digit advances in the result register.
The principle reached series production with Thomas de Colmar's arithmometer in the nineteenth century and stayed in use in office calculators well into the twentieth, for example in the TIM Time is Money. Its limit is bulk: every digit needs a whole cylinder, so the machines are heavy and long. This explains the success of the pinwheel calculator, which does the same job with a thin disc and is among the most widespread technologies of intelligence before the computer.
Source: Jaap Scherphuis, Jaap's Mechanical Calculators, e John Wolff's Web Museum (Calculating Machines), per il meccanismo e la derivazione da Leibniz e Thomas de Colmar.
An example
The case below is constructed, because the term does not yet appear in the articles. In the payroll office of a manufacturing company in the 1920s the clerk sets the hourly wage by moving the sliders, then turns the crank as many times as the hours worked: under the cover the stepped drums rotate and the register shows the week's pay.
Enrico Giubertoni. Licensed under CC BY-NC 4.0: you may quote, translate and adapt this entry with the author’s name and a link, stating any changes. For commercial use, write to info@enricogiubertoni.com
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