The term is loosely used to refer to any clock that shows, in addition to the time of day, astronomical information. This could include the location of the Sun and Moon in the sky, the age and Lunar phases, the position of the Sun on the ecliptic and the current zodiac sign, the sidereal time, and other astronomical data such as the Moon's nodes for indicating eclipses), or a rotating star map. The term should not be confused with an astronomical regulator, a high precision but otherwise ordinary pendulum clock used in observatories.
Astronomical clocks usually represent the Solar System using the geocentric model. The center of the dial is often marked with a disc or sphere representing the Earth, located at the center of the Solar System. The Sun is often represented by a golden sphere (as it initially appeared in the Antikythera mechanism, back in the 2nd century BC), shown rotating around the Earth once a day around a 24-hour analog dial. This view accorded both with the daily experience and with the philosophical world view of pre-Copernican Europe.
The courtier and bibliophile Louis de Gruuthuse in front of an astronomical clock. Henri Suso, Horloge de Sapience, 1470-1480
The Antikythera mechanism is the oldest known analog computer and a precursor to astronomical clocks. A complex arrangement of multiple gears and gear trains could perform functions such as determining the position of the sun, moon and planets, predict eclipses and other astronomical phenomena and tracking the dates of Olympic Games.[1] Research in 2011 and 2012 led an expert group of researchers to posit that European astronomical clocks are descended from the technology of the Antikythera mechanism.[2]
The early development of mechanical clocks in Europe is not fully understood, but there is general agreement that by 1300–1330 there existed mechanical clocks (powered by weights rather than by water and using an escapement) which were intended for two main purposes: for signalling and notification (e.g. the timing of services and public events), and for modelling the solar system. The latter is an inevitable development because the astrolabe was used both by astronomers and astrologers, and it was natural to apply a clockwork drive to the rotating plate to produce a working model of the solar system. American historian Lynn White Jr. of Princeton University wrote:[8]
Most of the first clocks were not so many chronometers as exhibitions of the pattern of the cosmos … Clearly, the origins of the mechanical clock lie in a complex realm of monumental planetaria, equatoria, and astrolabes.
The astronomical clocks developed by the English mathematician and cleric Richard of Wallingford in St Albans during the 1330s,[9] and by medieval Italian physician and astronomer Giovanni Dondi dell'Orologio in Padua between 1348 and 1364[10] are masterpieces of their type. They no longer exist, but detailed descriptions of their design and construction survive, and modern reproductions have been made. Wallingford's clock may have shown the sun, moon (age, phase, and node), stars and planets, and had, in addition, a wheel of fortune and an indicator of the state of the tide at London Bridge. De Dondi's clock was a seven-faced construction with 107 moving parts, showing the positions of the sun, moon, and five planets, as well as religious feast days.[10]
Both these clocks, and others like them, were probably less accurate than their designers would have wished. The gear ratios may have been exquisitely calculated, but their manufacture was somewhat beyond the mechanical abilities of the time, and they never worked reliably. Furthermore, in contrast to the intricate advanced wheelwork, the timekeeping mechanism in nearly all these clocks until the 16th century was the simple verge and foliot escapement, which had errors of at least half an hour a day.[11][12]
Astronomical clocks were built as demonstration or exhibition pieces, to impress as much as to educate or inform. The challenge of building these masterpieces meant that clockmakers would continue to produce them, to demonstrate their technical skill and their patrons' wealth. The philosophical message of an ordered, heavenly-ordained universe, which accorded with the Gothic-era view of the world, helps explain their popularity.
The growing interest in astronomy during the 18th century revived interest in astronomical clocks, less for the philosophical message, more for the accurate astronomical information that pendulum-regulated clocks could display.
Generic description
Although each astronomical clock is different, they share some common features.[13]
Time of day
How the 24-hour analog dial might be interpreted.Diagram showing how the zodiac is projected on to the ecliptic dial – the symbols are often drawn inside the dial.Stereographic projection from the North Pole.
Most astronomical clocks have a 24-hour analog dial around the outside edge, numbered from I to XII then from I to XII again. The current time is indicated by a golden ball or a picture of the sun at the end of a pointer. Local noon is usually at the top of the dial, and midnight at the bottom. Minute hands are rarely used.
