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

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

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2o6                        ALBERUNTS INDIA.

If  the moon   stands  in  the  eveoi quarters   of  the
ecliptic (i.e. the summer and winter quarters), just the
reverse takes place.
Another           Pulisa adds together the declinations   of   sun   and

Pulisa. ^ moon in vyattpdta, if they stand on different sides of
the solstice, and in 'oaidhritct, if they stand on the same
side of the solstice. Further, he takes the difference
between the declinations of sun and moon in vycttipdtct,
if they stand on the same side, and in vaidhritct, if they
stand on different sides. This is the first value which
is kept in memory, i.e. the middle time.

Further, he reduces the minutes of the days to mdshas,
supposing that they are less than one-fourth of a day.
Then he computes their motions by means of the hhukti
of sun and moon and the dragon's head and tail, and
he computes their places according to the amount of
middle time, which they occupy, in the past and the
future. This is the second value which is kept in
memory.

By this method he manages to find out the condition
of the past and the future, and compares it with the
middle time. If the time of the two declinations
equalling each other for both sun and moon is past
or future, in that case the difference between the two
values kept in memory is the portio divisionis (divisor) ;
but if it is past for the one and future for the other,
the sum of the two values kept in memory is the pjortio
divisionis.
p.ige 300.          Further, he multiplies the minutes of the days,'which

have been found, by the first value kept in memory,
and divides the product by the portio divisionis. The
quotient represents the minutes of the distance from the
middle time which minutes may either be past or future.
Thus the time of the two declinations equalling each
other becomes known.

The author of the canon Karctnatilaka makes us
return to the arc of the declination which has been
  Page 206