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

ABU L' WEFA AND HIS ALMAGEST 19
an original discovery, and which he vigorously defended against
other claimants. In future it will be hopeless for anybody to
claim the discovery for Abu 'l Wefa as the matter has now been
thoroughly sifted, both by mathematicians and orientalists.
The Almagest of Abu 'l Wefa has never been published in
full, but there are three translations of the chapters in question,¹
which only differ in some trivial points. In no part of the book
does he make any advance on Ptolemy or claim to have made
any new discovery, and in speaking of three inequalities he
merely does what the other Arabian astronomers do.² He begins
by describing the first (equation of the centre) and the second
(evection) and states when they reach their maxima. He then
says that we have found³ a third inequality, which takes place
when the centre of the epicycle is between the apogee and the
perigee of the eccentric, and which reaches its maximum when
the Moon is about a tathlith or a tasdis from the Sun, while it is
insensible in syzygy and quadrature. The maximum is ¾°. He
explains that this is caused by a deviation of the line or apsides
of the epicycle, and he describes quite correctly the construction
adopted by Ptolemy (whose name he does not mention), letting
the line of apsides be directed, not to the Earth but to another
point on the line of apsides of the eccentric. It is difficult for an
unbiassed reader to understand how anyone could fail to see that
Abu 'l Wefa is simply copying Ptolemy. Sedillot maintained
that the words tathlith and tasdis mean the octants (where the
variation reaches its maximum); but every other orientalist who
has expressed an opinion, states that by their roots the words
correspond to the numbers 6 and 3, in other words, to elonga-
tions 60° and 120° from the Sun. This is in accordance with

1. By Reinaud, Munk, and de Slane(for Biot)in the Journal des Savants, Mar-
   ch, 1845 (14 pp. the whole section on the Moon) ; by Sedillot, Materiaux, i.
   pp. 45--49 ; and by Carra de Vaux, “L’ almageste d’ Abu 'l Wefa
   Albūzdjani,” Journal asiatique, 8° Serie, T. xix. (1892), pp. 408--471
   (translation on pp. 443-44). Most of the chapters on the planets are lost.
2. The unknown author of a short resume of astronomy (in the Bibl. Nationale)
   even calls the inequality of prosneusis the first equation (Carra de Vaux,
   1.c. p. 460). This is not unreasonable, since the equation of the centre
   must be taken from the lunar tables, using as argument not the mean
   anomaly but the latter corrected for the effect of the prosneusis.
3. He uses exactly the same expression when speaking of the first and second
   inequalities.