Bīrūnī, Muḥammad ibn Aḥmad, Alberuni's India (v. 2)

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



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equal to the diameter of CD, and its sought-for part is
ZX.    The number which is thus found must be sub¬
tracted from the diameter of the earth, and the remainder
will be ZX."
The author       For such mistakes as occur in this computation, the


the corrupt   author, Brahmagupta, is not to be held responsible, but

state of his                    .-,                                  tip

manuscript   WO rather suspect that the fault lies with the manu-
gupta.   '    script.    We, however, cannot go beyond the text we

Page 241.

have at our disposal, as we do not know how it may be
in a correct copy.

The measure of the shadow adopted by Brahma¬
gupta, from which he orders the reader to subtract,
cannot be a mean one, for a mean measure stands in the
midst, between too little and too much. Further, we
cannot imagine that this measure should be the greatest
of the measures of the shadow, including the plus (?); for
ZF, which is the minus, is the base of a triangle, of
which the one side, EC, cuts SL in the direction of the
sun, not in the direction of the end of the shadow.
Therefore ZF has nothing whatsoever to do with the
shadow (conjectural rendering).
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