129:
243:
205:
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962:
457:
52:
138:
1145:, 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1920s the Shortt-Synchronome briefly became the highest standard for timekeeping in observatories before quartz clocks superseded pendulum clocks as precision time standards.
640:
616:
597:
1105:. 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.
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234:
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36:
883:. 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.
3184:
92:, 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
1027:. 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
906:. 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.
302:(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
939:
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
952:
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
925:
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
297:
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
809:
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
1108:
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
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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
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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
992:
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
930:
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
1277:
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
578:
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
862:
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.
543:
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
1920:
810:
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.
357:, 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
1140:
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
1132:, 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
494:
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
325:
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
180:
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
1928:
424:. 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
345:
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
1109:
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
520:: 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
1096:
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
1077:
731:
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
350:
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.
1023:
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
1121:
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.
786:
281:, 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
2080:"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]"
683:; 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
1117:, 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
1035:
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
860:
537:
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.
2216:
330:
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
1358:
189:
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 '
990:
926:
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
2079:
879:
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
487:
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.
909:
Beginning around 1900, some of the highest precision scientific clocks had pendulums made of ultra-low-expansion materials such as the nickel steel alloy
550:
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.
389:
on naval and commercial vessels. Beginning in the 19th century, astronomical regulators in naval observatories served as primary standards for national
940:
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
306:. The increased accuracy resulting from these developments caused the minute hand, previously rare, to be added to clock faces beginning around 1690.
194:
993:
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
84:: 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
413:
standards in the 1930s. With an error of less than one second per year, the Shortt was the most accurate commercially produced pendulum clock.
1655:
1282:
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:
176:
beginning around 1602. Galileo discovered the key property that makes pendulums useful timekeepers: they are isochronic, which means that the
944:
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
673:
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
712:
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
464:
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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An indicator or dial that records how often the escapement has rotated and therefore how much time has passed, usually a traditional
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in 1726. With these improvements, by the mid-18th century precision pendulum clocks achieved accuracies of a few seconds per week.
2111:
2007:
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Most quality clocks, including all grandfather clocks, have a "seconds pendulum", in which each swing of the pendulum takes one
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185:. It was partly constructed by his son in 1649, but neither lived to finish it. The introduction of the pendulum, the first
17:
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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.
1767:
821:; its period is independent of changes in amplitude. Therefore, the swing of the pendulum in clocks is limited to 2° to 4°.
739:
The pendulum swings with a period that varies with the square root of its effective length. For small swings the period
872:
loses time. Many older quality clocks used wooden pendulum rods to reduce this error, as wood expands less than metal.
115:
will affect the motion of the pendulum, causing inaccuracies, so other mechanisms must be used in portable timepieces.
1963:
1440:
1223:
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723:(a complete cycle takes two seconds), which is approximately one metre (39 inches) long from pivot to center of bob.
1205:
1698:
674:
193:' 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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Pendulum clocks remained the world standard for accurate timekeeping for 270 years, until the invention of the
440:, Columbia, Pennsylvania, USA). The largest pendulum clocks, exceeding 30 m (98 ft), were built in
1925:
Export licensing hearing, Reviewing
Committee on the Export of Works of Art and Objects of Cultural Interest
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2211:
817:
of error increases with amplitude, so when limited to small swings of a few degrees the pendulum is nearly
677:
than metal. The rod is usually suspended from the clock frame with a short straight spring of metal ribbon
1578:
313:
innovation that followed the invention of the pendulum brought many improvements to pendulum clocks. The
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1158:
slipping friction sleeve which allows it to be turned on its arbor. The hour hand is driven not from the
265:, the most accurate pendulum clock ever manufactured, which served as the time standard during the 1930s.
1629:
824:
Small swing angles tend toward isochronous behavior due to the mathematical fact that the approximation
727:
often have a half-second pendulum, which is approximately 25 centimetres (9.8 in) long. Only a few
2338:
2318:
970:
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clocks have 'auto-beat' or 'self-regulating beat adjustment' devices, and do not need this adjustment.
800:
322:
97:
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By the end of the 19th century specialized escapements were used in the most accurate clocks, called
1662:
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Pendulum clock
Ansonia. C. 1904, SANTIAGO, hanging oak gingerbread clock, eight-day time and strike.
373:
on ships during long sea voyages drove the development of the most accurate pendulum clocks, called
2748:
1186:
406:
277:
262:
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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
510:
212:
that has been converted to use a pendulum. To accommodate the wide pendulum swings caused by the
1499:
1273:
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
3213:
2358:
1387:
1363:
1159:
1024:
1018:
827:
480:
432:. The most accurate experimental pendulum clock ever made may be the Littlemore Clock built by
365:
and used to schedule work and set other clocks. The need for extremely accurate timekeeping in
286:
2119:
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1477:
3187:
2819:
2764:
2718:
2703:
2348:
1822:
1397:
716:, exerting a brief push through the crutch and fork on the pendulum rod to keep it swinging.
