Anti magnetic deck watch with Guillaume balance Circa 1939

Silver open faced lever deck watch by Breguet
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A rare Swiss silver open faced anti magnetic deck watch with Guillaume balance, circa 1939. Sold to the Service Hydrographique de la Marine on 28 August 1939. Nickel finished lever movement stamped with the Viper’s head, 20 jewels, Guillaume balance. Later glazed cuvette and plain metal cuvette. White enamel dial with Arabic numerals, blued steel spade hands and subsidiary seconds. Large case, hinged back engraved , Case and movement signed and numbered, dial signed. Accompanied by Besançon Bulletin d’Observatoire.
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Diameter: 74 mm
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Signed: Marine Service Hydrographique 4054 No-Magnetic Breguet