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92-524: Giovanni Malerba organised the first competition in 1933 as a reaction to a competition in a neighbouring village which revolved around seven clock towers . The competition has been held every year since its inception, including throughout the Second World War and in 1939 when the Federazione Italiana di Atletica Leggera (FIDAL) ordered that all cross country competitions be postponed. The course

184-463: A church or municipal building such as a town hall . Not all clocks on buildings therefore make the building into a clock tower. The mechanism inside the tower is known as a turret clock . It often marks the hour (and sometimes segments of an hour) by sounding large bells or chimes , sometimes playing simple musical phrases or tunes. Some clock towers were previously built as Bell towers and then had clocks added to them. As these structures fulfil

276-474: A mannequin , every hour. It was possible to re-program the length of day and night daily in order to account for the changing lengths of day and night throughout the year, and it also featured five robotic musicians who automatically play music when moved by levers operated by a hidden camshaft attached to a water wheel . Line (mains) synchronous tower clocks were introduced in the United States in

368-481: A master clock and slave clocks . Where an AC electrical supply of stable frequency is available, timekeeping can be maintained very reliably by using a synchronous motor , essentially counting the cycles. The supply current alternates with an accurate frequency of 50  hertz in many countries, and 60 hertz in others. While the frequency may vary slightly during the day as the load changes, generators are designed to maintain an accurate number of cycles over

460-528: A quartz crystal , or the vibration of electrons in atoms as they emit microwaves , the last of which is so precise that it serves as the definition of the second . Clocks have different ways of displaying the time. Analog clocks indicate time with a traditional clock face and moving hands. Digital clocks display a numeric representation of time. Two numbering systems are in use: 12-hour time notation and 24-hour notation. Most digital clocks use electronic mechanisms and LCD , LED , or VFD displays. For

552-400: A "particularly elaborate example" of a water clock. Pope Sylvester II introduced clocks to northern and western Europe around 1000 AD. The first known geared clock was invented by the great mathematician, physicist, and engineer Archimedes during the 3rd century BC. Archimedes created his astronomical clock, which was also a cuckoo clock with birds singing and moving every hour. It is

644-560: A 'great horloge'. Over the next 30 years, there were mentions of clocks at a number of ecclesiastical institutions in England, Italy, and France. In 1322, a new clock was installed in Norwich , an expensive replacement for an earlier clock installed in 1273. This had a large (2 metre) astronomical dial with automata and bells. The costs of the installation included the full-time employment of two clockkeepers for two years. An elaborate water clock,

736-478: A Scottish clockmaker, patented the electric clock in 1840. The electric clock's mainspring is wound either with an electric motor or with an electromagnet and armature. In 1841, he first patented the electromagnetic pendulum. By the end of the nineteenth century, the advent of the dry cell battery made it feasible to use electric power in clocks. Spring or weight driven clocks that use electricity, either alternating current (AC) or direct current (DC), to rewind

828-522: A chain that turns a gear in the mechanism. Another Greek clock probably constructed at the time of Alexander was in Gaza, as described by Procopius. The Gaza clock was probably a Meteoroskopeion, i.e., a building showing celestial phenomena and the time. It had a pointer for the time and some automations similar to the Archimedes clock. There were 12 doors opening one every hour, with Hercules performing his labors,

920-626: A clock added in 2002, has a roof height of 240 m (790 ft), and an antenna height of 272 m (892 ft). The Abraj Al Bait , a hotel complex in Mecca constructed in 2012, has the largest and highest clock face on a building in the world, with its Makkah Royal Clock Tower having an occupied height of 494.4 m (1,622 ft), and a tip height of 601 m (1,972 ft). The tower has four clock faces, two of which are 43 m (141 ft) in diameter, at about 400 m (1,300 ft) high. Clock A clock or chronometer

1012-753: A clock was put up in a clock tower, the medieval precursor to Big Ben , at Westminster , in 1288; and in 1292 a clock was put up in Canterbury Cathedral . The oldest surviving turret clock formerly part of a clock tower in Europe is the Salisbury Cathedral clock , completed in 130. A clock put up at St. Albans , in 1326, 'showed various astronomical phenomena'. Al-Jazari of the Artuqid dynasty in Upper Mesopotamia constructed an elaborate clock called

