Leibniz's Stepped Reckoner

Timeline

1. c. 1672–1673Paris and London · Western EuropeLeibniz hoped to make calculation 'easy, rapid, and certain' by machine, adding multiplication and division beyond Pascal's adding machine. In early 1673 he showed the Royal Society in London a wooden or early metal model that could not yet complete multiplication and division automatically. Hooke subsequently criticized its completeness at the Society.
2. 1673–1676London · LondonOn April 9, 1673, Leibniz was elected a Fellow of the Royal Society. He promised to complete an arithmetic machine capable of automatic multiplication and division, but his main efforts in the Paris period shifted to calculus, and the machine long failed to satisfy the Society. Oldenburg's correspondence repeatedly mentioned this unfulfilled promise, becoming a point of friction in Leibniz's relationship with the Society.
3. 1676–1694Hanover · HanoverWhile serving at the Hanover court, Leibniz commissioned craftsmen to continue work on the stepped drum and carrying mechanism, producing a metal machine capable of demonstrating the four arithmetic operations around 1694. Carrying remained unreliable and practical value was limited, but the mechanism's principles were complete. In 1710 he published an illustrated description in Berlin's Miscellanea, bringing the design into printed knowledge.