Sully, Thiout, Berthoud – Horologists and Writers

Last updated on September 4, 2020

1717Henry Sully – Règle artificielle du tem(p)s [Artificial regulation of time]

1741Antoine Thiout (L’ainé) – Traité de l’horlogerie mécanique et pratique [Treatise on mechanical and practical horology]

1763Ferdinand Berthoud – Essai sur l’horlogerie [Essay on horology]

I recently purchased a fine 1972 reprint of Thiout’s exceptional and influential book, painstakingly written by one of the leading horologists in France at the time. I have also ordered a 1978 reprint of Berthoud’s book.

Thiout was born in 1694 in Joinville, France and died in 1761 in Paris. At the time that he published his book, he was 47 years old and had mastered all aspects of watch and clock making.

Berthoud was born in Plancemont Switzerland in 1727, and came to Paris in 1747, becoming master watch-clockmaker there in 1754. He died in 1807. His horological accomplishments are numerous, and he also mastered all aspects of the profession.

Henry Sully had published his groundbreaking book “Règle artificielle du temps” [Artificial regulation of time”] in 1714, then 1717, and finally edited and reprinted posthumously in 1737. It was one of the first horological book of significance in the French language (oddly enough, written by an Englishman!), and opened the door for several other more detailed and comprehensive books on the subjects, written and published in France in the mid and later parts of the 18th century.

The two most notable of the books that came after Sully’s, are Thiout’s 1741 Traité, and Ferdinand Berthoud’s “Essai sur l’horlogerie” [Horological Essay], published in 1763 and re-edited in 1786. In Thiout’s book, the well-written text is in support of the fine plates showing various horological tools in use at the time, as well as detailed views of clock and watch components. In Berthoud’s book, the text is lengthier and more finely written (Berthoud was a formidable writer) and in his case, the plates and diagrams are in support of the text. That is one way of comparing the two works, though both have their merits and are fine in their own right. Both works were published in two volumes: Thiout’s text totals 400 pages, and there are 91 plates of figures; Berthoud’s text has 477 pages in Volume I and 542 pages in Volume II, and there are 7 tables and 38 plates of figures.

It’s unfortunate that neither work was translated into English, as there was nothing of comparative comprehension being written in England at the time. Actually, content from Thiout’s book, and especially Berthoud’s, found their way into English books that came later (notably Thomas Reid’s Treatise on Clock and Watchmaking, published in Glasgow in 1826).

Original copies of Thiout’s and Berthoud’s books in good condition are rather expensive, and of interest mainly to horological book collectors. However some fine facsimile reprints of both books were produced in the 1970’s which makes the text and diagrams eminently available to the researcher or horological enthusiast. Thiout’s book was reprinted in a single volume in 1972 by Editions du Palais Royal in Paris. Berthoud’s book was reprinted in an attractive two volume edition in 1978 in a limited run of 475 copies.

Many recent reprints of these books are available from various overseas publishers but the quality is suspect and the plates are likely not captured very well, if at all. It should also be noted that various copies of both works are available online in scanned digital copies. The quality varies, and the diagram plates are often incomplete. But it’s an inexpensive way for those interested in the actual text of the works to have access to them.

Back to Thiout. He joined the Parisian guild of horologists in 1724, and had shops on Rue du Four in 1724, and Quai Pelletier from 1741-48 [according to Tardy]. At the time of the publication of his massive tome, he was a master horloger [watch-clockmaker] in Paris, and horloger to the Duke of Orléans, and the Dowager Queen of Spain. In 1737, he developed a new repeating mechanism. The time required for him to write the book must have been considerable. Not only did he painstakingly describe and sketch (obviously re-drawn for publication by a professional draftsman) the various horological tools in use at his time (some of them surprisingly sophisticated and complex), but he also wrote at length about good practices in horology, and described all forms of watches and clocks, and their various components, being produced at that time. The book also features a 28 page detailed dictionary of horological terms used at the time, which demonstrates that French horologists had a very rich and descriptive vocabulary for their profession.

A few other horologists assisted Thiout by providing some chapters to the book, including Jacob Enderlin, Pierre Gaudron, and (posthumously), Henry Sully. The latter is a very detailed description of design elements of the verge escapement, which does not appear in any of Sully’s publications while he was alive, nor in the 1737 re-edition of his famous book (Règles…). In 1726, Sully had described his intent to publish a very detailed and fulsome horological work in 6 volumes, that would cover all aspects of the Art and profession. Sadly he died in 1728 and was not able to fulfill his objective, but probably inspired Thiout and later Berthoud to produce such comprehensive works themselves. It is likely that Sully had started writing parts of his projected tome, and that some of these were found in papers after his death. Most probably, the chapter in Thiout’s book about the verge escapement came from Sully’s papers.

Other horological practitioners and authors came out with their own horological books after Thiout and Berthoud (for example, Lepaute wrote a fine one in 1755), but Thiout was the trend-setter (himself influenced by Sully before him), and Berthoud wrote arguably the finest horological book of that century.

Other than Sully’s insightful article on the verge escapement, the Thiout “Traité” has a most interesting article provided by Pierre Gaudron (1695-1745), on pages 338-356.  Gaudron was the clockmaker to the Regent, the Duke of Orléans.  His lengthy and detailed article provides meticulous insights and advice on how to examine watch movements (by a watchmaker who needs to service or repair it).  


Gaudron starts by saying that many watchmakers commonly take apart the watch as a first step, which he says is the wrong thing to do.  Rather, the watch must be observed very carefully while still in its case, to identify any issues in need of addressing before disassembly takes place.  Gaudron goes on to say that many watchmakers regard watch service and repair (racommodage) as being the least esteemed discipline of the profession, but that they are wrong.  In fact, Gaudron says that the skilled watch repairman is the most distinguished, since more experience, knowledge, and abilities are required to troubleshoot a watch that is fully assembled and not working properly.


Gaudron’s long text (almost 9,000 words!), if it were edited into stepwise instructions more commonly seen in watch repair books of the recent century, would constitute a rich source of information and knowledge on how to best deal with the verge-fusee watches of that era.  Perhaps that could be an interesting future project, including translating it into English.  This would constitute an excellent resource for people who need or like to take apart, troubleshoot and repair old verge watches from the 17th and early 18th centuries.


In closing that chapter, Thiout comments on Gaudron’s text in a practical way: 
“There are excellent things in his method, but I believe that a customer would not be happy if we were to execute it in all circumstances.  The price that would have to be charged for servicing each watch, given the time that would be needed to carry out such a thorough assessment, would not be well received.  Because of this, I think that this method is better applicable to the watchmaker who is finishing new watches, rather than the one who simply services them.”

Bonne lecture!

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