311,500 CHF
The First French Wearable Precision Timekeeper Inventée et construite par Ferdinand Berthoud, Exécuite par Louis Berthoud, production started 1765, finished 1785 and sold in 1787 to His Royal Highness The Prince of Asturias, future King of Spain Charles IV. Extremely important, unique, exceptionally fine, the first French wearable Longitude Timekeeper (Montre de poche à Longitude), the first French watch with spring detent escapement, gridiron temperature compensation and regulator dial, accompanied by gilt brass stand. Three-body, "Tambour", glazed back (brass back enclosed), polished, gimbaled pendant, hinged bezel. Gilt brass dial plate with applied silver Roman hour ring at the top with quarter-hour divisions, lower to the right applied silver minute chapter with five-minute Arabic markers, to he left subsidiary seconds. Blued steel "arrowhead" hands. 54.1 mm. (24’’’), gilt duoplan brass full plate, cylindrical pillars, fusee and chain with maintaining power, spring detent escapement of special construction with large impulse roller, unlocking pin engaging long U-shaped passing spring mounted on the impulse roller, large monometallic three-arm balance with regulating screws and blued steel balance spring colleted with a bracket hold with two screws and studded in special stud with horizontal and vertical adjustments, gridiron temperature compensation changing the active length of the balance spring via two levers and one spring, no motion work, hands driven direct
Auctioneer:
Antiquorum
Date:
2002-10-19
