118:
232:
194:
1255:
951:
446:
41:
127:
1134:, which was accurate to better than one second per year. A slave pendulum in a separate clock was linked by an electric circuit and electromagnets to a master pendulum in a vacuum tank. The slave pendulum performed the timekeeping functions, leaving the master pendulum to swing virtually undisturbed by outside influences. In the 1920s the Shortt-Synchronome briefly became the highest standard for timekeeping in observatories before quartz clocks superseded pendulum clocks as precision time standards.
629:
605:
586:
1094:. During most of the pendulum's swing the wheel is prevented from turning because a tooth is resting against one of the pallets; this is called the "locked" state. Each swing of the pendulum a pallet releases a tooth of the escape wheel. The wheel rotates forward a fixed amount until a tooth catches on the other pallet. These releases allow the clock's wheel train to advance a fixed amount with each swing, moving the hands forward at a constant rate, controlled by the pendulum.
3163:
223:
210:
1165:
617:
25:
872:. An increase in temperature would cause the pendulum rod to expand, but the mercury in the container would also expand and its level would rise slightly in the container, moving the center of gravity of the pendulum up toward the pivot. By using the correct amount of mercury, the centre of gravity of the pendulum remained at a constant height, and thus its period remained constant, despite changes in temperature.
3173:
81:, until the 1930s, the pendulum clock was the world's most precise timekeeper, accounting for its widespread use. Throughout the 18th and 19th centuries, pendulum clocks in homes, factories, offices, and railroad stations served as primary time standards for scheduling daily life, work shifts, and public transportation. Their greater accuracy allowed for the faster pace of life which was necessary for the
1016:. Rotation of the mass winds and unwinds the suspension spring, with the energy impulse applied to the top of the spring. The main advantage of this type of pendulum is its low energy use; with a period of 12â15 seconds, compared to the gravity swing pendulum's period of 0.5â2s, it is possible to make clocks that need to be wound only every 30 days, or even only once a year or more. Since the
895:. If properly combined, the length change of the high-expansion rods compensated for the length change of the low-expansion rods, again achieving a constant period of the pendulum with temperature changes. This type of pendulum became so associated with quality that decorative "fake" gridirons are often seen on pendulum clocks, that have no actual temperature compensation function.
291:(also called the Royal pendulum), 0.994 m (39.1 in) long, in which the time period is two seconds, became widely used in quality clocks. The long narrow clocks built around these pendulums, first made by William Clement around 1680, who also claimed invention of the anchor escapement, became known as
928:
To keep time accurately, pendulum clocks must be level. If they are not, the pendulum swings more to one side than the other, upsetting the symmetrical operation of the escapement. This condition can often be heard audibly in the ticking sound of the clock. The ticks or "beats" should be at precisely
941:
can achieve a higher accuracy than relying on the sound of the beat; precision regulators often have a built-in spirit level for the task. Older freestanding clocks often have feet with adjustable screws to level them, more recent ones have a leveling adjustment in the movement. Some modern pendulum
914:
The viscosity of the air through which the pendulum swings will vary with atmospheric pressure, humidity, and temperature. This drag also requires power that could otherwise be applied to extending the time between windings. Traditionally the pendulum bob is made with a narrow streamlined lens shape
286:
around 1658, which reduced the pendulum's swing to 4â6°. The anchor became the standard escapement used in pendulum clocks. In addition to increased accuracy, the anchor's narrow pendulum swing allowed the clock's case to accommodate longer, slower pendulums, which needed less power and caused less
798:
under the pendulum bob which moves the bob up or down on its rod. Moving the bob up reduces the length of the pendulum, reducing the pendulum's period so the clock gains time. In some pendulum clocks, fine adjustment is done with an auxiliary adjustment, which may be a small weight that is moved up
1097:
Although the escapement is necessary, its force disturbs the natural motion of the pendulum, and in precision pendulum clocks this was often the limiting factor on the accuracy of the clock. Different escapements have been used in pendulum clocks over the years to try to solve this problem. In the
860:
A major source of error in pendulum clocks is thermal expansion; the pendulum rod changes in length slightly with changes in temperature, causing changes in the rate of the clock. An increase in temperature causes the rod to expand, making the pendulum longer, so its period increases and the clock
1146:
with moving hour and minute hands. Many clocks have a small third hand indicating seconds on a subsidiary dial. Pendulum clocks are usually designed to be set by opening the glass face cover and manually pushing the minute hand around the dial to the correct time. The minute hand is mounted on a
981:
varies with latitude and elevation on Earth, the highest precision pendulum clocks must be readjusted to keep time after a move. For example, a pendulum clock moved from sea level to 4,000 feet (1,200 m) will lose 16 seconds per day. With the most accurate pendulum clocks, even moving the
919:
in astronomical observatories were often operated in a chamber that had been pumped to a low pressure to reduce drag and make the pendulum's operation even more accurate by avoiding changes in atmospheric pressure. Fine adjustment of the rate of the clock could be made by slight changes to the
1266:
that expressed the wealth and culture of their owners. They evolved in a number of traditional styles, specific to different countries and times as well as their intended use. Case styles somewhat reflect the furniture styles popular during the period. Experts can often pinpoint when an
567:
that senses when the pendulum is in the right position to receive the impulse. These should not be confused with more recent quartz pendulum clocks in which an electronic quartz clock module swings a pendulum. These are not true pendulum clocks because the timekeeping is controlled by a
851:
becomes valid as the angle approaches zero. With that substitution made, the pendulum equation becomes the equation of a harmonic oscillator, which has a fixed period in all cases. As the swing angle becomes larger, the approximation gradually fails and the period is no longer fixed.
532:
dial: this rare complication was used in early days to set the clock by the passage of the sun overhead at noon. It displays the difference between the time indicated by the clock and the time indicated by the position of the sun, which varies by as much as ±16 minutes during the
1909:
799:
or down the pendulum rod. In some master clocks and tower clocks, adjustment is accomplished by a small tray mounted on the rod where small weights are placed or removed to change the effective length, so the rate can be adjusted without stopping the clock.