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93:
803:. All pendulum clocks have a means of adjusting the rate. This is usually an adjustment nut
128:
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published in 1658. Huygens contracted the construction of his clock designs to clockmaker
8:
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2403:
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1110:
813:
The period of a pendulum increases slightly with the width (amplitude) of its swing. The
547:
468:
A power source; either a weight on a cord or chain that turns a pulley or sprocket, or a
429:
314:
242:
186:
81:
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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
402:
386:
172:, who actually built the clock. Huygens was inspired by investigations of pendulums by
161:
147:
85:
428:, which kept more accurate time because it was synchronized to the oscillation of the
285:. Clockmakers' realization that only pendulums with small swings of a few degrees are
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2753:
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2509:
2413:
2184:
2172:
1959:
1828:
1558:
1505:
1436:
1330:
1292:
1113:, took over in precision clocks. It is used in almost all pendulum clocks today. The
1081:
1062:, one example, uses a torsion pendulum with a long oscillation period of 60 seconds.
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in the early 20th century had to be recalibrated when moved to a different latitude.
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have been developed for clocks, one of the most widely used being a polyalcanoate
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524:, strike on the quarter hours, and may play melodies or Cathedral chimes, usually
456:
80:
element. The advantage of a pendulum for timekeeping is that it is an approximate
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1953:
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The escapement is a mechanical linkage that converts the force from the clock's
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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.
425:
169:
137:
101:
1042:
A torsion pendulum clock requiring only annual winding is sometimes called a "
639:
45:
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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615:
575:
339:
255:
209:
51:
2037:
1710:
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in the module, and the swinging pendulum is merely a decorative simulation.
483:) that steps up the speed of the power so that the pendulum can use it. The
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Computer-Aided Design and
Kinematic Simulation of Huygens's Pendulum Clock
2221:
917:, which required very little compensation for the effects of temperature.
275:, had wide pendulum swings of 80â100°. In his 1673 analysis of pendulums,
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3044:
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35:
1921:"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
220:
164:, and patented the following year. He described it in his manuscript
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2538:
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233:
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in the 1930s and '40s. Pendulum clocks are now kept mostly for their
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1175:
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Additional functions in clocks besides basic timekeeping are called
445:
2685:
2528:
2438:
2296:
2286:
1770:. Time and Frequency Services, NIST. April 30, 2002. Archived from
994:
627:
563:
73:
513:. More elaborate pendulum clocks may include these complications:
381:
and kept accurate within a fraction of a second by observation of
3024:
3014:
2936:
2927:
2912:
2799:
2644:
2567:
2276:
1709:(2). Inst. of Electrical and Electronic Engineers. Archived from
1279:
1051:
1036:
998:
733:
105:
2814:
1951:
1803:. National Institute of Standards and Technology. Archived from
3122:
2281:
2044:. Nat'l Assoc. of Watch and Clock Collectors. pp. fig. 7b.
1002:
720:
713:
571:
441:
1955:
The
Measurement of Time: Time, Frequency, and the Atomic Clock
886:
The most widely used temperature-compensated pendulum was the
3132:
2881:
2572:
2520:
2139:
1927:. UK Museums, Libraries, and Archives Council. Archived from
1794:"Time and frequency measurement at NIST: The first 100 years"
1005:
shape of the Earth. Thus precision regulator clocks used for
910:
903:
899:
687:(a hard mineral that will retain a highly polished surface).
684:
111:
Pendulum clocks must be stationary to operate. Any motion or
69:
1239:
As in any mechanism with moving parts, regular cleaning and
377:. These precision instruments, installed in clock vaults in
2271:
2257:
1350:
895:
398:
77:
2140:
Gore, Jeff; Alexander van
Oudenaarden (January 15, 2009).
96:. The home pendulum clock was replaced by less-expensive
258:, that served as the US time standard from 1909 to 1929,
2217:
The earliest Dutch and French
Pendulum clocks, 1657-1662
562:
the power source is replaced by an electrically powered
531:
Calendar dials: show the day, date, and sometimes month.
397:
wires. From 1909, US National Bureau of
Standards (now
2226:
1153:
The indicating system is almost always the traditional
156:
The pendulum clock was invented on 25 December 1656 by
2017:. National Assoc. of Watch and Clock Collectors: 20â22
1952:
Audoin, Claude; Bernard Guinot; Stephen Lyle (2001).
1699:"Origin and Evolution of the Anchor Clock Escapement"
1039:
which has low temperature coefficient of elasticity.
978:
875:
The first pendulum to correct for this error was the
830:
752:
1257:
and pins may wear out and break and need replacing.
