Important Collectors’ Wristwatches, P...

Geneva, Nov 16, 2008

LOT 501

Constant Force Escapement Hess &Metford, Succ.rs de Heil & Hess a Geneve, ?Chronometre Force Constant?, No. 2023. Made circa 1850. Very fine and extremely rare, 18K yellowgold half hunting-cased pocket watch with constant force escapement.

CHF 25,000 - 30,000

USD 23,000 - 28,000 / EUR 16,000 - 20,000

Sold: CHF 21,600

C. Four-body with engine-turned covers ?à grains d?orge?, polished borders, the front cover with scallop-edged polished chapter ring with radial black Roman numerals, inner minute track, reeded band. Hinged gold cuvette. D. White enamel with radial Roman numerals, outer minute track, subsidiary seconds. Blued steel spade hands.M. 42mm., frosted gilt, bar caliber, 10 jewels, constant force escapement with two stacked escape wheels using a tensioning spring to provide the constant force, large curved lever arm with counterpoise and recessed into the plate for security, cut bimetallic compensation balance, blued steel Breguet balance spring, index regulator. Dial and cuvette signed. Diam. 50 mm.


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Grading System
Grade: AAA

Excellent
Case: 3

Good
Movement: 2

Very good
Dial: 2-01

Very good

HANDS Original

Notes

A constant force escapement incorporates a remontoire device to ensure constant force between the escape wheel and the balance. The escapement of the present watch works in the following way: The upper escape wheel comes to rest on the pallet fork which is at the same level. When the balance returns the anchor recoils which has the result of putting pressure on the internal tensioning spring. At the moment that the pallet exits, this spring is released and transmits power to the lower escape wheel. This wheel then gives the impulse to the anchor. The small spring therefore gives an impulse force that is constant during the entire operation of the escapement. The constant force escapement works very well, though the timekeeping results are not as good as those for a precision pocket chronometer.
Hess & Metford Active in Geneva between 1840 and 1860 and succeeded the firm of Heil & Hess. The company?s reputation was principally for the sale of complicated, high quality pocket watches destined for North America. See: Dictionnaire des Horologers Genevois, Antiquorum Editions, Geneva, 1998.
Literature: The constant force escapement is discussed and this watch illustrated in: ?Un chronometre de poche avec un échappement à force constante?, Adolphe Chapiro, Bulletin Ancaha, No. 98, Automne-Hiver, 2003.