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A watch is a small portable clock that displays the current time and sometimes the current day, date, month and year. In modern times they are usually worn on the wrist, although before the 20th century 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).
In earlier times mechanical timepieces were used, powered by a spring wound regularly by the user. The invention of "Automatic" or "Self-Winding" watches allowed for a constant winding without special action from the wearer: it works by an irregular weight that rotates to the movement of the wearer's body, automatically winding the watch.
Watches may be collectibleA collectible is a manufactured item designed for people to collect. Collectibles are specifically created for the purpose of collecting (see also hobby). In this respect, they are distinguishable from other subjects of collections, which may also include; they are often made of precious metals, and can be considered an article of jewelry.
The first necessity for portability in time keeping was navigationThis article concerns navigation in the sense of determination of position and direction on the surface of the Earth. See Navigation (disambiguation) for other meanings. There are several traditions of navigation . Polynesian navigation The Polynesian nav and mappingThe word mapping has several senses: In mathematics and related technical fields, it is some kind of function: see map (mathematics). In formal logic, it is sometimes used for a functional predicate''. In computer science, it is usually a computable funct in the 15th century14th century 15th century 16th century other centuries) As a means of recording the passage of time, the 15th century was that century which lasted from 1401 to 1500. Events Renaissance affects philosophy, science and art. The New Monarchs come to power i. The latitudeLatitude denoted φ, gives the location of a place on Earth north or south of the Equator. Latitude is an angular measurement ranging from 0° at the Equator to 90° at the poles. Usually, the difference in latitude largely affects the climate and/or wea could be measured by looking at the stars, but the only way a ship could measure its longitudeMap of Earth showing vertical lines of longitude Longitude sometimes denoted λ, describes the location of a place on Earth east or west of a north-south line called the Prime Meridian. Longitude is given as an angular measurement ranging from 0° at was by comparing timezones; by comparing the midday time of where they were to the one it should be in Europe, a sailor could know how far he was from home. For that reason, most maps in that time are distorted horizontally although they were vertically precise.
The first clocks measured time with pendulumA gravity pendulum is a weight on the end of a rigid rod, which, when given some initial lift from the vertical position, will swing back and forth under the influence of gravity over its central (lowest) point. A torsion pendulum consists of a body suspes, which were useless in boats. The invention of a spring mechanism was crucial for the first portable clocks. The miniaturisation technologies permitted it from becoming a huge weight inside a ship to a small piece of jewellery inside a pocket. Aaron Lufkin Dennison founded Waltham Watch Company in 1850, which was the pioneer of the industrial manufacturing by interchangeable parts, the American System of Watch Manufacturing.