Epigraphia Indica Vol 17

Author(s): F W Thomas, H Krishna Sastri
Publisher: Archaeological Survey of India

Page 42

No. 6.]
THE FIRST ABYA SIDDHANTA, MEAN SYSTEM.
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two exceptions in the nine centuries, embraced im Table LXXVI. Between A.D. 751 and 827 there in a man of five intercalary moan Pausha montha, anda between A.D. 1242 and 1318 there is & run of five interoplany mean Advina month
In eleven instances the names of the mean intercalary months given in Table LXXVI differ from those stated in the Indian Calendars These differences are due to the former calculations having been based on Professor Jacobi's eartiest Tables pablished 30 years ago, while the present ones agree with the results of caloulation made by his more potent elementary fixtures: Each difference is specially notied at foot of Table LXXVI.
The nakshatra. 308. In the mean system the position at any moment of the mean moon in the ecliptio circle, i.o the mean moon's nakshatra; is found by adding her mean distance from the mean sun to the latter's longitude ; that is to say, by adding to the value of the mean sun's longitude) the value of a at the same moment as fonnd by calonlation for the mean tithi.. All work by the Tables being in the first instance for the mean positions of sun and moon at mean sunrise of any day, Table LXXX provides the sun's mean long., ., in 10,000ths of the circle, for each period of 24-hours measured from the moment of mean Mosha sankranti, while Table LXXXI states the same inorense for fractions of the day. To obtain the value of e for mean sunrise of any day it is necessary to note fired its valde after the interval of days between the day of Masha. samkranti and the given day (Table LXXX), and, since that value is measured from the moment of Megha-sadikrinti and not from mean sunrise, afterwards to deduet from the value so obtained the increase daring that fraction of the day (Table LXXXI), The result is the required s, or the mean sun's long. at mean sunrise of the given day, Then staan, the nakshatra inder required, or the mean moon's place in the echiptio cirolorat mean sunrise of that
day:
The Rula for work, then, is as follows. Find the value of a (=t), the mean tithi-index at mean sunrise of the given day (Estample 2 below). Note the serial number of the day as measured from Jan. 1. Deduct from this the serial number of the day of mean Moha-sankranti (Table LXXVI, col. 18, in brackets). This gives the number of intervening days. Turn to Table LXXX and note the value of against that interval of days. Deduct from this the mean ean's movement given in Table LXXXI during the hours and miuutes stated in Table LXXVI, col. 17. The result is the required value of at mean sunrise of the given day. Add , to a.. This = n, the required nakshatra-index. Table LXVIII above, or Table VIIT, Indian Calendar, gives the name of the nakshatra
The Tables. 309. Table LXXVI corresponds to Table I. Indian Calendar in formation and is to be used in the same way. Here the value of a is the valne of t. It gives the tithi-index direct without further calonlation,
Table LXXVII shows the duration and colleetive duration of mean solar months, and the increase in the moon's phase, a, during each such month.
Table LXXVIII givee the value of a at the beginning of each Kaliyaga centary.
Table LXXIX corresponds, with a necessary shift of position, to Table LXXIV above, the nse of which is fully explained in my former papers, $$ 279, 301.
1 To find the valae of a, ort, i.e. the exact moon's phare, in 10,000ths of the circle, at any moment of any dey, note its valde at mean sonrise of the Brit civil day of the lani-solar yop, mgiven in Table LXXVI (col. 28), and add its value for intervening dayshours, etc. (Tablas LIV, LXV. under heading a).