Important Watches, Collector's Wrist...

Hong Kong, Jun 08, 2001

LOT 240

Patek, Philippe & Cie, Genève, No. 170390, case No. 404420, circa 1915.Very fine and rare 18 K gold, hunting cased, keyless, ?EXTRA? adjusted watch with special balance and First Class ?Bulletin de Marche? with a pair of gold ?spade? hands and original mahogany fitted box.

HKD 35,000 - 43,000

USD 4,500 - 5,500

Sold: HKD 48,300

C. Four-body, ?deux filets?, polished, gold hinged cuvette. D. White enamel, Roman numerals, outer minute ring, subsidiary sunk seconds. Blued steel ?spade? hands. M. 41 mmø (18'''), nickel, 20 jewels, straight-line counterpoised lever escapement, cut bimetallic compensation balance, blued-steel Breguet balance spring, Guillaume balance with gold screws, center bridge signed ?EXTRA?, engraved twice, according to the Observatory Contest rules, with the serial number, wolf-tooth winding wheels, "san-neck" micrometric regulator.Signed on dial, case and movement.Diam. 55 mm.


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Grading System
Grade: AAA

Excellent
Case: 3

Good
Movement: 3*

Good

Overhaul recommended, at buyer's expense
Dial: 3 - 01

Notes

Superbly adjusted Swiss watches of the period, and particularly those of Patek Philippe ones were signed ?EXTRA?.Anibal (acier au nickel pour balanciers), an alloy invented by Dr. Charles Edouard Guillaume, exhibits peculiar properties, both in terms of thermal expansion and in changes in elasticity. In 1899, Guillaume noticed that steel with an addition of 44.4% nickel has a negative square coefficient of thermal expansion. This, combined with brass in bimetallic lamina, makes its expansion close to quadratic. Balances with bimetallic rims made of anibal and brass are usually called Guillaume balances, oras their inventor called them, integral balances. Combined with special balance springs, they show amazing temperature stability, sometimes not exceeding 1/50 second per day per 1oC.