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

of 29-30 and as such falls short of a lunation and (4) that
the minimum length of a Solar month is 29-20-40 only.
Then he gives a general and broad explanation as to how a
Kshayamāsa occurs on the following lines. Let us call NS
as the interval between a New Moon and the subsequent
Saṁkrānti. In other words it is the Suddhi. Suppose
Bhādrapada goes without a Saṁkrānti thus becoming an
Adhikamāsa. Then in Āswayuja NS will have a small
value, because the Saṁkrānti S which should have occured
at the general rate of one per a lunation, has not occured
before the lapse of Bhādrapada and being belated a little
must have occured close on the heels of the New Moon of
Bhādrapada. Let this interval NS have a particular value
say x. Thereafter the Solar months grow gradually smaller
i.e. the Saṁkrāntis occur earlier ; so in Kārtica the value
of NS decreases. It might decrease to such an extent that
the next Saṁkrānti might occur before the next New Moon.
Suppose this does not happen in Kārtica ; then in Marga-
sira the value of this NS is still smaller and there is a
greater likelihood of another Saṁkrānti occuring during this
Mārgasira. Then the value of NS being the smallest in
the month of Pausha, another Saṁkrānti is bound to take
place during this month at the latest. In other words S
now occurs before the next N i.e. the Saṁkrānti occurs just
a little before the next New Moon. Let now this SN be a
small quantity say y; or what is the same the next NS or
the Suddhi will be nearly a lunation. There after the
Solar months begin to gain in length i.e. S occurs later and
later. This means NS gains in length. Being nearly of
a length equal to a lunation, and now gradually increasing
it is bound to exceed a lunation shortly thereafter. This
again means that S occurs later than the next New Moon,
which is to say that one more lunation goes without a
Saṁkrānti. Thus it is that another Adhikamāsa occurs
shortly after the occurence of a Kshayamāsa. Hence in
the course of one year there occur two Adhikamāsās and
one Kshayamāsa which means again that the balance of an