Bīrūnī, Muḥammad ibn Aḥmad, Alberuni's India (v. 1)

(London :  Kegan Paul, Trench, Trübner & Co.,  1910.)



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CHAPTER XXVI.                           277

refute them by saying that, if such were the case, stones
and trees would fall from the earth."

But Brahmagupta does not agree with them, and says
that that would not necessarily follow from their theory,
apparently because he thought that all heavy things are
attracted towards the centre of the earth. He says :
" On the contrary, if that were the case, the earth would
not vie in keeping an even and uniform pace ivith the
minutes of heaven, the prdnas of the times."

There seems to be some confusion in this chapter,
perhaps by the fault of the translator. For the minutes
of heaven are 21,600, and are called prdna, i.e. breaths,
because according to them each minute of the meridian
revolves in the time of an ordinary human breath.

Supposing this to be true, and that the earth makes
a complete rotation eastward in so many breaths as
heaven does according to his (Brahmagupta's) view, we
cannot see what should prevent the earth from keeping
an even and uniform pace with heaven.

Besides, the rotation of the earth does in no way im¬
pair the value of astronomy, as all appearances of an
astronomic character can quite as well be explained
according to this theory as to the other. There are,
however, other reasons which make it impossible.
This question is most difficult to solve. TJie most pro¬
minent of both modern and ancient astronomers have
deeply studied the question of the moving of the earth,
and tried to refute it. We, too, have composed a book
on the subject called Miftdh-ilm-alhai'a (Key of
Astronomy), in which we think we have surpassed our
predecessors, if not in the words, at all events in the
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