Creative minds don’t follow rules, they follow will.
Amit Kalantri

Jean-Antoine Lépine
Jean-Antoine Lépine (1720-1814)

The Machine Arithmetique of Lépine (sent for approval to l’Academie Royale des Sciences in 1725) was firstly described in the 1735 book of Jean Gallon Machines et inventions approuvées par l’Academie Royale des Sciences, depuis son établissment jusqu’a présent; avec leur description (see Gallon description of Lepine). The machine of Lépine was a solid, but simple adding device, with limited practical usefulness.

Jean Gaffin Gallon (1706-1775) was a colonel in the French army, and later the chief engineer for the port of Le Havre. In the early 1730s, the French Academie Royal des Sciences asked him to edit all the descriptions of the machines the Academie had approved. Six volumes were produced in Gallon’s lifetime, and a seventh volume appeared posthumously in 1777. This set of works contains both descriptions and engravings of all the inventions approved from the beginnings of the Academie in 1666 until 1735. The devices are described in chronological order. They cover all the areas then known in arts, sciences, engineering, and manufacturing. Notable among the many descriptions is one for Pascal’s adding machine and others by Perrault, Lepine, de Mean (which was really only a table upon which products could be looked up), and three by Hillerin de Boistissandeau.

We cannot be sure who actually made this calculator. Most probably the machine was devised (and sent for approval to the Academie Royale des Sciences) in the early 1720s by Philibert Depigny (1692-1727) (his surname was also spelled Lépine, Lespine, and L’Epine), a watchmaker and mechanic of King Louis XV of France, who used to make music boxes for the King, but the survived to our time devices were manufactured by his son—the famous and inventive French watchmaker Jean-Antoine Lépine (also King’s watchmaker, but of Louis XVI and Napoleon Bonaparte) many years later.

Jean-Antoine Lépine (born as Depigny), was born in Challex, a small village a few kilometers west of Geneva, on 18 November 1720, and later became one of the greatest watchmakers of all times, with numerous inventions in this area. He was fully capable to create such a simple calculating device, but in 1725 he was only five and he still lived in the house of his parents Philibert Depigny, and Marie, née Girod, in Challex, so obviously he was a little bit young for inventing machines 🙂 Jean-Antoine Lépine used to sign his clocks with the same inscription “LEPINE – INVENIT ET FECIT”, which can be found on the lid of one of the calculating devices, mentioned below.

The Arithmetical Machine of Lépine
The Arithmetical Machine of Lépine (© CNAM, Paris)

The Machine Arithmetique of Lépine was obviously inspired by the famous Pascaline of Blaise Pascal, although in Lepine’s machine, carrying took place through the flex of spring and not, as in Pascal’s device, through the fall of a weight. It seems several working copies of the calculator had been manufactured because at least two of them are still preserved to our time. The smaller one, an 8-digit device, is kept now in the collection of CNAM Museum in Paris (see the upper image), while the bigger, 20-digit device (see the lower image) is in the National Museum of American History in Washington. The machine in Washington is inscribed “DE LEPINE – INVENIT ET FECIT – 1725”, and is marked inside the lid “reparé en 1844 par le Chr Thomas de Colmar” (repairs done in 1844 by Charles Xavier Thomas of Colmar). It is a device made of leather and wood (the case), and brass and steel (the body), with overall dimensions: 4.8 cm x 49.2 cm x 26.4 cm, while the machine in Paris is smaller: Length: 34 cm; Height: 6 cm; Width: 13 cm; Mass: 3.250 kg.

The Arithmetical Machine of Lépine
The Arithmetical Machine of Lépine (© National Museum of American History in Washington)

Let’s examine the variation of the device, described in the publication of the French Academy. The machine is a 12-digital adding device, which rightmost two dials are used for adding sols and deniers (french monetary units at this time, 1 sol is equal to 1/20 of the livre, 1 denier is 1/12 of the sol) and are divided into 12 and 20 parts. The next ten dials are decimal.

The wheels are arranged in two rows. The tens carry from the 6th (last of the lower row) wheel to the 7th (first in the upper row) dial is performed by means of a mechanical system (marked with L in the lower figure), which consists of two small rods (marked with 1), two springs (2) and a clamp (3). On every full revolution of the 6th wheel, one of the pins (which is prolonged) raises the lower clamp, and pushes the side clamp, which rotates the 7th wheel to 1/10 revolution. The two springs and the clamp sidelong are destined for fixing and supporting.

The Arithmetical Machine of de Lépine, front view
The Arithmetical Machine of Lépine, front view

The 12 wheels in the upper part of the machine are not connected one to another and can be used for storing the intermediate results. In the lower figure can be seen the fixing mechanism of each wheel, which consists of a spring and a clamp (marked with P1 and P2) (the fixing mechanism of the lower wheels (which are destined for the showing of the result) is manufactured in the same manner). The rotating of these wheels can be done by means of clamps M (see the upper figure), which are connected with the axes of the wheels and are rotating by means of the stylus E. Over the windows, where can be seen inscribed over the periphery of the wheels digits, are inscribed the proper units—deniers, sols, units, tents, and so on to the billions, numbered clockwise.

The stylus E actually has two edges—short and long. The entering of numbers is done by rotating the dials, which are divided into 12, 20, 10 and so on parts. Bellow each one of these dials is mounted another dial, which has the same number divisions. Over the periphery of the lower disks are inscribed digits, which can be seen in the windows, situated over the disks and are used for showing the entered number.

If in the openings of the dial has been pushed the long edge of the stylus, then it will be rotated together with the lower disk. If it has been pushed the short edge of the stylus, then it will be rotated only the upper disk, but the lower disk, showing entered number, will remain static.

The result is presented in the two rows of windows, which are placed over the entering dials, where can be seen 12 smaller disks F. Transfer of the digits from the entering dials to these wheels is made by a system of clamps and springs. The tens carry is done by means of a similar system.

Arithmetical machine of de Lépine, back view
The Arithmetical Machine of Lépine, back view

Over the periphery of the disks F, which are placed below entering dials and are showing the entered number, actually are inscribed two rows of digits. The first row is used during the adding and multiplication, and the second (its digits are a complement to 10 of the first row)—during the subtraction and division. Only one of the rows can be seen at a particular moment, and which row can be seen is determined by the clamp S, which can be seen on the left side of the figure. Rotating this clamp, we can show one or another row, depending on if we want to add or subtract. The resetting of the result to 0 can be done by means of clamps R, which are similar to clamps M, used for entering the numbers in the recording mechanism.

It seems the machine of Lépine possesses all the defects of Pascaline—the mechanism does not offer reliable transmission (carrying) of the units into the tens, the tens into the hundreds, etc.