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.