1630:"Pendulum clock designed by Galileo, Item #1883-29"
743:, the time for one complete cycle (two swings), is
984:
854:
780:
2112:"The Gravity Pendulum and its Horological Quirks"
1661:. Georgia Institute of Technology. Archived from
420:in 1927, and were used as time standards through
3200:
1981:"Scientist's historic clock collection for sale"
934:
781:{\displaystyle T=2\pi {\sqrt {\frac {L}{g}}}\,}
1824:Splitting the Second: The Story of Atomic Time
566:that provides the impulses to the pendulum by
2242:
1679:Proceedings of the Royal Society of London,
2077:
1865:"The Evolution of the Quartz Crystal Clock"
1541:
1458:"The Evolution of the Quartz Crystal Clock"
1269:One-Year German Regulator Clock. Circa 1850
1204:. Unsourced material may be challenged and
866:
361:, were installed in places of business and
251:Some of the most accurate pendulum clocks:
2249:
2235:
2082:(Press release) (in Polish). GdaĆsk Museum
1557:. Taylor & Francis. pp. 123â125.
1539:
1537:
1535:
1533:
1531:
1529:
1527:
1525:
1523:
1521:
1435:. New York: MacMillan. pp. 330, 334.
57:Vienna regulator style pendulum wall clock
1958:. UK: Cambridge Univ. Press. p. 83.
1901:. JagAir Institute of Time and Technology
1547:Clocks and Watches: The leap to precision
1224:Learn how and when to remove this message
1165:
931:internal pressure in the sealed housing.
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586:
1862:
1856:
1791:
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1075:
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902:and low-thermal-expansion metal such as
455:
219:
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2008:"Some thoughts on the Littlemore clock"
2005:
1999:
1978:
1972:
1627:A modern reconstruction can be seen at
1518:
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1491:
1489:
1487:
460:Ansonia Clock model mechanism: c. 1904.
14:
3201:
2118:. Timezone.com website. Archived from
2078:Gierszewski, Andrzej (June 29, 2023).
1847:
1801:2001 IEEE Int'l Frequency Control Symp
1653:
1430:
570:, and the escapement is replaced by a
407:Shortt-Synchronome free pendulum clock
216:, "wings" have been added on the sides
146:The first pendulum clock, invented by
2230:
1918:
1912:
1820:
1814:
1654:Bennet, Matthew; et al. (2002).
1550:
1497:
1243:is required. Specific low viscosity
436:in the 1990s (donated in 2003 to the
3183:
2109:
2054:
2035:
1484:
1202:adding citations to reliable sources
1169:
1852:. New York: MacMillan. p. 615.
1012:
920:
393:that distributed time signals over
24:
1881:10.1002/j.1538-7305.1948.tb01343.x
1474:10.1002/j.1538-7305.1948.tb01343.x
1148:
795:is the length of the pendulum and
309:The 18th and 19th century wave of
25:
3240:
2200:
556:electromechanical pendulum clocks
271:These early clocks, due to their
3224:Inventions by Christiaan Huygens
3182:
3173:
3172:
2006:Mumford, Bryan (November 2005).
1919:Betts, Jonathan (May 22, 2008).
1504:. New York: Garland Publishing.
1174:
956:
675:coefficient of thermal expansion
658:consists of a wood or metal rod
638:
626:
614:
595:
401:) based the US time standard on
241:
232:
136:
127:
50:
34:
2133:
2103:
2094:
2071:
2059:(in French). Patrimoine-Horloge
2048:
2029:
1945:
1899:"The Reifler and Shortt clocks"
1891:
1841:
1785:
1760:
1751:
1742:
1733:
1724:
664:with a metal weight called the
438:National Watch and Clock Museum
289:motivated the invention of the
2015:Horological Science Newsletter
1690:
1647:
1621:
1596:
1571:
1449:
1424:
843:
837:
13:
1:
1979:Kennedy, Maev (May 7, 2003).
1869:Bell System Technical Journal
1827:. US: CRC Press. p. 30.
1768:"A Revolution in Timekeeping"
1462:Bell System Technical Journal
1418:
1065:
27:Clock regulated by a pendulum
2212:The (Not So) Simple Pendulum
2142:"The Yin and Yang of Nature"
2100:Milham 1945, pp. 74, 197â212
1636:. Science Museum, London, UK
1585:. Science Museum, London, UK
654:The pendulum in most clocks
451:
76:, a swinging weight, as its
41:Pendulum clock conceived by
7:
2987:Geological history of Earth
1381:
1125:were used in tower clocks.
558:such as used in mechanical
385:overhead, were used to set
98:synchronous electric clocks
10:
3245:
2339:Orders of magnitude (time)
2155:(7227). MacMillan: 271â2.
1848:Milham, Willis I. (1945).
1697:Headrick, Michael (2002).
1431:Milham, Willis I. (1945).
1069:
1016:
971:gravitational acceleration
621:Grandfather clock pendulum
391:time distribution services
334:by Graham in 1721 and the
298:wear on the movement. The
118:
3168:
3110:
3063:
3050:Time translation symmetry
2995:
2935:
2925:
2847:
2774:
2694:
2635:
2519:
2437:
2347:
2309:
2295:
2264:
2057:"GenĂšve [Geneva]"
1987:. London: Scott Trust Ltd
1863:Marrison, Warren (1948).
1677:, p.3, also published in
1498:Macey, Samuel L. (1994).
1456:Marrison, Warren (1948).
1318:Comtoise or Morbier clock
1260:
1084:, one of the most common
855:{\displaystyle \sin(x)=x}
2256:
2036:Hall, E.T. (June 1996).
