The Curta is a hand-held mechanical calculator designed by Curt Herzstark. It is known for its extremely compact design: a small cylinder that fits in the palm of the hand. It was affectionately known as the "pepper grinder" or "peppermill" due to its shape and means of operation; its superficial resemblance to a certain type of hand grenade also earned it the nickname "math grenade".
Curta Type II mechanical calculator
Curta Type I, on display at the Musée des Arts et Métiers, Paris.
A partially disassembled Curta calculator, showing the digit slides and the stepped drum behind them
Curta Type I calculator, top view
A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically, or (historically) a simulation such as an analog computer or a slide rule. Most mechanical calculators were comparable in size to small desktop computers and have been rendered obsolete by the advent of the electronic calculator and the digital computer.
Four of Pascal's calculators and one machine built by Lépine in 1725, Musée des Arts et Métiers
Replica of Schickard´s calculator
Detail of a replica of an 18th-century calculating machine, designed and built by German Johann-Helfrich Müller.
A mechanical calculator from Anton Braun, dated 1727
