Automatic watch with rotor : its history is still going on
Addendum to the book "Perpétuelles à roue de
(Perpetual watches with verge escapement), by Joseph Flores
2009 edition - AFAHA Besançon
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
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.