English heavy silver pocket chronometer watch Circa 1810

Silver chronometer by Robert Pennington
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A rare heavy English pocket chronometer with spring detent escapement, according to Thomas Earnshaw, circa 1810.
This watch has a white enamel dial with Roman numerals for the hours and Arabic for the minutes, blue hands and subsidiary seconds, a silver tiered case with an engraved crest and crown, and gold hinges. And a full plate movement, a chain/fusee with Harrison’s maintaining power, a spring detent escapement, a Pennington’s auxiliary compensation balance and a blued freesprung helical balance spring with a left hand spiral (special feature by Pennington).
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Diameter: 62 mm
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Weight: 218 g
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Signed: Robert Pennington, London
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Robert Pennington
Robert Pennington was a renowned watchmaker who worked in London from about 1780 to his death in 1813. He is thought to have invented the screw balance, a very early version of which was used in the chronometer we have here.
Pennington worked with William Howells and a number of other makers; between 1794 and 1799 the group produced at least 27 examples of Thomas Mudges’s ‘marine timekeepers’ commissioned by Mudge’s son. Pennington also created the magnificent drawings of plates in “A Description with Plates” which Mudge Jr. published in 1799.