1748:Milham 1945, pp. 193â195
1703:Control Systems Magazine
1088:used in pendulum clocks
1050:", sometimes given as a
867:Temperature compensation
278:Horologium Oscillatorium
263:Shortt-Synchronome clock
3005:Absolute space and time
2656:Astronomical chronology
2207:The Invention of Clocks
1792:Sullivan, D.B. (2001).
1739:Milham 1945, p.181, 441
1288:Act of Parliament clock
1130:astronomical regulators
1025:torsion pendulum clocks
801:acceleration of gravity
375:astronomical regulators
256:Riefler regulator clock
160:scientist and inventor
3055:Time reversal symmetry
2359:Italian six-hour clock
2038:"The Littlemore Clock"
1551:Macey, Samuel (1994).
1388:Pendulum (mathematics)
1364:Torsion pendulum clock
1270:
1166:Maintenance and Repair
1136:to turn on a solenoid
1089:
1019:Torsion pendulum clock
986:
966:
856:
782:
700:, called the "crutch"
587:Gravity-swing pendulum
461:
225:
217:
18:Astronomical regulator
2820:Time and fate deities
2765:The Unreality of Time
2704:A series and B series
1398:Flying pendulum clock
1359:Schoolhouse regulator
1268:
1079:
987:
964:
857:
783:
706:, ending in a "fork"
459:
355:Industrial Revolution
223:
207:
94:Industrial Revolution
3071:Chronological dating
3040:Theory of relativity
2384:Daylight saving time
1850:Time and Timekeepers
1821:Jones, Tony (2000).
1554:Encyclopedia of Time
1501:Encyclopedia of Time
1433:Time and Timekeepers
1198:improve this section
1007:celestial navigation
976:
950:watch timing machine
828:
750:
526:Westminster quarters
505:with rotating hands.
367:celestial navigation
317:invented in 1675 by
199:Ahasuerus Fromanteel
197:, and in England by
2364:Thai six-hour clock
2161:2009Natur.457..271G
2042:Horological Science
1934:on October 25, 2009
1730:Milham 1945, p. 190
1713:on October 25, 2009
1608:The Galileo Project
1123:Gravity escapements
1111:deadbeat escapement
1031:is provided by the
935:Leveling and "beat"
430:electric power grid
387:marine chronometers
379:naval observatories
321:and popularized by
315:deadbeat escapement
187:harmonic oscillator
82:harmonic oscillator
2894:Rosy retrospection
2872:Mental chronometry
2696:Philosophy of time
2116:Community Articles
2055:Guilbaud, GĂ©rard.
1393:Cycloidal pendulum
1271:
1090:
982:
967:
852:
778:
462:
409:before phasing in
304:grandfather clocks
226:
218:
162:Christiaan Huygens
148:Christiaan Huygens
86:Christiaan Huygens
3196:
3195:
3106:
3105:
3081:Circadian rhythms
2899:Tenseâaspectâmood
2754:Temporal finitism
2631:
2630:
2607:Grandfather clock
1834:978-0-7503-0640-9
1757:Milham 1945, p.83
1656:"Huygens' Clocks"
1579:"Huygens' Clocks"
1564:978-0-8153-0615-3
1545:Andrewes, W.J.H.
1331:Grandfather clock
1322:Crystal regulator
1293:Anniversary clock
1234:
1233:
1226:
1082:anchor escapement
1048:anniversary clock
985:{\displaystyle g}
888:gridiron pendulum
775:
774:
646:Gridiron pendulum
608:grandfather clock
604:anchor escapement
363:railroad stations
336:gridiron pendulum
328:thermal expansion
291:anchor escapement
273:verge escapements
224:Grandfather clock
16:(Redirected from
3236:
3186:
3185:
3176:
3175:
3093:Glottochronology
2933:
2932:
2849:Human experience
2709:B-theory of time
2307:
2306:
2251:
2244:
2237:
2228:
2227:
2195:
2194:
2192:
2191:
2146:
2137:
2131:
2130:
2128:
2127:
2110:Arnstein, Walt.
