Swiss gold hunting cased lever chronometer pocket watch Circa 1875

Gold keyless lever pocket watch
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A very fine and rare, 18K gold, hunting cased lever chronometer pocket watch, circa 1875. Keyless cover winding to the English patent of Benjamin Haas in 1873. An entirely engine-turned and engraved with foliage and geometric patterns, the front cover with central engraved fleur-de-lis beneath a crown, a hand setting button in the pendant. Hinged gold cuvette. White enamel dial, radial Roman numerals, outer minute track with five-minute Arabic numerals, subsidiary seconds. Blued steel Breguet hands.
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A matte gilt movement, bar calibre, stamped with three coats of arms, calibrated and counterpoised straight-line lever escapement, cut bimetallic compensation balance with blued steel Breguet balance spring, index regulator, patented winding mechanism by closing the cover which transmits the power via two levers to a ratchet wheel on the barrel arbour, a safety device disengaging the mechanism when fully wound, going train with an additional wheel driving a steel wheel fixed to the centre wheel having half the diameter of the driving one, second motion train driven from the canon pinion and advanced directly by pushing the teeth of the minute wheel. Dial, cuvette and movement signed, movement also punched R.T. & F.
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Diameter: 50 mm
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Signed: B. Haas Jeune  Genève
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In 1873 Benjamin Haas patented a winding mechanism (English patent No. 3945 of Dec. 2, 1873). The idea was to use the energy generated by closing the front cover to wind the watch. The initial idea was improved upon; his watch features a well-developed system with a 36-hour power reserve generated by 12 closings. To achieve this, Haas changed the going train, adding a wheel, which allowed him three hours’ winding by a single closing. He designed a safety device to disengage the mechanism when fully wound, which prevents damage to the cover.