346:, the faster pace of life and scheduling of shifts and public transportation like trains depended on the more accurate timekeeping made possible by the pendulum. Daily life was organized around the home pendulum clock. More accurate pendulum clocks, called
1129:
to give the pendulum an impulse without requiring a mechanical linkage, were developed. The most accurate pendulum clock was the Shortt-Synchronome clock, a complicated electromechanical clock with two pendulums developed in 1923 by W.H. Shortt and
1121:, which were employed in naval observatories and for scientific research. The Riefler escapement, used in Clemens-Riefler regulator clocks was accurate to 10 milliseconds per day. Electromagnetic escapements, which used a switch or
483:
that gives the pendulum precisely timed impulses to keep it swinging, and which releases the gear train wheels to move forward a fixed amount at each swing. This is the source of the "ticking" sound of an operating pendulum
314:
around 1715 in his precision "regulator" clocks gradually replaced the anchor escapement and is now used in most modern pendulum clocks. Observation that pendulum clocks slowed down in summer brought the realization that
169:
of swing of a pendulum is approximately the same for different sized swings. Galileo in 1637 described to his son a mechanism which could keep a pendulum swinging, which has been called the first pendulum clock design
1917:
413:. The French Time Service included pendulum clocks in their ensemble of standard clocks until 1954. The home pendulum clock began to be replaced as domestic timekeeper during the 1930s and 1940s by the synchronous
334:
Until the 19th century, clocks were handmade by individual craftsmen and were very expensive. The rich ornamentation of pendulum clocks of this period indicates their value as status symbols of the wealthy. The
1098:
18th and 19th centuries, escapement design was at the forefront of timekeeping advances. The anchor escapement (see animation) was the standard escapement used until the 1800s when an improved version, the
509:: strikes a bell or gong on every hour, with the number of strikes equal to the number of the hour. Some clocks will also signal the half hour with a single strike. More elaborate types, technically called
1085:
into impulses that keep the pendulum swinging back and forth. It is the part that makes the "ticking" sound in a working pendulum clock. Most escapements consist of a wheel with pointed teeth called the
1066:
720:
use longer pendulums, the 1.5 second pendulum, 2.25 m (7.4 ft) long, or occasionally the two-second pendulum, 4 m (13 ft) which is used in the Great Clock of
Westminster which houses
339:
of each country and region in Europe developed their own distinctive styles. By the 19th century, factory production of clock parts gradually made pendulum clocks affordable by middle-class families.
1012:
Also called torsion-spring pendulum, this is a wheel-like mass (most often four spheres on cross spokes) suspended from a vertical strip (ribbon) of spring steel, used as the regulating mechanism in
1110:
the wheel train must turn the large hands on the clock face on the outside of the building, and the weight of these hands, varying with snow and ice buildup, put a varying load on the wheel train.
775:
270:, Huygens showed that wide swings made the pendulum inaccurate, causing its period, and thus the rate of the clock, to vary with unavoidable variations in the driving force provided by the
2069:"Rusza konkurs na nowÄ
nazwÄ dla rekordowego zegara z Muzeum Nauki GdaĆskiej [A competition for a new name for the record clock from the GdaĆsk Science Museum is starting]"
672:; this avoids instabilities that were introduced by a conventional pivot. In the most accurate regulator clocks the pendulum is suspended by metal knife edges resting on flat
1106:, a small spring mechanism rewound at intervals which serves to isolate the escapement from the varying force of the wheel train, was used in a few precision clocks. In
1024:
of the spring, which varies with temperature, it is more affected by temperature changes than a gravity-swing pendulum. The most accurate torsion clocks use a spring of
849:
526:
dial: shows the phase of the moon, usually with a painted picture of the moon on a rotating disk. These were useful historically for people planning nighttime journeys.
2205:
319:
and contraction of the pendulum rod with changes in temperature was a source of error. This was solved by the invention of temperature-compensated pendulums; the
1347:
178:
used in timekeeping, increased the accuracy of clocks enormously, from about 15 minutes per day to 15 seconds per day leading to their rapid spread as existing '
979:
915:
to reduce air drag, which is where most of the driving power goes in a quality clock. In the late 19th century and early 20th century, pendulums for precision
2068:
868:
invented by Graham in 1721, which was used in precision regulator clocks into the 20th century. These had a bob consisting of a container of the liquid metal
476:
of the gear train also divide the rotation rate down to give wheels that rotate once every hour and once every 12 or 24 hours, to turn the hands of the clock.
898:
Beginning around 1900, some of the highest precision scientific clocks had pendulums made of ultra-low-expansion materials such as the nickel steel alloy
539:
attachment: repeats the hour chimes when triggered by hand. This rare complication was used before artificial lighting to check what time it was at night.
378:
on naval and commercial vessels. Beginning in the 19th century, astronomical regulators in naval observatories served as primary standards for national
929:
equally spaced intervals to give a sound of, "tick...tock...tick...tock"; if they are not, and have the sound "tick-tock...tick-tock..." the clock is
295:. The increased accuracy resulting from these developments caused the minute hand, previously rare, to be added to clock faces beginning around 1690.
183:
982:
clock to the top of a tall building would cause it to lose measurable time due to lower gravity. The local gravity also varies by about 0.5% with
73:: It swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates. From its invention in 1656 by
402:
standards in the 1930s. With an error of less than one second per year, the Shortt was the most accurate commercially produced pendulum clock.
1644:
1271:
clock was made within a few decades by subtle differences in their cases and faces. These are some of the different styles of pendulum clocks:
165:
beginning around 1602. Galileo discovered the key property that makes pendulums useful timekeepers: they are isochronic, which means that the
933:
and needs to be leveled. This problem can easily cause the clock to stop working, and is one of the most common reasons for service calls. A
662:
on the end. The bob is traditionally lens-shaped to reduce air drag. Wooden rods were often used in quality clocks because wood had a lower
701:
which embraces the pendulum rod. Each swing of the pendulum releases the escape wheel, and a tooth of the wheel presses against one of the
453:
The mechanism which runs a mechanical clock is called the movement. The movements of all mechanical pendulum clocks have these five parts:
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1853:
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An indicator or dial that records how often the escapement has rotated and therefore how much time has passed, usually a traditional
331:
in 1726. With these improvements, by the mid-18th century precision pendulum clocks achieved accuracies of a few seconds per week.
2100:
1996:
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708:
Most quality clocks, including all grandfather clocks, have a "seconds pendulum", in which each swing of the pendulum takes one
2195:
174:. It was partly constructed by his son in 1649, but neither lived to finish it. The introduction of the pendulum, the first
1782:
2237:
1821:
1551:
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but from the minute hand's shaft through a small set of gears, so rotating the minute hand manually also sets the hour hand.
1756:
810:; its period is independent of changes in amplitude. Therefore, the swing of the pendulum in clocks is limited to 2° to 4°.
728:
The pendulum swings with a period that varies with the square root of its effective length. For small swings the period
861:
loses time. Many older quality clocks used wooden pendulum rods to reduce this error, as wood expands less than metal.
104:
will affect the motion of the pendulum, causing inaccuracies, so other mechanisms must be used in portable timepieces.
1952:
1429:
1212:
738:
712:(a complete cycle takes two seconds), which is approximately one metre (39 inches) long from pivot to center of bob.
1194:
1687:
663:
182:' clocks were retrofitted with pendulums. By 1659 pendulum clocks were being manufactured in France by clockmaker
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Pendulum clocks are long lived and don't require a lot of maintenance, which is one reason for their popularity.
