Unusual Swiss silver open faced cylinder watch Circa 1857

Silver keyless pocket watch 
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An extremely unusual and very early Swiss silver open faced pocket watch with first generation crown winding after patent No. 9208 made by Patek Philippe in Geneva, circa 1857. The movement is fitted with a cylinder escapement and wolf’s teeth. The textured silver dial with an Orac decor in the center, applied gold Roman hour numerals, outer dot minute divisions and steel Breguet hands. The original case has gold hinges and a signed cuvette engraved Invention Brévetée de Patek, Philippe & Co à Genève.
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Diameter: 46 mm
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Weight: 71 g
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Signed: Patek, Philippe & Co Genève