The Chartres Cathedral – Cathedral of Our Lady of Chartres – is widely considered one of the finest examples of French Gothic architecture, and the building has indeed several aspects in its appearance and history that guarantee a special place among mediaeval cathedrals in Europe.
It was common in the Middle Ages that a building had been constructed through subsequent periods and completed only centuries after the beginning, but the majority of Chartres Cathedral was built with unusual speed (cca. 1198-1260) resulting in a remarkably consistent design and realization. Compared to other mediaeval churches the building has seen only relatively minor changes since the consecration in 1260. Most mediaeval cathedrals in France were looted and destroyed several times during the Wars of Religion and the Revolution, but Chartres Cathedral was spared the damage, even during World War II. Thanks to that, most of the original 13th century architectural details – even the huge stained glass windows and the sculptures and carvings of the portals and the interior – survived intact, the majority preserved in excellent condition. One of the many peculiarities of the cathedral is the numerous portrayals of the Zodiac signs on various architectural elements.
PORTAIL ROYAL: labours of the months and Zodiac signs (1142-1150)
The Portail Royal on the west facade has always been the main entrance of the cathedral. Apart from the crypts under the cathedral surviving from two earlier churches standing on this site, the west facade together with the two towers is the oldest part of today’s building – they are remnants of the earlier, partly Romanesque cathedral destroyed by a fire in 1194, incorporated into the current building. The Romanesque cathedral was built in more phases from 1020 until 1155, the Royal Portail dates from around 1140-50, representing a transition to the new Gothic style. It has three portals: a larger central portal accompanied with two smaller side portals, all of them with sculptures and lintels displaying a complex visual and theological scheme: the End of Time (Judgment Day) on the central, the infancy of Christ on the right, his second coming on the left portal. The Portail Royal derived its name from the tall statues on the doorjambs representing kings and queens of the Old Testament.
The archivolts on the left portal contain carvings of the Zodiac signs mingled with the labours of the associated 12 months – a common element appearing on many mediaeval churches in various forms, representing the cyclical nature of time and the wholeness of the Creation.
However, in this case the depiction has some very unusual characteristics: there are 12 labours of the month carvings on the archivolts but only 10 signs are portrayed. The most probable – albeit somewhat prosaic – explanation for this unusual arrangement is that the plans were changed while construction and there was not enough place left for the carvings originally intended. Thus, the two twin signs, Pisces and Gemini got a separate place at the bottom of the right portal’s inner left archivolt, and while the iconography of Gemini is standard, Pisces is rather unorthodox. There’s only one fish depicted, representing water, one of the four ancient elements, surrounded by the symbols of the other three: small flames (fire) under the fish’s belly, trees (earth) standing behind it with perching birds (air).
There’s also a less known Zodiac cycle on the Portail Royal: nested into the meandering ornament on the doorjambs of the central portal delicate carvings portray the Zodiac sings.
NORTH TRANSEPT PORCH: labours of the months and Zodiac signs (1198-1217)
The transept (crossing) – just as the largest part of the cathedral – was built in the main construction period (1198-1260), according to the new design made after the 1194 fire. The deep, three-portal north and south porches were completed around 1215.
As usual for northern European cathedrals, the iconographical themes of the northern facade focus on Christ’s early life and Old Testament stories: the glorification of Mary on the center, the incarnation of Christ on the left, Job and the Judgment of Solomon on the right portal of the porch. The two outer archivolts of the right portal contain labours of the months and Zodiac signs carvings, in this case without any deviation from the common characteristics.
The arrangement of the signs and the monthly rural activities on the arches follows the path of the Sun throughout the year: the cycle starts with January from the left bottom, continues until June, pictured at the top of the arch, as daylight increases until the summer solstice, then the cycle ends with decreasing daylight until the winter solstice in December, at the right bottom of the arch. The two extra carvings at the bottom of the outmost arch depicting the Zodiac signs portray Winter and Summer: a men’s figure dressed appropriately to the season.
SOUTH AMBULATORY WINDOW: labours of the months and Zodiac signs (1215-1218)
One of the most distinctive features of Gothic cathedrals is the new combination of architectural elements like pointed arches, clustered columns and flying buttresses, making the insertion of huge colored windows possible on every level of the building.
