Watch. A pocket Instrument for measuring time, excited into action by a steel spring coiled up, and acting by various ingenious contrivances. The spring is in box, called the barrel, and combined with a pyramidal fusee, on which a coning chain is wound by the key. The spring being fastened at one end to the barrel, and at the other end to on arbor, or axle, unwinds off the fusee, turning it, and keeping the watch going, while the action accords by its various size with the varied energy of the spring. The force being thus produced, other wheels are put in motion, and time is exactly measured by the hands on the dial. Watches were invented about the year 1500, and are much esteemed in all countries. Watches are manufactured to a great extent at Geneva, and at Paris, and three or four other towns in France; in England, at Liverpool and Coventry. But It is in London where theart of watchmaking reigns with unrivalled sway, both in extent and perfection. The extreme variation in twelve months of two watches made in London, by the same artist, was only from nine-tenths of a second to 2" 8 in a temperature varying from 82p to 39°, according to an official report made from the Royal Observatory at Greenwich.