Fine, rare Swiss 18k gold lever with power reserve Circa 1919

Open faced keyless lever by Patek Philippe
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A fine and rare Swiss 18 carat gold open faced keyless lever watch with power reserve and guillaume balance, circa 1919. Nickel finished first quality lever movement, 20 jewels, Guillaume balance with gold poising screws, micrometer regulator, wolf’s tooth winding. Inscribed gold cuvette reading Calvin from Mother 1924. White enamel dial with Arabic numerals, subsidiary dial for power reserve and constant seconds. Plain case, hinged back with hidden hinges. Case and movement signed by watchmaker and retailer, cuvette numbered, dial signed by retailer.
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Diameter: 46 mm
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Signed: Patek, Philippe & Co Geneva, Switzerland – Bailey, Banks & Biddle Co, Philadelphia