In Chartres Cathedral most of the 176 windows were filled with stained glass, extensively using a new, very bright, sodium cobalt colored blue developed on the site of the Saint Denis Basilica. The windows cover a total area of cca. 2600 m2, the majority of them made and installed between 1205 and 1240, with a few lancet panels surviving from the Romanesque building destroyed by the fire. The depicted scenes include panels of the Virgin and the Child, Biblical stories from the Old and New Testament, the Lives of the Saints and some prominently displayed coats of arms of donors of some windows.
One of the south ambulatory windows repeats again the labour of the months and Zodiac signs cycle featured on the west and north facades. For the man of the Middle Ages the Zodiac signs symbolized not only the passing of time in a cycle of a year, or of life and death. The agricultural labours associated with the 12 months and the corresponding signs were presented as work blessed by God, imposed on Adam and his descendants to find their way to salvation (Vincent de Beauvais). The top quartrefoil of the roughly 8.1m high and 2.2m wide lancet window portrays Christ with the Alpha and the Omega, as the beginning and ending of the cycles. The labours of the months are depicted on the left side, the associated Zodiac signs on the rights side panels, 8 month/sign individually, four pairs sharing the four central quatrefoils. The two bottom panels are signature panels of the window donors.
There are some odd inconsistencies in the order and pairing of the months and the signs: May/Gemini proceeds April/Taurus, July and June (paired with Leo) are interchanged, the caption November is missing and December occurs twice.
ASTRONOMICAL CLOCK: Zodiac sings on the dial (>1407-1528)
Common people’s everyday life in the Middle Ages was determined by the daily routine and the annual cycles of the agricultural tasks rather than the days of the calendar. However, to calculate the exact date of major religious ceremonies and feasts and the time of the daily prayers had been paramount, thus keeping track of time and date had been the duty of the church. For hundreds of years the easiest way to tell local time was to use a sundial – meridian sundials had been used even after the invention of the mechanical clock to determine local noon for the public and for adjusting the clocks.
The oldest sundial of Chartres Cathedral dates probably to the 13th century, and the first mention of an astrological clock on the cathedral displaying not only the hours but also the period of the year with Zodiac signs comes from 1407. According to the description it is probably the same clock we can see today, with subsequently installed additions and adjustments of the mechanism and the dial in the 16th century. Although most of the mechanism was disassembled and used to forge pikes during the Revolution, the clock went through restoration in 2006 and the dial is still preserved in the choire on the north side.
The 105 cm diameter dial of the clock is formed of four independent plates assembled by a central axis. The outmost ring shows the twenty-four hours of the day with a needle indicating the local time, the next ring – an azure blue background decorated with golden stars – displays the lunar day and the phases of the moon, the central plate with the painted Zodiac signs moving one degree every day indicates the course of the sun in the ecliptic. A small sun moving along a slit in the needle indicates the height of the sun relative to the horizon, showing also the hours of sunrise and sunset. The clock was adjusted every noon with a sundial.
images © Philippe Giron
The twelve Zodiac signs on the architectural astronomical instruments of Rashi Valaya Yantra in Jantar Mantar observatory, Jaipur, India, 18th century.
Aries, Taurus, Cancer, Libra, Scorpio, Capricornus, Aquarius (with minor editions) © Yann Forget CC BY-SA 2.0
Gemini, Leo, Virgo, Sagittarius, Pisces (with minor editions) © Mariam Varliani
In the roughly 14 hundred years from Ptolemy writing The Almagest in the 2nd century until the invention of the telescope made more accurate astronomical observations possible at the beginning of the 1600s, many transcripts and transcripts of transcripts were made of his star catalogue by astronomers of the mediaeval East and Europe, but only a few of them contributed to the original work with additions or corrections based on their own observations. One of these astronomers was Mīrzā Muhammad Tāraghay bin Shāhrukh, better known as Ulugh Beg, Timurid ruler of the region of Samarkand in the 15th century.
Ulugh Beg became governor of Samarkand in 1409, when his father Shah Rukh finally managed to take possession of the eastern portion of the empire established by his father Timur (Tamerlane) and moved his capital to Herat. Coming from an educated family – his parents were patrons of art and science, his mother’s efforts had even made the education of woman acceptable for a short time – his intension was to turn the city into an intellectual center.