The Sun indicator or hand gives an approximate indication of both the Sun's azimuth and altitude. For azimuth (bearing from the north), the top of the dial indicates South, and the two VI points of the dial East and West. For altitude, the top is the zenith and the two VI and VI points define the horizon. (This is for the astronomical clocks designed for use in the northern hemisphere.) This interpretation is most accurate at the equinoxes, of course.
If XII is not at the top of the dial, or if the numbers are Arabic rather than Roman, then the time may be shown in Italian hours (also called Bohemian, or Old Czech, hours). In this system, 1 o'clock occurs at sunset, and counting continues through the night and into the next afternoon, reaching 24 an hour before sunset.
In the photograph of the Prague clock shown at the top of the article, the time indicated by the Sun hand is about 9am (IX in Roman numerals), or about the 13th hour (Italian time in Arabic numerals).
Calendar and zodiac
The year is usually represented by the 12 signs of the zodiac, arranged either as a concentric circle inside the 24-hour dial, or drawn onto a displaced smaller circle, which is a projection of the ecliptic, the path of the Sun and planets through the sky, and the plane of the Earth's orbit.
The ecliptic plane is projected onto the face of the clock, and, because of the Earth's tilted angle of rotation relative to its orbital plane, it is displaced from the center and appears to be distorted. The projection point for the stereographic projection is the North pole; on astrolabes the South pole is more common.
The ecliptic dial makes one complete revolution in 23 hours 56 minutes (a sidereal day), and will therefore gradually get out of phase with the hour hand, drifting slowly further apart during the year.
To find the date, find the place where the hour hand or Sun disk intersects the ecliptic dial: this indicates the current star sign, the sun's current location on the ecliptic. The intersection point slowly moves around the ecliptic dial during the year, as the Sun moves out of one astrological sign into another.
In the diagram showing the clock face on the right, the Sun's disk has recently moved into Aries (the stylized ram's horns), having left Pisces. The date is therefore late March or early April.
If the zodiac signs run around inside the hour hands, either this ring rotates to align itself with the hour hand, or there's another hand, revolving once per year, which points to the Sun's current zodiac sign.
Moon
A dial or ring indicating the numbers 1 to 29 or 30 indicates the moon's age: a new moon is 0, waxes become full around day 15, and then wanes up to 29 or 30. The phase is sometimes shown by a rotating globe or black hemisphere, or a window that reveals part of a wavy black shape beneath.
Hour lines
Unequal hours were the result of dividing up the period of daylight into 12 equal hours and nighttime into another 12. There is more daylight in the summer, and less night time, so each of the 12 daylight hours is longer than a night hour. Similarly in winter, daylight hours are shorter, and night hours are longer. These unequal hours are shown by the curved lines radiating from the center. The longer daylight hours in summer can usually be seen at the outer edge of the dial, and the time in unequal hours is read by noting the intersection of the sun hand with the appropriate curved line.
Aspects
Astrologers placed importance on how the Sun, Moon, and planets were arranged and aligned in the sky. If certain planets appeared at the points of a triangle, hexagon, or square, or if they were opposite or next to each other, the appropriate aspect was used to determine the event's significance. On some clocks you can see the common aspects – triangle, square, and hexagon – drawn inside the central disc, with each line marked by the symbol for that aspect, and you may also see the signs for conjunction and opposition. On an astrolabe, the corners of the different aspects could be lined up on any of the planets. On a clock, though, the disc containing the aspect lines can't be rotated at will, so they usually show only the aspects of the Sun or Moon.
On the Torre dell'Orologio, Brescia clock in northern Italy, the triangle, square, and star in the centre of the dial show these aspects (the third, fourth, and sixth phases) of (presumably) the moon.
"Dragon" hand: eclipse prediction and lunar nodes
The Moon's orbit is not in the same plane as the Earth's orbit around the Sun but crosses it in two places. The Moon crosses the ecliptic plane twice a month, once when it goes up above the plane, and again 15 or so days later when it goes back down below the ecliptic. These two locations are the ascending and descending lunar nodes. Solar and lunar eclipses will occur only when the Moon is positioned near one of these nodes because at other times the Moon is either too high or too low for an eclipse to be seen on the Earth.
