Clock

timepiecemechanical clockanalog clockanalogtimepiecesclocksmechanical clocksanalogue clockchronometerclocks and watches
A clock is an instrument used to measure, keep, and indicate time.wikipedia
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Watch

wristwatchwatcheswristwatches
Watches and other timepieces that can be carried on one's person are often distinguished from clocks.
A watch is a timepiece intended to be carried or worn by a person.

Time

temporaldurationsequence of events
A clock is an instrument used to measure, keep, and indicate time.
Time in physics is unambiguously operationally defined as "what a clock reads".

Pendulum clock

regulator clockClock pendulumregulator
The next development in accuracy occurred after 1656 with the invention of the pendulum clock.
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element.

Balance wheel

foliotbalancecompensation balance
A major advance occurred with the invention of the verge escapement, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like balance wheels.
A balance wheel, or balance, is the timekeeping device used in mechanical watches and some clocks, analogous to the pendulum in a pendulum clock.

Verge escapement

verge and foliotfoliotcrown wheel and verge escapement
A major advance occurred with the invention of the verge escapement, which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like balance wheels.
The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'.

Horology

horologisthorologicalhorologists
Traditionally in horology, the term clock was used for a striking clock, while a clock that did not strike the hours audibly was called a timepiece.
Clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of instruments used to measure time.

Crystal oscillator

crystalquartz oscillatorquartz crystal
This object can be a pendulum, a tuning fork, a quartz crystal, or the vibration of electrons in atoms as they emit microwaves.
Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones.

Liquid-crystal display

LCDliquid crystal displayLCD screen
Most digital clocks use electronic mechanisms and LCD, LED, or VFD displays.
LCD screens are also used on consumer electronics products such as DVD players, video game devices and clocks.

Harmonic oscillator

harmonic oscillatorsharmonic oscillationdamped harmonic oscillator
The timekeeping element in every modern clock is a harmonic oscillator, a physical object (resonator) that vibrates or oscillates at a particular frequency.
Harmonic oscillators occur widely in nature and are exploited in many manmade devices, such as clocks and radio circuits.

Escapement

detent escapementCross-beat escapementduplex escapements
Arab engineers at the time also developed a liquid-driven escapement mechanism which they employed in some of their water clocks.
An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands.

Automaton

automataautomaticautomatons
Al-Muradi's clock also employed the use of mercury in its hydraulic linkages, which could function mechanical automata.
It is more often used to describe non-electronic moving machines, especially those that have been made to resemble human or animal actions, such as the jacks on old public striking clocks, or the cuckoo and any other animated figures on a cuckoo clock.

Gear

single reduction geargearscogwheel
The first geared clock was invented in the 11th century by the Arab engineer Ibn Khalaf al-Muradi in Islamic Iberia; it was a water clock that employed a complex gear train mechanism, including both segmental and epicyclic gearing, capable of transmitting high torque.

Salisbury cathedral clock

a clock thereclocklarge clock
The Salisbury Cathedral clock, built in 1386, is considered to be the world's oldest surviving mechanical clock that strikes the hours.
The Salisbury cathedral clock is a large iron-framed clock without a dial, in Salisbury Cathedral, England.

Fusee (horology)

fuseefuseeschain and fusee
This resulted in the invention of the stackfreed and the fusee in the 15th century, and many other innovations, down to the invention of the modern going barrel in 1760.
Used in antique spring-powered mechanical watches and clocks, a fusee (from the French fusée, wire wound around a spindle) is a cone-shaped pulley with a helical groove around it, wound with a cord or chain which is attached to the mainspring barrel.

Movement (clockwork)

movementmovementswatch movement
Spring power presented clockmakers with a new problem: how to keep the clock movement running at a constant rate as the spring ran down.
In horology, a movement, also known as a caliber, is the mechanism of a watch or timepiece, as opposed to the case, which encloses and protects the movement, and the face, which displays the time.

Marine chronometer

chronometerchronometersChronoscope
In 1735, Harrison built his first chronometer, which he steadily improved on over the next thirty years before submitting it for examination.
A marine chronometer is a timepiece that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of accurately measuring the time of a known fixed location, for example Greenwich Mean Time (GMT) and the time at the current location.

Stackfreed

This resulted in the invention of the stackfreed and the fusee in the 15th century, and many other innovations, down to the invention of the modern going barrel in 1760.
A stackfreed is a simple spring-loaded cam mechanism used in some of the earliest antique spring-driven clocks and watches to even out the force of the mainspring, to improve timekeeping accuracy.

Anchor escapement

deadbeat escapementdeadbeatGraham escapement
In 1670, William Clement created the anchor escapement, an improvement over Huygens' crown escapement.
The escapement is a mechanism in a mechanical clock that maintains the swing of the pendulum by giving it a small push each swing, and allows the clock's wheels to advance a fixed amount with each swing, moving the clock's hands forward.

Electric clock

electric clockssynchronous electric clockelectromechanical clock
The electric clock was patented in 1840.
An electric clock is a clock that is powered by electricity, as opposed to a mechanical clock which is powered by a hanging weight or a mainspring.

Repeater (horology)

repeaterminute repeaterrepeating clock
The repeating clock, that chimes the number of hours (or even minutes) was invented by either Quare or Barlow in 1676.
A repeater is a complication in a mechanical watch or clock that chimes the hours and often minutes at the press of a button.

John Harrison

H-4H4H4 and H5
John Harrison, who dedicated his life to improving the accuracy of his clocks, later received considerable sums under the Longitude Act.
Following his father's trade as a carpenter, Harrison built and repaired clocks in his spare time.

Quartz clock

quartz watchquartzquartz movement
In 1927 the first quartz clock was built by Warren Marrison and J.W. Horton at Bell Telephone Laboratories in Canada.
A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time.

Clockkeeper

clock-keeper
The costs of the installation included the full-time employment of two clockkeepers for two years.
A clockkeeper, sometimes seen as clock keeper, refers to a form of employment seen prevalently during Middle Age Europe involving the tracking of time and the maintaining of clocks and other timekeeping devices.

Charlemagne

Charles the GreatEmperor CharlemagneCharles
In 797 (or possibly 801), the Abbasid caliph of Baghdad, Harun al-Rashid, presented Charlemagne with an Asian Elephant named Abul-Abbas together with a "particularly elaborate example" of a water clock.
In 797 (or possibly 801), the caliph of Baghdad, Harun al-Rashid, presented Charlemagne with an Asian elephant named Abul-Abbas and a clock.

Atomic clock

atomic clocksatomiccaesium clock
As of the 2010s, atomic clocks are the most accurate clocks in existence.
An atomic clock is a clock device that uses a hyperfine transition frequency in the microwave, or electron transition frequency in the optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.