.

1)- Chain-guide assuring the immobilization of the rotor
2)- Wheel of the on the plate pivoting inverter
3)- Ratchet " " " " " (not visible on photo)
4)- Pinion " " " " " (not visible on photo)
5)- Wheel of the inverter fixed under the rotor
6)- Ratchet of " " " " " " (not visible on photo)
7)- Pinion of " " " " " " (not visible on photo)
8)- Pinion of the relay-wheel, moving the ratchet wheel of the fusee
9)- Relay-wheel moving the pinions of the two inverters
10)- Immobilization-circle fixed on the rotor
11)- Rotor

When I published my analysis of an ancient document from the French Science Academy of Paris in 1993, in which the reporters J.B.Leroy and De Fouchy described a watch presented by the Belgian watchmaker Hubert Sarton (1748/1828, from Liège) as :"a watch which winds herself under the action of a copper mass moved by the walk", I failed to convince most of the historians who didn't have an horologic technical background. It did look like a type of Watch we would nowadays call "automatic".
Without any drawing, this report is a technical description of the watch brought by Sarton, and this may seem rather dense for a non-technician, and quite difficult to understand.
Therefore, since my first publication 15 years ago, this invention has been concurrently attributed to two different watchmakers:
- the Swiss Abraham-Louis Perrelet, as said in 1950 by the Swiss historian Alfred Chapuis,
- or the Belgian Hubert Sarton whose automatic Watch was studied and described by the French Science Academy of Paris in 1778.
Such a case is not unique, but it would be necessary to be able to present original documents for both, which as far as I know is not the case concerning the attribution to Perrelet.
The last evidence !
As it has often happened in my historical inquiries, a new document fortunately appeared in september 2009, as I just ended the reprint of my former book "Perpetuals with verge escapement" (AFAHA edition).
On August 17 Mr André Thiry from Liège, a friend of mine was working on his book on the famous clock and watchmaker Hubert Sarton. As part of his research, he wrote to the French Science Academy in Paris, and asked for information on Sartons apprenticeship.
The answer he received on September 2nd mentioned "a drawing (1 p)" that nobody had ever heard about, and that Mr Thiry left me the pleasure to request.
What do this drawing represent ?
On a sheet of approximately 30 x 30 cm is drawn a watch mechanism with a semi-circular mass (named "contrepoix" on the sketch), turning on a central pivot, also known as a pendulum mass, or a "rotor". The author of this sketch, probably Sarton himself, hatched the mass to make it stand out.
Then, some circles represent the wheels of the automatic mechanism. They are accompanied by explanations and even by the number of teeth of certain wheels, which leaves no doubt as to what they represent.
The comparison of the following simplified and coloured sketch with one of the well-known mechanism makes it obvious.
A separate circle of about 39mm diameter, on the left, could represent the actual size of the mechanism.