English duplex watch with eight-day power reserve Circa 1817

Open faced duplex escapement by Colbert
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A rare and interesting English pocket watch with eight-day power reserve and duplex escapement, circa 1817.
Silver polished case with case maker’s punch mark HM. Signed enamel dial with radial Roman hours, auxiliary seconds, and gold spade hands. Signed, EIGHT DAY WATCH, numbered, brass, gilt full plate movement with chain/fusee, screwed chatons, moulded movement pillars, duplex escapement, and florally engraved balance cock with segment shaped cutting for regulation.
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Diameter: 64 mm
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Weight: 191 g
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Signed: J.G. Colbert, London
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J.G.I. Colbert was a member of the Clockmakers’ Company and worked first at 12 Tottenham Court Road (between Regents Park and Russell Square) and later at Grafton Street near Berkeley Square. He was very likely an immigrant watchmaker from France or the French-speaking regions of Switzerland; his name and the fact that the watches wind through the dial – which is typically French – strongly indicate this.
The marks are too faint to enable us to determine the maker of the silver case. The maker of the pendant – who may have created the case too – was Michael Atkins at 4 Red Lion Street in Clerkenwell; his mark was registered on February 1, 1813.
The duplex escapement used in this watch is based on designs by Baptiste Dutertre, who had developed the fundamental concepts around 1724.

Pierre Le Roy converted the designs into a workable escapement mechanism in the 1850s; in the first half of the 19th century the duplex escapement was quite frequently used in England for high-quality watches; it was eventually replaced by the chronometer and lever escapements, which performed even better.