Objects

used in the calculating engine of a class of mechanical calculators. Invented by Leibniz in 1673, it was used for three centuries until the advent of the electronic calculator in the mid-1970s. Gottfried Wilhelm Leibniz built a machine called the stepped reckoner based on the design of the stepped drum in 1694. It was made famous by Thomas de Colmar when he used it, a century and a half later, in his Arithmometer, the first mass-produced calculating machine. It was also used in the Curta calculator, a very popular portable calculator introduced in the second part of the 20th century.