In 1417 he began to build a madrasah – an institute for higher education – in Samarkand for studying different disciplines of secular science from astronomy and mathematics to medicine and poetry.
The two-story building-complex arranged around a rectangular courtyard with an imposing entrance portal and two minarets at the front facade included dormitory cells and rooms for the scholars and students, four lecture rooms at the four corners and a mosque at the west wall of the courtyard. Ulugh Beg invited the best scholars he could find as lecturers, and the Ulugh Beg Madrasah soon became the leading center of Islamic education in Central Asia. Today the building is still standing at the Registan, the center of Samarkand, with two other madrasahs built in the 17th century on two other sides of the square.
Although educated and active on many fields, Ulugh Beg’s main interests – inspired probably by a childhood visit to the remnants of the Marāgha Observatory, where Persian astronomer al-Tusi and his team completed around 1270 the star catalogue called the Ilkhanic tables (Zīj-i Īlkhānī) – had always been mathematics and astronomy. In 1420 he started to build the enormous observatory Gurkhani Zīj near Samarkand, with huge structures used as instruments to increase the accuracy of astronomical observations and measurements to the maximum. The observatory was unparalleled in its time.
‘Its circular main building, beautifully decorated with glazed tiles and marble plates, had a diameter of about 46 m and three stories reaching a height of approximately 30 m above ground level. The north–south axis of the main building was occupied by a huge sextant with a radius of 40 m (called Fakhrī sextant after that of Khujandī). On the scale of this instrument, which partially lay in an underground slit with a width of half a meter, 70 cm corresponded to 1° of arc, so that the solar position could be read off with a precision of 5″. On the flat roof of the main building various smaller instruments could be placed, such as an armillary sphere, a parallactic ruler, and a triquetrum. Among other instruments known to have been used in Samarqand are astrolabes, quadrants, and sine and versed sine instruments.’
Around this time Ulugh Beg was already working together with numerous scholars he invited to join his madrasah, among them renowned scientist Qāḍī Zāda al-Rūmī and the excellent Islamic astronomer and mathematician Jamshid al-Kāshī, author of an updated star catalogue called Khaqani Zīj. With a team of about 60-70 fellow scientists, based on systematical observations and computations carried out between 1420 and 1437 they completed an astronomical handbook with tables called Zīj-i-Sultani.
The catalogue includes the coordinates of 1018 stars, the listing is based on Abd al-Rahman al-Sufi‘s Kitab al-Kawakib al-Thabita – The Book of Fixed Stars from the late 10th century, an augmented and improved version of Ptolemy’s Almagest.
As Ulugh Beg explains in the preface:
“Determination of the Places of the Fixed Stars in Longitude and Latitude.
Before the time of Ptolemy 1,022 fixed stars had been observed. Ptolemy has given them in a catalogue in the Almagest. The stars are distributed in six magnitudes; the largest are of the first and the smallest of the sixth magnitude. Each magnitude is divided into thirds, and in order to recognize the stars, 48 figures or constellations have been imagined, of which 21 are north of the ecliptic, 12 in the Zodiac, and 15 south of the ecliptic. The larger number of the stars are within the figures, the others are in the neighborhood, and are designated as unformed stars of the constellation.
Abd Al Rahman Sufi composed a treatise on the stars which all learned men have received with gratitude. Before determining by our own observations the position of these stars, we have laid them down on a sphere according to this treatise, and we have found that the greater part of them are situated differently from their appearance in the heavens. This determined us to observe them ourselves with the assistance of Divine Providence, and we have found that they were advanced from the epoch at which Sufi’s work was written, so that on giving them, according to this general observation, their absolute positions, we no longer found any difference from their appearance to the eye.
It is on this principle that we have reobserved all the stars already determined, with the exception of 27 which are too far to the south to be visible at the latitude of Samarkand (…) and we have taken these 27 stars from the work of Abd Al Rahman Sufi, taking account of the difference of epoch.
