The Leibniz Step Reckoner and Curta Calculators
In 1673, Leibniz built the first true four-function calculator. His unique, drum-shaped gears formed the basis of many successful calculator designs for the next 275 years, an unbroken record for a single underlying calculator mechanism. Leibniz built several versions of the Stepped Reckoner over about 45 years. Only one survives today.
The Leibniz Step Reckoner
Gottfried Leibniz’s 1673 “Step Reckoner” introduced a design innovation that enabled a single gear to represent any digit from 0 to 9 in just one revolution. This stepped-drum approach dominated calculator design for the next two centuries.
For over 200 years, illustrators often depicted the Leibniz mechanism, which stimulated many subsequent inventors.View Artifact Detail
The hand-cranked Curta was popular with sports car rallyists and airplane pilots, even after electronic calculators were available. The exquisite mechanism is still studied. There are several beautiful animations on the web, and a registry of current owners.View Artifact Detail
While imprisoned in Buchenwald concentration camp in World War II, Curt Herzstark refined his pre-war design of a calculator featuring a modified version of Leibniz’s stepped drum. After the war, Herzstark’s Curta made history as the smallest all-mechanical, four-function calculator ever built.