Swiss silver deck watch with extra adjusted lever chronometer Circa 1912

Silver open faced keyless deck watch
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A very fine Swiss, silver deck and pocket extra adjusted lever chronometer with 36-hour power reserve indicator and Guillaume balance, circa 1912. Obtained the Geneva Observatory rating certificate on June 11, 1913, and sold it on December 8, 1917. Accompanied by the Extract from the Archives. A polished case, silver hinged cuvette. Heavy, solid silver dial, bold champlevé radial Roman numerals, outer champlevé minute track, an up-and-down sector at 12, and subsidiary seconds. Blued steel spade hands.
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Straight-line calibrated lever escapement, 21 jewels, Anibal-brass Guillaume balance with winged arms, gold temperature adjustment screws and platinum mean time ones, special alloy Breguet balance spring with Phillips’ inner and outer terminal curves, diamond endstone, swan-neck micrometric regulator, Patek Philippe & Cie. keyless winding (Swiss patent 2680, 27 September 1890), differential up-and-down mechanism. Dial, case and movement signed. Property of an American Gentleman.
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Diameter: 60 mm
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Signed: Patek Philippe & Cie  Genève