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

79 Adhikamāsa is there in that year. In other words, the occurence of a Kshayamāsa during the course of an year as per a stipulated convention does not preclude the average occurence of an Adhikamāsa which is normally due after an average lapse of 32½ Solar months. That the occurence of a Kshayamāsa entails the occurrence of two Adhikamāsās on either side may be also seen in another way. Twelve lunations put together have a length of 354⅓ days approxi- mately during the course of which only eleven Saṁkrāntis could occur in case the initial Śuddhi is 21 days, for, sub- tracting this 21 from 354⅓, there remain 333⅓ days only which could contain only ten Solar months and not eleven. Ten Solar months are contained if there be only eleven Saṁkrāntis. Out of these eleven, two are consumed in a single lunation which happens to be a Kshayamāsa. Hence the remaining eleven lunations have to contain only nine Saṁkrāntis which means that two lunations have to go without Saṁkrāntis. In other words there are to be two Adhikamāsās during that year. Further both these Adhi- kamāsās could not occur on one side of the Kshayamāsa for the following reason. Since a Kshayamāsa could occur only during the course of Kārtica or Mārgasirsha or Pansha which alone are longer than the corresponding solar months, in the event of both the Adhikamāsās taking their place on one side of these months, they are to take place in nine lunations which are on one side of the three months beginning with Kārtica. This means that only seven Saṁkrāntis are to occur during the course of 9 × 29½ days = 265½ days. Even seven Solar months fall short of this period so that it is impossible that only seven Saṁkrāntis should occur in this period. Hence, the two Adhikamāsās which are to occur during the year containing a Kshaya- māsa have to take their place on either side of the Kshaya- māsa. Bhāskara mentions that when the daily motion of the Sun equals 61', the length of the Solar month will be 1800/61 = 29–30 approximately. He also states that the minimum