Some astronomical clocks keep track of the position of the lunar nodes with a long pointer that crosses the dial, with its length extended out to both sides of the dial to pointing at two opposite points on the solar or lunar dial. This so-called "dragon" hand makes one complete rotation around the ecliptic dial every 19years. It is sometimes decorated with the figure of a serpent or lizard (Greek: drakon) with its snout and tail-tip touching the outer dial, traditionally labelled Latin: "caput draconam" and Latin: "cauda draconam" even if the decorative dragon is omitted (not to be confused with the similar-seeming names of the two sections of the constellation Serpens).
During the two yearly eclipse seasons the Sun pointer coincides with either the dragon's snout or tail. When the dragon hand and the full Moon coincide, the Moon is on the same plane as the Earth and Sun, and so there is a good chance that a lunar eclipse will be visible on one side of the Earth. When the new Moon is aligned with the dragon hand there is a moderate possibility that a solar eclipse might be visible somewhere on the Earth.
Historical examples
Su Song's Cosmic Engine
The Science Museum (London) has a scale model of the 'Cosmic Engine', which 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 featured a clock escapement and was indirectly powered by a rotating wheel either with falling water and liquid mercury, which freezes at a much lower temperature than water, allowing operation of the clock during colder weather. A full-sized working replica of Su Song's clock exists in 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.[14]
Astrarium of Giovanni Dondi dell'Orologio
The Astrarium of Giovanni Dondi dell'Orologio was a complex astronomical clock built between 1348 and 1364 in Padova, 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 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 30cm in diameter, showing the positional data for the Primum Mobile, Venus, Mercury, 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. For example, Dondi's dial for Mercury uses a number of intermediate wheels, including: a wheel with 146 teeth, and a wheel with 63 internal (facing inwards) teeth that meshed with a 20 tooth pinion.
Arguably the most complicated of its kind ever constructed, the last of a total of four astronomical clocks designed and made by Norwegian Rasmus Sørnes (1893–1967), is characterized by its superior complexity compactly housed in a casing with the modest measurements of 0.70 x 0.60 x 2.10 m. Features include locations of the sun and moon in the zodiac, Julian calendar, Gregorian calendar, sidereal time, GMT, local time with daylight saving time and leap year, solar and lunar cycle corrections, eclipses, local sunset and sunrise, moon phase, tides, sunspot cycles and a planetarium including Pluto's 248-year orbit and the 25 800-year periods of the polar ecliptics (precession of the Earth's axis). All wheels are in brass and gold-plated. Dials are silver-plated. The clock has an electromechanical pendulum.
Sørnes also made the necessary tools and based his work on his own astronomical observations. Having been exhibited at the Time Museum in Rockford, Illinois (since closed), and at the Chicago Museum of Science and Industry, the clock was sold in 2002 and its current location is not known. The Rasmus Sørnes Astronomical Clock No. 3, the precursor to the Chicago Clock, his tools, patents, drawings, telescope, and other items, are exhibited at the Borgarsyssel Museum in Sarpsborg, Norway.
Table clocks
There are many examples of astronomical table clocks, due to their popularity as showpieces. To become a master clockmaker in 17th-century Augsburg, candidates had to design and build a 'masterpiece' clock, an astronomical table-top clock of formidable complexity. Examples can be found in museums, such as London's British Museum.
Currently Edmund Scientific among other retailers offers a mechanical Tellurium clock, perhaps the first mechanical astronomical clock to be mass-marketed.
More recently, independent clockmaker Christiaan van der Klaauw[nl] created a wristwatch astrolabe, the "Astrolabium" in addition to the "Planetarium 2000", the "Eclipse 2001" and the "Real Moon." Ulysse Nardin also sells several astronomical wristwatches, the "Astrolabium," "Planetarium", and the "Tellurium J. Kepler."
Two of Holland America's cruise ships, the MS Rotterdam and the MS Amsterdam, both have large astronomical clocks as their main centerpieces inside the ships' atriums.