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1104-591: A common sight in many parts of the world with some being iconic buildings. One example is the Elizabeth Tower in London (usually called " Big Ben ", although strictly this name belongs only to the bell inside the tower). There are many structures that may have clocks or clock faces attached to them and some structures have had clocks added to an existing structure. According to the Council on Tall Buildings and Urban Habitat

1196-401: A day, so the clock may be a fraction of a second slow or fast at any time, but will be perfectly accurate over a long time. The rotor of the motor rotates at a speed that is related to the alternation frequency. Appropriate gearing converts this rotation speed to the correct ones for the hands of the analog clock. Time in these cases is measured in several ways, such as by counting the cycles of

1288-400: A few seconds over trillions of years. Atomic clocks were first theorized by Lord Kelvin in 1879. In the 1930s the development of magnetic resonance created practical method for doing this. A prototype ammonia maser device was built in 1949 at the U.S. National Bureau of Standards (NBS, now NIST ). Although it was less accurate than existing quartz clocks , it served to demonstrate

1380-416: A fire at the abbey of St Edmundsbury (now Bury St Edmunds ), the monks "ran to the clock" to fetch water, indicating that their water clock had a reservoir large enough to help extinguish the occasional fire. The word clock (via Medieval Latin clocca from Old Irish clocc , both meaning 'bell'), which gradually supersedes "horologe", suggests that it was the sound of bells that also characterized

1472-493: A kind of early clocktower . The Greek and Roman civilizations advanced water clock design with improved accuracy. These advances were passed on through Byzantine and Islamic times, eventually making their way back to Europe. Independently, the Chinese developed their own advanced water clocks ( 水鐘 ) by 725 AD, passing their ideas on to Korea and Japan. Some water clock designs were developed independently, and some knowledge

1564-401: A large astrolabe-type dial, showing the sun, the moon's age, phase, and node, a star map, and possibly the planets. In addition, it had a wheel of fortune and an indicator of the state of the tide at London Bridge . Bells rang every hour, the number of strokes indicating the time. Dondi's clock was a seven-sided construction, 1 metre high, with dials showing the time of day, including minutes,

1656-403: A more accurate clock: This has the dual function of keeping the oscillator running by giving it 'pushes' to replace the energy lost to friction , and converting its vibrations into a series of pulses that serve to measure the time. In mechanical clocks, the low Q of the balance wheel or pendulum oscillator made them very sensitive to the disturbing effect of the impulses of the escapement, so

1748-573: A new problem: how to keep the clock movement running at a constant rate as the spring ran down. This resulted in the invention of the stackfreed and the fusee in the 15th century, and many other innovations, down to the invention of the modern going barrel in 1760. Early clock dials did not indicate minutes and seconds. A clock with a dial indicating minutes was illustrated in a 1475 manuscript by Paulus Almanus, and some 15th-century clocks in Germany indicated minutes and seconds. An early record of

1840-542: A pendulum, which would be virtually useless on a rocking ship. In 1714, the British government offered large financial rewards to the value of 20,000 pounds for anyone who could determine longitude accurately. John Harrison , who dedicated his life to improving the accuracy of his clocks, later received considerable sums under the Longitude Act. In 1735, Harrison built his first chronometer, which he steadily improved on over

1932-488: A precisely constant frequency. The advantage of a harmonic oscillator over other forms of oscillator is that it employs resonance to vibrate at a precise natural resonant frequency or "beat" dependent only on its physical characteristics, and resists vibrating at other rates. The possible precision achievable by a harmonic oscillator is measured by a parameter called its Q , or quality factor, which increases (other things being equal) with its resonant frequency. This

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2024-507: A seconds hand on a clock dates back to about 1560 on a clock now in the Fremersdorf collection. During the 15th and 16th centuries, clockmaking flourished, particularly in the metalworking towns of Nuremberg and Augsburg , and in Blois , France. Some of the more basic table clocks have only one time-keeping hand, with the dial between the hour markers being divided into four equal parts making

2116-464: A seven-sided brass or iron framework resting on 7 decorative paw-shaped feet. The lower section provided a 24-hour dial and a large calendar drum, showing the fixed feasts of the church, the movable feasts, and the position in the zodiac of the moon's ascending node. The upper section contained 7 dials, each about 30 cm in diameter, showing the positional data for the Primum Mobile , Venus, Mercury,

