Ferdinand Berthoud
Ferdinand Berthoud was born on March 18th 1727 in Plancemont-sur-Couvet, Neuchâtel, Switzerland. He died in Groslay (Val d'Oise) on June 20th 1807. He was both a scientist and a watchmaker, born into a family of horologists. At the age of fourteen, he was taken on by his brother, Jean-Henry, as a clockmaker's apprentice in Couvet. On April 16th 1745, aged 18, he moved to Paris, where he continued to improve his skills as a clockmaker.
In 1752 Ferdinand submitted to the french academy of sciences an equation clock marking leap years. On December 4th 1753, following a ruling from the King's Council in contradiction of by-laws and by special favour of the sovereign, Ferdinand Berthoud was officially granted the title of Master Watchmaker at the age of 26. In 1763, Ferdinand Berthoud was appointed by the King to examine John Harrison's H4 Marine Timekeeper in London. Harrison categorically refused to let Berthoud see the clock. His journey opened the doors to the English scientific fraternity, thanks to the importance of his horological work and publications. On February 16th 1764 he was appointed a "foreign associate member" of the Royal Society in London.
To read a full unabridged account of Ferdinand Berthoud's professional life, please click here.
The watch was commissioned by Berthoud to be made by the Jean Martin in 1806. It was designed following Berthouds watch No.73 but made slightly smaller than the original, simplifying parts of the escapement. A year later Berthoud passed away. (In Catherine Cardinal’s book about Ferdinand Berthoud, on pages 226-227, there is evidence that Jean Martin was at active until 1807.)
The watch was delivered to Jean Chaptal, Count de Chanteloup, a physician and politician
Berthoud was honoured with membership in both the Institute de France in Paris as well as the above mentioned Royal Society in London. Ferdinand Berthoud wrote several scientific treatises, including 'Essaie sur l'horolger' in 1763 and 'Traité des horologes marine' in 1773. In his 'Supplement au Traité des Montres à Longitude' he mentions this timepiece.
Dimensions: case diameter 59mm, thickness 20.7mm, movement diameter 52.9mm.
The Claude Chaptal, Count de Chateloup coat of arms
The movement is key-wound through the inner case-back
Both the bezel and outer case back can be opened easily with the thumbnail to be able to set and wind the watch.
The hands are adjusted using the same key for winding up the mainspring, accessed by opening the front bezel.
The hands were made from steel, hardened and blued by heating.
The open bezel
The outer minutes, hours and seconds chapter rings are made in silver.
The case reference and hallmarks
The references scratched into the case back on the far left and right were probably made by watchmakers in the past once they had serviced the watch.
The design of the dial with small hour and minute indication allowed for a large surface enabling an ornate and detailed engraving siting both the maker who had been commissioned to make the piece as Berthoud who designed the watch and made the original version upon which this was based.
Montre Astronomique. Ferdinand Berthoud. Inv. 1775. Reduite et Exécutée Par Jean Martin, An 1806.
This small subsidiary dial indicates the amplitude of the balance. Hidden under the steel plate is a hand fitted onto the balance staff which rotates with it. When this image was taken the watch was wound down and not ticking, hence the reason the hand is not in view.
The steel plate is the end piece for the balance staff holding the cap jewel limiting the vertical movement of the balance staff.
Views of the inner case back (jacket) open showing movement.
At 12 o’clock is the barrel containing the mainspring, to its left is the fusee and below it the going train. At 3 o’clock is the balance assembly.
The detent escapement is hidden under the dial
Top view of the barrel showing the ratchet wheel and click system.
Once the tension from the mainspring is armed by turning the ratchet wheel ensuring the chain connecting the barrel to the fusee is aligned, the second screw in the click is added, locking, blocking and strengthening the click contsruction.
The movement and dial assembly removed from the case.
Originally the seconds hand had a tail that at some point during the last 200 years was broken or deliberately removed.
Full view of the movement removed from the case.
Gilded bridges and main-plate, blued steel screws.
The fusee and barrel.
The cone on the fusee is far more inclined than on modern fusee’s due to the greater variation in the torque of the mainspring.
The complete going train including the fusee is jewelled.
The jewels were in essence ‘rubbed in’ or riveted in place unlike today when jewels are a friction fit and can be adjusted in position with in the thickness of the bridge or main-plate they sit. This means that here, the pieces had to be carefully made to ensure that when the movement was assembled all tolerances were correct.
The complex balance assembly.
The overall balance assembly is heavily over-engineered to build a strong, precise and rigid structure.
The balance spring is extremely tall compared to others of the same period, and made since. In order to allow for a means to be able to adjust the ‘flatness’ of the balance spring when in place, a complex stud system was developed. (The stud is the part that links the balance spring to the balance cock.)
The stud is the steel piece with 4 small screws. By adjusting these screws the balance springs flat position could be easily manipulated, effectively rocking the stud until the flat plane of the balance spring was correct. The large central blue screw pushed down on the brass plate and locks the stud in position once the four small blue screws are adjusted and the concentric position of the balance spring is decided, which insures the most even movement of the spring as it breathes in and out whilst oscillating. The entire construction is a way to ensure accurate adjustment of the balance springs external point of attachment.
The blued steel balance spring is fixed to the balance staff (the central axle upon which the balance wheel and spring are fixed), by a small plate screwed in place sandwiching it solidly and ensuring that the terminal curve was concentric with the centre of the staff.
A four-armed compensating balance wheel, rim with 4 gold adjustment screws as well as four bimetallic strips on the balance wheel circumference; gold adjustment nuts are fixed to the end of these strips.
The two gold nuts could be turned to alter their position and then tightened against each other to lock them in place. Their position influence the accurate of the balance wheel under different temperatures.
The upper bridge with four blued screws holds in place the diamond end stone.
Summary
Many elements make this timepiece special beyond its antiquity. It is an example of a highly technically advanced piece of horology whereby simple systems such as the stud have been remastered to compliment an unusually high balance spring. The jeweling is ahead of time in relation to the number of bearings that were jewelled running through to the fusee, and the rigidity of the overall construction is far more solid than watches built in this period or since.
Thanks to Ferdinand Berthoud company for the dates and historical information noted in this page.
GALLERY
In the grid below are both images used in the description of this page plus more. Please click on the image to enlarge and see in full.
To learn more about Ferdinand Berthoud