Besides these there are 8 stars mentioned by Abd Al Rahman Sufi in his book, of which Ptolemy gives the positions, but which Abd Al Rahman Sufi could not find, and which notwithstanding all our researches, we have been unable to discover. For that reason we do not indicate those stars in the present catalogue.(…)
In our catalogue we have given the position of the stars for the beginning of the year 841 of the Hegira, so that at any time we may be able to find the place of any stars on the supposition that they advance one degree in seventy solar years.”
The preface to the tables consists of four parts. The first three parts contain methodical descriptions of different astronomical measurements and calculations e.g. determining the length and initial days of years and months, the equation of the Sun and Moon, positions and characteristics of the stars and the seven planets, calculating eclipses, Moon phases and determining the position of the twelve celestial houses: the Zodiac signs. The fourth part of the preface is about astrology: horoscopes and nativities. Ulugh Beg, like many other Persian rulers, believed in astrology and fortune‐telling.
The catalogue also includes sheets of the motions and eclipses of the Sun, the Moon and the planets, longitude and latitude of several cities in various countries, trigonometric tables etc.
In 1449 Ulugh Beg was killed by his oldest son Abdal-Latif Mirza on his way to Mecca, his observatory was demolished by religious extremists, the library was looted, the scholars were forced to flee. Ali Qushji, a former student and leading astronomer at the observatory managed to take a copy of the original manuscript with him. This manuscript was translated from the original Farsi to Arabic and later to Latin, French and English – today, all known versions of the Zij-i-Sultani are translations.
The observatory buildings were excavated in 1908 by Russian archaeologist V. L. Vyatkin. Foundations of the three story cylindrical structure and underground sections of the giant marble sextant can be seen on site.
The work of Ulugh Beg and his colleague astronomers may not be ‘revolutionary’ in the sense of creating something absolutely new, but the accuracy of collecting, reobserving, recalculating, updating and correcting the data of existing catalogues, and listing altogether 1018 stars make Zij-i-Sultani one of the most important star inventories in the history and a highly influential work of Persian astronomy and astrology, that continued to be used in the Islamic world until the 19th century.
The nearly 600 years long construction history (1386-1965) of the Milan Cathedral – il Duomo di Milano – is necessarily entangled with the history of the city. The cathedral is a special ‘imprint’ of the different architectural styles and the changes of public taste during that period, and of many trifle and defining moments in the city’s political, economic and social life. One of these stories is the construction of the cathedral’s sundial in the late 18th century.
In 1786 Maria Teresa issued a decree for the Lombardy region (under Austrian control that time) to change the official measurement of days from ‘Italian hours’ – a day lasting from sunset until sunset – to ‘French hours’ – a day beginning 12 hours after local solar noon (the moment when the sun transits the celestial meridian – roughly the time when it’s highest above the horizon on that day). To comply with this regulation a precise instrument had to be constructed for the city of Milan, capitol of Lombardy, to determine the moment of solar noon each day – that was the purpose of creating ‘La Meridiana‘, the sundial of the Milan Cathedral.
The cathedral as site was chosen by the Austrian and local authorities because the building seemed to meet all the technical and economic conditions – darkness, width, convenient access for citizens, relatively low expense of realization. The assignment was carried out by Giovanni Angelo De Cesaris (1749-1832) and Guido Francesco Reggio (1745-1804), astronomers of the Brera Astronomical Observatory, by creating a special sundial adapted to the characteristics of the building.
A sundial for indicating solar noon consist of a gnomon (signifier) and a surface with the local meridian line – if positioned precisely, the gnomon’s shadow (or sun spot, depending on the type of the gnomon) crosses the meridian line exactly at solar noon. The Latin contractions am and pm – ante meridiem and post meridiem – refer to the Sun passing the meridian.
In the Milan Cathedral the gnomon is a 25.2 mm diameter hole created on the vault of the building at 23.82 meters above the floor, and the meridian is a 15 mm thin brass line embedded in the marble floor, crossing the nave of the cathedral from south to north just at the entrance, ending with an about 3 meter long section running on the north wall, to the point that signals the winter solstice. The reason of this unusual extending of the meridian is the fact that the gnomonic hole couldn’t be adjusted lower because of the thickness of the marble coating of the vault’s structure, and the width of the cathedral turned out to be insufficient to contain the whole meridian line on the floor.
