Swiss rare open faced silver deck chronometer Circa 1919

Silver watch with extremely unusual chronometer caliber
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An experimental deck chronometer made by Vacheron Constantin SA in Geneva, Switzerland, circa  1919. This watch has an open faced contest case crafted from silver and is glazed on both sides. The silvered dial features Roman hour numerals, an outer minute track, a subsidiary seconds dial at 6 o’clock, power reserve indication at 12 and blued steel spade hands. The numbered, extremely unusual chronometer movement is fitted with 21 jewels, an experimental construction for the power reserve, a chronometer balance, lever escapement and eight adjustments.
The dial and movement are signed.
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Diameter: 64 mm
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Weight: 190 g
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Signed: Vacheron & Constantin Genève Suisse
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The watch presented here participated in the 1919 Geneva Observatory Chronometer Competition in the category “First Class Chronometers”, achieving a score of 711 points and placing 29^th out of 81 chronometers. This piece also participated in the 1919-1920 chronometer competition organized by the National Physical Laboratory in Teddington, London, England and was awarded “Especially Good” in the Kew – Class A category, scoring a sensational 92.8 points.
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This chronometer has a special, in all probability, experimental, signed mechanism for the power reserve indicator. No other pocket chronometer by Vacheron & Constantin with this construction is known. They, like Patek Philippe, produced these extremely rare movements primarily for competition purposes. As a rule, they were not intended for sale and therefore had no standard case design. Often owned by the manufacturer for decades before they eventually came into circulation.
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Today, these watches are extremely rare and naturally sought after collector’s items.