Thomas de Colmar arithmometer, no. 696, in box
Thomas De Colmar Arithmometer 1867, in box. Charles X Thomas de Colmar invented his Arithmometer in 1820, but it was not made commercially until the 1860s. It was the first commercially successful calculating machine and could be used for addition, subtraction, division and mulitiplication. The mechanism was based on the stepped reckoner invented by Liebniz (1646-1716). Machines of this type were made well into the 20th century, and usually referred to as being of the 'Thomas de Colmar' type.