2208-418: A structure is defined as a building if at least fifty percent of its height is made up of floor plates containing habitable floor area. Structures that do not meet this criterion, are defined as towers . A clock tower historically fits this definition of a tower and therefore can be defined as any tower specifically built with one or more (often four) clock faces and that can be either freestanding or part of

2300-574: A sundial. While never reaching the level of accuracy of a modern timepiece, the water clock was the most accurate and commonly used timekeeping device for millennia until it was replaced by the more accurate pendulum clock in 17th-century Europe. Islamic civilization is credited with further advancing the accuracy of clocks through elaborate engineering. In 797 (or possibly 801), the Abbasid caliph of Baghdad , Harun al-Rashid , presented Charlemagne with an Asian elephant named Abul-Abbas together with

2392-626: A way of mass-producing clocks by using interchangeable parts . Aaron Lufkin Dennison started a factory in 1851 in Massachusetts that also used interchangeable parts, and by 1861 was running a successful enterprise incorporated as the Waltham Watch Company . In 1815, the English scientist Francis Ronalds published the first electric clock powered by dry pile batteries. Alexander Bain ,

2484-421: A working model of the solar system. Simple clocks intended mainly for notification were installed in towers and did not always require faces or hands. They would have announced the canonical hours or intervals between set times of prayer. Canonical hours varied in length as the times of sunrise and sunset shifted. The more sophisticated astronomical clocks would have had moving dials or hands and would have shown

2576-436: Is a device that measures and displays time . The clock is one of the oldest human inventions , meeting the need to measure intervals of time shorter than the natural units such as the day , the lunar month , and the year . Devices operating on several physical processes have been used over the millennia . Some predecessors to the modern clock may be considered "clocks" that are based on movement in nature: A sundial shows

2668-570: Is also derived from the Middle English clokke , Old North French cloque , or Middle Dutch clocke , all of which mean 'bell'. The apparent position of the Sun in the sky changes over the course of each day, reflecting the rotation of the Earth. Shadows cast by stationary objects move correspondingly, so their positions can be used to indicate the time of day. A sundial shows the time by displaying

2760-431: Is considered to be the world's oldest surviving mechanical clock that strikes the hours. Clockmakers developed their art in various ways. Building smaller clocks was a technical challenge, as was improving accuracy and reliability. Clocks could be impressive showpieces to demonstrate skilled craftsmanship, or less expensive, mass-produced items for domestic use. The escapement in particular was an important factor affecting

2852-459: Is why there has been a long-term trend toward higher frequency oscillators in clocks. Balance wheels and pendulums always include a means of adjusting the rate of the timepiece. Quartz timepieces sometimes include a rate screw that adjusts a capacitor for that purpose. Atomic clocks are primary standards , and their rate cannot be adjusted. Some clocks rely for their accuracy on an external oscillator; that is, they are automatically synchronized to

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2944-548: The Artuqid king of Diyar-Bakr, Nasir al-Din , made numerous clocks of all shapes and sizes. The most reputed clocks included the elephant , scribe, and castle clocks , some of which have been successfully reconstructed. As well as telling the time, these grand clocks were symbols of the status, grandeur, and wealth of the Urtuq State. Knowledge of these mercury escapements may have spread through Europe with translations of Arabic and Spanish texts. The word horologia (from

3036-797: The Parliament of Canada in Ottawa , and the Zytglogge clock tower in the Old City of Bern , Switzerland . The tallest freestanding clock tower in the world is the Joseph Chamberlain Memorial Clock Tower (Old Joe) at the University of Birmingham in Birmingham , United Kingdom. The tower stands at 100 metres (330 feet) tall and was completed in 1908. The clock tower of Philadelphia City Hall

3128-494: The Republic of China (Taiwan)'s National Museum of Natural Science , Taichung city. This full-scale, fully functional replica, approximately 12 meters (39 feet) in height, was constructed from Su Song's original descriptions and mechanical drawings. The Chinese escapement spread west and was the source for Western escapement technology. In the 12th century, Al-Jazari , an engineer from Mesopotamia (lived 1136–1206) who worked for

