A very fine and very rare John Arnold & Son 18K gold pocket chronometer with white enamel dial, gold hands and large subsidiary seconds in plain polished consular case engraved with a contemporary crest. The movement is signed with the partnership signature ‘John Arnold & Son’, in use from about 1787.

This type of pocket chronometer from the 4th Series was called "Of the Second Kind" and features fractional numbering on the movement. If the movement was finished in order with the other watches of the series, it would have been completed in the 1790s. It may have been completed after the series was finished, or perhaps a new case fitted by Arnold a few years later if the buyer wished to perhaps upgrade from a silver to a gold case.

John Roger Arnold (1769-1843) was the son of John Arnold, one of the most famous British watch and clock makers.

In 1783, John Roger started working with his father before moving to Paris as an apprentice to Abraham-Louis Breguet in 1792. He was admitted as a member of the Clockmaker's Company in 1796 and became Master in 1817.

After the death of John Arnold senior, John Roger continued the business under "Arnold & Son", maintaining his father's reputation of one of the leading watch and clock makers of his epoch. In 1830 he moved to 84 Strand and started a flourishing ten years partnership with E. J. Dent, during which the two associates were undertaking various experiments, especially in regard to the influence of magnetism on chronometers.

When Dent left in 1840, Arnold continued on his own until his death in February 1843 after which Charles Frodsham immediately purchased the commerce which prospered until 1858 under the name of Arnold and Frodsham.

Arnold Senior's inventions comprise the helical balance spring for chronometers and a detent escapement similar to the modern chronometer escapement. To this day he is considered one of the leading chronometer makers of all times.