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 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.