Large Swiss silver pocket chronometer deck watch Circa 1942

Silver open faced deck watch
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A large Swiss silver open faced keyless pocket chronometer deck watch, made by Vacheron & Constantin in Geneva, circa 1942. A plain silver case made by FFBA, Fédération de Fabricants de Boîtes d’Argent, S. Graber, Renan. Silver dial with suspended Arabic numerals, outer minute track, subsidiary at 6 and blued steel hands. Movement with a lever escapement, cut bimetallic compensated balance with gold poising screws, index regulator with swanneck spring and micrometric screw. Signature on the dial, case and movement.
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Diameter: 60 mm
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Signed: Vacheron & Constantin, Geneva
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Deck Watch: A deck watch is a precision watch used on the deck of boats for navigational purposes, point reading to avoid disturbing the proper functioning of the marine chronometer, which remains in a specific area of the ship, chronometer room or captain’s cabin. For more information on this type of time-keeper, now a collector’s item, see Norbert Eder’s reference book.
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Guillaume Balance: The Guillaume balance is a compensated bimetallic balance, made of anibal, an alloy of steel, nickel and brass, after the works of Dr Charles-Edouard Guillaume, 1861-1938, with which the middle temperature error is practically eliminated. The middle temperature error, or Dent’s anomaly, is the difference between the rate of a chronometer at the mean temperature and the average of the rates at extreme temperatures. This type of balance was used by the horological manufactories since 1904.