2107:
2101:
2098:
2092:
2091:
2089:
2087:
2075:
2069:
2068:
2066:
2064:
2052:
2046:
2045:
2033:
2027:
2026:
2024:
2022:
2012:
2003:
1997:
1996:
1994:
1992:
1976:
1970:
1969:
1949:
1943:
1942:
1940:
1939:
1933:
1916:
1910:
1909:
1907:
1906:
1895:
1889:
1888:
1883:. Archived from
1860:
1854:
1853:
1845:
1839:
1838:
1818:
1812:
1811:
1809:
1798:
1789:
1783:
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1694:
1688:
1676:
1674:
1673:
1667:
1660:
1651:
1645:
1644:
1642:
1641:
1634:Time Measurement
1625:
1619:
1618:
1616:
1615:
1604:"Pendulum Clock"
1600:
1594:
1593:
1591:
1590:
1575:
1569:
1568:
1543:
1516:
1515:
1495:
1482:
1481:
1476:. Archived from
1453:
1447:
1446:
1428:
1373:Vienna regulator
1297:torsion pendulum
1229:
1222:
1218:
1215:
1209:
1178:
1170:
1143:Frank Hope-Jones
1080:Animation of an
1013:Torsion pendulum
991:
989:
988:
983:
928:regulator clocks
921:Atmospheric drag
877:mercury pendulum
861:
859:
858:
853:
807:
787:
785:
784:
779:
776:
767:
766:
710:
704:
694:
681:
671:
662:
642:
633:Mercury pendulum
630:
618:
599:
541:Equation of time
332:mercury pendulum
319:Richard Towneley
300:seconds pendulum
245:
236:
214:verge escapement
191:verge and foliot
183:(picture at top)
140:
131:
54:
38:
21:
3244:
3243:
3239:
3238:
3237:
3235:
3234:
3233:
3199:
3198:
3197:
3192:
3164:
3155:Time immemorial
3102:
3059:
3020:Coordinate time
2991:
2945:Geological time
2921:
2904:Time management
2867:Generation time
2851:
2843:
2788:
2770:
2690:
2649:
2627:
2515:
2433:
2350:
2343:
2299:
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2255:
2203:
2198:
2189:
2187:
2169:10.1038/457271a
2144:
2138:
2134:
2125:
2123:
2108:
2104:
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2095:
2085:
2083:
2076:
2072:
2062:
2060:
2053:
2049:
2034:
2030:
2020:
2018:
2010:
2004:
2000:
1990:
1988:
1977:
1973:
1966:
1950:
1946:
1937:
1935:
1931:
1917:
1913:
1904:
1902:
1897:
1896:
1892:
1861:
1857:
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1761:
1756:
1752:
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1729:
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1695:
1691:
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1669:
1665:
1658:
1652:
1648:
1639:
1637:
1628:
1626:
1622:
1613:
1611:
1602:
1601:
1597:
1588:
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1577:
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1572:
1565:
1544:
1519:
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1496:
1485:
1454:
1450:
1443:
1429:
1425:
1421:
1384:
1379:
1263:
1230:
1219:
1213:
1210:
1195:
1179:
1168:
1151:
1149:Time indication
1074:
1068:
1029:restoring force
1021:
1015:
977:
974:
973:
959:
937:
923:
869:
829:
826:
825:
805:
765:
751:
748:
747:
708:
702:
692:
679:
669:
660:
652:
651:
650:
649:
648:
643:
635:
634:
631:
623:
622:
619:
611:
610:
600:
589:
454:
269:
268:
267:
266:
248:
247:
246:
238:
237:
174:Galileo Galilei
154:
153:
152:
151:
143:
142:
141:
133:
132:
121:
90:Galileo Galilei
62:
61:
60:
59:
58:
55:
47:
46:
43:Galileo Galilei
39:
28:
23:
22:
15:
12:
11:
5:
3242:
3232:
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3114:
3112:
3108:
3107:
3104:
3103:
3101:
3100:
3098:Time geography
3095:
3090:
3088:Clock reaction
3085:
3084:
3083:
3073:
3067:
3065:
3061:
3060:
3058:
3057:
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2930:
2923:
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2896:
2891:
2890:
2889:
2887:time signature
2884:
2874:
2869:
2864:
2858:
2856:
2845:
2844:
2842:
2841:
2840:
2839:
2829:
2828:
2827:
2817:
2812:
2807:
2802:
2797:
2791:
2789:
2787:
2786:
2781:
2775:
2772:
2771:
2769:
2768:
2761:
2759:Temporal parts
2756:
2751:
2746:
2741:
2736:
2731:
2729:Eternal return
2726:
2721:
2716:
2714:Chronocentrism
2711:
2706:
2700:
2698:
2692:
2691:
2689:
2688:
2683:
2678:
2673:
2668:
2663:
2658:
2652:
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2648:
2647:
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2554:
2553:
2543:
2542:
2541:
2525:
2523:
2517:
2516:
2514:
2513:
2506:
2501:
2499:Hindu Panchang
2496:
2491:
2486:
2481:
2476:
2471:
2466:
2465:
2464:
2459:
2454:
2443:
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2416:
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2262:
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2253:
2246:
2239:
2231:
2225:
2224:
2219:
2214:
2209:
2202:
2201:External links
2199:
2197:
2196:
2132:
2102:
2093:
2070:
2047:
2028:
1998:
1971:
1964:
1944:
1911:
1890:
1887:on 2011-07-17.
1875:(3): 510â588.
1855:
1840:
1833:
1813:
1810:on 2011-09-27.
1784:
1759:
1750:
1741:
1732:
1723:
1689:
1646:
1620:
1595:
1570:
1563:
1517:
1510:
1483:
1480:on 2007-05-13.
1468:(3): 510â588.
