Very fine English silver pair cased pocket chronometer Circa 1819

Silver chronometer by Miles
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A very fine and rare English, silver, pair cased pocket chronometer with Earnshaw’s footed spring detent escapement and free sprung helical balance spring, circa 1819.
The case with London hallmarks for 1819-1820. Outer: two body, polished, maker’s mark HG. Inner: two body, bassine, polished, maker’s mark TG. White enamel dial with radial Roman numerals, outer minute track, subsidiary seconds. Gold pear hands.
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A matte gilt movement, three quarter plate with a separate bridge for the barrel, ring turned pillars, fuse and chain with Harrison’s maintaining power, jewelled Earnshaw escapement with footed spring detent, cut bi metallic compensation balance with wedge shaped weights and brass timing screws, free sprung blued steel helical balance spring with inner and outer terminal curves, diamond end stone, foliate engraved cock.
Dial and movement signed.
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Diameter: 58 mm
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Signed: Miles  London
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Septimus Miles was free of the Clockmakers Company in 1797. A watch by him with rack lever escapement is in the Guildhall Museum, London.