Arnold refines the detent escapement In 1775, John Arnold refined the ineffective design of the detent escapement invented by French watchmaker Pierre Le Roy in 1748. Arnold's was the first effective design of a detent escapement. His redesign used the detent escapement with an overcoil balance spring. With this improvement, Arnold's watches were the first really accurate pocket timekeepers, keeping time to within one or two seconds per day. His version is considered to be the most accurate of all escapements using a balance wheel. Arnold duly patented his design in 1782 after engaging in a heated contest with Thomas Wright to perfect the invention of a working spring-detent escapement for watches, while Wright managed to manufacture the earliest known pocket chronometer with a spring-detent escapement. Image Credit Spring-detent escapement watch with gold case by John Arnold and Son, London Science Museum Group / The Clockmakers' Museum, Object Number: L2015-3344 © The Board of Trustees of the Science Museum, CC BY-NC-SA 4.0, https://collection.sciencemuseumgroup.org.uk/objects/co8557883/spring-detent-escapement-watch-with-gold-case-by-john-arnold-and-son-watch-detent
