and which were quite unlike anything else made in France or Switzerland at the time.Catalogue of precision watches in the British Museum. 1990 Cat. No 176 Plate 140b. Arnold and the 'Tourbillon' Arnold also appears to have been the first to think of the concept of the Tourbillon; this must have derived from his known work on the recognition and elimination of positional errors. In the Tourbillon device, the balance and escapement is continuously rotated and virtually eliminates errors arising from the balance wheel not being perfectly balanced whilst in vertical positions. Arnold appears to have experimented with this idea but died in 1799, before he could develop it further. It is known that Breguet made a successful and practical Tourbillon mechanism around 1795 but, nevertheless, he acknowledged Arnold as the inventor by presenting his first Tourbillon in 1808 to Arnold's son John Roger. As a tribute to his friend Arnold Sr., he incorporated his first Tourbillon mechanism into one of Arnold's early pocket chronometers, Arnold No.11. An engraved commemorative inscription on this watch reads:"The first Tourbillon timekeeper by Breguet incorporated into one of the first works of Arnold. Breguet's homage to the revered memory of Arnold, given to his son AD 1808."'' This important and significant watch is now in the British Museum's collection of clocks and watches. By the time of Arnold's death in 1799, he was the most famous watchmaker in the world, recognized for his preeminence as the inventor of the precision chronometer. John Roger Arnold Arnold's son John Roger Arnold was born in 1769 and served an apprenticeship with both his father and the eminent French watchmaker Abraham Louis Breguet. He became Master of the Worshipful Company of Clockmakers in 1817. From 1787, he and his father founded the company Arnold & Son. After his father's death in 1799, John Roger continued the business, taking John Dent into partnership between 1830 and 1840. After his death in 1843, the company was bought by Charles Frodsham. See also Larcum Kendall Thomas Earnshaw Arnold & Son - Swiss Made Watches References 1736 births 1799 deaths English inventors People from Bodmin British scientific instrument makers English watchmakers (people) Inventors from Cornwall