The computing engine of an arithmometer has a set of linked Leibniz wheels coupled to a crank handle. Each turn of the crank handle rotates all the Leibniz wheels by one full turn. The input sliders move counting wheels up and down the Leibniz wheels, which are themselves linked by a carry mechanism.

What does the Thomas machine do?

It has three levers that are moved back to enter digits on brass stepped drums. A fourth lever, to the left of these, is labeled Multiplication, and used to determine the number of times the stepped drums rotate. Hence in this early machine, Thomas attempted direct multiplication by a single digit.

Who developed the Arithmometer?

Charles Xavier Thomas de Colmar (1785-1870) was a French engineer. In 1820, he invented the first arithmometer, one of the first known mechanical calculators, Following this first model, a smaller and improved version was introduced in 1855 at the Exposition Universelle in Paris.