1448:
1441:
1422:
1420:
1417:
1416:
1415:
1408:Balance spring
1405:
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1275:status symbols
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1231:
1182:
1180:
1173:
1167:
1164:
1150:
1147:
1070:Main article:
1067:
1064:
1044:400-Day clock"
1017:Main article:
1014:
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581:quartz crystal
568:magnetic force
552:
551:
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538:
532:
529:
522:chiming clocks
518:Striking train
507:
506:
499:
496:
488:
473:
453:
450:
434:Edward T. Hall
426:electric clock
250:
249:
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195:Nicolaus Hanet
170:Salomon Coster
145:
144:
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125:
124:
123:
122:
120:
117:
88:, inspired by
66:pendulum clock
56:
49:
48:
40:
33:
32:
31:
30:
29:
26:
9:
6:
4:
3:
2:
3241:
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3217:
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3214:Clock designs
3212:
3210:
3207:
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3179:
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3077:
3076:Chronobiology
3074:
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3011:
3010:Arrow of time
3008:
3006:
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3000:
2998:
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2988:
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2982:Geochronology
2980:
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2860:
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2855:
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2846:
2838:
2835:
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2833:
2832:Wheel of time
2830:
2826:
2823:
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2676:Periodization
2674:
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2614:
2610:
2608:
2605:
2603:
2602:Digital clock
2600:
2598:
2595:
2591:
2588:
2584:
2581:
2579:
2576:
2575:
2574:
2571:
2569:
2566:
2564:
2561:
2559:
2556:
2552:
2549:
2548:
2547:
2544:
2540:
2537:
2536:
2535:
2532:
2531:
2530:
2527:
2526:
2524:
2522:
2518:
2512:
2511:
2507:
2505:
2502:
2500:
2497:
2495:
2492:
2490:
2487:
2485:
2482:
2480:
2477:
2475:
2472:
2470:
2467:
2463:
2460:
2458:
2455:
2453:
2450:
2449:
2448:
2445:
2444:
2442:
2440:
2436:
2430:
2427:
2425:
2422:
2420:
2417:
2415:
2412:
2410:
2407:
2405:
2402:
2400:
2397:
2395:
2392:
2390:
2387:
2385:
2382:
2380:
2379:Relative hour
2377:
2375:
2374:24-hour clock
2372:
2370:
2369:12-hour clock
2367:
2365:
2362:
2360:
2357:
2356:
2354:
2352:
2346:
2340:
2337:
2335:
2332:
2330:
2327:
2325:
2322:
2320:
2317:
2316:
2314:
2312:
2308:
2305:
2303:
2298:
2294:
2288:
2285:
2283:
2280:
2278:
2275:
2273:
2270:
2269:
2267:
2263:
2259:
2252:
2247:
2245:
2240:
2238:
2233:
2232:
2229:
2223:
2220:
2218:
2215:
2213:
2210:
2208:
2205:
2204:
2186:
2182:
2178:
2174:
2170:
2166:
2162:
2158:
2154:
2150:
2143:
2136:
2122:on 2013-02-04
2121:
2117:
2113:
2106:
2097:
2081:
2074:
2058:
2051:
2043:
2039:
2032:
2016:
2009:
2002:
1986:
1982:
1975:
1967:
1965:0-521-00397-0
1961:
1957:
1956:
1948:
1930:
1926:
1922:
1915:
1900:
1894:
1886:
1882:
1878:
1874:
1870:
1866:
1859:
1851:
1844:
1836:
1830:
1826:
1825:
1817:
1806:
1802:
1795:
1788:
1774:on 2007-05-28
1773:
1769:
1763:
1754:
1745:
1736:
1727:
1712:
1708:
1704:
1700:
1693:
1687:
1685:
1680:
1668:on 2008-04-10
1664:
1657:
1650:
1635:
1631:
1624:
1609:
1605:
1599:
1584:
1580:
1574:
1566:
1560:
1556:
1555:
1548:
1542:
1540:
1538:
1536:
1534:
1532:
1530:
1528:
1526:
1524:
1522:
1513:
1507:
1503:
1502:
1494:
1492:
1490:
1488:
1479:
1475:
1471:
1467:
1463:
1459:
1452:
1444:
1442:0-7808-0008-7
1438:
1434:
1427:
1423:
1413:
1409:
1406:
1404:
1401:
1399:
1396:
1394:
1391:
1389:
1386:
1385:
1376:Zaandam clock
