ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

18 ASTRONOMY IN ANCIENT NATIONS
of Hipparchus, but varying considerably and irregularly. Ibn
Jūnis, who quotes this, adds that he has himself found 5° 3' or 5°
8', while other observers are said to have found from 4° 58' to
4° 45'.¹ Want of perseverance and of accurate instruments
caused them to miss a remarkable discovery, that of the
variation of the lunar inclination.
Abu 'l Wefa and his Almagest
But an even more remarkable discovery has been claimed
for an Arabian astronomer. In 1836 the younger Sedillot
announced that he had found the third inequality, the variation,
distinctly announced in Abu 'l Wefa's Almagest. A fierce
controversy raged for a number of years as to the reality of
this discovery, Sedillot alone defending his hero with desperate
energy and refusing to listen to any arguments, while Biot,
Libri and others as strenuously maintained that Abu 'l Wefa
simply spoke of the second part of the evection, the prosneusis
of Ptolemy. The fight had died out when, in 1862, Chasles
suddenly took up the cudgels for Sedillot and pointed out what
seemed to him to be some contradictions in Ptolemy's statement.²
Nobody answered this until Bertrand did so in 1871; he called
attention to several inaccuracies in the text of Abu 'l Wefa as
we possess it now, and also showed that Abu 'l Wefa did not
add his "mohazat" to the prosneusis, the latter not being
included in his "second anomaly."³ It is unnecessary to enter
into a more detailed account of the controversy; but to show
that any weapon was considered good enough with which to
defend Abu 'l Wefa, it may be mentioned that Sedillot and
Chasles tried to prove that Tycho Brahe must have copied his
discovery from Abu 'l Wefa, because he calls it hypothesis
redintegrata. Tycho used this same phrase in speaking of his
own planetary system, which he most emphatically claimed as

1. Sedillot, Prolegomenes, p. xxxviii. Materiaux pour servir a l' hist. des scienc-
   es chez les Grecs et les Orientaux, T. I. p. 283. The sons of Mūsā ben Sakir
   (about 850) seem to have been the first to find a value differing from that
   of the ancients. Abraham ben Chija, a Jewish writer who lived about A.
   D. 1100 says that Ptolemy found 5°, but that according to the opinion of
   the Ishmaelites it is 4½° (Sphaera mundi, Basle, 1546 p. 102).
2. Lettre a M. Sedillot sur la question de la variation lunaire, Paris, 1862, 15 pp.
   4° and Comptes Rendus, vol. 54, p. 1002.
3. Comptes Rendus, vol. 73, pp. 581, 756, 889; Journal des Savants, 11 Oct.