Rare Swiss gunmetal and gilt lever pocket watch Circa 1910

Gunmetal and gilt lever without mainspring barrel by Isaac Grasset
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A fine and rare Swiss gunmetal and gilt open faced keyless lever pocket watch without mainspring barrel built to the design of Swiss Patents No. 5019 and 14528, circa 1910. Gilt brass movement, 13 jewels, the mainspring rolled around the winding shaft, straight line lever escapement, cut bi metallic compensation balance, blued steel Breguet balance spring, index regulator. Glazed gilt rimmed cuvette for viewing the movement. White enamel dial with Arabic numerals, outer minute track, subsidiary seconds, and original gilt Louis XV hands. Polished case with gilt bezel rim, hinge and bow. Movement with Swiss Patent numbers 5019 & 14528.
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Diameter: 53 mm
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Signed: Isaac Grasset Genève
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Isaac Grasset & Cie. A watchmaker and lapidary whose workshop was at 44, rue Wendt in Geneva. He applied for several patents, such as a polishing and lapidaring machine in 1892, a device to set time by means of the pendant in 1896, a micrometric index in 1899, patents No. 5019 and No. 14528 for a helical mainspring rolled around the winding stem.