Swiss 18k gold lever chronometer with keyless cover winding Circa 1885

Gold pocket watch with engraved monogram
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A very fine Swiss, 18K gold, hunting cased lever chronometer pocket watch with keyless cover winding, circa 1885. Accompanied by copies of the original patents. The front cover is engraved with a monogram, the back with a trophy of happy marriage. Gold hinged cuvette. White enamel dial, radial Roman numerals, outer minute track with five-minute gilt painted Arabic numerals, subsidiary seconds. Gold spade hands. A silver-nickel movement, Geneva striping decoration, stamped twice with Seal of Geneva Quality Mark.
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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. Signed on the cuvette.
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Diameter: 53 mm
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Signed: B. Haas Jeune  Genève-Paris
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In 1873 Benjamin Haas patented an interesting winding mechanism (English patent No. 3945 of Dec 2, 1873). The idea was to utilize the energy generated when closing the front cover to wind the watch. The initial idea was improved; 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 an additional wheel, which allowed him three hours’ winding by a single closing. He designed a safety device disengaging the mechanism when fully wound, which prevented damage to the cover.