Between the years A.D. 877 and 929 there flourished the famous calculator and astronomer, Muhammad bin Jaber al Battani, Latinized as Albategnius. He was the author of the astronomical work entitled 'The Sabaean Tables,' and adopted nearly the system and the hypothesis of Ptolemy, but rectified them in several points, and made other discoveries, which procured him a distinguished place among the scholars whose labours have enriched astronomical science. Al-Battani approached much nearer to the truth than the ancients as far as the movements of the fixed stars are concerned. He measured the greatness of the eccentricity of the solar orbit, and a more correct result cannot be obtained. To the work containing all his discoveries he gave the name of 'As-Zij-as Sabi,' which was translated into Latin under the title 'De Scientia Stellarum.' The first edition of it appeared at Nuremberg in A.D. 1537, but it is believed that the original work is in the library of the Vatican. He was classed by Lalande among the forty-two most celebrated astronomers of the world. He died A.D. 929-930. Another celebrated astronomer, Ali bin Yunis, was a native of Egypt, and appears to have lived at the court of the demented tyrant of Egypt, Al-Hakim bramrillah, and under his patronage to have composed the celebrated astronomical tables called, after his name, 'The Hakimite Tables.' Ibn Khallikan states that he had seen these tables in four volumes, and that more extensive ones had not come under his notice. These tables were considered in Egypt to be of equal value to those of the astronomer Yabya bin Ali Mansur, who had in A.D. 830, by order of the Khalif Mamun, undertaken astronomical observations both at Baghdad and Damascus. Ibn Yunis spent his life in the preparation of astronomical tables and in casting horoscopes, for it must be remembered that with the Muslims astronomy and astrology were synonymous, and their most learned astronomers were also their most skilful astrologers. His character for honesty was highly esteemed, and he was also well versed in other sciences, and displayed an eminent talent for poetry. He died A.D. 1009, and is not to be confounded with his father, Ibn Yunis, the historian, who died A.D. 958.