3220-419: The anchor escapement , an improvement over Huygens' crown escapement. Clement also introduced the pendulum suspension spring in 1671. The concentric minute hand was added to the clock by Daniel Quare , a London clockmaker and others, and the second hand was first introduced. In 1675, Huygens and Robert Hooke invented the spiral balance spring , or the hairspring, designed to control the oscillating speed of

3312-415: The balance wheel . This crucial advance finally made accurate pocket watches possible. The great English clockmaker Thomas Tompion , was one of the first to use this mechanism successfully in his pocket watches , and he adopted the minute hand which, after a variety of designs were trialled, eventually stabilised into the modern-day configuration. The rack and snail striking mechanism for striking clocks ,

3404-437: The "castle clock" and described it in his Book of Knowledge of Ingenious Mechanical Devices in 1206. It was about 3.3 metres (11 feet) high, and had multiple functions alongside timekeeping . It included a display of the zodiac and the solar and lunar paths, and a pointer in the shape of the crescent moon that travelled across the top of a gateway , moved by a hidden cart and causing automatic doors to open, each revealing

3496-511: The "constant-level tank". The main driving shaft of iron, with its cylindrical necks supported on iron crescent-shaped bearings, ended in a pinion, which engaged a gear wheel at the lower end of the main vertical transmission shaft. This great astronomical hydromechanical clock tower was about ten metres high (about 30 feet), featured a clock escapement , and was indirectly powered by a rotating wheel either with falling water or liquid mercury . A full-sized working replica of Su Song's clock exists in

3588-455: The 'Cosmic Engine', was invented by Su Song , a Chinese polymath , designed and constructed in China in 1092. This great astronomical hydromechanical clock tower was about ten metres high (about 30 feet) and was indirectly powered by a rotating wheel with falling water and liquid mercury , which turned an armillary sphere capable of calculating complex astronomical problems. In Europe, there were

3680-503: The 17th and 18th centuries, but maintained a system of production that was geared towards high quality products for the elite. Although there was an attempt to modernise clock manufacture with mass-production techniques and the application of duplicating tools and machinery by the British Watch Company in 1843, it was in the United States that this system took off. In 1816, Eli Terry and some other Connecticut clockmakers developed

3772-400: The 1830s, when the use of the telegraph and trains standardized time and time zones between cities. Many devices can be used to mark the passage of time without respect to reference time (time of day, hours, minutes, etc.) and can be useful for measuring duration or intervals. Examples of such duration timers are candle clocks , incense clocks , and the hourglass . Both the candle clock and

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3864-931: The 1920s. Some clock towers have become famous landmarks. Prominent examples include Elizabeth Tower built in 1859, which houses the Great Bell (generally known as Big Ben ) in London , the tower of Philadelphia City Hall , the Rajabai Tower in Mumbai , the Spasskaya Tower of the Moscow Kremlin , the Torre dell'Orologio in the Piazza San Marco in Venice , Italy , the Peace Tower of

3956-473: The AC supply, vibration of a tuning fork , the behaviour of quartz crystals, or the quantum vibrations of atoms. Electronic circuits divide these high-frequency oscillations to slower ones that drive the time display. The piezoelectric properties of crystalline quartz were discovered by Jacques and Pierre Curie in 1880. The first crystal oscillator was invented in 1917 by Alexander M. Nicholson , after which

4048-516: The Greek ὥρα —'hour', and λέγειν —'to tell') was used to describe early mechanical clocks, but the use of this word (still used in several Romance languages ) for all timekeepers conceals the true nature of the mechanisms. For example, there is a record that in 1176, Sens Cathedral in France installed an ' horologe ', but the mechanism used is unknown. According to Jocelyn de Brakelond , in 1198, during

4140-533: The Lion at one o'clock, etc., and at night a lamp becomes visible every hour, with 12 windows opening to show the time. The Tang dynasty Buddhist monk Yi Xing along with government official Liang Lingzan made the escapement in 723 (or 725) to the workings of a water-powered armillary sphere and clock drive , which was the world's first clockwork escapement. The Song dynasty polymath and genius Su Song (1020–1101) incorporated it into his monumental innovation of

