Watches

A watch is a small portable clock that displays the time and sometimes the day, date, month and year. In modern times they are usually wrist-watches, worn on the wrist with a watch-strap (made of e.g. more...

leather , metal, or nylon), although before the 20th century and cheap miniaturization, most were pocket watches, which had covers and were carried separately, often in a pocket, and hooked to a watch chain.

Current watches are often digital watches, using a piezoelectric crystal, usually quartz, as an oscillator (see quartz clock).

Mechanical timepieces are still used, usually powered by a spring wound regularly by the user, e.g. a stem winder. The invention of "Automatic" or "Self-Winding" watches allowed for a constant winding without special action from the wearer: it works by an eccentric weight, called a winding rotor, that rotates to the movement of the wearer's body. The back-and-forth motion of the winding rotor couples to a ratchet to automatically wind the watch.

Watches may be collectible; they are often made of precious metals, and can be considered an article of jewelry.

Types of watch

Pocket clock

The earliest need for portability in time keeping was navigation and mapping in the 15th century. The latitude could be measured by looking at the stars, but the only way a ship could measure its longitude was by comparing the midday (high noon) time of the local longitude to that of a European meridian (usually Paris or Greenwich) - a time kept on a shipboard clock. However, the process was notoriously unreliable until the introduction of John Harrison's chronometer. For that reason, most maps from the 15th century to c.1800 have precise latitudes but distorted longitudes.

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