Swiss gold open faced keyless winding lever Circa 1893-1894

Gold pocket watch with open face by Patek Philippe
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A Swiss 18 Carat pink gold keyless winding pocket watch with open face, circa 1893-1894.
Gilded brass movement, going barrel, straight line equilibrated lever escapement, cut bimetallic compensated balance with gold poising screws and blued steel hairspring with a terminal curve, index regulator with swan neck spring and precision regulating device for fast/slow using an eccentric snail. Enamel dial with Roman radial hours, outer minutes track with Arabic five minutes numerals, subsidiary dial for the seconds, and pink gold Louis XV style hands. Round shaped 18 Carat pink gold polished case, case back engraved in taille douce (fine cut) with the cypher C D. Cuvette (dome) engraved in taille douce (fine cut) with the mention C. Drillon // 1895.
Dial, case and movement signed. Accompanied by original fitted box, original certificate and spare glass.
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Diameter: 49 mm
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Signed: Patek Philippe & Co, Genève
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Movement is based on the French invention patent No. 142 376, delivered on April 16, 1881, to Jean-Adrien Philippe (1815-1894), Geneva, for a régulateur de precision (precision regulating device for fast/slow using an eccentric snail). The movement was also based on the Swiss invention patent No. 2 680, delivered on September 27 1890, to Patek, Philippe & Cie, Geneva, for a Remontoir avec mise à l’heure perfectionné (the definitive version of the keyless-winding and setting device), and, on the US design patent No. 20 483, delivered on January 13, 1891, to Adrien Philippe, Geneva, for a Watch bridges for Watch-Movements.