1375:
1372:
1370:
1367:
1365:
1362:
1360:
1357:
1354:
1352:
1349:
1347:
1344:
1342:
1339:
1337:
1336:Lantern clock
1334:
1332:
1329:
1327:
1324:
1321:
1319:
1316:
1314:
1311:
1309:
1308:Bracket clock
1306:
1304:
1301:
1298:
1294:
1291:
1289:
1286:
1285:
1283:
1281:
1276:
1267:
1258:
1256:
1252:
1250:
1249:synthetic oil
1246:
1242:
1237:
1228:
1225:
1217:
1207:
1203:
1199:
1193:
1192:
1188:
1183:This section
1181:
1177:
1172:
1171:
1163:
1161:
1156:
1146:
1144:
1139:
1138:electromagnet
1135:
1131:
1126:
1124:
1120:
1116:
1112:
1106:
1104:
1100:
1095:
1087:
1083:
1078:
1073:
1063:
1061:
1057:
1053:
1049:
1045:
1040:
1038:
1034:
1030:
1026:
1020:
1010:
1008:
1004:
1000:
996:
979:
972:
963:
957:Local gravity
954:
951:
947:
943:
932:
929:
918:
916:
912:
907:
905:
901:
897:
893:
892:John Harrison
889:
884:
882:
878:
873:
864:
849:
846:
840:
834:
831:
822:
820:
816:
811:
808:
802:
799:is the local
798:
794:
771:
768:
762:
759:
756:
753:
746:
745:
744:
742:
737:
735:
730:
726:
725:Mantel clocks
722:
717:
715:
711:
705:
699:
695:
688:
686:
682:
676:
672:
667:
663:
657:
656:(see diagram)
647:
641:
629:
617:
609:
605:
602:Pendulum and
598:
584:
582:
577:
576:photodetector
573:
569:
565:
561:
560:Master clocks
557:
549:
546:
542:
539:
536:
533:
530:
527:
523:
519:
516:
515:
514:
512:
511:complications
504:
500:
497:
493:
489:
486:
482:
478:
474:
471:
467:
466:
465:
458:
449:
447:
443:
439:
435:
431:
427:
423:
419:
414:
412:
408:
404:
400:
396:
392:
388:
384:
383:star transits
380:
376:
372:
369:to determine
368:
364:
360:
356:
351:
349:
343:
341:
340:John Harrison
337:
333:
329:
324:
323:George Graham
320:
316:
312:
307:
305:
301:
296:
292:
288:
284:
280:
279:
274:
264:
261:
257:
254:
244:
235:
222:
215:
211:
210:lantern clock
206:
202:
200:
196:
192:
188:
184:
179:
175:
171:
167:
163:
159:
149:
139:
130:
116:
114:
113:accelerations
109:
107:
103:
99:
95:
91:
87:
83:
79:
75:
71:
67:
53:
44:
37:
19:
3150:Time capsule
3144:Tempus fugit
3142:
3064:Other fields
2763:
2744:Perdurantism
2666:Calendar era
2618:
2611:
2597:Cuckoo clock
2534:astronomical
2508:
2334:Unit of time
2265:Key concepts
2188:. Retrieved
2152:
2148:
2135:
2124:. Retrieved
2120:the original
2115:
2105:
2096:
2086:February 11,
2084:. Retrieved
2073:
2063:February 11,
2061:. Retrieved
2050:
2041:
2031:
2019:. Retrieved
2014:
2001:
1989:. Retrieved
1985:The Guardian
1984:
1974:
1954:
1947:
1936:. Retrieved
1929:the original
1924:
1914:
1903:. Retrieved
1893:
1885:the original
1872:
1868:
1858:
1849:
1843:
1823:
1816:
1805:the original
1800:
1787:
1776:. Retrieved
1772:the original
1762:
1753:
1744:
1735:
1726:
1715:. Retrieved
1711:the original
1706:
1702:
1692:
1683:
1682:
1678:
1670:. Retrieved
1663:the original
1649:
1638:. Retrieved
1633:
1623:
1612:. Retrieved
1607:
1598:
1587:. Retrieved
1582:
1573:
1553:
1546:
1500:
1478:the original
1465:
1461:
1451:
1432:
1426:
1369:Turret clock
1355:Pillar clock
1346:Master clock
1341:Mantel clock
1326:Cuckoo clock
1313:Cartel clock
1272:
1253:
1238:
1235:
1220:
1214:January 2024
1211:
1196:Please help
1184:
1152:
1129:
1127:
1119:tower clocks
1107:
1102:
1099:escape wheel
1098:
1091:
1047:
1043:
1041:
1022:
997:between the
968:
946:spirit level
941:
938:
924:
915:fused silica
908:
890:invented by
885:
876:
874:
870:
823:
818:
814:
812:
804:
796:
792:
790:
740:
738:
729:tower clocks
718:
707:
701:
691:
689:
678:
668:
659:
655:
653:
555:
553:
521:
508:
463:
418:quartz clock
415:
374:
358:
352:
344:
308:
295:Robert Hooke
276:
270:
259:
252:
182:
165:
155:
110:
72:that uses a
65:
63:
3229:Oscillators
3160:Time travel
3138:System time
3045:Time domain
3030:Proper time
2854:use of time
2825:Father Time
2805:Immortality
2795:Ages of Man
2724:Endurantism
2681:Regnal year
2661:Big History
2590:water-based
2489:Solar Hijri
2399:Hexadecimal
