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

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

Tools


 

Jump to page:

Table of Contents

  Page 207  



CHAPTER LXXIX.                          207

kept in memory.    If the corrected place of the moon Another
is less than three zodiacal signs, it is that which we the author
want; if it is between three and six signs, he subtracts natnaka.
it from six signs, and if it is between six and nine
signs, he adds six signs thereto ; if it is more than nine
signs, he subtracts it from twelve signs.    Thereby he
gets the second place of the moon, and this he compares
with the moon's place at the time of the correction.
If the second place of the moon is less than the first,
the time of the two declinations equalling each other is
future; if it is more than the first, the time of their
equalling each other is past.

Further, he multiplies the difference between the two
places of the moon by the bhukti of the sun, and divides
the product by the bhukti of the moon. The quotient
he adds to the place of the sun at the time of the cor¬
rection, if the second place of the moon is larger than
the first; but he subtracts it from the sun's place, if the
second place of the moon is less than the first. Thereby
he finds the place of the sun for the time when the two
declinations are equal to each other.

For the purpose of finding it, he divides the difference
between the two places of the moon by the bhukti of
the moon. The quotient gives minutes of days, indi¬
cative of the distance. By means of them he com¬
putes the places of sun and moon, of the dragon's head
and tail, and of the two declinations. If the latter are
equal, it is that which we want to find. If they are
not equal, the author repeats the calculation so long
till they are equal and till the correct time has been
found.

Thereupon he computes the measure of sun and moon.
However, he disregards half of the sum of them, so that
in the further calculation he uses only the one half of
their measures. He multiplies it by 60 and divides the
product by the bhuktyantarct. The quotient represents
the minutes of the falling (pdtct ?).
  Page 207