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426:
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Pendulum clocks remained the world standard for accurate timekeeping for 270 years, until the invention of the
429:, Columbia, Pennsylvania, USA). The largest pendulum clocks, exceeding 30 m (98 ft), were built in
1914:
Export licensing hearing, Reviewing
Committee on the Export of Works of Art and Objects of Cultural Interest
2684:
2200:
806:
of error increases with amplitude, so when limited to small swings of a few degrees the pendulum is nearly
666:
than metal. The rod is usually suspended from the clock frame with a short straight spring of metal ribbon
1567:
302:
innovation that followed the invention of the pendulum brought many improvements to pendulum clocks. The
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1147:
slipping friction sleeve which allows it to be turned on its arbor. The hour hand is driven not from the
254:, the most accurate pendulum clock ever manufactured, which served as the time standard during the 1930s.
1618:
813:
Small swing angles tend toward isochronous behavior due to the mathematical fact that the approximation
716:
often have a half-second pendulum, which is approximately 25 centimetres (9.8 in) long. Only a few
2327:
2307:
959:
942:
clocks have 'auto-beat' or 'self-regulating beat adjustment' devices, and do not need this adjustment.
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311:
86:
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By the end of the 19th century specialized escapements were used in the most accurate clocks, called
1651:
954:
Pendulum clock
Ansonia. C. 1904, SANTIAGO, hanging oak gingerbread clock, eight-day time and strike.
362:
on ships during long sea voyages drove the development of the most accurate pendulum clocks, called
2737:
1175:
395:
266:
251:
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1179:
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is kept wound by changes in atmospheric temperature and pressure with a bellows arrangement. The
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around 1726. This consisted of a "grid" of parallel rods of high-thermal-expansion metal such as
499:
201:
that has been converted to use a pendulum. To accommodate the wide pendulum swings caused by the
1488:
1262:
Pendulum clocks were more than simply utilitarian timekeepers; due to their high cost they were
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gift. Torsion pendulums are also used in "perpetual" clocks which do not need winding, as their
3202:
2347:
1376:
1352:
1148:
1013:
1007:
816:
469:
421:. The most accurate experimental pendulum clock ever made may be the Littlemore Clock built by
354:
and used to schedule work and set other clocks. The need for extremely accurate timekeeping in
275:
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1541:
1466:
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2808:
2753:
2707:
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2337:
1811:
1386:
705:, exerting a brief push through the crutch and fork on the pendulum rod to keep it swinging.
343:
82:
792:. All pendulum clocks have a means of adjusting the rate. This is usually an adjustment nut
117:
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published in 1658. Huygens contracted the construction of his clock designs to clockmaker
8:
2933:
2392:
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1099:
802:
The period of a pendulum increases slightly with the width (amplitude) of its swing. The
536:
457:
A power source; either a weight on a cord or chain that turns a pulley or sprocket, or a
418:
303:
231:
175:
70:
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which is turned by the clock's wheel train, and surfaces the teeth push against, called
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pendulum clocks, accurate to about 10 milliseconds per day. In 1929 it switched to the
391:
375:
161:, who actually built the clock. Huygens was inspired by investigations of pendulums by
150:
136:
74:
417:, which kept more accurate time because it was synchronized to the oscillation of the
274:. Clockmakers' realization that only pendulums with small swings of a few degrees are
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2742:
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2498:
2402:
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1948:
1817:
1547:
1494:
1425:
1319:
1281:
1102:, took over in precision clocks. It is used in almost all pendulum clocks today. The
1070:
1051:, one example, uses a torsion pendulum with a long oscillation period of 60 seconds.
998:
in the early 20th century had to be recalibrated when moved to a different latitude.
876:
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634:
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324:
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have been developed for clocks, one of the most widely used being a polyalcanoate
950:
513:, strike on the quarter hours, and may play melodies or Cathedral chimes, usually
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69:
element. The advantage of a pendulum for timekeeping is that it is an approximate
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31:
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The escapement is a mechanical linkage that converts the force from the clock's
679:
The pendulum is driven by an arm hanging behind it attached to the anchor piece
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The pendulum, a weight on a rod, which is the timekeeping element of the clock.
414:
158:
126:
90:
1031:
A torsion pendulum clock requiring only annual winding is sometimes called a "
628:
34:
around 1637. The earliest known pendulum clock design, it was never completed.
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Since the pendulum rate will increase with an increase in gravity, and local
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654:
604:
564:
328:
244:
198:
40:
2026:
1699:
572:
in the module, and the swinging pendulum is merely a decorative simulation.
472:) that steps up the speed of the power so that the pendulum can use it. The
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101:
2211:
Computer-Aided Design and
Kinematic Simulation of Huygens's Pendulum Clock
2210:
906:, which required very little compensation for the effects of temperature.
264:, had wide pendulum swings of 80â100°. In his 1673 analysis of pendulums,
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3126:
3033:
3018:
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24:
1910:"Expert's Statement, Case 6 (2008-09) William Hamilton Shortt regulator"
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and the poles, with gravity increasing at higher latitudes due to the
209:
153:, and patented the following year. He described it in his manuscript
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2527:
2417:
1233:
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383:
359:
222:
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in the 1930s and '40s. Pendulum clocks are now kept mostly for their
2157:
1164:
498:
Additional functions in clocks besides basic timekeeping are called
434:
2674:
2517:
2427:
2285:
2275:
1759:. Time and Frequency Services, NIST. April 30, 2002. Archived from
983:
616:
552:
62:
502:. More elaborate pendulum clocks may include these complications:
370:
and kept accurate within a fraction of a second by observation of
3013:
3003:
2925:
2916:
2901:
2788:
2633:
2556:
2265:
1698:(2). Inst. of Electrical and Electronic Engineers. Archived from
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1040:
1025:
987:
722:
94:
2803:
1940:
1792:. National Institute of Standards and Technology. Archived from
3111:
2270:
2033:. Nat'l Assoc. of Watch and Clock Collectors. pp. fig. 7b.
991:
709:
702:
560:
430:
1944:
The
Measurement of Time: Time, Frequency, and the Atomic Clock
875:
The most widely used temperature-compensated pendulum was the
3121:
2870:
2561:
2509:
2128:
1916:. UK Museums, Libraries, and Archives Council. Archived from
1783:"Time and frequency measurement at NIST: The first 100 years"
994:
shape of the Earth. Thus precision regulator clocks used for
899:
892:
888:
676:(a hard mineral that will retain a highly polished surface).
673:
100:
Pendulum clocks must be stationary to operate. Any motion or
58:
1228:
As in any mechanism with moving parts, regular cleaning and
366:. These precision instruments, installed in clock vaults in
2260:
2246:
1339:
884:
387:
66:
2129:
Gore, Jeff; Alexander van
Oudenaarden (January 15, 2009).
85:. The home pendulum clock was replaced by less-expensive
247:, that served as the US time standard from 1909 to 1929,
2206:
The earliest Dutch and French
Pendulum clocks, 1657-1662
551:
the power source is replaced by an electrically powered
520:
Calendar dials: show the day, date, and sometimes month.
