Important Modern and Vintage Timepieces.

Geneva, Nov 13, 2010

LOT 352

Constant Force escapement Attributed to Louis Richard, Le Locle, movement No. 87517, case No. 101. Made circa 1860. Fine and extremely rare, 18K gold, keyless and key-wound pocket watch with highly unusual experimental constant force escapement and gold wheel train.

C. Three body, ?bassine et filets?, mastermark ?FS?, polished, engine-turned back cover. Gold engine-turned cuvette. D. White enamel, radial Roman numerals, outer minute track, subsidiary seconds. Blued steel spade hands. M. 42.8 mm,19???, matte gilt, gold train, wolf?s tooth winding without coasting, highly unusual escapement which combines detent chronometer and lever with constant force action: the escape wheel consisting of two stacked wheels of different diameter, the lower delivering the impulse, the upper for locking with a detent spring, impulse is delivered to a roller mounted in jewels on a pivoted detent, the roller turns freely to minimize the friction, the locking spring is part of the detent mounted perpendicular to it, detent with spiral spring acting as a remontoir, end of the detent fitted with a large roller mounted in jewels rolling on a large half-cylinder mounted on the balance staff, the energy in the constant force spring giving impulse to the balance via the roller, constant force spring mounted on an adjustable plate to control the energy delivered to the balance and acting as an amplitude adjustment, cut bimetallic compensation balance with gold meantime and temperature adjustment screws, flat balance spring, index regulator with micrometric screw. Stamped ?FS? inside back cover, movement scratch numbered on the dial plate. Diam. 49.5 mm.