Swiss silver and gold Adjusted Extra lever watch Circa 1913

Silver and gold open faced lever chronometer watch by Patek Philippe
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A very fine, rare Swiss silver and gold open faced keyless Adjusted Extra lever chronometer pocket watch, circa 1913. Geneva Observatory Rating Certificate obtained on November 21, 1911. Sold on August 7, 1922. Adjusted Extra rhodium plated movement, Geneva striping decoration, engraved twice with the movement number, 17 jewels, wolf’s tooth winding, straight-line counterpoised and calibrated lever escapement, anibal-brass Guillaume balance with winged arms, gold and platinum temperature adjustment screws, blued steel Breguet balance spring with terminal curve, diamond endstone, swan neck micrometer regulator. Hinged silver cuvette. White enamel dial with Breguet numerals, outer minute track, subsidiary seconds dial and original blued steel Breguet hands. Polished case, gold hinges, collar and thumbpieces. Dial, case, cuvette and movement signed, case and movement numbered. Accompanied by the Extract from the Archives.
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Diameter: 51.5 mm
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Signed: Patek, Philippe & Cie Genève
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When destined for Observatory Timing Contests, the movements of Patek Philippe watches, like those of other makers, were double engraved with the movement serial numbers. The inscription ‘Extra’ on the bridge of the movement refers to the high finishing of all the parts of the movement.