386:
wires. From 1909, US National Bureau of
Standards (now
2215:
1142:
The indicating system is almost always the traditional
145:
The pendulum clock was invented on 25 December 1656 by
2006:. National Assoc. of Watch and Clock Collectors: 20â22
1941:
Audoin, Claude; Bernard Guinot; Stephen Lyle (2001).
1688:"Origin and Evolution of the Anchor Clock Escapement"
1028:
which has low temperature coefficient of elasticity.
967:
864:
The first pendulum to correct for this error was the
819:
741:
1246:
and pins may wear out and break and need replacing.
1619:"Pendulum clock designed by Galileo, Item #1883-29"
732:, the time for one complete cycle (two swings), is
973:
843:
769:
2101:"The Gravity Pendulum and its Horological Quirks"
1650:. Georgia Institute of Technology. Archived from
409:in 1927, and were used as time standards through
3189:
1970:"Scientist's historic clock collection for sale"
923:
770:{\displaystyle T=2\pi {\sqrt {\frac {L}{g}}}\,}
1813:Splitting the Second: The Story of Atomic Time
555:that provides the impulses to the pendulum by
2231:
1668:Proceedings of the Royal Society of London,
2066:
1854:"The Evolution of the Quartz Crystal Clock"
1530:
1447:"The Evolution of the Quartz Crystal Clock"
1258:One-Year German Regulator Clock. Circa 1850
1193:. Unsourced material may be challenged and
855:
350:, were installed in places of business and
240:Some of the most accurate pendulum clocks:
2238:
2224:
2071:(Press release) (in Polish). GdaĆsk Museum
1546:. Taylor & Francis. pp. 123â125.
1528:
1526:
1524:
1522:
1520:
1518:
1516:
1514:
1512:
1510:
1424:. New York: MacMillan. pp. 330, 334.
46:Vienna regulator style pendulum wall clock
1947:. UK: Cambridge Univ. Press. p. 83.
1890:. JagAir Institute of Time and Technology
1536:Clocks and Watches: The leap to precision
1213:Learn how and when to remove this message
1154:
920:internal pressure in the sealed housing.
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575:
1851:
1845:
1780:
1685:
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891:and low-thermal-expansion metal such as
444:
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1997:"Some thoughts on the Littlemore clock"
1994:
1988:
1967:
1961:
1616:A modern reconstruction can be seen at
1507:
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1478:
1476:
449:Ansonia Clock model mechanism: c. 1904.
3190:
2107:. Timezone.com website. Archived from
2067:Gierszewski, Andrzej (June 29, 2023).
1836:
1790:2001 IEEE Int'l Frequency Control Symp
1642:
1419:
559:, and the escapement is replaced by a
396:Shortt-Synchronome free pendulum clock
205:, "wings" have been added on the sides
135:The first pendulum clock, invented by
2219:
1907:
1901:
1809:
1803:
1643:Bennet, Matthew; et al. (2002).
1539:
1486:
1232:is required. Specific low viscosity
425:in the 1990s (donated in 2003 to the
3172:
2098:
2043:
2024:
1473:
1191:adding citations to reliable sources
1158:
1841:. New York: MacMillan. p. 615.
1001:
909:
382:that distributed time signals over
13:
1870:10.1002/j.1538-7305.1948.tb01343.x
1463:10.1002/j.1538-7305.1948.tb01343.x
1137:
784:is the length of the pendulum and
298:The 18th and 19th century wave of
14:
3229:
2189:
545:electromechanical pendulum clocks
260:These early clocks, due to their
3213:Inventions by Christiaan Huygens
3171:
3162:
3161:
1995:Mumford, Bryan (November 2005).
1908:Betts, Jonathan (May 22, 2008).
1493:. New York: Garland Publishing.
1163:
945:
664:coefficient of thermal expansion
647:consists of a wood or metal rod
627:
615:
603:
584:
390:) based the US time standard on
230:
221:
125:
116:
39:
23:
2122:
2092:
2083:
2060:
2048:(in French). Patrimoine-Horloge
2037:
2018:
1934:
1888:"The Reifler and Shortt clocks"
1880:
1830:
1774:
1749:
1740:
1731:
1722:
1713:
653:with a metal weight called the
427:National Watch and Clock Museum
278:motivated the invention of the
2004:Horological Science Newsletter
1679:
1636:
1610:
1585:
1560:
1438:
1413:
832:
826:
1:
1968:Kennedy, Maev (May 7, 2003).
1858:Bell System Technical Journal
1816:. US: CRC Press. p. 30.
1757:"A Revolution in Timekeeping"
1451:Bell System Technical Journal
1407:
1054:
16:Clock regulated by a pendulum
2201:The (Not So) Simple Pendulum
2131:"The Yin and Yang of Nature"
2089:Milham 1945, pp. 74, 197â212
1625:. Science Museum, London, UK
1574:. Science Museum, London, UK
643:The pendulum in most clocks
440:
65:, a swinging weight, as its
30:Pendulum clock conceived by
7:
2976:Geological history of Earth
1370:
1114:were used in tower clocks.
547:such as used in mechanical
374:overhead, were used to set
87:synchronous electric clocks
10:
3234:
2328:Orders of magnitude (time)
2144:(7227). MacMillan: 271â2.
1837:Milham, Willis I. (1945).
1686:Headrick, Michael (2002).
1420:Milham, Willis I. (1945).
1058:
1005:
960:gravitational acceleration
610:Grandfather clock pendulum
380:time distribution services
323:by Graham in 1721 and the
287:wear on the movement. The
107:
3157:
3099:
3052:
3039:Time translation symmetry
2984:
2924:
2914:
2836:
2763:
2683:
2624:
2508:
2426:
2336:
2298:
2284:
2253:
2046:"GenĂšve [Geneva]"
1976:. London: Scott Trust Ltd
1852:Marrison, Warren (1948).
1666:, p.3, also published in
1487:Macey, Samuel L. (1994).
1445:Marrison, Warren (1948).
1307:Comtoise or Morbier clock
1249:
1073:, one of the most common
844:{\displaystyle \sin(x)=x}
2245:
2025:Hall, E.T. (June 1996).
1737:Milham 1945, pp. 193â195
1692:Control Systems Magazine
1077:used in pendulum clocks
1039:", sometimes given as a
856:Temperature compensation
267:Horologium Oscillatorium
252:Shortt-Synchronome clock
2994:Absolute space and time
2645:Astronomical chronology
2196:The Invention of Clocks
1781:Sullivan, D.B. (2001).
1728:Milham 1945, p.181, 441
1277:Act of Parliament clock
1119:astronomical regulators
1014:torsion pendulum clocks
790:acceleration of gravity
364:astronomical regulators
245:Riefler regulator clock
149:scientist and inventor
3044:Time reversal symmetry
2348:Italian six-hour clock
2027:"The Littlemore Clock"
1540:Macey, Samuel (1994).
