18th November 1820
Thomas de Colmar patents the Arithmometer

The Arithmometer or Arithmomètre was the first commercially successful mechanical calculator.

Charles Xavier Thomas de Colmar (May 5, 1785 – March 12, 1870) started designing the device in 1818, and was granted a patent on November 18th 1820.

Related information:

• Brevet 1420 18 Novembre 1820 (original Patent document, in French)

Image:

• Arithmometer schematics, from original patent document
  Credit: Public domain.

Related Items in the Collection:

Thomas de Colmar launches the Arithmometer