Swiss gold watch with unusual safety winding feature Circa 1890

Gold open faced lever watch 
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A fine and rare Swiss, large 18K gold keyless free-sprung pocket watch with unusual safety winding feature, circa 1890. The back cover with an applied foliate monogram, slides in the band to activate winding. Hinged gold-rimmed glazed cuvette. White enamel dial with radial Roman numerals, outer minute track and Arabic five-minute numerals, subsidiary seconds. Gold spade hands. A matte gilt movement, three-quarter plate, 19 jewels in screwed chatons, calibrated and counterpoised straight-line lever escapement, cut bimetallic compensation balance, free-sprung blued steel balance spring with a terminal curve.
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Diameter: 55 mm
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Signed: No Name
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This watch has an unusual safety feature for winding. When the watch is fully wound in the normal way, the winding disengages so that the crown then turns freely. When the watch is running down, the slide in the band re-engages the winding so the watch can be wound in the usual way.