We are indebted to Mr. D. Reggiani of Savona, whose exhaustive technical and historical study in Italian (from which we have taken the drawings here published), done in 1982 , will accompany this lot.
This watch was considered by Louis Berthoud to be the most important of the chronometers he made.
Literature:
"La Longitude en Mer à l?Heure de Louis Berthoud et Henri Motel" by Jean-Clude Sabrier, Antiquorum Editions, Geneva, 1993.novembre06(da108a123).qxd 10-10-2006 11:49 Pagina 111
Louis Berthoud
(1754-1813)
he son of Pierre Berthoud, counsellor and master-clockmaker at Couvet, Pierre-Louis Berthoud (known as Louis Berthoud) was born in November 1754 in Placemont, Canton of Neuchâtel. At twelve, he began his apprenticeship in his father?s workshop. He was hardly fifteen when his exceptional skill was noticed by his uncle, the famous Ferdinand Berthoud, who invited him to Paris to be initiated into precision clockmaking.
Ten years later Ferdinand Berthoud retired to his property in Groslay, leaving his Paris workshop in the hands of Louis? brother Henry. On several occasions Ferdinand Berthoud had requested that his nephew be officially attached to his establishment, but the response was always negative. Disappointed, Louis Berthoud returned to Couvet. However, Henry committed suicide on June 29, 1783, and Ferdinand asked his nephew Louis to return to Paris to take over the business.
Louis Berthoud seems to have arrived in Paris in the spring of 1784. On June 5, 1784, he became Elève Horloger Méchanicien de la Marine?. That same year Louis Berthoud married Thérèse Bezout, the niece and adopted daughter of Etienne Bezout, mathematician and member of the Académie des Sciences. It was not without some bitterness that Louis Berthoud worked in his uncle?s shadow. In 1812, he wrote: ?... I lived several years overwhelmed by the bitterest distaste. It is with a sentiment of the most profound recognition that I offer here to M. Monge, then Minister of the Marine, the respect and thanks that I owe to the goodness of his heart and to his fine spirit. I owe them also to M. Thevenard... for having helped me to emerge from the oblivion into which it seemed I should be for ever plunged.?
Berthoud produced a series of lever watches after examining one such watch produced in England by Josiah Emery, and also a watch made in France on the same principles. However, he soon abandoned the lever escapement in favor of the detent. He chose a pivoted detent escape-ment for a pocket longitude watch delivered to Chastenet de Puységur in 1787.
Finally in 1792, following a proposal by the Bureau de Consultation, the Minister of the Interior awarded Berthoud the maximum prize of 6000 livres with distinction in the first class of national premiums for this watch. The mechanism of the watch, which is of an entirely new conception, is described by Louis Berthoud in a sealed document deposited in the Académie des Sciences 9 May 1792. It was the sum awarded by the Minister that allowed Berthoud to gain his professional independence.
In 1804 the Ecole d?Horlogerie de la Marine was founded. Seven pupils of the Ecole Impériale des Arts et Métiers at Chalons were chosen to be instructed at government expense. Following the Imperial Decree of 10 March 1806, Louis Berthoud was charged with the training of four of these pupils, Motel, Henriot, Saulnier and Laurent. In 1812 Louis Berthoud published his ?Entretiens sur l?horlogerie à l?usage de la Marine?. In this short book, published a year before his death, Berthoud lavished on his pupils, in twelve ?conversations?, his last recommendations and advice, for exercising with success the difficult métier that they had chosen.
Louis Berthoud had two sons: Jean Louis Simon Henri, usually called Louis like his father, (1793-1880), who on 17 April 17, 1819 married Thérèse Joly, the daughter of a watch-case maker; and Charles Auguste, (1798-1876), who married the second daughter of the same watch-case maker, Henriette Pauline Joly, on January 26, 1822.
Louis Berthoud died at Chaillot 18 September 1813 at the age of 59.
Provenance:
Made for the Chevalier de Borda (1733-1799).
Later owned by Monsieur Bouvard, Director of the Paris Observatory.
First Decimal Marine Watch
The present watch represents a unique and defining moment in the history of watchmaking and is the first high precision timekeeper made using the decimal system. It is evocative of a turbulent and short-lived period in France's history when the new Republic decreed the use of decimal time. It was commissioned by one of the great scientists and mathematicians of eighteenth century France and what is particularly significant is that the research for its making began on 27th January 1792 - 22 months before the law was voted to establish decimal time on 24th November 1793. This was also 8 months before the official foundation of the Republic on 22nd September 1792. To make this watch work with the decimal system Berthoud was forced to calculate a whole new gear train and produce a new calibre. The amount of work that Berthoud expended on this watch producing various trial wheels and countless calculations is exceptional, indeed Berthoud considered this watch to be the most important chronometer that he made. He worked very closely with the Chevalier de Borda on the making of this watch and consulted him on almost every aspect of its making, even following his advice as to the construction of the wheel train. This shows that even a genius like Berthoud took de Borda's opinions very seriously and commented that he was ?not less content to be confirmed by his (Borda's) opinion?. The calculations and designs for this watch were carefully recorded by Berthoud and are reproduced in full in ?La Longitude en mer à l'heure de Louis Berthoud et Henri Motel?, Jean-Claude Sabrier, Antiquorum Editions, 1993.
