English 18K yellow gold and platinum lever pocket watch Circa 1875

Platinum and gold open faced pocket watch 
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A very fine and very rare English, platinum and 18K yellow gold pocket watch in the style of Breguet with a short gold chain and ratchet key, circa 1875. An engine turned case with a platinum band. Hinged gold cuvette. Silver, engine-turned dial, brushed chapter ring with radial Roman numerals and outer dot minute markers, subsidiary seconds. Gold Breguet hands. A frosted gilt movement, Lepine type calibre, 14 jewels, female winding arbour, lateral lever escapement, cut bimetallic compensation balance with gold peripheral timing and temperature adjustment screws, blued steel Breguet balance spring, index regulator. Movement signed and numbered, case numbered.
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Diameter: 49 mm
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Signed: J & H Jump  London
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The case is slightly rusted and the dial oxidized.
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Jump, Joseph & Henry Joseph. London (Old Bond Street) 1872-80, then Pall Mall, London 1880 – dead 1899. Then became Jump 8c Sons, moving to Mount Street, London 1898-1934, when ceased trading. Royal warrant 1910