Arithmometer

The Arithmometer or 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 and manufactured from 1851 to 1915, it became the first commercially successful mechanical calculator. Its sturdy design gave it a strong reputation of reliability and accuracy 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.

Its production debut of 1851 launched the mechanical calculator industry which ultimately built millions of machines well into the 1970s. For forty years, from 1851 to 1890, 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.

The arithmometers of this period were four-operation machines ; a multiplicand inscribed on the input sliders could be multiplied by a single-digit multiplier by simply pulling on a ribbon (quickly replaced by a crank handle). It was a complicated design and very few machines were built. Additionally, no machines were built between 1822 and 1844.

This hiatus of 22 years coincides almost exactly with the period of time during which the British government financed the design of Charles Babbage's difference engine, which on paper was far more sophisticated than the arithmometer. It could not be built with the technology of that time, however.

In 1844 Thomas reintroduced his machine at the Exposition des Produits de l'Industrie Française in the newly created category of Miscellaneous measuring tools, counters and calculating machines but only received an honorable mention.

He restarted the development of the machine in 1848. In 1850, as part of a marketing effort, Thomas built a few machines with exquisite Boulle marquetry boxes that he gave to the crown heads of Europe. He filed two patents and two patents of addition in between 1849 and 1851.

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