Project for the Chevalier de Borda's marine watch
The Chevalier de Borda had owned Berthoud's marine watch No. 14, which was another high precision watch with anti-friction rollers. Berthoud decided to make the frame of No. 26 (the present watch) with the same height of frame as No. 14 but of course this new watch for decimal time required wheels with completely different numbers of teeth than a standard 12-hour watch. Another problem Berthoud encountered was that Borda required the watch to have center seconds and he was not able to find an easy or suitable way to do this without suppressing the fusee or mounting the seconds on an intermediate wheel. Not wanting to use either method he decided to construct a new and simple calibre. The preliminary details were as follows:
The disposition of the wheels:
Contrate wheel: set flush
Centrewheel: against the plate
Third wheel: center of the frame
Wheel meshing with that of the escapement: a little above Escape wheel: near the small plate
The wheel counts were calculated as follows:
The center wheel will have 108 or 120 teeth
The third wheel 120 teeth, with a pinion of 18 to the contrate wheel - this of 96 teeth
Pinion of the intermediary wheel: 16 leaves
That of the escape wheel will not be determined until a trial wheel has been cut, making all the pinions by hand, I will also make that of the center wheel of 18 or 20 teeth
The dial will be of 25.5 to 26 lignes (interestingly, close inspection of the dial has revealed "ghost" numerals of 1-12 in each half-hour sector inside the decimal numerals, these can only be seen in a raking light).
After these preliminary studies, Berthoud submitted his plans to Borda. In his notebook for the 27th February 1792 he wrote ?Today I consulted M. le Chevalier de Borda to decide whether to make an intermediary wheel between the contrate wheel and the escape wheel, or to make it in the ordinary way, although this gives me a small escape wheel pinion and a high numbered wheel. His (Borda's) opinion is that it is preferable to add an extra wheel, and that it is always a disadvantage to make small low numbered pinions because the arbors always become very fatigued, the gearing uneven etc? I was persuaded of these truths, but I am not less content to be confirmed by his opinion.
I am also decided to make the seconds hand beat 2 1/2 to the second instead of 3 which I had intended. That is 500,000 beats for one revolution of the hour hand or 24 ordinary hours, which comes very close to the speed of watches of six beats per second and which will give me more ease for my revolutions?. By 12th April 1792 Berthoud had crystallized his ideas on the wheel count further and says ?Hour wheel with 100 teeth and pinion of 10 for the intermediate wheel for the minutes. Four for decimal beats the contrate wheel must have either 100 teeth with a 10 leaf pinion to the escape wheel of 20, or 120 teeth for the contrate wheel and a pinion of 12 to the escape wheel, or 125 teeth for the contrate wheel, a pin-ion of 10 and 16 teeth for the escape wheel. The speed of an ordinary watch of 4 beats the second is 343,000 beats for 24 hours. Thus the decimal watch with 400,000 beats per 24 hours comes closer to the ordinary watch of 5 beats per second?. Berthoud experimented with the calculations for the wheels of this watch continuously through-out 1792 and it was not until May 1793 that he perfected the wheel train, fusee and mainspring, every aspect had to be considered and the beat count caused him particular concern which was due to his worries that there would not be enough power to drive the watch for at least 30-hours.
On 10th January 1793 he writes ?The spring that I tried today lifted 16 gros, it makes five 1/2 coils in the barrel. The fusee has 7 1/2 turns; it is taken up by 4 1/2 turns on the barrel and is stretched by a quarter of a turn, so at least three quarters of a coil rest free in the barrel as the spring makes about five coils. The equalising capacity is good. The force is 120 gros for 30 hours, it is the same force as I had in the silver-cased watch No. 19 for M. Quenot?.
This watch also inspired Berthoud with further new ideas about the wheel train.
7th March 1793 - Experiments with the decimal watch made for M. de Borda.
?Wishing to surpress a wheel in my watches and so give myself the possibility of fitting rollers to all of them, the center wheel had to be given a double revoloution, this is that it should make 48 turns in 24 hours; to have this same wheel very large, of 150 teeth, the third wheel, with a pinion of 10, of 120 teeth, and the contrate wheel, also with a pinion of 10, which at the same time acts as an escapement ratchet, of 25 teeth. One must therefore construct below the case flange, a small fusee and going barrel, with wheels of ordinary numbers, which will serve to pace the three hands - the whole for 18,000 beats per hour?
The final number of teeth and pinion leaves used in this watch are as follows: Fusee: 72 teeth
First wheel: 120 teeth, 18 pinion leaves
Hour wheel: 120 teeth, 20 pinion leaves
Third wheel carrying the seconds hand: 80 teeth, 16 pinion leaves Escape wheel: 10 teeth, 16 pinion leaves
Forced to create a new calibre to meet the needs of the decimal division of time, Louis Berthoud decided to use this watch to try out the flying escapement described in the sealed document 288 deposited at the Academie des Sciences, 9 May 1972. After several attempts to perfect it, he was forced to abandon definitively this escapement of which he had had great hopes. He then resumed use of his normal pivoted detent escapement.
Decimal Time
After the French Revolution a new calendar was adopted, and the system of time measurement was completely changed. The revolutionary year was divided into 12 equal months having 30 days each and an additional 5-day (6-day in a leap year) holiday month; each month was divided into three decades, each having 10 days. The 24-hour day was divided into ten hours of 100 minutes each, and each minute was subdivided into 100 seconds. Thus, for example, 12:30 PM was 5:20:83.3 in decimal time. The law introducing the changes was passed on 24 November 1793. Whereas the new standards for weights and measures were relatively easy to implement, the new division of time proved impossible to enforce because the traditional system was too deeply ingrained in people's minds. Therefore the provision for decimal hours was suspended on April 7, 1795, leaving the mandatory Revolutionary calendar in place. The Republican calendar law was effective until 9 September 1805. When the law was introduced, the demand for Revolutionary watches was greater than the makers could produce. The standard practice was to convert a duo-decimal watch from the stock made few years before. For that a watchmaker had to replace the balance spring with a longer one to make the center wheel rotate 10 times per day instead of 12 and change the motion train to accommodate 1:10 ratio instead of 1:12.
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