Technically interesting English gold full hunter cased watch Circa 1873

Pocket watch with independent center seconds
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A  technically interesting gold full hunter cased watch with independent center seconds, made in London 1873. The plain case of this watch is crafted from 18 Carat gold and its cuvette is inscribed with In memory of our dear father, died 1pril 25^th 1904, aged 76. The white enamel dial has black Roman hour numerals, a subsidiary minutes dial with black Arabic numerals at six o’clock and original gold hands. The very fine quality movement has an extremely unusual lever escapement, a high speed oscillator in 1/5 seconds intervals, a diamond end stone, two barrels and independent jumping stoppable center seconds.
Dial and movement have matching numbers and the cuvette is signed.
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Diameter: 52 mm
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Weight: 127 g
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Signed: Ethan Hill James                
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It remains a mystery why the dial is marked “Duplex” although it is an original English lever escapement.