The sun’s light projecting through the gnomonic hole remains visible for about half an hour each day, the spot reaches the meridian exactly at solar noon. The position of the crossing point changes constantly along the brass line through the year according to the Sun’s relative height. To indicate this movement there are marble slabs embedded along the meridian marking the period of the year with the corresponding Zodiac signs and the date when the Sun enters them. The sign of Capricornus, marking the winter solstice, is in a special position placed on the north wall, due to the above mentioned circumstances.
The constructing of the sundial began in May 1786 and was completed in October of the same year. The passage of the Sun at the meridian was signaled every day by attendants through the tower of Palazzo della Ragione to the tower of Castello Sforzesco, where a canon was fired announcing midday for the whole city. In the 19th century the sundial was used to adjust the city’s mechanical public clocks.
During the centuries the sundial went through a few modifications, audits and restorations mainly due to alterations of the cathedral’s interior and roof. The last audit was performed in 1976, when the excavations of the metro-line construction caused a lowering of the building’s floor level. These days, thanks to restoration, La Meridiana works precisely again.
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Have you ever wondered how come that Zodiac constellations have Greek origin and mythology, Latin names, and most of them contain Arabic named stars?
The answer lies in the thousands of years old history of the constellations.
Randomly grouping stars on the night sky and associating them with lores and myths is probably as old as mankind. Depictions from the early ages found in European caves date back to more than 10.000 years.
The earliest evidences of an effort to catalogue the stars come from inscribed stones, clay writing tablets and artifacts from Mesopotamia, around 3000 B.C. These texts and depictions already described the stars of the twelve Zodiac signs and were the source of the classical Greek constellations first mentioned in Homer’s and Hesiod’s works around the 7-8th century B.C. The knowledge of the Sumerians and Babylonians probably made its way to Egypt with the Cretans, where early Greek scholars first heard and wrote about the constellations.
According to an Alexandrian prose called Catasterismi attributed to Eratosthenes, by the 3rd century B.C. most of the stars and constellations – including the Zodiac signs – became associated with the Hellenistic myths, as we know them today.
From the next few hundred years several Greek works are known about constellations and myths, many of them are transcripts or commentaries of former texts. The book that is the key to our linguistic enigma is probably one of the most important and influential scientific texts of all times: Alexandrian astronomer Ptolemy’s Almagest, originally titled Syntaxis Mathematica, written cca. 150 A.D.
Ptolemy’s catalogue includes 1022 stars grouped into 48 constellations, based partly on his own celestial observations, partly on historical astronomical records from 8th century Babylonia and 2nd century B.C. astronomer and mathematician Hipparchus.
The Almagest and the geocentric Ptolemaic planetary model had been the cornerstone of cosmology and astronomy for the next 14 hundred years until Copernicus, but not the original Greek version. During the fall of the Roman Empire the original manuscript and the Greek transcripts had been lost in Western Europe.
However, there were several translations made into Arabic from the 9th century, and the great Muslim astronomer Abd al-Rahman al-Sufi attempted to accommodate and augment Ptolemy’s star list with the traditional Arabic constellations and star names in his version af the Almagest titled Kitab al-Kawakib al-Thabitah – The Book of Fixed Stars.
Later in the 12th century in Western Europe these Arabic transcripts were used for translation in Latin – the established language of science in that era – and while the names of the Greek constellations were translated, most of the Arabic star names were preserved. These names usually referred to the position of a star in a certain constellation e.g.: Hamal,’ head of the Ram’, head of Aries; Rigel, ‘foot of the Giant’, the brightest star of Orion.
The name Almagest derived similarly: Ptolemy’s work was later titled ‘The Great Treatise’, and the superlative Arabic form of this – al-majisti – became the source of the popular title.
Ptolemy’s 48 constellations – including the twelve Zodiac constellations – formed the basis of the 88 constellations we use today, officially approved by the International Astronomical Union in 1928. They preserved the Latin names of the constellations, an although for scientific purposes inside a constellation the stars are referred to by the letters of the Greek alphabet in order of magnitude, the traditional names of the brightest stars are still in use. Thus, Alpha Tauri means the brightest star of Taurus, in Arabic called Aldebaran, the Follower, for following the Pleiades during the nightly motion of the celestial sphere across the sky.