Examples by country
Austria
Innsbruck. The astronomical clock in the gable of 17–19 Maria-Theresien-Strasse is a 20th-century copy of the astronomical clock of the Ulm Rathaus.[15]
Peuerbach. The facade of Peuerbach Town Hall features an astrolabe clock, an enlarged copy of Georg von Peuerbach's original astrolabe of 1457.[16]
Belgium
Lier. The Zimmer tower houses an astronomical clock installed by Louis Zimmer in 1930. On twelve dials surrounding a central clockface, it gives indications including the time around the world, the date, the moon phase, and the equation of time, and includes a tide clock.
Senzeilles[fr]. The Senzeilles astronomical clock[fr] was constructed by self-taught Lucien Charloteaux between 1896 and 1912. A domestic clock housed in a wooden case, it gives indications including the solar, mean and sidereal time around the world, the positions of the constellations and planets, and the appearance of Halley's Comet.[17]
Dubrovnik. The Dubrovnik Bell Tower constructed in 1444 has housed a clock since its creation, though due to earthquake damage, both the tower and the clock were replaced in 1929. A rotating moon ball shows the lunar phase.
Prague. The Prague astronomical clock at the Old Town Hall is one of the most famous astronomical clocks. The central section was completed in 1410, the calendar dial was added in 1490. The clock was renovated after damage during World War II, and in 1979. On the hour, Death strikes the time, and the twelve apostles appear at the doors above the clock.
Olomouc. The Olomouc astronomical clock at the Town Hall is a rare example of a heliocentric astronomical clock. Dated 1422 by legend, but first mentioned in history in 1517, the clock was remodelled approximately once every century; in 1898 the astrolabe was replaced with a heliocentric model of the solar system. Badly damaged by the retreating German army in 1945, the clock was remodelled in socialist realism style in 1955, under the Communist government. The religious and royal figures were replaced with athletes, workers, farmers, scientists, and other members of the proletariat.
Litomyšl. The tower of the Old Town Hall has an art nouveau astronomical clock, installed in 1907.[18]
Prostějov. The astronomical clock in the tower of the New Town Hall was installed in 1910.
Hojsova Stráž. An astronomical clock in the Bohemian Forest was inaugurated in 2017. It has a concentric dial showing the 24-hour time, the date and zodiac, and the moon phase, and a star map dial with a dragon hand, and indicates the time of sunrise and sunset.[19]
Třebíč. At the Třebíč Astronomical Observatory, a modern astronomical clock which shows the time in world cities, the time of sunrise and sunset, the date and zodiac, and the orbits of the planets.
Žatec. The Temple to Hops and Beer[cs], a museum and amusement complex dedicated to beer, has an astronomical clock on which the zodiac indication illustrates the annual processes of beer production.[20]
Auxerre. The 15th-century clock in the Tour de l'Horloge[fr] has a 24-hour sun hand and a moon hand which completes a revolution in a lunar day of 24 hours 50 minutes, and shows the lunar phase on a rotating moon ball.
Beauvais. The Beauvais astronomical clock in Beauvais Cathedral, constructed 1865–1868 by Auguste-Lucien Vérité, has 52 dials that display the times of sunrise, sunset, moonrise, moonset, the phases of the moon, the solstices, the position of the planets, the current time in 18 cities around the world, and the tidal hours. Its 68 automata enact the Last Judgement on the hour.
Munster. The Church of Saint-Léger houses the Clock of Creation, installed in 2008. It shows the time, the day of the week, the month and zodiac, and the moon phase.[21]
Rouen. The Gros Horloge has a movement built in 1389, with a dial added in 1529. It indicates the moon phase on a rotating sphere above the dial, and the day of the week in an aperture at the base of the dial.
Strasbourg. The Strasbourg astronomical clock is the third clock housed in Strasbourg Cathedral, following 14th-century and 16th-century predecessors. Constructed by Jean-Baptiste Schwilgué from 1838 to 1843, it shows many astronomical and calendrical functions (including what is thought to be the first complete mechanization of the computus needed to compute Easter) and several automata.
