This substantial, well constructed and beautifully finished watch was evidently made for navigational use at sea. As such, it is a fascinating and extremely rare survival from the early period of the use of mechanical timekeepers for calculating longitude ? perhaps the most intractable and difficult technological problem of the 18th century. The maker Tavernier was evidently very proud of this watch as he has incorporated his initials into the elaborate design of the balance cock. The movement can be locked into the case and once locked requires the special pinion-ended key to release it. This feature is provided so that no unauthorized person could interfere with the movement when in use. The dial and hands can be still accessed which suggests the likelyhood that the watch was once housed in a lockable gimballed wooden box similar to the one surviving example for a watch of this period known as `La Petite Ronde` made by Julien Le Roy for navigational use at sea. Early marine timekeepers such as the present watch did not of course use the spring detent escapement which was not invented until around 1781 by John Arnold. Most of the watches designed for use at sea before the introduction of the detent escapement were fitted with a modified verge escapement including John Harrison?s H4 completed in 1759 which ultimately won the longitude prize in England. In France, the technical advances in timekeepers for marine navigation occurred more or less simultaneously with those being developed in England largely due to the fact that Ferdinand Berthoud was personally familiar with Harrison?s inventions. In France however, no standard form of marine timekeeper seems to have been made, each maker preferring his own particular form of construction. This resulted in quite a number of different calibers including the present watch which uses a cylinder escapement, the escape wheel having 60-teeth and second-beating balance therefore the seconds hand which is mounted on the escape wheel pinion gives dead-seconds. Tavernier?s use of the cylinder escapement in this watch is interesting, the cylinder escapement whilst prone to shock-damage and difficult to repair is otherwise quite stable and reliable and used in this watch perhaps for that reason, also the cylinder may have appealed to Tavernier as an experimental alternative to adapting a verge or other form of escapement. The fusee incorporates Harrison?s maintaining power, the balance is of very large diameter, the balance spring a short spiral of steel with only three acting turns.
JEAN-PIERRE TAVERNIERØ C. 1720 - AFTER 1804 Father of Louis and Pierre-Benjamin. He was received Master on March 1, 1746, and established a shop in the rue de Bucy. He was particularly renowned for his watches, but also sold clocks, using cases by B. Lieutaud and F. Rémond. Among his clients was the Duc de Caylus. After Jean-Pierre?s death, his activity was continued by his son Louis
LITERATURE ?The Time Museum Catalogue of Chronometers?, Anthony G. Randall, 1991.
?Watches?, Clutton & Daniels, 1979, fig. 155d ?La Petite Ronde?.
?Les Ouvriers du Temps?, Jean-Dominique Augarde, Editions Antiquorum, Genève, 1996