To insure the life of the observatory beyond his own reign, Mangû provided it with a waqf endowment – the first known application of applying to astronomy the mechanism for endowing madrasa and hospital. The resulting revenues financed the observatory during the reigns of subsequent rulers until the dissolution of the Mongol state about 1316. Nasir al-Tusî’s sons succeeded him in directing the observatory, and it may be that he and they were the waqf administrators. The charitable endowment allowed the observatory to become an institution for instruction in the secular, or ancient sciences – the natural sciences excluded from the madrasas. In this, too, the observatory followed the pattern of Islamic teaching hospitals.
The Marâgha Observatory had a main building surmounted by a dome, through a hole in which the sun could be observed. It included an enormous library (by one account more than 400,000 volumes) and housed terrestrial and celestial globes. Many of the observatory’s rooms were excavated caves. (Astronomical observations are often made when a star passes overhead at the zenith, and for these altitude measurements, an excavated trench with a mural quadrant is fine.) Among its instruments were a fixed armillary sphere with five rings, a mural quadrant, a solar armilla, an equinoctial ring, and a parallactic ruler. The instruments went to produce a set of zijes, the so-called Ilkhâni Tables which provided data for all seven moving stars.
Marâgha formed a precedent for Mongol astronomical patronage. In the fifteenth century, Ulugh Beg (grandson of Timûr, feared in Europe as Tamerlane) erected the most magnificent of Islamic observatories at Samarqand. He became an expert astronomer, apparently constructing his observatory around an existing madrasa. He initiated astronomical instruction at the madrasa and drew talented astronomers, notably Ghiyâth al-Dîn al-Kashî (d. 1429), to the observatory, which he endowed with a waqf. The observatory apparently survived Ulugh Beg’s reign (he was murdered by his son), settling into a slow decline over the succeeding century. The Islamic tradition of grand astronomical institutions continued into the sixteenth century, with the construction of an observatory at Istanbul under the direction of Takiyüddin al-Rasid (1526–1585). It functioned for several years before being dismantled in 1580, at the request of the sultan who founded it. The last of the great Islamic observatories came in South Asia early in the eighteenth century, courtesy of Maharaja Swai Jai Singh II.
The Islamic tradition may be placed in perspective by introducing the late sixteenth-century astronomical fiefdom of Tycho Brahe (1546–1601), granted by King Frederick II of Denmark and financed by Tycho’s inherited fortune supplemented by Frederick’s largesse. Tycho had workshops for his instrument-makers, a mill for producing paper, and a printing press. The main house of Tycho’s Uraniborg functioned as a chateau, complete with running water, kitchen, chemical laboratories, workrooms, library (housing a five-foot-in-diameter celestial globe) and bedrooms. Tycho had large instruments mounted on the top of the house. A separate observatory building had more instruments set in subterranean rooms equipped with plinths. With its generous royal endowment and its massive, innovative instruments, Uraniborg was nothing other than the European counterpart of the Istanbul Observatory. Tycho’s observatory was an inspiration for Francis Bacon’s invocation of the notion of a House of Salomon, which in turn became a model for the Royal Society of London. In a sense, we may trace modern scientific institutions to medieval Islam.
It is doubtful that Tycho had first-hand information about the observatories of his Islamic predecessors. His instruments followed Ptolemy’s instructions, which he adapted and added to on the basis of European tradition – just as medieval Islamic astronomers began with Ptolemy and constructed innovative measuring arms, armillary spheres, and scales. Medieval Islamic observatories, located as they were between Western Europe and Eastern Asia, nevertheless suggest questions about interchanges between West and East.
When we look west, we find little direct Islamic inspiration for the organization of astronomical activity. The area of closest contact between Islam and Christianity, Andalusia, was insulated against the urge to construct grand state observatories. The insularity derived from the effective independence of Western Islam and especially the diverse Spanish emirates and kingdoms. This is not to say that intellectuals in Spain were less interested in the stars than were people in Central Asia. Certainly the eleventh-century group of astronomers around al-Zarqâli (d. 1100) who compiled zijes that became known in Europe as the Toledan Tables undertook significant observations, but the work was apparently accomplished without a permanent observing facility.
What about the East? Can it be that the inspiration for Islamic observatories came from China? There is no doubt that various Chinese governments maintained astronomical offices, and with them the means of making sophisticated astronomical observations, for at least seven centuries before a similar spirit infected Islamic authorities.
Knowledge of the sky was an imperial prerogative from the time of the Han. The heavens were held to have conferred a mandate on the imperial house, and reading the stars was a way of learning whether terrestrial policies found divine favour. Portent astrology (where one sought divine instruction from the sky by reading celestial signs) rather than individual fate astrology (the notion of a preordained future that suffused western Eurasia) dominated the court institutions of Chinese astronomy. New rulers and new regimes, in fact, promulgated new calendars as a practical sign of their celestial mandate. In the Han, astronomy went under the Office of the Grand Historian, for it combined the functions of archivist and omen reader. About 90 BC, the head of this office, Ssu-ma Chhien, compiled the dynastic history known as the Shih Chi, which had chapters devoted to calendar construction and astrology. This tradition continued (with the same kind of ups and downs that characterize institutions of higher learning in the Mediterranean basin) for two millennia.
The Chinese dynasty at the time of the rise of Islam, the Thang, received ambassadors and merchants from Byzantium, Persia, and elsewhere. Among the foreigners living in China under the Thang were Indian astronomers. In the seventh century there are indications of Brahmin astronomy being translated into Chinese. Beginning around 650, three families of Indian astronomers held positions in the imperial astronomical bureau. Of these, astronomers of the Gautama family found their calendrical work officially adopted. Chhüthan Shi-Ta or Gautama Siddhartha (fl. 718), the greatest of the clan, became director of Thang astronomy and wrote a major mathematical work in 729 which featured the zero symbol, division of the circle into 360 degrees (the Chinese circle traditionally contained 364.25 degrees), and sexagesimal minutes and seconds. No doubt the resident Indian astronomer families made use of trigonometry, then unknown in China. Despite internecine disputes about astronomical secrets (the Chinese Buddhist monk and brilliant mathematician I-hsing became involved in some of these disputes), the Indian families produced an officially accepted calendar, calculated solar eclipses, and wrote an astrological treatise.
The observatory where the Indian astronomers lived and worked was large, even by modern standards. Two grand astrologers supervised the Astronomical Bureau in Thang China, an institution that combined features of observatory and college. They operated one of the largest astronomical schools of any time. In the bureau’s astrological department, 2 professors supervised 5 observers and 150 students; one professor of calendar-making oversaw 2 technicians and 41 students; 6 professors of time-keeping had 37 technicians, 440 clerks to handle various bells and drums that signalled the hours, and 360 students. Separate from the Astronomical Bureau was the Divination Bureau. Divination concerned foreseeing the future on the basis of traditions ranging from the I-Ching (Book of Changes)