Batumi. The facade of the former National Bank Building on Europe Square has an astronomical clock based on the clock at Mantua, which shows the positions of the sun and moon in the zodiac, and the moon phase.[22]
A group of interior astronomical clocks of the 14th, 15th and 16th centuries in churches of Hanseatic League towns in northern Germany, known as the Hanseatic clocks (the group also includes the clock at Gdańsk, now in Poland).
Wismar. The 15th-century astronomical clock in St. Mary's Church[de] was destroyed by bombing in 1945.
A group of 16th-century clocks on the facade of town halls in southern Germany, which have a 12-hour dial, a moon phase indication, and a calendar dial indicating the positions of the sun and moon in the zodiac, with a dragon hand:
Ulm. The 16th-century astronomical clock of Ulm Town Hall[de] has a 24-hour astrolabe format, although the zodiac is repeated as a rotating ring of gold sculptures, and the outer ring of the dial is a 12-hour chapter ring.
Cologne. At the Cologne Planetarium[de], a modern astronomical clock which shows the hour in regular and sidereal time, the moon phase, positions of the sun and moon in the zodiac, and the rotation of the earth according to the geocentric model.[25]
Esslingen am Neckar. At the headquarters of Festo, Professor Hans Scheurenbrand has constructed the Harmonices Mundi (named after Kepler's book of the same name), which consists of an astronomical clock, a world time clock, and a 74 bell glockenspiel.[26]
Munich. The Old Town Hall and the Deutsches Museum both have clocks which indicate the moon phase on a rotating ball, and the zodiac on a fixed ring within a 12-hour dial.
Schramberg. The Town Hall has an astronomical clock installed in 1913.[27] Its indications are similar to the clock of Ulm (except that the outer hour ring is 24-hour), with an offset astrolabe ring repeated as a golden zodiac ring.
Worms. The clock tower Worms Town Hall[de] has a modern calendar dial that shows the month, the positions of the sun and moon in the zodiac, the moon phase, and has a dragon hand.
St. Nicholas' Church, Stralsund
St. Mary's Church, Rostock
Münster Cathedral
St. Mary's Church, Lübeck
Ulm
Deutsches Museum, Munich
Hungary
Budapest: A modern astronomical clock with automata, at the Clock Museum.[28]
Bassano del Grappa. 24-hour dial with zodiac indication on the Palazzo del Municipio, first installed in 1430, reconstructed by Bartolomeo Ferracina in 1747.[30]
Cremona. The 16th-century astronomical clock of the Torrazzo, the bell tower of Cremona Cathedral, is the largest medieval clock in Europe.
Macerata. An astronomical clock installed in the Torre Civica[it], a modern replica of the original clock of 1571, which shows the orbits of the planets.
Mantua. Astronomical clock was installed in 1473 in the Torre dell'Orologio of the Palazzo della Ragione.
Merano. Clock tower at the entrance to Merano town cemetery, installed in 1908 by Philipp Hörz of Ulm,[33] with a calendar dial showing the month, zodiac, and moon phase.
Messina. The Messina astronomical clock in the tower of Messina Cathedral. Multi-dial clock equipped with complex automata. Constructed between 1930 and 1933 by the Ungerer Company of Strasbourg. It is one of the largest astronomical clocks in the world.
Valletta. The clock of the Grandmaster's Palace, installed in 1745, shows the hour, date, month, and lunar phase, and has bells struck by four jacquemarts.[37]
Stará Bystrica: An astronomical clock in the stylized shape of Our Lady of Sorrows was built in the town square in 2009. The astronomical part of the clock consists of an astrolabe displaying the astrological signs, positions of the Sun and Moon, and the lunar phases. Its statues and automata depict Slovakian historical and religious figures. The clock is controlled by computer using DCF77 signals.[38][39]
Stará Bystrica
South Korea
Honcheonsigye: is an astronomical clock made by Song Yi-Yeong (송이영;宋以潁), a professor of Gwansanggam (관상감;觀象監) (one of the scientific institution of Joseon Dynasty) in 1669.[40] It was designated as South Korean national treasure number 230 in August 9, 1985. The clock used the alarm clock technology created by Christiaan Huygens in 1657.[41] This relic shows that Huygens' technology was spread to East Asia in just 12 years. Also, It demonstrates the astronomy and mechanical engineering technology of the Joseon Dynasty. Korea has been making armillary sphere since the 15th century as part of King Sejong's technology development policy, and this clock is an important historical document that shows the fusion of East Asian astronomy and European mechanical technology.