4232-426: The astronomical clock tower of Kaifeng in 1088. His astronomical clock and rotating armillary sphere still relied on the use of either flowing water during the spring, summer, and autumn seasons or liquid mercury during the freezing temperatures of winter (i.e., hydraulics ). In Su Song's waterwheel linkwork device, the action of the escapement's arrest and release was achieved by gravity exerted periodically as

4324-558: The blind and for use over telephones, speaking clocks state the time audibly in words. There are also clocks for the blind that have displays that can be read by touch. The word clock derives from the medieval Latin word for 'bell'— clocca —and has cognates in many European languages. Clocks spread to England from the Low Countries , so the English word came from the Middle Low German and Middle Dutch Klocke . The word

4416-565: The clock's accuracy, so many different mechanisms were tried. Spring-driven clocks appeared during the 15th century, although they are often erroneously credited to Nuremberg watchmaker Peter Henlein (or Henle, or Hele) around 1511. The earliest existing spring driven clock is the chamber clock given to Phillip the Good, Duke of Burgundy, around 1430, now in the Germanisches Nationalmuseum . Spring power presented clockmakers with

4508-539: The clocks constructed by Richard of Wallingford in Albans by 1336, and by Giovanni de Dondi in Padua from 1348 to 1364. They no longer exist, but detailed descriptions of their design and construction survive, and modern reproductions have been made. They illustrate how quickly the theory of the mechanical clock had been translated into practical constructions, and also that one of the many impulses to their development had been

4600-565: The clocks readable to the nearest 15 minutes. Other clocks were exhibitions of craftsmanship and skill, incorporating astronomical indicators and musical movements. The cross-beat escapement was invented in 1584 by Jost Bürgi , who also developed the remontoire . Bürgi's clocks were a great improvement in accuracy as they were correct to within a minute a day. These clocks helped the 16th-century astronomer Tycho Brahe to observe astronomical events with much greater precision than before. The next development in accuracy occurred after 1656 with

4692-559: The competition's longevity is due to, in part, the support the race receives from the local community. The race was elected to serve as the Italian national cross country championships in 1996; Gennaro Di Napoli and Patrizia Di Napoli took the honours. The event hosted the European Cross Country Club Championships alongside the traditional race in 2011; Portuguese club Grupo Desportivo e Recreativo Conforlimpa won

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4784-622: The concept. The first accurate atomic clock, a caesium standard based on a certain transition of the caesium-133 atom, was built by Louis Essen in 1955 at the National Physical Laboratory in the UK. Calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale ephemeris time (ET). As of 2013, the most stable atomic clocks are ytterbium clocks, which are stable to within less than two parts in 1 quintillion ( 2 × 10 ). The invention of

4876-469: The continuous flow of liquid-filled containers of a limited size. In a single line of evolution, Su Song's clock therefore united the concepts of the clepsydra and the mechanical clock into one device run by mechanics and hydraulics. In his memorial, Su Song wrote about this concept: According to your servant's opinion there have been many systems and designs for astronomical instruments during past dynasties all differing from one another in minor respects. But

4968-416: The definition of a tower they can be considered to be clock towers. Although clock towers are today mostly admired for their aesthetics, they once served an important purpose. Before the middle of the twentieth century, most people did not have watches, and prior to the 18th century even home clocks were rare. The first clocks did not have faces, but were solely striking clocks , which sounded bells to call

5060-471: The desire of astronomers to investigate celestial phenomena. The Astrarium of Giovanni Dondi dell'Orologio was a complex astronomical clock built between 1348 and 1364 in Padua , Italy, by the doctor and clock-maker Giovanni Dondi dell'Orologio . The Astrarium had seven faces and 107 moving gears; it showed the positions of the sun, the moon and the five planets then known, as well as religious feast days. The astrarium stood about 1 metre high, and consisted of

5152-399: The earlier armillary sphere created by Zhang Sixun (976 AD), who also employed the escapement mechanism and used liquid mercury instead of water in the waterwheel of his astronomical clock tower. The mechanical clockworks for Su Song's astronomical tower featured a great driving-wheel that was 11 feet in diameter, carrying 36 scoops, into each of which water was poured at a uniform rate from