1377:Pendulum (mathematics)
1353:Torsion pendulum clock
1259:
1155:Maintenance and Repair
1125:to turn on a solenoid
1078:
1008:Torsion pendulum clock
975:
955:
845:
771:
689:, called the "crutch"
576:Gravity-swing pendulum
450:
214:
206:
2809:Time and fate deities
2754:The Unreality of Time
2693:A series and B series
1387:Flying pendulum clock
1348:Schoolhouse regulator
1257:
1068:
976:
953:
846:
772:
695:, ending in a "fork"
448:
344:Industrial Revolution
212:
196:
83:Industrial Revolution
3060:Chronological dating
3029:Theory of relativity
2373:Daylight saving time
1839:Time and Timekeepers
1810:Jones, Tony (2000).
1543:Encyclopedia of Time
1490:Encyclopedia of Time
1422:Time and Timekeepers
1187:improve this section
996:celestial navigation
965:
939:watch timing machine
817:
739:
515:Westminster quarters
494:with rotating hands.
356:celestial navigation
306:invented in 1675 by
188:Ahasuerus Fromanteel
186:, and in England by
2353:Thai six-hour clock
2150:2009Natur.457..271G
2031:Horological Science
1923:on October 25, 2009
1719:Milham 1945, p. 190
1702:on October 25, 2009
1597:The Galileo Project
1112:Gravity escapements
1100:deadbeat escapement
1020:is provided by the
924:Leveling and "beat"
419:electric power grid
376:marine chronometers
368:naval observatories
310:and popularized by
304:deadbeat escapement
176:harmonic oscillator
71:harmonic oscillator
2883:Rosy retrospection
2861:Mental chronometry
2685:Philosophy of time
2105:Community Articles
2044:Guilbaud, GĂ©rard.
1382:Cycloidal pendulum
1260:
1079:
971:
956:
841:
767:
451:
398:before phasing in
293:grandfather clocks
215:
207:
151:Christiaan Huygens
137:Christiaan Huygens
75:Christiaan Huygens
3185:
3184:
3095:
3094:
3070:Circadian rhythms
2888:Tenseâaspectâmood
2743:Temporal finitism
2620:
2619:
2596:Grandfather clock
1823:978-0-7503-0640-9
1746:Milham 1945, p.83
1645:"Huygens' Clocks"
1568:"Huygens' Clocks"
1553:978-0-8153-0615-3
1534:Andrewes, W.J.H.
1320:Grandfather clock
1311:Crystal regulator
1282:Anniversary clock
1223:
1222:
1215:
1071:anchor escapement
1037:anniversary clock
974:{\displaystyle g}
877:gridiron pendulum
764:
763:
635:Gridiron pendulum
597:grandfather clock
593:anchor escapement
352:railroad stations
325:gridiron pendulum
317:thermal expansion
280:anchor escapement
262:verge escapements
213:Grandfather clock
3225:
3175:
3174:
3165:
3164:
3082:Glottochronology
2922:
2921:
2838:Human experience
2698:B-theory of time
2296:
2295:
2240:
2233:
2226:
2217:
2216:
2184:
2183:
2181:
2180:
2135:
2126:
2120:
2119:
2117:
2116:
2099:Arnstein, Walt.
2096:
2090:
2087:
2081:
2080:
2078:
2076:
2064:
2058:
2057:
2055:
2053:
2041:
2035:
2034:
2022:
2016:
2015:
2013:
2011:
2001:
1992:
1986:
1985:
1983:
1981:
1965:
1959:
1958:
1938:
1932:
1931:
1929:
1928:
1922:
1905:
1899:
1898:
1896:
1895:
1884:
1878:
1877:
1872:. Archived from
1849:
1843:
1842:
1834:
1828:
1827:
1807:
1801:
1800:
1798:
1787:
1778:
1772:
1771:
1769:
1768:
1753:
1747:
1744:
1738:
1735:
1729:
1726:
1720:
1717:
1711:
1710:
1708:
1707:
1683:
1677:
1665:
1663:
1662:
1656:
1649:
1640:
1634:
1633:
1631:
1630:
1623:Time Measurement
1614:
1608:
1607:
1605:
1604:
1593:"Pendulum Clock"
1589:
1583:
1582:
1580:
1579:
1564:
1558:
1557:
1532:
1505:
1504:
1484:
1471:
1470:
1465:. Archived from
1442:
1436:
1435:
1417:
1362:Vienna regulator
1286:torsion pendulum
1218:
1211:
1207:
1204:
1198:
1167:
1159:
1132:Frank Hope-Jones
1069:Animation of an
1002:Torsion pendulum
980:
978:
977:
972:
917:regulator clocks
910:Atmospheric drag
866:mercury pendulum
850:
848:
847:
842:
796:
776:
774:
773:
768:
765:
756:
755:
699:
693:
683:
670:
660:
651:
631:
622:Mercury pendulum
619:
607:
588:
530:Equation of time
321:mercury pendulum
308:Richard Towneley
289:seconds pendulum
234:
225:
203:verge escapement
180:verge and foliot
172:(picture at top)
129:
120:
43:
27:
3233:
3232:
3228:
3227:
3226:
3224:
3223:
3222:
3188:
3187:
3186:
3181:
3153:
3144:Time immemorial
3091:
3048:
3009:Coordinate time
2980:
2934:Geological time
2910:
2893:Time management
2856:Generation time
2840:
2832:
2777:
2759:
2679:
2638:
2616:
2504:
2422:
2339:
2332:
2288:
2280:
2249:
2244:
2192:
2187:
2178:
2176:
2158:10.1038/457271a
2133:
2127:
2123:
2114:
2112:
2097:
2093:
2088:
2084:
2074:
2072:
2065:
2061:
2051:
2049:
2042:
2038:
2023:
2019:
2009:
2007:
1999:
1993:
1989:
1979:
1977:
1966:
1962:
1955:
1939:
1935:
1926:
1924:
1920:
1906:
1902:
1893:
1891:
1886:
1885:
1881:
1850:
1846:
1835:
1831:
1824:
1808:
1804:
1796:
1785:
1779:
1775:
1766:
1764:
1755:
1754:
1750:
1745:
1741:
1736:
1732:
1727:
1723:
1718:
1714:
1705:
1703:
1684:
1680:
1660:
1658:
1654:
1647:
1641:
1637:
1628:
1626:
1617:
1615:
1611:
1602:
1600:
1591:
1590:
1586:
1577:
1575:
1566:
1565:
1561:
1554:
1533:
1508:
1501:
1485:
1474:
1443:
1439:
1432:
1418:
1414:
1410:
1373:
1368:
1252:
1219:
1208:
1202:
1199:
1184:
1168:
1157:
1140:
1138:Time indication
1063:
1057:
1018:restoring force
1010:
1004:
966:
963:
962:
948:
