Thomas Arithmometer

In 1820, Charles Xavier Thomas de Colmar (1785-1870), of France, submitted a patent for a calculating machine which he had thought up while serving in the French Army. His Thomas Arithmometer, also known as Thomas Machine, was to become the first commercially successful adding machine, and it was produced in large quantities up until 1930. Based on Leibniz's calculating machine, the device utilized stepped drum gears for calculation and was capable of performing the four operations in a simple and reliable way. Because of its unidirectional drum, division and subtraction required setting a lever. The success of the machine was due to the many springs and other contrivances that neutralized the momentum of moving parts so they would not move beyond their intended point - the cause of failure in earlier machines. The major innovation, however, was to reverse the operating function in the result registers (up to sixteen digits) that allowed for reliable and stable calculation over extended periods of time without gear re-alignment. The machine took up an entire desk and required two people to carry it. It spurred on many rivals, eventually leading to quite sophisticated calculating machines that overcame the pitfalls of the stepped-drum design. About 1,500 machines were made by the Compagnie d'Assurance Le Soleil, founded by Thomas, and other contractors, between 1820 and 1930. The Thomas Machine had many clones, and the term Arithmometer became synonymous with four function calculating machine. Thomas received France's Chevalier of the Legion of Honor for the product.