Important Collector's, Watches, Wrist...

Geneva, Hotel Des Bergues, Oct 15, 2000

LOT 241

French, Royal Exchange, London, No. 646.Fine and unusual deck watch chronometer in gimbals, with a special balance.

CHF 6,500 - 8,500

USD 3,600 - 5,000

Sold: CHF 8,050

C. Three-body, cylinder type, fire-gilded, the back with winding aperture with spring-loaded cover, suspended in gimbals, locking arm at 4 o?clock. D. Silvered with Roman numerals and outer minute ring, subsidiary sunk seconds, mounted by three brackets with milled pins fitting crescent-shaped openings in the pillar plate, blued-steel 'spade' hands. M. 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.


LOADING IMAGES
Click to full view
Image
Grading System
Grade: AA

Very good
Case: 4 - 5 - 14
Movement: 4*

Fair

Overhaul recommended, at buyer's expense
Dial: 4 - 6 - 01

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).