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EPIGRAPHIA INDICA.
[VOL. XII.
round. In selecting the day attention should be paid to the character of the year, whether it is a common or a leap year.
The items taken from the tables I-III should be added together; the several sums are the mean Longitudes of the planets for the beginning of the day (mean sunrise at Lauka); e.g. for the 12th April 1168 A.D. our calcalation stands as follows:
Mercury.
80
1968 A.D.
800 Years.
12 April (L)
Sum
orl
281° 50'
197 52
57 25
537° 57 177° 7'
Venus.
159° 49'
233 39
163 25
556° 53' 196° 53'
Mars.
324° 54'
248 21
53 27
626° 42' 266 42
Jupiter.
123° 51'
200 20
8 29
332° 40'
Saturn.
349° 15'
309 28
3 25
662° 8' 302 8
Sun.
256° 8'
19 43
100 32
376° 23'
16 32
Having thus found the mean Longitudes of the 5 planets, we must convert them into true Longitudes. This is rather a wearisome process which requires four calculations for each planet; the process is not the same for all planets, but Mercury and Venus are differently treated from Mars, Jupiter, and Saturn. In these calculations Tablés IV & V, called Commutation and Anomalistic Tables, are to be used as will be explained in the Rules to be given presently. Particular care should, however, be given to the sign of the equations: if the argument is found in the first column (on the left side), the equation is positive; if it is in the last column (on the right sight), it is negative.
Rules for converting mean Longitude into true Longitude.
I-MERCURY AND VENUS.
1. Subtract mean Sun from mean Mercury (or Venus); take out the corresponding equation from the Commutation Table; apply half of it to mean Sun, Result: Mercury (or Venus) once corrected.
2. Subtract Mercury once corrected from Mercury's Apsis (see bottom of table II); take ont the corresponding equation from the Anomalistic Table; apply half of it to Mercury once corrected. Result: Mercury twice corrected.
3. Subtract Mercury twice corrected from Mercury's Apsis; take out the corresponding equation from the Anomalistic Table; apply it (whole) to mean Sun. Result: Mercury thrice
corrected.
4. Subtract Mercury thrice corrected from mean Mercury; take out corresponding equation from the Commutation Table; apply it (whole) to Mercury thrice corrected. Result: true Mercury.
II.-MARS, JUPITER, SATURN.
1. Subtract mean Mars from mean Sun; take out the corresponding equation from the Commutation Table; apply half of it to mean Mars. Result: Mars once corrected.
2. Subtract Mars once corrected from Mars' Apsis (see bottom of Table II); take out the corresponding equation from the Anomalistic Table; apply half of it to Mars once corrected. Result: Mars twice corrected.
3. Subtract Mars twice corrected from Mars' Apsis; take out the corresponding equation from the Anomalistic Table; apply it (whole) to mean Mars. Result: Mars thrice corrected.
4. Subtract Mars thrice corrected from mean Sun; take out corresponding equation from the Commutation Table; apply it (whole) to Mars thrice corrected. Result: true Mars.
1 Subtracting 360° where the Longitude exceeds 360°.
Or Jupiter or Saturn; and so in the sequel.
