John Arnold was an English watchmaker and inventor.

John Arnold was the first to design a practical and accurate watch. and also brought the word “chronometer” has come to be used in the modern sense This means a precision timer. His technical advances made it possible to produce marine chronometers for use on ships starting around 1782. Their basic design has been preserved. With slight modifications, remaining unchanged until the end of the 20th century, including being one of the inventors of the modern mechanical clock together with One of Abraham-Louis Breguet's most important inventions was the overcoil balance spring. It is still used in most mechanical wristwatches.

Around 1770, Arnold developed a portable, precision timer. But compared to Harrison's complex and expensive watches, Arnold's basic design was simple. At the same time, it is consistently accurate and mechanically reliable. Importantly, the relatively simple and original movement design allows for volume production at a reasonable price. At the same time, it makes maintenance and modification easier.