Vr.s.asam.kra ̄nti, etc. For the sake of the reader’s convenience the approximate
date ofsam.kra ̄ntisin the modern calendar is given in the second column.
Ama ̄nta and Pu ̄rn.ima ̄nta One should remember that there are two different
systems of naming the month, i.e. ama ̄nta(“new moon ending”) and pu ̄rn.ima ̄nta
(“full moon ending”). In the bright half month (s ́ukla-paks.a) nothing is different,
but in the dark half month (kr.s.n.na-paks.a), the pu ̄rn.ima ̄ntamonth name is ahead
of the ama ̄nta month name by one. Roughly speaking, sough Indian calendars
follow the ama ̄ntamethod, while in north India the pu ̄rn.ima ̄ntasystem has been
used since ancient times.
Intercalary month (adhima ̄sa) Since a lunar month (synodic month) is a little
shorter than a solar month, sometimes there occurs a lunar month which does
not contain any sam.kra ̄nti. Such an additional month (adhima ̄sa) was called by
the name of the following month prefixed by adhika-. In the example of figure
18.2 the month after Vais ́a ̄kha is called Adhika-Jyais.t.ha. An adhima ̄sawas
regarded as inauspicious and no religious ceremony was performed during this
month. Thus it is also called malama ̄sa(“impure month”).
Omitted month (ks.ayama ̄sa) In very rare cases there occurs a month which con-
tains two sam.kra ̄ntis. In such cases the second sam.kra ̄ntidoes not contribute to
the naming of the month and it is omitted as ks.ayama ̄sa. When such a case
happens there are inevitably two adhima ̄sas, one before and the other after the
ks.ayama ̄sa. In such years the first adhima ̄sais called sam.sarpaand the rituals can
be performed as usual. The month containing two sam.kra ̄ntis is called am.haspati,
while the second adhima ̄sa is the adhima ̄saproper when rituals are not performed
(see Kane 1962: vol. 5, p. 671).
The possibility of ks.ayama ̄sawas first mentioned by Bha ̄skara II in his
Siddha ̄ntas ́iroman.i. He correctly remarks that a ks.ayama ̄sausually occurs in
every 141 years and sometimes after the interval of 19 years. According to him,
ks.ayama ̄sais possible only during the three months beginning with Ka ̄rttika. In
figure 18.3 I have shown the case where Paus.a is omitted. The ks.ayama ̄sa shows
the theoretical nature of the Indian calendar.
386 michio yano
Mina-s.k.
330 °Mesa-s.k.
0 °Vrsa-s.k.
30 °Mithuna-s.k.
60 °Palguna Caitra Vaisakha Adhika-Jyaistha·· Jyaistha·····́Figure 18.2: Adhima ̄sa(ama ̄ nta system).