Between the 1624 invention of Blaise Pascal’s calculating machine and 1820, there were about 25 manufacturers of such devices. Because there were so many—most had little funding and only one person involved—very few machines were actually manufactured in any quantity.

By 1820 the first calculating machine to be commercially successful and produced in large numbers was the “Arithmometer.” Invented by Frenchman Charles Xavier Thomas de Colmar (1785–1870) while he was serving in the French army, it was based on a Leibniz’s “stepped drum” mechanism (see above). Colmar’s machine used a simple system of counting gears and an automatic carry (automatically shifting a 1 to the left when the sum of a certain column was greater than 9). The technology of the times also helped catapult Colmar’s success. Because it included springs and other machinery that offset the momentum of moving parts, the Arithmometer stopped at a specific, intended point, unlike what often happened with the older calculating machines.