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

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



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CHAPTER LIII.                             55

which in the method of ahargana deviate to some other
process. Unfortunately that which we possess of the
book is badly translated. What we are able to quote
from it is the following :—•

He subtracts 821 from the years of the Sakakala.
The remainder is the basis. This would be the year
132 for our gauge-year. He writes down this number
in three different places. He multiplies the first num¬
ber by 132 degrees. The product gives the number
17,424 for our gauge-date. He multiplies the second
number by 46 minutes, and gets the product 6072.
He multiplies the third number by 34, and gets the
product 4488. He divides it by 50, and the quotient
represents minutes, seconds, &c., viz. 89' ^6". Then
he adds to the sum of degrees in the upper place
112, changing the seconds to minutes, the minutes to
degrees, the degrees to circles. Thus he gets 48 circles
358° 41' 46''. This is the mean place of the moon when
the sun enters Aries.                                                 •

Further, he divides the degrees of the mean place of
the moon by 12. The quotient represents days. The
remainder of the division he multiplies by 60, and adds
thereto the minutes of the mean place of the moon. He
divides the sum by 12, and the cjuotient represents Page 230.
ghatis and minor portions of time. Thus we get 27°
23' 29", i.e. ctdhimdsa days. No doubt this number
represents the past portion of the adhimdsa month,
which is at present in the course of formation.

The author, in regard to the manner in which the
measure of the ctdhimdsa month is found, makes the
following remark:—

He divides the lunar number which we have men¬
tioned, viz. 132° 46' 34", by 12. Thereby he gets as
the portio anni 11° 3' 52' 50'", and as the portio mensis
0° 55' 19'' 24"' lO'''. By means of the latter portio he
computes the duration of the time in which 30 days
sum up as  2 years, 8 months,   16  days,  4 ghati, 45
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