Spain
Astorga: The interior face of the clock of Astorga Cathedral has a 24-hour dial which shows the lunar phase and the date.[42]
Sweden
Lund: Lund astronomical clock in Lund Cathedral in Sweden, (Horologium mirabile Lundense) was made around 1425, probably by the clockmaker Nicolaus Lilienveld in Rostock. After it had been in storage since 1837, it was restored and put back in place in 1923. Only the upper, astronomical part is original, while some of the other remaining medieval parts can be seen at the Cathedral museum. When it plays, one can hear In Dulci Jubilo from the smallest organ in the church, while seven wooden figures, representing the three magi and their servants, pass by.
Fjelie[sv]: Emil Ahrent, the local priest, constructed and donated an astronomical clock to Fjelie Church in 1946.
Bern. The Zytglogge is a famous 15-century astronomical clock housed in a medieval fortification tower.
A set of 16th-century clocks which show the zodiac and the days of the week in concentric rings within a 12-hour clock face, with a moon phase ball above:
Schaffhausen: The astronomical clock by Joachim Habrecht[de] in the gable of the Fronwagturm, installed in 1564, has five hands, including indications of the positions of the sun and moon in the zodiac, and a dragon hand indicating the lunar nodes.[43]
Solothurn. This astronomical clock, installed by Lorenz Liechti[de] and Joachim Habrecht[de] in 1545 to replace an original of 1452, shows the positions of the sun and moon in the zodiac.[45]
Winterthur. This astrolabe astronomical clock was installed in 1529. The building which housed it was demolished in 1870. The clock is now an exhibit at the Museum Lindengut.[46]
Zug: The astronomical clock of the Zytturm was installed in 1574. Its calendar dial shows the zodiac, the lunar phase, the day of the week and the leap year cycle.
A group of four famous astronomical clocks in the West Country, dating from the 14th and 15th centuries, all of which show the 24-hour time and the moon phase:
York. The York Minster astronomical clock, an astronomical clock installed in 1955 as a memorial to airmen killed in World War II, shows the positions of the sun and stars from the perspective of a pilot flying over York. It was damaged by fire in 1984, and is not currently working.
1 2 Burnett-Stuart, George. "De Dondi's Astrarium". Almagest. Computastat Group Ltd. Archived from the original on 30 May 2008. Retrieved 21 April 2008.
The Prague astronomical clock or Prague Orloj is a medieval astronomical clock attached to the Old Town Hall in Prague, the capital of the Czech Republic.
The Strasbourg astronomical clock is located in the Cathédrale Notre-Dame of Strasbourg, Alsace, France. It is the third clock on that spot and dates from the time of the first French possession of the city (1681–1870). The first clock had been built in the 14th century and the second in the 16th century when Strasbourg was a Free imperial city of the Holy Roman Empire.
Rasmus Jonassen Sørnes was a Norwegian inventor, clockmaker and radio technician, and is most famous for his advanced astronomical clocks, the most precise of which has an inaccuracy of 7 seconds during 1000 years. During his lifetime, Sørnes also designed and built a large variety of agricultural, radio-technical and mechanical devices, only a few of them patented.
St Mark's Clock is housed in the Clock Tower on the Piazza San Marco in Venice, Italy, adjoining the Procuratie Vecchie. The first clock housed in the tower was built and installed by Gian Paolo and Gian Carlo Rainieri, father and son, between 1496 and 1499, and was one of a number of large public astronomical clocks erected throughout Europe during the 14th and 15th centuries. The clock has had an eventful horological history, and been the subject of many restorations, some controversial.
The Zimmer tower is a tower in Lier, Belgium, also known as the Cornelius tower, that was originally a keep of Lier's 14th-century city fortifications. In 1930, astronomer and clockmaker Louis Zimmer (1888–1970) built the Jubilee Clock, which is displayed on the front of the tower, and consists of 12 clocks encircling a central one with 57 dials. These clocks showed time on all continents, phases of the moons, times of tides and many other periodic phenomena.
