Leibniz stepped reckoner

This calculating machine, invented by Gottfried Wilhelm Leibniz, was built in the years from 1690 to 1720. It represents a historic milestone in the development of mechanical calculating machines because it was the first to perform all four arithmetic operations. Leibniz's operating mechanism, known as the stepped cylinder or Leibniz wheel, allowed multiplication to be performed mechanically and remained an indispensable component of mechanical calculators for over 200 years. Functioning replica of the only remaining original (at the Nieders„chsische Landesbibliothek in Hanover), built to plans by N. Joachim Lehmann. Photo: Jan Braun, HNF