Stepped reckoner
More info
- Creator
- Gottfried Wilhelm Leibniz
- Released
- 1673
- Type
- Mechanical calculator
- Predecessor
- Pascaline
Leibniz's machine was the first to handle all four arithmetic operations, and the stepped gear inside it stayed in calculators for three hundred years.
Leibniz demonstrated a model to the Royal Society in 1673 and then kept tinkering for twenty years. The key part is the stepped drum: a cylinder with teeth of increasing length, so a gear sliding along it meshes with anywhere from zero to nine of them. That let a digit be set mechanically, and multiplication became repeated addition driven by the crank.
Only two were built, and the carry never propagated reliably across the full register. The idea long outlived its inventor anyway — the arithmometer, the Brunsviga and eventually the Curta all rest on the stepped drum or close relatives of it.
Leibniz also described binary arithmetic and observed that a machine ought to find base two easier than base ten. He built his own in decimal regardless. It took until Zuse for anyone to take him at his word.