8,050 CHF
French, Royal Exchange, London, No. 646.Fine and unusual deck watch chronometer in gimbals, with a special balance. Three-body, cylinder type, fire-gilded, the back with winding aperture with spring-loaded cover, suspended in gimbals, locking arm at 4 o’clock. 20’’’, full-plate, engraved balance cock and barrel cover, fusee with chain, Earnshaw-type spring detent escapement with triangular-shaped lockinjewel inserted from the side, bimetallic compensation balance with a device to protect the free ends of each sector from accidental distortion, blued-steel helical balance spring with two terminal curves.Signed on dial and movement.Dim. of canister 60 mm. Box: 11x15x8 cm. Notes Balance sensitivity is inversely proportional to the total thickness of the rim, which means the thicker the rim, the less sensitive the balance. However, thin rims are too fragile and are more responsive to deformation caused by centrifugal force, to say nothing of the fingers of watchmakers. The device found in this lot was invented, about 1800, to prevent this damage. It is interesting to note that the problem persisted into the 20th century. There is, for instance, a patent by J. Rauschenbacfor a device to prevent distortion of bimetallic rims by watchmakers during cleaning (Swiss patent No. 54169 of 1911).
Auctioneer:
Antiquorum
Date:
2000-10-15