5244-551: The earliest dates are less certain. Some authors, however, write about water clocks appearing as early as 4000 BC in these regions of the world. The Macedonian astronomer Andronicus of Cyrrhus supervised the construction of the Tower of the Winds in Athens in the 1st century BC, which housed a large clepsydra inside as well as multiple prominent sundials outside, allowing it to function as

5336-472: The energy it loses to friction , and converts its oscillations into a series of pulses. The pulses are then counted by some type of counter , and the number of counts is converted into convenient units, usually seconds, minutes, hours, etc. Finally some kind of indicator displays the result in human readable form. The timekeeping element in every modern clock is a harmonic oscillator , a physical object ( resonator ) that vibrates or oscillates repetitively at

5428-421: The escapement had a great effect on the accuracy of the clock, and many escapement designs were tried. The higher Q of resonators in electronic clocks makes them relatively insensitive to the disturbing effects of the drive power, so the driving oscillator circuit is a much less critical component. This counts the pulses and adds them up to get traditional time units of seconds, minutes, hours, etc. It usually has

5520-459: The first carillon clock as it plays music simultaneously with a person blinking his eyes, surprised by the singing birds. The Archimedes clock works with a system of four weights, counterweights, and strings regulated by a system of floats in a water container with siphons that regulate the automatic continuation of the clock. The principles of this type of clock are described by the mathematician and physicist Hero, who says that some of them work with

5612-543: The first quartz crystal oscillator was built by Walter G. Cady in 1921. In 1927 the first quartz clock was built by Warren Marrison and J.W. Horton at Bell Telephone Laboratories in Canada. The following decades saw the development of quartz clocks as precision time measurement devices in laboratory settings—the bulky and delicate counting electronics, built with vacuum tubes at the time, limited their practical use elsewhere. The National Bureau of Standards (now NIST ) based

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5704-404: The incense clock work on the same principle, wherein the consumption of resources is more or less constant, allowing reasonably precise and repeatable estimates of time passages. In the hourglass, fine sand pouring through a tiny hole at a constant rate indicates an arbitrary, predetermined passage of time. The resource is not consumed, but re-used. Water clocks, along with sundials, are possibly

5796-402: The invention of the pendulum clock by Christiaan Huygens . A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The mechanism of a timepiece with a series of gears driven by a spring or weights is referred to as clockwork ; the term is used by extension for a similar mechanism not used in a timepiece. The electric clock

5888-441: The invention of the pendulum clock . Galileo had the idea to use a swinging bob to regulate the motion of a time-telling device earlier in the 17th century. Christiaan Huygens , however, is usually credited as the inventor. He determined the mathematical formula that related pendulum length to time (about 99.4 cm or 39.1 inches for the one second movement) and had the first pendulum-driven clock made. The first model clock

5980-404: The mechanical clock in the 13th century initiated a change in timekeeping methods from continuous processes, such as the motion of the gnomon 's shadow on a sundial or the flow of liquid in a water clock, to periodic oscillatory processes, such as the swing of a pendulum or the vibration of a quartz crystal , which had the potential for more accuracy. All modern clocks use oscillation. Although

6072-422: The mechanisms they use vary, all oscillating clocks, mechanical, electric, and atomic, work similarly and can be divided into analogous parts. They consist of an object that repeats the same motion over and over again, an oscillator , with a precisely constant time interval between each repetition, or 'beat'. Attached to the oscillator is a controller device, which sustains the oscillator's motion by replacing

6164-513: The men's team title while the women's title went to Turkey's Üsküdar Belediyesi Spor Kulübü. Clock towers Clock towers are a specific type of structure that house a turret clock and have one or more clock faces on the upper exterior walls. Many clock towers are freestanding structures but they can also adjoin or be located on top of another building. Some other buildings also have clock faces on their exterior but these structures serve other main functions. Clock towers are

6256-456: The moon, Saturn, Jupiter, and Mars. Directly above the 24-hour dial is the dial of the Primum Mobile , so called because it reproduces the diurnal motion of the stars and the annual motion of the sun against the background of stars. Each of the 'planetary' dials used complex clockwork to produce reasonably accurate models of the planets' motion. These agreed reasonably well both with Ptolemaic theory and with observations. Wallingford's clock had

