Rare Swiss gold lever made for the English market Circa 1889

Gold chronograph pocket watch
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A rare and unusual Swiss 18K gold keyless pocket watch, circa 1889. With patent chronograph and 30-minute register of uncommon construction. Made for the English market, the case with Chester hallmarks for 1889-1890. A polished case and a hinged gold cuvette. White enamel dial, radial Roman numerals, outer minute track, outermost chronograph track divided into fifths with five-minute Arabic numerals, sunk subsidiary seconds, 30-minute register with the hand rotating counterclockwise and blued steel hands. A frosted gilt, 3/4-plate movement, 14 jewels, lateral counterpoised lever escapement, cut-bimetallic compensation balance with blued steel Breguet balance spring, index regulator, patented chronograph mechanism.
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Diameter: 50 mm
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Signed: No name
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The case is slightly scratched and the dial is chipped under the bezel, not visible when closed.