926:
912:
858:
818:
815:
814:
794:
754:
740:
737:
736:
697:
691:
681:
668:
658:
649:
641:
640:
639:
638:
637:
632:
624:
623:
620:
612:
611:
608:
600:
599:
589:
578:
443:
258:
257:
256:
255:
237:
236:
235:
227:
226:
163:Galileo Galilei
143:
142:
141:
140:
132:
131:
130:
122:
121:
110:
79:Galileo Galilei
51:
50:
49:
48:
47:
44:
36:
35:
32:Galileo Galilei
28:
17:
12:
11:
5:
3231:
3221:
3220:
3215:
3210:
3205:
3200:
3183:
3182:
3180:
3179:
3169:
3158:
3155:
3154:
3152:
3151:
3146:
3141:
3136:
3129:
3124:
3119:
3114:
3109:
3103:
3101:
3097:
3096:
3093:
3092:
3090:
3089:
3087:Time geography
3084:
3079:
3077:Clock reaction
3074:
3073:
3072:
3062:
3056:
3054:
3050:
3049:
3047:
3046:
3041:
3036:
3031:
3026:
3021:
3016:
3011:
3006:
3001:
2996:
2990:
2988:
2982:
2981:
2979:
2978:
2973:
2968:
2967:
2966:
2961:
2956:
2951:
2946:
2941:
2930:
2928:
2919:
2912:
2911:
2909:
2908:
2895:
2890:
2885:
2880:
2879:
2878:
2876:time signature
2873:
2863:
2858:
2853:
2847:
2845:
2834:
2833:
2831:
2830:
2829:
2828:
2818:
2817:
2816:
2806:
2801:
2796:
2791:
2786:
2780:
2778:
2776:
2775:
2770:
2764:
2761:
2760:
2758:
2757:
2750:
2748:Temporal parts
2745:
2740:
2735:
2730:
2725:
2720:
2718:Eternal return
2715:
2710:
2705:
2703:Chronocentrism
2700:
2695:
2689:
2687:
2681:
2680:
2678:
2677:
2672:
2667:
2662:
2657:
2652:
2647:
2641:
2639:
2637:
2636:
2631:
2625:
2622:
2621:
2618:
2617:
2615:
2614:
2613:
2612:
2598:
2593:
2588:
2583:
2582:
2581:
2576:
2575:
2574:
2569:
2559:
2554:
2549:
2544:
2543:
2542:
2532:
2531:
2530:
2514:
2512:
2506:
2505:
2503:
2502:
2495:
2490:
2488:Hindu Panchang
2485:
2480:
2475:
2470:
2465:
2460:
2455:
2454:
2453:
2448:
2443:
2432:
2430:
2424:
2423:
2421:
2420:
2415:
2410:
2405:
2400:
2395:
2390:
2385:
2380:
2375:
2370:
2365:
2360:
2355:
2350:
2344:
2342:
2334:
2333:
2331:
2330:
2325:
2320:
2315:
2310:
2304:
2302:
2293:
2282:
2281:
2279:
2278:
2273:
2268:
2263:
2257:
2255:
2251:
2250:
2243:
2242:
2235:
2228:
2220:
2214:
2213:
2208:
2203:
2198:
2191:
2190:External links
2188:
2186:
2185:
2121:
2091:
2082:
2059:
2036:
2017:
1987:
1960:
1953:
1933:
1900:
1879:
1876:on 2011-07-17.
1864:(3): 510â588.
1844:
1829:
1822:
1802:
1799:on 2011-09-27.
1773:
1748:
1739:
1730:
1721:
1712:
1678:
1635:
1609:
1584:
1559:
1552:
1506:
1499:
1472:
1469:on 2007-05-13.
1457:(3): 510â588.
1437:
1430:
1411:
1409:
1406:
1405:
1404:
1397:Balance spring
1394:
1389:
1384:
1379:
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1367:
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1327:
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1317:
1312:
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1294:
1289:
1279:
1273:
1264:status symbols
1251:
1248:
1221:
1220:
1171:
1169:
1162:
1156:
1153:
1139:
1136:
1059:Main article:
1056:
1053:
1033:400-Day clock"
1006:Main article:
1003:
1000:
970:
947:
944:
925:
922:
911:
908:
857:
854:
840:
837:
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574:
570:quartz crystal
557:magnetic force
541:
540:
534:
527:
521:
518:
511:chiming clocks
507:Striking train
496:
495:
488:
485:
477:
462:
442:
439:
423:Edward T. Hall
415:electric clock
239:
238:
229:
228:
220:
219:
218:
217:
216:
184:Nicolaus Hanet
159:Salomon Coster
134:
133:
124:
123:
115:
114:
113:
112:
111:
109:
106:
77:, inspired by
55:pendulum clock
45:
38:
37:
29:
22:
21:
20:
19:
18:
15:
9:
6:
4:
3:
2:
3230:
3219:
3216:
3214:
3211:
3209:
3206:
3204:
3203:Clock designs
3201:
3199:
3196:
3195:
3193:
3178:
3170:
3168:
3160:
3159:
3156:
3150:
3147:
3145:
3142:
3140:
3137:
3135:
3134:
3130:
3128:
3125:
3123:
3120:
3118:
3115:
3113:
3110:
3108:
3105:
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3102:
3098:
3088:
3085:
3083:
3080:
3078:
3075:
3071:
3068:
3067:
3066:
3065:Chronobiology
3063:
3061:
3058:
3057:
3055:
3051:
3045:
3042:
3040:
3037:
3035:
3032:
3030:
3027:
3025:
3022:
3020:
3017:
3015:
3012:
3010:
3007:
3005:
3002:
3000:
2999:Arrow of time
2997:
2995:
2992:
2991:
2989:
2987:
2983:
2977:
2974:
2972:
2971:Geochronology
2969:
2965:
2962:
2960:
2957:
2955:
2952:
2950:
2947:
2945:
2942:
2940:
2937:
2936:
2935:
2932:
2931:
2929:
2927:
2923:
2920:
2918:
2913:
2907:
2903:
2899:
2896:
2894:
2891:
2889:
2886:
2884:
2881:
2877:
2874:
2872:
2869:
2868:
2867:
2864:
2862:
2859:
2857:
2854:
2852:
2849:
2848:
2846:
2844:
2839:
2835:
2827:
2824:
2823:
2822:
2821:Wheel of time
2819:
2815:
2812:
2811:
2810:
2807:
2805:
2802:
2800:
2797:
2795:
2792:
2790:
2787:
2785:
2782:
2781:
2779:
2774:
2771:
2769:
2766:
2765:
2762:
2756:
2755:
2751:
2749:
2746:
2744:
2741:
2739:
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2731:
2729:
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2721:
2719:
2716:
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2711:
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2694:
2691:
2690:
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2682:
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2673:
2671:
2668:
2666:
2665:Periodization
