The arithmometer was the first digital mechanical calculator strong enough and reliable enough to be used daily in an office environment. This calculator could add and subtract two numbers directly and could perform long multiplications and divisions effectively by using a movable accumulator for the result.
Arithmomètre built by Louis Payen around 1887
Detail of an arithmometer built before 1851. The one-digit multiplier cursor (ivory top) is the leftmost cursor
One of the first machines with a unique serial number (10-digit machines with serial numbers from 500 to 549) built around 1863
Front panel of a Thomas arithmometer with its movable result carriage extended
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