LA MONTRE A LONGITUDE VERTICALE NO. 46

Details
LA MONTRE A LONGITUDE VERTICALE NO. 46
BY FERDINAND BERTHOUD
DATED 1790

DIALS AND HANDS
The gilt-brass dial plate inscribed No. 46. M. à Longit Inve par Ferdinand Berthoud 1790 and acting as the outer side of the pillar plate, three small subsidiary silvered dials mounted thereon; viz the hours with Roman numerals, upper minutes ring and lower seconds with Arabic chapters, all hands of blued steel with circular counter-weights, start/stop lever control between hour and minute dials, hinged bezel
MOVEMENT
The movement constructed on three separate planes, viz
THE BOTTOM ASSEMBLY
This comprises a pillar plate of four turned pillars (63 mm. diam.) pinned to a top plate and carrying the 14,400 count train, the one-day running fusee is wound clockwise, mounted on the fusee arbor beneath the great wheel and fusee cap is a pinion which drives a wheel carrying the hour hand, this wheel does not form any part of the going train; opposite this wheel on the other side of the fusee is the second wheel of the going train and this carries the minute hand, thence to the third wheel which drives the fourth wheel which carries the seconds hand, thence to the fifteen teeth brass escape wheel, thence to the polished steel pivoted dentent. All wheels have four-armed crossings
TOP AND MIDDLE ASSEMBLIES
The top assembly is a three pillared pinned sub-frame of gibbous form (50 mm. max. diam.), its underside with three pinned pillars whereby the whole assembly is mounted above the bottom assembly and which provides the middle space in which the balance rim oscilliates; within the top frame are mounted three balance staff friction rollers, on the top plate the balance top pivot cock; above this the Berthoud heat compensation assembly comprising a steel pivoted index arm traversing an engraved scale with adjustable steel curb pins, the compensation controlled by a bimetallic strip (40 mm. long, 4.5 mm. high) the outer end of which is clamped to a vertical brass post mounted above the top plate
BALANCE
Brass three-arm uncut rim with three underslung brass cheese head screws; oversprung robust blued steel balance spring of six turns. Protruding from inside of the rim a pin traversing above a balance amplitude scale engraved on the main-frame top plate. Polished steel impulse roller, stop/start brass pressure spring to side of balance rim operated thorugh the dial
MOUNTING
Circular plate base (110 mm. diam.) with three adjustable ball feet and central vertical screw to lock bottom of bowl, vertical arm with stirrup assembly to accommodate bowl pendant
BOWL
Heavy brass drum shape, at the top a male gimballed stirrup pendant mounting to fit female stirrup assembly on vertical support arm
72mm. diam.
115mm. high
To be sold with; Ferdinand Berthoud Histoire de la Measure du Temps, Paris: An. X (1802). 2 vols, 4to., engraved plates, contemporary sheep, gilt spines; and Traité des Montres à Longitudes, Paris: 1792; 4 parts in one vol., 4to., engraved plates, contemporary sheep, gilt spine (3)
Provenance
Antiquorum, Geneva, 16, October 1988, Lot 415, sold for SFr.170,000
Literature
Musée International d'Horlogerie, La Chaux-de-Fonds, exhibition catalogue, Ferdinand Berthoud, 1727-1807 - Horloger Méchanicien du Roi et de la Marine, 1984, 212-3.
The British Museum, Catalogue of Watches, VI, 1990, pp.14-16,
Hans Von Bertele, Marine & Pocket Chronometers, Schiffer, 1991

Lot Essay

Ferdinand Berthoud, 1727-1807, is rightly accredited with the title of France's greatest 18th century clockmaker. Born in Placement, near Le Locle he was the son of an architect and judiciary and apprenticed to his brother Jean-Henri at the age of fourteen. In 1745 he borrowed 200 Livres to travel to Paris where an elder brother resided and where it is said he worked for some time in the workshop of Julien LeRoy. Like other brilliant academics he seems to have quickly established a fine reputation. Besides having a brilliant mechanical mind Ferdinand Berthoud also applied himself to astronomy, mathematics, and physics all of which he used to design and invent an amazing array of innovative marine timepieces. However in order to bring his inventions and ideas to everyone's attention Berthoud published an incredible four thousand pages of horological literature which included ten books written between 1759 (at the age of 32) and 1802, one of which, Traité des Montres à Longitude published in 1792 has the first 22 pages entirely devoted to the present chronometer No. 46 and is included in the lot
When it was made in 1790 M.M. (Montre Marine) No. 46 was the most versatile marine timepiece that Berthoud had designed to date. It was in fact made by his premier pupil Vincent Martin who held the title of clockmaker to the French Navy in Brest. Martin completed the chronometer to Berthoud's exact specification and so as to leave no one in any doubt Berthoud published these specifications in the Traité des Montres à Longitudes. In it he not only states that No. 46 was constructed by Vincent Martin but also gives the reasons why he was embarking on an enrirely different type of timepiece.
Furthermore Berthoud also mentions that another apprentice, Cayetano Sanchez, would also construct an identical model. Sanchez had been sent by the Spanish Governmant to study under Berthoud (who received 20,000 Francs for the pleasure) and later under the English horologist Josiah Emery so that he could return to Spain and teach other clockmakers the art of chronometer making. (See the following lot for further evidence of this arrangement).
Berthoud explains that M.M. No. 46 was designed to be used primarily to calculate the longitude at sea and for this purpose the chronometer was suspended from a gimballed stand. However Berthoud wanted the timepiece to have greater versatility so he also designed it small enough to be used as a pocket or deck watch which was facilitated by modifying its pendant gimbal stand from which it could be easily detached. Conversely it could be locked so as to then act as a desk timepiece. It was in fact a multi-purpose marine chronometer and the first of its type in France. Berthoud also set out to correct some of the other errors that his earlier timepieces were showing. To this end he made a much smaller and lighter balance wheel that beat a more efficient four alternations per second rather than the six beats used by previous chronometers. His other improvements were to the varied use of anti-friction rollers and also to the temperature compensation by employing a combination of steel and copper (which meant abandoning the grid-iron compensation altogether). In addition he used an all new but simple detatched pivoted detent escapement and then lastly a main-spring that could be adjusted by a fusee that also had maintaining power.
In order to put M.M. No.46 into context it is as well to note that although Harrison's H4 had been on sea trials in 1761 and Berthoud's M.M. No. 3 used on expeditions from 1763, marine chronometry whilst not in an infant state was still regarded as an experimental science. Ferdinand Berthoud patently regarded M.M. No. 46 as one of his most important works and devoted a great deal of time to explain its virtues and then chose it as one of the clocks included in the frontspiece of his most celebrated book Histoire de la Mesure de Temps (also included in this lot). A number of Berthoud's early chronometers have survived but the vast majority are in public institutions such as La Musée des Art et Métiers (Paris), La Musée International d'Horlogerie (La Chaux-de-Fonds) and the British Museum, leaving the few remaining private examples highly treasured possessions.

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