6348-497: The motions of all the known planets, an automatic calendar of fixed and movable feasts , and an eclipse prediction hand rotating once every 18 years. It is not known how accurate or reliable these clocks would have been. They were probably adjusted manually every day to compensate for errors caused by wear and imprecise manufacture. Water clocks are sometimes still used today, and can be examined in places such as ancient castles and museums. The Salisbury Cathedral clock , built in 1386,

6440-482: The next thirty years before submitting it for examination. The clock had many innovations, including the use of bearings to reduce friction, weighted balances to compensate for the ship's pitch and roll in the sea and the use of two different metals to reduce the problem of expansion from heat. The chronometer was tested in 1761 by Harrison's son and by the end of 10 weeks the clock was in error by less than 5 seconds. The British had dominated watch manufacture for much of

6532-496: The oldest time-measuring instruments, with the only exception being the day-counting tally stick . Given their great antiquity, where and when they first existed is not known and is perhaps unknowable. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and Egypt around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but

6624-421: The position of a shadow on a (usually) flat surface that has markings that correspond to the hours. Sundials can be horizontal, vertical, or in other orientations. Sundials were widely used in ancient times . With knowledge of latitude, a well-constructed sundial can measure local solar time with reasonable accuracy, within a minute or two. Sundials continued to be used to monitor the performance of clocks until

6716-420: The principle of the use of water-power for the driving mechanism has always been the same. The heavens move without ceasing but so also does water flow (and fall). Thus if the water is made to pour with perfect evenness, then the comparison of the rotary movements (of the heavens and the machine) will show no discrepancy or contradiction; for the unresting follows the unceasing. Song was also strongly influenced by

6808-418: The prototype mechanical clocks that appeared during the 13th century in Europe. In Europe, between 1280 and 1320, there was an increase in the number of references to clocks and horologes in church records, and this probably indicates that a new type of clock mechanism had been devised. Existing clock mechanisms that used water power were being adapted to take their driving power from falling weights. This power

6900-408: The race to new heights, taking three victories over five editions. A junior race was introduced in 1960, the first international women's race was held in 1971, and student races were added to the program in the late 1970s. Olympic and World champions graced the course at every edition in the 1970s. By the mid-eighties, East African runners had established themselves, frequently reaching the podium in

6992-542: The senior races. It was part of the IAAF World Cross Challenge the following decade, remaining at the forefront of European cross country running. The course was significantly changed throughout the 2000s, only the Cozzi and Meraviglia mills remained as part of the course and gradually only the semi-functioning Meraviglia was included. Both former champion David Bedford and meet organiser Vito Garofalo stressed that

7084-476: The spring or raise the weight of a mechanical clock would be classified as an electromechanical clock . This classification would also apply to clocks that employ an electrical impulse to propel the pendulum. In electromechanical clocks the electricity serves no time keeping function. These types of clocks were made as individual timepieces but more commonly used in synchronized time installations in schools, businesses, factories, railroads and government facilities as

7176-477: The surrounding community to work or to prayer. They were therefore placed in towers so the bells would be audible for a long distance. Clock towers were placed near the centres of towns and were often the tallest structures there. As clock towers became more common, the designers realized that a dial on the outside of the tower would allow the townspeople to read the time whenever they wanted. The use of clock towers dates back to antiquity . The earliest clock tower

7268-460: The term clock was used for a striking clock , while a clock that did not strike the hours audibly was called a timepiece . This distinction is not generally made any longer. Watches and other timepieces that can be carried on one's person are usually not referred to as clocks. Spring-driven clocks appeared during the 15th century. During the 15th and 16th centuries, clockmaking flourished. The next development in accuracy occurred after 1656 with

7360-509: The time by displaying the position of a shadow on a flat surface. There is a range of duration timers, a well-known example being the hourglass . Water clocks , along with sundials, are possibly the oldest time-measuring instruments. A major advance occurred with the invention of the verge escapement , which made possible the first mechanical clocks around 1300 in Europe, which kept time with oscillating timekeepers like balance wheels . Traditionally, in horology (the study of timekeeping),

