Month-going weight driven going train with maintaining power and Graham dead-beat escapement. Spring driven striking train with locking-plate with hour-strike and once every half hour on a chime. Indications of hours, minutes, seconds, year calendar as well as astronomical equation.
Isochronous pendulum with steel and brass rods and compensation indication on knife suspension.
Enamel dial signed Coteau at the bottom. Indication of hours and minutes, year calendar and equation indication. Two gilt brass hands and three steel hands.
The casing of the clock is attributed to Balthazar Lieutaud. The case has an oak frame veneered with amaranth, ebony, boxwood, tulipwood, and end grain vines (noeuds de vigne). The case rests on a wooden plinth of later date. The body of the clock case has a door in the front that is slightly downward tapering, with a glass pane. The hood has a round door with a convex glass lens mounted in a gilt brass frame.
The noeud de vigne veneer is made by cutting end grain vine slices that are arranged in a pattern and filled with end grain bits of the thinner shoots of the vine, resulting in a very distinct texture.
The case is ornamented with very finely chased ormolu bronzes.
The isochronous pendulum
The clock is constructed for maritime purposes, hence the equation indication. To enhance the precision of the time keeping the clock is fitted with an isochronous or compensated pendulum. In 1726 John Harrison invents the temperature compensated gridiron pendulum. The difference of dilatation in various metals when heated is used to construct clock pendulums that are indifferent to changes of the environmental temperature. The original design of the gridiron pendulum is adapted by John Ellicott (1706-1776).
The isochronous pendulum in this clock is of a very specific design of Berthoud’s own hand and aims to achieve a higher precision than the commonly used types with round metal rods. The construction and its idiosyncrasies is extensively described by Berthoud in his “Essai sur l’Horlogerie” (1763, Vol. II chapter 44 and ill. Planche XXXIV). Berthoud is very meticulous in the way he calculates the effects and in the scientific underpinning of his design.
Ferdinand Berthoud (1727-1807)
Ferdinand Berthoud was born 18 march 1727 in Plancement in the Swiss canton Neuchâtel. At the early age of 14 he became an apprentice clockmaker to his brother Jean-Henri Berthoud. After completing his apprenticeship at the age of 19 he moved in with his brother Jean-Jacques in Paris to accomplish his training. It is believed in his early years in Paris he worked for Julien Le Roy. That is how he would have met Pierre Le Roy who would become very well known in the field of maritime time keeping.
On 4 December 1753 Berthoud becomes master clockmaker by Royal Decree and in contradiction to the corporative rule. In 1755 he will edit a series of articles concerning horology for Diderot’s ‘l’Encyclopédie’.
In 1763 the French king sends Berthoud to London, accompanied by Charles Étienne Louis Camus and Jérôme Lalande, to study John Harrison’s H4 marine clock. For the amount of 500 livres Harrison demonstrates his H1, H2, and H3 model to the delegation. He refuses, however, to show his H4 type, the actual goal of their visit. Nevertheless, Berthoud benefits from his visit to London, because he manages to get introduced to the Royal Society and becomes an “associate foreign member” on 16 February 1764.
In 1765 Berthoud travels to London a second time in an attempt to see Harrison’s famous H4 maritime clock. Berthoud gets his introduction through the intervention of the Saxon minister Heinrich von Brühl. Harrison, however, demands the insurmountable and dissuasive amount of 4.000 pounds for the demonstration, being fully aware that Berthoud was capable of using the principle of the H4 to the benefit of the French Navy. Eventually it is Thomas Mudge who clarifies the principles of H4 to Berthoud, without showing him the actual clock.
With his newly acquired insights in marine horology, Berthoud writes to the duke of Praslin with a proposal to develop two new maritime clocks, number 6 and number 8, and suggests a remuneration of 3.000 livres yearly on the basis of his work in the past and in anticipation of the cost for development of the new models. He also applies for the title “horloger mécanicien du Roi et de la marine”. On 24 July 1768 the king accepts to finance the project for two new marine clocks.
On 3rd November 1768 the numbers 6 and 8 were put aboard the frigate Isis at Rochefort under the command of Eveux de Fleurieu. This marked the start of a large number of experiments on maritime time keeping that were continued by Berthoud’s nephew Pierre Louis Berthoud.
Berthoud is awarded the title Clockmaker to the French Royal Navy, and Chevalier of the Legion of Honour. He dies in 1807 in Groslay.
Joseph Coteau (1740-1801)
Being the most renowned enameller of his time, Coteau worked with most of the best contemporary Parisian clockmakers. He was born in Geneva, where he became master painter-enameler of the Académie de Saint Luc in 1766. Several years later he settled in Paris, and from 1772 to the end of his life, he worked from the rue Poupée. Coteau is known for a technique of relief enamel painting, which he perfected along with Parpette and which was used for certain Sèvres porcelain pieces, as well as for the dials of very fine clocks. Among the pieces that feature this distinctive décor are a covered bowl and tray in the Sèvres Musée national de la Céramique (Inv. SCC2011-4-2); a pair of “cannelés à guirlandes” vases in the Louvre Museum in Paris (see the exhibition catalogue Un défi au goût, 50 ans de création à la manufacture royale de Sèvres (1740-1793), Musée du Louvre, Paris, 1997, p. 108, catalogue n° 61); and a ewer and the “Comtesse du Nord” tray and bowl in the Pavlovsk Palace in Saint Petersburg (see M. Brunet and T. Préaud, Sèvres, Des origines à nos jours, Office du Livre, Fribourg, 1978, p. 207, fig. 250). A blue Sèvres porcelain lyre clock by Courieult, whose dial is signed “Coteau” and is dated “1785”, is in the Musée national du château in Versailles; it appears to be identical to the example mentioned in the 1787 inventory of Louis XVI’s apartments in Versailles (see Y. Gay and A. Lemaire, “Les pendules lyre”, in Bulletin de l’Association nationale des collectionneurs et amateurs d’Horlogerie ancienne, autumn 1993, n° 68, p. 32C).
One of the most important Parisian cabinetmakers of the Louis XV period and the early Neoclassical period, he was born into a dynasty of Parisian furniture makers – both his father and grandfather were cabinetmakers. He became a master in 1749 and opened a workshop in the rue de la Pelleterie. He quickly specialised in the creation of regulator and cartel cases, acquiring his bronze mounts from the finest bronziers and chasers of the period, including Charles Grimpelle, Caffieri and Jean-Charles Delafosse.
Signature: on the dial and on the clockwork: Berthoud à Paris; dial signed: Coteau
Case attributed to Balthazar Lieutaud.
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