English plain silver open faced pocket chronometer Circa 1802

Silver chronometer by John Roger Arnold
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An English silver open faced pocket chronometer, Hallmarked London 1802. Chronometer movement with spring detent escapement, OZ balance, diamond endstone, helical hairspring, plate completely signed and numbered. White enamel dial with Roman numerals and gold hands. Plain case. Maker’s mark TH for Thomas Hardy. Dial and movement signed and numbered.
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Diameter: 63 mm
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Weight: 204 g
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Signed: Arnold – Jn R Arnold London
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John Roger Arnold (1769-1843) was the son of the famous English watchmaker John Arnold. John Roger first apprenticed to his father, the watchmaker John Arnold, and continued his training with Abraham Louis Breguet. In 1787 he became a partner in his father’s company, which was then called John Arnold & Son. His specialities were deck and pocket chronometers. In 1796 he became a Master at the Clockmakers Company. In 1821 he received a patent for a compensation balance. From 1830 to 1840 he was partner of Edward John Dent in the company Arnold & Dent. During their partnership the two watchmakers were experimenting in different directions, but focused on the effect of magnetism on chronometers.