2663:
2661:
2658:
2656:
2653:
2651:
2648:
2646:
2643:
2642:
2640:
2635:
2632:
2630:
2627:
2626:
2623:
2611:
2610:
2606:
2605:
2604:
2603:
2599:
2597:
2594:
2592:
2591:Digital clock
2589:
2587:
2584:
2580:
2577:
2573:
2570:
2568:
2565:
2564:
2563:
2560:
2558:
2555:
2553:
2550:
2548:
2545:
2541:
2538:
2537:
2536:
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2529:
2526:
2525:
2524:
2521:
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2519:
2516:
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2513:
2511:
2507:
2501:
2500:
2496:
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2479:
2476:
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2471:
2469:
2466:
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2456:
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2433:
2431:
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2409:
2406:
2404:
2401:
2399:
2396:
2394:
2391:
2389:
2386:
2384:
2381:
2379:
2376:
2374:
2371:
2369:
2368:Relative hour
2366:
2364:
2363:24-hour clock
2361:
2359:
2358:12-hour clock
2356:
2354:
2351:
2349:
2346:
2345:
2343:
2341:
2335:
2329:
2326:
2324:
2321:
2319:
2316:
2314:
2311:
2309:
2306:
2305:
2303:
2301:
2297:
2294:
2292:
2287:
2283:
2277:
2274:
2272:
2269:
2267:
2264:
2262:
2259:
2258:
2256:
2252:
2248:
2241:
2236:
2234:
2229:
2227:
2222:
2221:
2218:
2212:
2209:
2207:
2204:
2202:
2199:
2197:
2194:
2193:
2175:
2171:
2167:
2163:
2159:
2155:
2151:
2147:
2143:
2139:
2132:
2125:
2111:on 2013-02-04
2110:
2106:
2102:
2095:
2086:
2070:
2063:
2047:
2040:
2032:
2028:
2021:
2005:
1998:
1991:
1975:
1971:
1964:
1956:
1954:0-521-00397-0
1950:
1946:
1945:
1937:
1919:
1915:
1911:
1904:
1889:
1883:
1875:
1871:
1867:
1863:
1859:
1855:
1848:
1840:
1833:
1825:
1819:
1815:
1814:
1806:
1795:
1791:
1784:
1777:
1763:on 2007-05-28
1762:
1758:
1752:
1743:
1734:
1725:
1716:
1701:
1697:
1693:
1689:
1682:
1676:
1674:
1669:
1657:on 2008-04-10
1653:
1646:
1639:
1624:
1620:
1613:
1598:
1594:
1588:
1573:
1569:
1563:
1555:
1549:
1545:
1544:
1537:
1531:
1529:
1527:
1525:
1523:
1521:
1519:
1517:
1515:
1513:
1511:
1502:
1496:
1492:
1491:
1483:
1481:
1479:
1477:
1468:
1464:
1460:
1456:
1452:
1448:
1441:
1433:
1431:0-7808-0008-7
1427:
1423:
1416:
1412:
1402:
1398:
1395:
1393:
1390:
1388:
1385:
1383:
1380:
1378:
1375:
1374:
1365:Zaandam clock
1364:
1361:
1359:
1356:
1354:
1351:
1349:
1346:
1343:
1341:
1338:
1336:
1333:
1331:
1328:
1326:
1325:Lantern clock
1323:
1321:
1318:
1316:
1313:
1310:
1308:
1305:
1303:
1300:
1298:
1297:Bracket clock
1295:
1293:
1290:
1287:
1283:
1280:
1278:
1275:
1274:
1272:
1270:
1265:
1256:
1247:
1245:
1241:
1239:
1238:synthetic oil
1235:
1231:
1226:
1217:
1214:
1206:
1196:
1192:
1188:
1182:
1181:
1177:
1172:This section
1170:
1166:
1161:
1160:
1152:
1150:
1145:
1135:
1133:
1128:
1127:electromagnet
1124:
1120:
1115:
1113:
1109:
1105:
1101:
1095:
1093:
1089:
1084:
1076:
1072:
1067:
1062:
1052:
1050:
1046:
1042:
1038:
1034:
1029:
1027:
1023:
1019:
1015:
1009:
999:
997:
993:
989:
985:
968:
961:
952:
946:Local gravity
943:
940:
936:
932:
921:
918:
907:
905:
901:
896:
894:
890:
886:
882:
881:John Harrison
878:
873:
871:
867:
862:
853:
838:
835:
829:
823:
820:
811:
809:
805:
800:
797:
791:
788:is the local
787:
783:
760:
757:
751:
748:
745:
742:
735:
734:
733:
731:
726:
724:
719:
715:
714:Mantel clocks
711:
706:
704:
700:
694:
688:
684:
677:
675:
671:
665:
661:
656:
652:
646:
645:(see diagram)
636:
630:
618:
606:
598:
594:
591:Pendulum and
587:
573:
571:
566:
565:photodetector
562:
558:
554:
550:
549:Master clocks
546:
538:
535:
531:
528:
525:
522:
519:
516:
512:
508:
505:
504:
503:
501:
500:complications
493:
489:
486:
482:
478:
475:
471:
467:
463:
460:
456:
455:
454:
447:
438:
436:
432:
428:
424:
420:
416:
412:
408:
403:
401:
397:
393:
389:
385:
381:
377:
373:
372:star transits
369:
365:
361:
358:to determine
357:
353:
349:
345:
340:
338:
332:
330:
329:John Harrison
326:
322:
318:
313:
312:George Graham
309:
305:
301:
296:
294:
290:
285:
281:
277:
273:
269:
268:
263:
253:
250:
246:
243:
233:
224:
211:
204:
200:
199:lantern clock
195:
191:
189:
185:
181:
177:
173:
168:
164:
160:
156:
152:
148:
138:
128:
119:
105:
103:
102:accelerations
98:
96:
92:
88:
84:
80:
76:
72:
68:
64:
60:
56:
42:
33:
26:
3139:Time capsule
3133:Tempus fugit
3131:
3053:Other fields
2752:
2733:Perdurantism
2655:Calendar era
2607:
2600:
2586:Cuckoo clock
2523:astronomical
2497:
2323:Unit of time
2254:Key concepts
2177:. Retrieved
2141:
2137:
2124:
2113:. Retrieved
2109:the original
2104:
2094:
2085:
2075:February 11,
2073:. Retrieved
2062:
2052:February 11,
2050:. Retrieved
2039:
2030:
2020:
2008:. Retrieved
2003:
1990:
1978:. Retrieved
1974:The Guardian
1973:
1963:
1943:
1936:
1925:. Retrieved
1918:the original
1913:
1903:
1892:. Retrieved
1882:
1874:the original
1861:
1857:
1847:
1838:
1832:
1812:
1805:
1794:the original
1789:
1776:
1765:. Retrieved
1761:the original
1751:
1742:
1733:
1724:
1715:
1704:. Retrieved
1700:the original
1695:
