Pascal's calculating machine, 1642, and Colmar's Arithmometer, c 1850.

Blaise Pascal (1623-1662), was France's most celebrated mathematician and physicist. This calculator is an exact replica of an original calculating machine preserved in the Conservatoire des Arts et Metiers at Paris. It was completed by him in 1642, and was designed for addition and subtraction, using a stylus to move the number wheels. Charles X Thomas de Colmar invented his Arithmometer in 1820. It was the first commercially succesful 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.