Pascal's calculating machine, 1642.
© Science Museum / Science & Society Picture Library
Replica, made by E Rognon in 1926. 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 Pascal in 1642, when he was only 19, to aid his father in his busines; it was designed for addition and subtraction, using a stylus to move the number wheels. Although it became well-known it could not be mas produced.