English gold museum quality pair cased duplex Circa 1806

Gold heavy watch with center seconds 
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An extremely fine and heavy, museum quality English 18 carat gold pair cased center seconds pocket watch with quarter hour and hour self strike made for the Chinese market by William Ilbery in London, circa 1806. The gilt full plate movement with chain and fusee, two hammers, an open barrel, a duplex escapement, chronometer balance with three weights and three screws, and a chatoned diamond endstone on the balance. Off-white enamel dial with Roman hours, an outer minute track with fifth of a second divisions, Arabic quarter hour numerals and fine heart shaped gold hands. Both the outer and inner cases are richly engraved and pierced, the outer case with maker’s mark WM and the inner case with a bottom bell. Movement signed and numbered.
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Diameter: 60 mm
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Weight: 222 g
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Signed: Ilbery London