Clock - Wikipedia, the free encyclopedia

Clock - Wikipedia, the free encyclopedia

Clock - Wikipedia, the free encyclopedia Clock From Wikipedia, the free encyclopedia Jump to: navigation, search For other uses, see Clock (disambiguation). Platform clock at King's Cross railway station, London. A clock is an instrument used to indicate, measure, keep, and co-ordinate time. The word clock is derived ultimately (via Dutch, Northern French, and Medieval Latin) from the Celtic words clagan and clocca meaning "bell". For horologists and other specialists the term clock continues to mean exclusively a device with a striking mechanism for announcing intervals of time acoustically, by ringing a bell, a set of chimes, or a gong.[dubious – discuss] A silent instrument lacking such a mechanism has traditionally been known as a timepiece.[1] In general usage today a "clock" refers to any device for measuring and displaying the time. Watches and other timepieces that can be carried on one's person are often distinguished from clocks.[2] Clock at the Royal Observatory, Greenwich Replica of an ancient Chinese incense clock The clock is one of the oldest human inventions, meeting the need to consistently measure intervals of time shorter than the natural units: the day; the lunar month; and the year. Devices operating on several different physical processes have been used over the millennia, culminating in the clocks of today. Contents 1 Sundials and other devices 2 Water clocks 3 Early mechanical clocks 3.1 A new mechanism 3.2 Early astronomical clocks 4 Later developments 5 How clocks work 5.1 Power source 5.2 Oscillator 5.2.1 Synchronized or slave clocks 5.3 Controller 5.4 Counter chain 5.5 Indicator 6 Types 6.1 Time display methods 6.1.1 Analog clocks 6.1.2 Digital clocks 6.1.3 Auditory clocks 7 Purposes 7.1 Ideal clocks 7.2 Navigation 8 Seismology 9 Specific types of clocks 10 See also 10.1 Newsgroup 11 Notes 12 References 13 External links [edit] Sundials and other devices The sundial, which measures the time of day by using the sun, was widely used in ancient times. A well-constructed sundial can measu...

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