Thin Swiss gold and enamel Bagnolet pocket watch Circa 1840-1850

Unsigned gold cylinder watch with open face from Geneva
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An extra thin, gold and enamel, open faced key winding pocket watch with inverted calibre known as Bagnolet, circa 1840-1850.
Half plate movement, calibre 13, cylinder escapement, inverted calibre known as Bagnolet. Eccentric silver dial engraved in taille-douce (fine-cut) with Roman numerals. Round-shaped 18K yellow gold and enamel case, cover and case back guilloché (engine-turned) in a vermicelli pattern with painted champlevé enamelled summer flowers above the dial aperture on the cover and on the centre of the back.
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Diameter: 35.5 mm
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Unsigned
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Lacking elements and repairs required
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In the Bagnolet calibre, the movement is inverted, and the train is reversed. The idea was to make a very thin watch by reducing the thickness of the bridges and the dial and eliminating the cuvette. Philippe Samuel Meylan is credited with the invention of the Bagnolet calibre.