what is watch?

A watch is a timepiece, typically worn either around the wrist or attached on a chain and carried in a pocket. In 996 AD Pope Sylvester II had made the first clock. Watches evolved from portable spring-driven clocks, which first appeared in 15th century Europe. Watches weren't widely worn in pockets until the 17th century. One account says that the word "watch" came from the Old English word woecce which meant "watchman", because it was used by town watchmen to keep track of their shifts. Another says that the term came from 17th century sailors, who used the new mechanisms to time the length of their shipboard watches (duty shifts). Compared to electronic movements, mechanical watches are less accurate, often with errors of seconds per day, and they are sensitive to position, temperature and magnetism. They are also costly to produce, require regular maintenance and adjustment, and are more prone to failure. Mechanical movements use an escapement mechanism to control and limit the unwinding and winding parts of a spring, converting what would otherwise be a simple unwinding into a controlled and periodic energy release. Mechanical movements also use a balance wheel together with the balance spring (also known as a hairspring) to control motion of the gear system of the watch in a manner analogous to the pendulum of a pendulum clock. Watches are made from several theories. As the sun watch, mechanical watch, Electronic watch, etc.

Yet atomic clocks could not fit loosely, but this chronometry of the best no doubt that the device will come true.