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113. The constant and regular motion of the moon along a path in the heavens among the fixed stars once in every month was a phenomenon that forced itself on the notice of Hindū observers from the earliest ages; and they divided the belt through which she passed into Nakshatras. twenty-seven parts called "nakshatras," which corresponded roughly to the twenty-seven and one-third days of her sidereal revolution. These were named after the principal stars or groups of stars lying along, or near to, that belt. But the distance of these groups from one another was seen to be unequal, and different systems were adopted for dividing the 360° of the circle. By the system of Garga, fifteen of the nakshatras are of equal length, viz. 13° 20′, six measure one and a half of this length, viz. 20°, and six measure half a length, or 6° 40 '. Another division was adopted by Brahmagupta in his Brāhma Siddhānta (composed in the year A.D. 628). He maintained the unequal division of the belt, but grounded his measurement on the 13° 10′ 35″ of the moon's daily mean motion instead of 13° 20′, allotting to fifteen nakshatras 13° 10′ 35″ each, to six 19° 45′ 52″ each, or ⁠1+1/2⁠ times, and to six 6° 35′ 17″ each, or one-half. Twenty-seven of these amounting to 355° 45′ 45″, the remainder 4° 14′ 15″ is allotted to a twenty-eighth nakshatra called "Abhijit."

One of these systems was certainly in use as late as A.D. 862, as is proved by the Dēōgaḍh inscription of Bhōjadēva of Kanauj (Fleet and Sh. B. Dikshit, Ind. Ant. XVII., 4, 23, 24; Kielhorn, ibid., XIX., p. 28, No. 30), but how much later and in what tracts is not yet known. The third system of division is called the "equal-space" division, according to which the whole belt of 360° is divided into twenty-seven equal parts, each measuring 13° 20′. This system sometimes, but not always, recognises the existence of the nakshatra Abhijit, but in doing so includes it as contained in parts of the nakshatras Uttara āshaḍhā and Śravana.^[1]

114. The first nakshatra of the cycle, Aśvinī, begins at the first point of the sidereal sign Mēsha.^[2] It ends, and the second begins, by the equal-space system and that of Garga, at 13° 20′, and by the Brāhma Siddhānta at 13° 10′ 35″; the rest in succession. The sun, the moon and the earth's meridian traverse the whole round of nakshatras, the first annually, the second monthly, the third daily; and this gives rise to a number of different chronometric calculations for calendrical and astrological purposes. Thus the sun's position in a nakshatra is often calculated, as well as his position in a zodiacal sign; the nakshatra in which the moon stands at sunrise of each day is one of the most important elements in the Southern calendar, and has been noted and calculated from very ancient times; and, since the earth's rotation brings a meridian round to every point of the heavens, roughly, once in each day,^[3] the time of day when each sign or nakshatra rises on the eastern horizon is calculated. At this moment of rising the particular point of the ecliptic is said to be lagna, "intersecting," "in contact with" the horizon.^[4]

115. The nakshatras were used for purposes of dates certainly as early as the 4th century A.D. The Singhalese chronicle, the Dipavaṁsa, which came to an end about the middle of that century, mentions the nakshatra current at the time of the first anointment of King Dēvānaṁpiya Tissa. It the event as taking place "in the season Hemanta in the second month when the moon was in the Ashaḍhā nakshatra." (J. R. A. S., Jan. 1909, p. 11, n. 2.) But as yet it is impossible to fix any date as that when the use of nakshatras began to be adopted in India for ordinary calendrical purposes. For astrological purposes they were known in late Vedic times. The Kauśika Sūtra of the Atharva describes