favourably received by the Arab astronomers than the first, and
the Sind Hind was superseded by the Almagest of Ptolemy. Better
astronomical instruments also came into use, though previously the
Al-Fezari above mentioned had been the first in Islam who constructed
astrolabes of various kinds, and had written several astronomical
treatises.

Mention might be made of about forty mathematicians and astronomers
who wrote books on these subjects. The best of them, such as
Al-Farghani (Alfraganius) and others, lived at the court of Mamun, who
built an astronomical observatory in Baghdad and another near
Damascus, on Mount Kasiun. He caused also two degrees of the meridian
to be measured on the plain of Sinjar, so as to ascertain the
circumference of the earth with more precision. In A.D. 824 there were
held philosophical disputations in his presence. Al-Farghani was the
author of an introduction to astronomy, which was printed by Golius at
Amsterdam in 1669, with notes.

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 ha