203 - John Arnold & Son - Invenit et Fecit

John Arnold & Son - Invenit et Fecit A rare gold pocket chronometer "Of The Second Kind" featuring John Arnold's spring detent escapement and Arnold's OZ balance Movm. No. 253/554, Dimensions 53 mm, circa 1787, Weight 130 g, Origin England Case: 18K gold, case maker’s punch mark “IL”. Dial: Enamel. Movement: Full-plate movement, chain/fusee, Arnold’s spring detent escapement, OZ balance, free-sprung helical gold balance spring with terminal curves on both sides. This smaller-sized pocket chronometer—now often referred to as the “301” series due to the difference in the two serial numbers—quickly became the standard production model of John Arnold and his son, John Roger, and formed the foundation of his worldwide reputation. As working watches in constant and important use, they were prone to accidents and were often updated, both by Arnold himself and by later repairers. This watch is one of the few examples that, apart from the dial, has been preserved in its original condition. The spring-detent escapement, as first invented by Arnold, featured a delicate steel detent fitted into a slot in the top plate. Because it was so fragile, many original detents have not survived, and most of Arnold’s watches now have later detents, the installation of which can mar the watch’s appearance. This detent is original to the watch and has the typical Arnold shape and finish. Mentioned in “100 Years of Precision Watches from John Arnold to Arnold & Frodsham” by Hans Staeger, Filderstadt 1997, page 175. Case: very good. Dial: very good, later custom-made, with hairline scratches. Movement: very good, capable of running, cleaning recommended.