English pocket chronometer with detent escapement Circa 1797

Silver pocket watch by John Roger Arnold
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An English pocket chronometer Of The Best Kind with spring detent escapement and Arnold’s Z balance, circa 1797.
Silver-gilt, polished, à goutte consular case with case maker punch mark TH (Thomas Hardy), turning pendant with applied foliate, and large lateral hinge. Signed, numbered, off-white enamel dial with radial Roman numerals, auxiliary seconds, and blued spade hands. Signed, keywind, frosted, gilt full plate movement with chain/fusee with Harrisons maintaining power, moulded cylindrical pillars, steel escape wheel, spring detent escapement, Z-balance with two weights and five screws, blued helical free-sprung balance spring with both sides passing terminal curves, very fine florally engraved balance cock, chatoned jewels on the chronometer, seconds and intermediate wheel, and chatoned diamond endstone on balance
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Diameter: 62 mm
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Weight: 184 g
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Signed: John Roger Arnold, London, Invt. et Fecit
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John Roger Arnold (1769-1843)
John Roger Arnold was the son of renowned British horologist John Arnold. He began his apprenticeship with A.-L. Breguet in Paris in 1792. The younger Arnold became a member of the Clockmaker’s Company in 1796 and was a Master in 1817. He took up a partnership with E.J. Dent in 1830 and the two craftsmen experimented heavily during their work together; in particular, they concentrated on the effects of magnetism on chronometers. Dent left Arnold in 1840, whereupon Arnold continued working on his own but died only three years later. Charles Frodsham bought the business after Arnold’s death in February 1843 and it flourished until 1858 under the name Arnold and Frodsham.