Clock

clockstimepiecemechanical clockanalog clockanalogtimepieceschronometermechanical clocksanalogue clockclocks and watches
A clock is an instrument used to measure, keep, and indicate time.wikipedia
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Watch

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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

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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

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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

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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

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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. In general usage today, a "clock" refers to any device for measuring and displaying the time.
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

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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

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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

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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
This is not considered an escapement mechanism clock as it was unidirectional, the Song dynasty polymath and genius Su Song (1020–1101) incorporated it into his monumental innovation of the astronomical clock-tower of Kaifeng in 1088. The cross-beat escapement was invented in 1584 by Jost Bürgi, who also developed the remontoire.
An escapement is a device in mechanical watches and clocks that transfers energy to the timekeeping element (the "impulse action") and allows the number of its oscillations to be counted (the "locking action").

Automaton

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Greek astronomer Andronicus of Cyrrhus supervised the construction of the Tower of the Winds in Athens in the 1st century B.C. The Greek and Roman civilizations are credited for initially advancing water clock design to include complex gearing, which was connected to fanciful automata and also resulted in improved accuracy.
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

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Greek astronomer Andronicus of Cyrrhus supervised the construction of the Tower of the Winds in Athens in the 1st century B.C. The Greek and Roman civilizations are credited for initially advancing water clock design to include complex gearing, which was connected to fanciful automata and also resulted in improved accuracy.
The first geared mechanical clocks were built in China in 725.

Salisbury cathedral clock

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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.

Bell

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Bells are also associated with clocks, indicating the hour by the striking of bells.

Fusee (horology)

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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 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)

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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.

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 escapementdeadbeatpocket watch
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

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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

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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.

Barrel (horology)

barrelgoing barrelbarrels
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 mechanical watches and clocks, a barrel is a cylindrical metal box closed by a cover, with a ring of gear teeth around it, containing a spiral spring called the mainspring, which provides power to run the timepiece.

Atomic clock

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

Remontoire

The cross-beat escapement was invented in 1584 by Jost Bürgi, who also developed the remontoire.
It was used in precision clocks and watches to place the source of power closer to the escapement, thereby increasing the accuracy by evening out variations in drive force caused by unevenness of the friction in the geartrain.