2349:Measurement
2311:Chronometry
2297:Measurement
1610:. Rice Univ
1403:Steam clock
1303:Banjo clock
1241:lubrication
1160:wheel train
1094:wheel train
1086:escapements
1060:Atmos clock
942:out of beat
819:isochronous
485:gear ratios
481:wheel train
444:(1972) and
422:World War 2
353:During the
348:clockmakers
311:horological
287:isochronous
78:timekeeping
3203:Categories
2862:Chronemics
2837:Kalachakra
2749:Presentism
2734:Eternalism
2640:Chronology
2578:mechanical
2529:Main types
2447:Main types
2190:2009-07-22
2126:2011-04-01
1938:2009-12-29
1905:2009-12-29
1778:2007-05-29
1717:2007-06-06
1672:2007-12-04
1640:2007-11-14
1614:2007-12-03
1589:2007-11-14
1511:0815306156
1419:References
1412:hairspring
1351:Ogee clock
1245:lubricants
1115:remontoire
1072:Escapement
1066:Escapement
1056:mainspring
1033:elasticity
698:escapement
535:Moon phase
503:clock face
492:escapement
477:gear train
470:mainspring
359:regulators
166:Horologium
102:decorative
3219:Pendulums
3118:Leap year
3035:Spacetime
2909:Yesterday
2810:Dreamtime
2784:Mythology
2671:Deep time
2583:stopwatch
2558:hourglass
2539:astrarium
2469:Gregorian
2462:Lunisolar
2439:Calendars
2429:Time zone
2302:standards
2185:205043569
2021:March 18,
1991:March 18,
1686:, 563â579
1185:does not
1134:phototube
835:
763:π
452:Mechanism
395:telegraph
371:longitude
3178:Category
2926:Time in
2917:Tomorrow
2779:Religion
2719:Duration
2686:Timeline
2620:Timeline
2419:Sidereal
2287:Eternity
2177:19148089
1382:See also
1295:(uses a
995:latitude
564:solenoid
548:Repeater
448:(2016).
283:movement
74:pendulum
3188:Commons
3111:Related
3025:Instant
3015:Chronon
2997:Physics
2937:Geology
2928:science
2800:Destiny
2645:History
2613:History
2568:sundial
2551:quantum
2494:Chinese
2484:Islamic
2394:Decimal
2389:Chinese
2351:systems
2277:Present
2157:Bibcode
1583:Stories
1280:antique
1255:Springs
1206:removed
1191:sources
1103:pallets
1052:wedding
1037:elinvar
999:equator
881:mercury
734:Big Ben
714:pallets
696:of the
606:from a
403:Riefler
260:(right)
150:in 1656
119:History
108:value.
106:antique
3209:Clocks
3128:Moment
3123:Memory
2975:period
2563:marine
2546:atomic
2521:Clocks
2479:Hebrew
2474:Julian
2409:Metric
2282:Future
2183:
2175:
2149:Nature
1962:
1831:
1561:
1508:
1439:
1261:Styles
1003:oblate
791:where
721:second
572:switch
495:clock.
446:GdaĆsk
442:Geneva
411:quartz
253:(left)
178:period
3133:Space
2965:epoch
2955:chron
2913:Today
2882:tempo
2877:Music
2739:Event
2573:watch
2457:Lunar
2452:Solar
2424:Solar
2414:Roman
2404:Hindu
2181:S2CID
2145:(PDF)
2011:(PDF)
1932:(DOC)
1808:(PDF)
1797:(PDF)
1666:(PDF)
1659:(PDF)
911:Invar
904:steel
900:brass
685:agate
544:year.
158:Dutch
70:clock
68:is a
2852:and
2815:KÄla
2510:List
2504:Maya
2300:and
2272:Past
2258:Time
2173:PMID
2088:2024
2065:2024
2023:2017
1993:2017
1960:ISBN
1829:ISBN
1559:ISBN
1506:ISBN
1437:ISBN
1189:any
1187:cite
1155:dial
1046:or "
896:zinc
815:rate
399:NIST
104:and
2970:era
2960:eon
2950:age
2329:TAI
2319:UTC
2165:doi
2153:457
1877:doi
1684:458
1549:in
1470:doi
1200:by
948:or
913:or
898:or
832:sin
806:(c)
709:(f)
703:(e)
693:(h)
680:(d)
670:(b)
666:bob
661:(a)
574:or
554:In
490:An
338:by
293:by
3205::
2915:â
2911:â
2324:UT
2179:.
2171:.
2163:.
2151:.
2147:.
2114:.
2040:.
2013:.
1983:.
1923:.
1873:27
1871:.
1867:.
1799:.
1707:22
1705:.
1701:.
1632:.
1606:.
1581:.
1520:^
1486:^
1466:27
1464:.
1460:.
1251:.
736:.
475:A
208:A
201:.
64:A
2250:e
2243:t
2236:v
2193:.
2167::
2159::
2129:.
2090:.
2067:.
2025:.
1995:.
1968:.
1941:.
1908:.
1879::
1837:.
1781:.
1720:.
1681:A
1675:.
1643:.
1617:.
1592:.
1567:.
1514:.
1472::
1445:.
1414:)
1410:(
1299:)
1227:)
1221:(
1216:)
1212:(
1208:.
1194:.
980:g
850:x
847:=
844:)
841:x
838:(
797:g
793:L
772:g
769:L
760:2
757:=
754:T
741:T
528:.
479:(
472:.
20:)
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