7452-482: The time in various time systems, including Italian hours , canonical hours, and time as measured by astronomers at the time. Both styles of clocks started acquiring extravagant features, such as automata . In 1283, a large clock was installed at Dunstable Priory in Bedfordshire in southern England; its location above the rood screen suggests that it was not a water clock. In 1292, Canterbury Cathedral installed

7544-536: The time standard of the United States on quartz clocks from late 1929 until the 1960s, when it changed to atomic clocks. In 1969, Seiko produced the world's first quartz wristwatch , the Astron . Their inherent accuracy and low cost of production resulted in the subsequent proliferation of quartz clocks and watches. Currently, atomic clocks are the most accurate clocks in existence. They are considerably more accurate than quartz clocks as they can be accurate to within

7636-427: The timing of services and public events) and for modeling the solar system. The former purpose is administrative; the latter arises naturally given the scholarly interests in astronomy, science, and astrology and how these subjects integrated with the religious philosophy of the time. The astrolabe was used both by astronomers and astrologers, and it was natural to apply a clockwork drive to the rotating plate to produce

7728-500: Was altered from 10 km to 12 in the late 1930s, in order to accommodate all five mills. The race began to grow after being selected as the course for the Italian Cross Country Championship in 1946 and 1949. The competition became an international one in 1952 and Tunisian runner Ahmed Labidi became the first foreign winner two years later. By the early 1960s, Olympic silver medallist Franjo Mihalić had brought

7820-466: Was built in 1657 in the Hague , but it was in England that the idea was taken up. The longcase clock (also known as the grandfather clock ) was created to house the pendulum and works by the English clockmaker William Clement in 1670 or 1671. It was also at this time that clock cases began to be made of wood and clock faces to use enamel as well as hand-painted ceramics. In 1670, William Clement created

7912-554: Was controlled by some form of oscillating mechanism, probably derived from existing bell-ringing or alarm devices. This controlled release of power – the escapement – marks the beginning of the true mechanical clock, which differed from the previously mentioned cogwheel clocks. The verge escapement mechanism appeared during the surge of true mechanical clock development, which did not need any kind of fluid power, like water or mercury, to work. These mechanical clocks were intended for two main purposes: for signalling and notification (e.g.,

8004-414: Was introduced during the 17th century and had distinct advantages over the 'countwheel' (or 'locking plate') mechanism. During the 20th century there was a common misconception that Edward Barlow invented rack and snail striking. In fact, his invention was connected with a repeating mechanism employing the rack and snail. The repeating clock , that chimes the number of hours (or even minutes) on demand

8096-446: Was invented by either Quare or Barlow in 1676. George Graham invented the deadbeat escapement for clocks in 1720. A major stimulus to improving the accuracy and reliability of clocks was the importance of precise time-keeping for navigation. The position of a ship at sea could be determined with reasonable accuracy if a navigator could refer to a clock that lost or gained less than about 10 seconds per day. This clock could not contain

8188-608: Was part of the tallest building in the world from 1894, when the tower was topped out and the building partially occupied, until 1908. Taller buildings have had clock faces added to their existing structure such as the Palace of Culture and Science in Warsaw , with a clock added in 2000. The building has a roof height of 187.68 m (615.7 ft), and an antenna height of 237 m (778 ft). The NTT Docomo Yoyogi Building in Tokyo , with

8280-404: Was patented in 1840, and electronic clocks were introduced in the 20th century, becoming widespread with the development of small battery-powered semiconductor devices . The timekeeping element in every modern clock is a harmonic oscillator , a physical object ( resonator ) that vibrates or oscillates at a particular frequency. This object can be a pendulum , a balance wheel , a tuning fork ,

8372-489: Was the Tower of the Winds in Athens , which featured eight sundials and was created in the 1st century BC during the period of Roman Greece . In its interior, there was also a water clock (or clepsydra), driven by water coming down from the Acropolis . In Song dynasty China , an astronomical clock tower was designed by Su Song and erected at Kaifeng in 1088, featuring a liquid escapement mechanism. In England,

8464-420: Was transferred through the spread of trade. Pre-modern societies do not have the same precise timekeeping requirements that exist in modern industrial societies, where every hour of work or rest is monitored and work may start or finish at any time regardless of external conditions. Instead, water clocks in ancient societies were used mainly for astrological reasons. These early water clocks were calibrated with

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