सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

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is due to occur during the course of the year, though it
has occured has been lost. So, to make amends, another
Adhikamāsa is to occur as is warranted by the convergents
cited above. It might be asked what if two Adhikamāsas
occur and why a Kshayamāsa be instituted at all. The
reason is not that a religious convention warrants it
but because the wedding of the luni-Solar year to the
Solar year has to be made on a particular principle. Nor-
mally, so long as a Samkramaṇa goes on occuring during
the course of a lunation, the two systems of reckoning
may be seen to be running parallel. But if a particular lunar
month does not contain a Samkramaṇa it is to be taken
as a warning that the luni-Solar reckoning has overtaken
the Solar by one lunation. This lunar month has to be
curtailed to make the two kinds of reckoning to proceed
side by side. This convention naturally raised the ques-
tion as to how to deal with a lunation which contains two
Saṁkrāntis. The Solar month their has to be deleted to
make the two systems run concurrently. This deletion of
a Solar month is achieved not by declaring the particular
Solar month as an Adhikamāsa but what is virtually the
same two lunar months are deemed to lapse during the
course of that solar month. This kind convention helped
the occurrence of one Adhikamāsa alone as scheduled be-
cause one of the two Adhikamāsas has been nullified by
the convention of a Kshayamāsa.
Why the proposition that a Kshayamāsa generally
occurs when the Śuddhi at the beginning of the Solar year
happens to be 21 tithis is quite evident because in such a
case generally Bhādrapada becomes an Adhikamāsa, which
again entails the occurence of two Samkramaṇas during the
course of one of the three lunations beginning with
Kārtica, which happen to be longer than the corresponding
Solar months. In other words a Kshayamāsa is expected
to occur only when Bhādrapada happens to be an Adhika-
māsa, and this in turns happens only when the Śuddhi
happens to be 21 at the beginning of the Solar year. Adhi-