Arithmometer

The arithmometer (French: arithmomètre) 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.

Patented in France by Thomas de Colmar in 1820^[1] and manufactured from 1851^[2] to 1915,^[3] it became the first commercially successful mechanical calculator.^[4] Its sturdy design gave it a strong reputation for reliability and accuracy^[5] and made it a key player in the move from human computers to calculating machines that took place during the second half of the 19th century.^[6]

Its production debut of 1851^[2] launched the mechanical calculator industry^[4] which ultimately built millions of machines well into the 1970s. For forty years, from 1851 to 1890,^[7] the arithmometer was the only type of mechanical calculator in commercial production, and it was sold all over the world. During the later part of that period two companies started manufacturing clones of the arithmometer: Burkhardt, from Germany, which started in 1878, and Layton of the UK, which started in 1883. Eventually about twenty European companies built clones of the arithmometer until the beginning of World War I.