As a young man, French inventor and automobile manufacturer Léon Bollée designed several calculating machines, including “Le Compteur,” which was intended as a cash register. Although the mechanism inside is strikingly simple, the machine features some very interesting ideas.

The special feature of the counter lies in its input method. Two separate dials allow whole numbers and decimal numbers to be entered separately. The heart of the machine, a central differential gear, even allows inputs to be made on both dials simultaneously, with the machine correctly calculating the sum.

In his project work, Marten Schauhoff prepared the machine for didactic purposes and modeled and animated it with great attention to detail. Join us in discovering how this simple but clever mechanism works in Léon Bollée's counter.