Calif al-Mansur, who began his reign in 754 A. D., appears to have been the first to show a decided taste for astronomical science, and for many centuries following him this interest is strikingly pronounced among the people of his country.[55] Scholars were eagerly attracted to the works of Ptolemy, which were many times translated into Arabic, and commentaries were written upon his description of the names and figures of the several constellations. The only alteration they allowed themselves to make in the names of the stars was to translate them into their own language, or to substitute for those they could not understand other names that conveyed an idea to their minds, applicable to the constellation before the eyes. Andromeda they called “The Chained Lady”; Cassiopeia they called “The Lady in the Chair”; Orion received the name “The Giant.” They followed in the construction of their armillary spheres and celestial globes the description laid down in Ptolemy’s ‘Syntaxis,’ modifying these astronomical instruments, from time to time, as their studies directed them.[56] The list of califs interested in astronomy is a long one, both of those who remained in the original homeland, and of those who went to the new home in the Iberian Peninsula.[57] The Mohammedan Hulagu Khan, for example, erected, about 1264, an observatory in his Mongol capital, Maragha, near Tabriz, which long remained a noted center for astronomical studies.[58] This observatory, however, was but one of a number of similar institutions erected either by the Arabs or by the Persians. We are told that the construction of astronomical instruments was brought to a high degree of perfection by these peoples in the thirteenth century.[59] The names of many of the Arabic astronomers who were particularly expert as globe makers are recorded, and there were many who wrote on the subject of celestial spheres, armillary spheres, and astrolabes, even before the tenth century.[60] The author of the ‘Fihrist,’ Ibn Abî Ja’kûb an-Nadîm, tells us that Kurra ben Kamîtâ al-Harrânî constructed a globe which he himself had seen.[61] This, he says, was made of unbleached material from Dabik, and colored, but that the colors were much faded. Ibn Alnabdi, who was known as a clever mechanic, mentions two globes which he had examined and admired for their excellency of execution, in the public library of Kahira, in the year 1043. One of these globes, he says, was made of brass, by Ptolemy himself; the other, of silver, was constructed by Abul Hassan Alsufi, for the immediate use of the king, Adad Eddoula.[62]