Lepine Adding Machine

In the 17th century, the French mathematician and philosopher Blaise Pascal built a machine that could be used to add numbers by the rotation of discs with a stylus. Pascal and his associates made several copies of this machine, but it never became a commercial product. In 1725 Jean Lepine, the watchmaker and mechanic for King Louis XV of France, built this stylus-operated adding machine in the tradition of Pascal. However, in Lepine’s machine, carrying took place through the flex of a spring and not, as in Pascal’s device, through the fall of a weight.

The brass instrument fits in a leather-covered wooden case. There are five rows of circles, with ten circles to a row. A window at the top of each circle shows a digit on a disc below. In the first and fourth row there are ten discs on the front of the machine, each with ten indentations in it. The indentations are numbered clockwise 0 to 9. In these rows, there is a stop at the bottom of each disc. All five rows of circles also have a circle of numbers ranging from 1 to 9. In the first and fourth row, these numbers are outside the discs with indentations in them and run counterclockwise, and one digit is not indicated (usually 5, though it may be 10 or 6 - in place of this digit there is an opening in the circle). In the other rows, the digits in the circles run clockwise. In the leftmost column of circles (labeled “Deniers”) numbers on the circles and discs run 1 to 11. The column one in from this (labeled “Sols” ) has numbers from 1 to 19. In each of the circles of numbers without discs, there is a pointer that points to the digit on the circle that is shown in the window. A stylus fits in the right side of the case.

The underlying discs of the top two rows of circles are linked. These circles are used in addition and multiplication. The underlying discs of the bottom three rows of circles are linked. These circles are used in subtraction and division. The underlying discs in each row have pinholes indicating their position. These pinholes are visible if the machine is removed from the case and inverted. A brass plate in the lid of the case has a multiplication table for the numbers 1 to 9. Openings in the plate reveal two rotating brass plates which give multiples of unit prices.

The machine is inscribed at the front right: DE L’EPINE (/) INVENIT ET FECIT (/) 1725. It is inscribed to the left of this: Nouvelle Machine d’arithmetique contenant toutes les parties de cette Science et dont les operations se font d’une maniere aussi curieuse et aussi promte [sic] que certaine. It is marked inside the lid: reparé en 1844 par [/] le Chr Thomas de Colmar. This refers to repairs done in 1844 by Charles Xavier Thomas of Colmar, a distinguished French inventor of calculating machines and prior owner of the machine.

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