Showing posts with label Clocks and Watches. Show all posts
Showing posts with label Clocks and Watches. Show all posts

Clocks and Watches


Clocks and Watches, devices used to measure or indicate the passage of time. A clock, which is larger than a watch, is usually intended to be kept in one place; a watch is designed to be carried or worn. Both types of timepieces require a source of power and a means of transmitting and controlling it, as well as indicators to register the lapse of time units.

In a clock, the source of power may be produced by weight, a mainspring, or an electric current. Except in electric or electronic clocks, periodic adjustments, such as lifting the weight or tightening the spring, are needed. The motive force generated by the power source in a mechanical clock is transmitted by a gear train and regulated by a pendulum or a balance wheel. In such a clock, the time may be reported audibly by the striking of a gong or chime and is registered visually by the rotation of wheels bearing numerals or by the position of hands on a dial. In electric or electronic clocks, time may be shown by a display of numbers.

A mechanical watch uses a coiled spring as its power source. As in spring-powered clocks, the watch conserves energy by means of a gear train, with a balance wheel regulating the motive force. In self-winding watches, the mainspring is tightened automatically by means of a weight on a rotor that responds to the arm movements of the wearer.