Theย history of timekeeping devicesย dates back to when ancient civilizations first observedย astronomical bodiesย as they moved across the sky. Devices and methods for keeping time have since then improved through a long series of new inventions and ideas.ย Sundialsย andย water clocksย originated fromย ancient Egypt, and were later used by theย Babylonians, theย Greeksย and theย Chinese; medieval Islamic water clocks were unrivalled in their sophistication until the mid-14thย century.ย Incenseย clocks, which may have been invented in India, were being used in China by the 6thย century. Theย hourglass, one of the few reliable methods of measuring time at sea, was a European invention and does not seem to have been used in China before the mid-16thย century.
In medieval Europe, purely mechanical clocks were developed after the invention of the bell-striking alarm, used to warn a man to toll theย monasticย bell. The weight-driven mechanical clock, controlled by the action of aย verge and foliot, was a synthesis of earlier ideas derived from European and Islamic science, and one of the most important inventions in the history of the timekeeping. The most famous mechanical clock was designed and built byย Henry de Vickย inย c.1360โfor the next 300 years, all the improvements in timekeeping were essentially developments based on it. The invention of theย mainspringย in the early 15thย century allowed small clocks to be built for the first time.
From the 17thย century, the discovery that clocks could be controlled byย harmonic oscillatorsย led to the most productive era in the history of timekeeping.ย Leonardo da Vinciย had produced the earliest known drawings of aย pendulumย in 1493โ1494, and in 1582ย Galileo Galileiย had investigated the regular swing of the pendulum, discovering thatย frequencyย was only dependent on length. Theย pendulum clock, designed and built by Dutch polymathย Christiaan Huygensย in 1656, was so much more accurate than other kinds of mechanical timekeepers that few clocks have survived with their verge and foliot mechanisms intact. Other innovations in timekeeping during this period include inventions for striking clocks, theย repeating clockย and theย deadbeat escapement. Errors in early pendulum clocks were eclipsed by those caused by temperature variation, a problem tackled during the 18thย century by the English clockmakersย John Harrisonย andย George Graham; only the invention ofย invarย in 1895 eliminated the need for such innovations.
From the 18thย century, a succession of innovations and inventions led to timekeeping devices becoming increasingly accurate. Following theย Scilly naval disaster of 1707, after which governments offered aย prizeย to anyone who could discover a way to determine longitude, Harrison built a succession of accurate timepieces. The electric clock, invented in 1840, was used to control the most accurate pendulum clocks until the 1940s, when quartz timers became the basis for the precise measurement of time and frequency. The wristwatch, which had been recognised as a valuable military tool during theย Boer War, became a symbol of masculinity and bravado after World War I. During the 20thย century the non-magneticย wristwatch, battery-driven watches, the quartz wristwatch, andย transistorsย and plastic parts were all invented. The most accurate timekeeping devices in practical use today areย atomic clocks, which can be accurate to within a few billionths of a second per year. They are used to calibrate other clocks and timekeeping instruments.
Aย clockย or aย timepieceis a device used toย measureย and indicateย time. The clock is one of the oldestย human inventions, meeting the need to measure intervals of time shorter than the natural units: theย day, theย lunar month,ย yearย andย galactic year. Devices operating on several physical processes have been used over theย millennia.
Some predecessors to the modern clock may be considered as “clocks” that are based on movement in nature: Aย sundialย shows the time by displaying the position of a shadow on a flat surface. There is a range of duration timers, a well-known example being theย hourglass.ย Water clocks, along with the sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of theย verge escapement, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers likeย balance wheels.
Traditionally, inย horology, the termย clockย was used for aย striking clock, while a clock that did not strike the hours audibly was called a timepiece. This distinction is no longer made.ย Watchesย and other timepieces that can be carried on one’s person are usually not referred to as clocks.ย Spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries,ย clockmakingย flourished. The next development in accuracy occurred after 1656 with the invention of theย pendulum clockย byย Christiaan Huygens. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The mechanism of a timepiece with a series of gears driven by a spring or weights is referred to asย clockwork; the term is used by extension for a similar mechanism not used in a timepiece. Theย electric clockย was patented in 1840, and electronic clocks were introduced in the 20th century, becoming widespread with the development of small battery-poweredย semiconductor devices.
The timekeeping element in every modern clock is aย harmonic oscillator, a physical object (resonator) that vibrates or oscillates at a particular frequency.ย This object can be aย pendulum, aย tuning fork, aย quartz crystal, or the vibration ofย electronsย inย atomsย as they emitย microwaves.
Clocks have different ways of displaying the time. The History of The First Clock Analog clocks indicate time with a traditional clock face, with moving hands. Digital clocks display a numeric representation of time. Two numbering systems are in use:ย 24-hour timeย notation andย 12-hourย notation. Most digital clocks use electronic mechanisms andย LCD,ย LED, orย VFDย displays. For the blind and for use over telephones,ย speaking clocksย state the time audibly in words. The History of The First Clock There are also clocks for the blind that have displays that can be read by touch. The study of timekeeping is known as horology.