The Besançon astronomical clock is housed in Besançon Cathedral. Auguste-Lucien Vérité of Beauvais designed and built Besançon's present astronomical clock, between 1858 and 1863. It replaced an earlier clock that Bernardin had constructed in the 1850s that proved unsatisfactory. Besançon's clock differs from those in Strasbourg, Lyon, and Beauvais. The clock is meant to express the theological concept that each second of the day the Resurrection of Christ transforms the existence of man and of the world.
Hampton Court astronomical clock is a sixteenth-century astronomical clock in Hampton Court Palace in England.
The Exeter Cathedral Astronomical Clock is a fifteenth-century astronomical clock in Exeter Cathedral, England. It displays the hour of the day, the day of the lunar month and the phase of the moon. The modern clock mechanism was installed in 1885 by Gillett & Bland of Croydon, and restored in 1910.
Wimborne Minster astronomical clock is a fourteenth-century astronomical clock in Wimborne Minster in Dorset, regarded as "one of the most ancient working clocks in Europe."
Lund astronomical clock, occasionally and at least since the 16th century referred to as Horologium mirabile Lundense, is a 15th-century astronomical clock in Lund Cathedral. Mentioned in written sources for the first time in 1442, it was probably made and installed sometime around 1423–1425, possibly by Nikolaus Lilienfeld. It is part of a group of related medieval astronomical clocks found in the area around the south Baltic Sea. In 1837 the clock was dismantled. Between 1909 and 1923, it was restored by the Danish clockmaker Julius Bertram-Larsen and the Swedish architect responsible for the upkeep of the cathedral, Theodor Wåhlin. From the old clock, the face of the clock as well as the mechanism, which was largely replaced during the 18th century, was salvaged and re-used. The casing, most parts of the calendar which occupies the lower part, and the middle section were made anew.
The Gros-Horloge is a 14th century astronomical clock in Rouen, Normandy.
The Lyon astronomical clock is a seventeenth-century astronomical clock in Lyon Cathedral.
The Ploërmel Astronomical Clock is a 19th-century astronomical clock in Ploërmel in Brittany, in north-west France.
The Astrarium of Giovanni Dondi dall'Orologio was a complex astronomical clock built between 1348 and 1364 in Padova, Italy, by the doctor and clock-maker Giovanni Dondi dall'Orologio. The Astrarium had seven faces and 107 moving parts; it showed the positions of the sun, the moon and the five planets then known, as well as religious feast days. It was one of the first mechanical clocks to be built in Europe.
The astronomical clock of Messina is an astronomical clock constructed by the Ungerer Company of Strasbourg in 1933. It is built into the campanile of Messina Cathedral.
The Torre dell'Orologio is a 16th-century building located in the Piazza della Loggia in Brescia, northern Italy.
The Torre dell'Orologio is a 15th-century renaissance tower on the Piazza delle Erbe in Mantua, Italy. It is attached to the Palazzo della Ragione, and next to the Rotonda di San Lorenzo. It houses an astronomical clock.
The Zytturm is a 13th-century tower in Zug, Switzerland, which houses an astronomical clock. The tower, which is 52 metres high, is located on Kolinplatz in the old town centre.
The Sion astronomical clock is an astronomical clock at the town hall of Sion in the canton of Valais, Switzerland. The clock was first installed in 1667–68; the present mechanism dates from 1902.
The Bourges astronomical clock is an astronomical clock in Bourges Cathedral in Bourges, France.
North, John (2005). God's Clockmaker, Richard of Wallingford and the invention of time. Hambledon and London.
Sørnes, Tor (2008). The Clockmaker Rasmus Sørnes. Borgarsyssel Museum, Sarpsborg, 2003 Norwegian edition, and 2008 English edition (available from the museum).
King, Henry (1978). Geared to the Stars: the evolution of planetariums, orreries, and astronomical clocks. University of Toronto Press.
Further reading
Needham, Joseph; Ling, Wang; deSolla Price, Derek J. (1986). Heavenly Clockwork: The Great Astronomical Clocks of Medieval China. Cambridge: Cambridge University Press. ISBN978-0-521-32276-8.
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