1691:
1681:
1672:
1671:
1667:
1659:. Retrieved
1652:the original
1638:
1627:. Retrieved
1622:
1612:
1601:. Retrieved
1596:
1587:
1576:. Retrieved
1571:
1562:
1542:
1535:
1489:
1467:the original
1454:
1450:
1440:
1421:
1415:
1358:Turret clock
1344:Pillar clock
1335:Master clock
1330:Mantel clock
1315:Cuckoo clock
1302:Cartel clock
1261:
1242:
1227:
1224:
1209:
1203:January 2024
1200:
1185:Please help
1173:
1141:
1118:
1116:
1108:tower clocks
1096:
1091:
1088:escape wheel
1087:
1080:
1036:
1032:
1030:
1011:
986:between the
957:
935:spirit level
930:
927:
913:
904:fused silica
897:
879:invented by
874:
865:
863:
859:
812:
807:
803:
801:
793:
785:
781:
779:
729:
727:
718:tower clocks
707:
696:
690:
680:
678:
667:
657:
648:
644:
642:
544:
542:
510:
497:
452:
407:quartz clock
404:
363:
347:
341:
333:
297:
284:Robert Hooke
265:
259:
248:
241:
171:
154:
144:
99:
61:that uses a
54:
52:
3218:Oscillators
3149:Time travel
3127:System time
3034:Time domain
3019:Proper time
2843:use of time
2814:Father Time
2794:Immortality
2784:Ages of Man
2713:Endurantism
2670:Regnal year
2650:Big History
2579:water-based
2478:Solar Hijri
2388:Hexadecimal
2338:Measurement
2300:Chronometry
2286:Measurement
1599:. Rice Univ
1392:Steam clock
1292:Banjo clock
1230:lubrication
1149:wheel train
1083:wheel train
1075:escapements
1049:Atmos clock
931:out of beat
808:isochronous
474:gear ratios
470:wheel train
433:(1972) and
411:World War 2
342:During the
337:clockmakers
300:horological
276:isochronous
67:timekeeping
3192:Categories
2851:Chronemics
2826:Kalachakra
2738:Presentism
2723:Eternalism
2629:Chronology
2567:mechanical
2518:Main types
2436:Main types
2179:2009-07-22
2115:2011-04-01
1927:2009-12-29
1894:2009-12-29
1767:2007-05-29
1706:2007-06-06
1661:2007-12-04
1629:2007-11-14
1603:2007-12-03
1578:2007-11-14
1500:0815306156
1408:References
1401:hairspring
1340:Ogee clock
1234:lubricants
1104:remontoire
1061:Escapement
1055:Escapement
1045:mainspring
1022:elasticity
687:escapement
524:Moon phase
492:clock face
481:escapement
466:gear train
459:mainspring
348:regulators
155:Horologium
91:decorative
3208:Pendulums
3107:Leap year
3024:Spacetime
2898:Yesterday
2799:Dreamtime
2773:Mythology
2660:Deep time
2572:stopwatch
2547:hourglass
2528:astrarium
2458:Gregorian
2451:Lunisolar
2428:Calendars
2418:Time zone
2291:standards
2174:205043569
2010:March 18,
1980:March 18,
1675:, 563â579
1174:does not
1123:phototube
824:
752:π
441:Mechanism
384:telegraph
360:longitude
3167:Category
2915:Time in
2906:Tomorrow
2768:Religion
2708:Duration
2675:Timeline
2609:Timeline
2408:Sidereal
2276:Eternity
2166:19148089
1371:See also
1284:(uses a
984:latitude
553:solenoid
537:Repeater
437:(2016).
272:movement
63:pendulum
3177:Commons
3100:Related
3014:Instant
3004:Chronon
2986:Physics
2926:Geology
2917:science
2789:Destiny
2634:History
2602:History
2557:sundial
2540:quantum
2483:Chinese
2473:Islamic
2383:Decimal
2378:Chinese
2340:systems
2266:Present
2146:Bibcode
1572:Stories
1269:antique
1244:Springs
1195:removed
1180:sources
1092:pallets
1041:wedding
1026:elinvar
988:equator
870:mercury
723:Big Ben
703:pallets
685:of the
595:from a
392:Riefler
249:(right)
139:in 1656
108:History
97:value.
95:antique
3198:Clocks
3117:Moment
3112:Memory
2964:period
2552:marine
2535:atomic
2510:Clocks
2468:Hebrew
2463:Julian
2398:Metric
2271:Future
2172:
2164:
2138:Nature
1951:
1820:
1550:
1497:
1428:
1250:Styles
992:oblate
780:where
710:second
561:switch
484:clock.
435:GdaĆsk
431:Geneva
400:quartz
242:(left)
167:period
3122:Space
2954:epoch
2944:chron
2902:Today
2871:tempo
2866:Music
2728:Event
2562:watch
2446:Lunar
2441:Solar
2413:Solar
2403:Roman
2393:Hindu
2170:S2CID
2134:(PDF)
2000:(PDF)
1921:(DOC)
1797:(PDF)
1786:(PDF)
1655:(PDF)
1648:(PDF)
900:Invar
893:steel
889:brass
674:agate
533:year.
147:Dutch
59:clock
57:is a
2841:and
2804:KÄla
2499:List
2493:Maya
2289:and
2261:Past
2247:Time
2162:PMID
2077:2024
2054:2024
2012:2017
1982:2017
1949:ISBN
1818:ISBN
1548:ISBN
1495:ISBN
1426:ISBN
1178:any
1176:cite
1144:dial
1035:or "
885:zinc
804:rate
388:NIST
93:and
2959:era
2949:eon
2939:age
2318:TAI
2308:UTC
2154:doi
2142:457
1866:doi
1673:458
1538:in
1459:doi
1189:by
937:or
902:or
887:or
821:sin
795:(c)
698:(f)
692:(e)
682:(h)
669:(d)
659:(b)
655:bob
650:(a)
563:or
543:In
479:An
327:by
282:by
3194::
2904:â
2900:â
2313:UT
2168:.
2160:.
2152:.
2140:.
2136:.
2103:.
2029:.
2002:.
1972:.
1912:.
1862:27
1860:.
1856:.
1788:.
1696:22
1694:.
1690:.
1621:.
1595:.
1570:.
1509:^
1475:^
1455:27
1453:.
1449:.
1240:.
725:.
464:A
197:A
190:.
53:A
2239:e
2232:t
2225:v
2182:.
2156::
2148::
2118:.
2079:.
2056:.
2014:.
1984:.
1957:.
1930:.
1897:.
1868::
1826:.
1770:.
1709:.
1670:A
1664:.
1632:.
1606:.
1581:.
1556:.
1503:.
1461::
1434:.
1403:)
1399:(
1288:)
1216:)
1210:(
1205:)
1201:(
1197:.
1183:.
969:g
839:x
836:=
833:)
830:x
827:(
786:g
782:L
761:g
758:L
749:2
746:=
743:T
730:T
517:.
468:(
461:.
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