Page:Alberuni's India Vol 2.djvu/86

78 equal to the diameter of CD, and its sought-for part is ZX. The number which is thus found must be subtracted from the diameter of the earth, and the remainder will be ZX."

For such mistakes as occur in this computation, the author, Brahmagupta, is not to be held responsible, but we rather suspect that the fault lies with the manuscript. We, however, cannot go beyond the text we have at our disposal, as we do not know how it may be in a correct copy.

The measure of the shadow adopted by Brahmagupta, 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, FC, 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).