Let us quote a few aphorisms from Book I of this ancient work.
27. By their [the planets'] movement the revolution is accounted complete at the end of the asterism Revatî.
29. In an age the revolutions of the Sun ... are 4,320,000.
30. Of the Moon 57,753,336.
31. ... of Jupiter 364,220.
32. ... of Saturn 146,568.
33. Of the Moon's apsis 488,203. Of its node, in the contrary direction 232,238.
34. Of asterisms 1,582,237,828.
36. ... From rising to rising of the Sun are reckoned terrestrial civil days.
37. Of these there are in an age 1,577,917,828. Of lunar days 1,603,000,080.
From these figures we find the mean value of the sidereal year during a cycle of 4320 thousand years to be 0.002403 of a day longer than at present, which of course means that there are slow changes in the length of the orbital major axis.
There is a point worthy of attention regarding the asterism Revatî, to which these revolutions are referred, and which is thus seen to mark the origin of the Hindû movable zodiac. The precise star has either disappeared, or has not, so far, been publicly indicated. But the place of the origin was carefully calculated in 1883, and found to have a longitude of about 20.5 degrees. Again, from the numerous facts connected with the important epoch of 3102 b. c., which marked the beginning of the current cycle of 432,000 years (See Traité de l'Astronomie Indienne et Orientale, by M. Bailly, M. Acad. Franç., 1787), its place was about five degrees westward of the other. This shows it to have a positive movement of 4´´ per year, giving one complete revolution in 324,000 years.
This proper motion, if that of an actual star, is of the same order of magnitude as that of many stars. It would perhaps be interesting to glance at the relation between stellar movements and the greater cycles dealt with in ancient astronomy, for all analogy would indicate revolution in orbits to be a general law; and moreover, probabilities would indicate that our system is not too remote from the center of the stellar system. Assuming the average cross speed to be twenty miles per second, stars at 7 light-years distance would make one revolution while the Earth's apsides made four. Those at 70 light-years, one in a "great age." Those at the estimated distance of the farthest visible stars, 5000 light-years, would perform a revolution in just one manvantara of 308 million years.
Doubtless all such revolutions are superposed on other lesser revolutions down to those known, as in cases of double stars, etc. And it may be suggested that there are not improbably a number of axes of revolution, or rather principal planes of revolution, having some harmonious mutual inclination.
In order properly to relate the above mean value of the sidereal year to its present value, we should have to know our place in this cycle of 4320 thousand years; and the same observation applies to the other figures. We may return to this point at another time, as the necessary data are given in the same work. The effect of stellar proper motions, already referred to, would have to be considered.
The figures for the Moon make the mean value of the sidereal month 1.103 seconds longer than its present estimated value.
Those for Jupiter make its mean sidereal period about a quarter of a day shorter than the present one of 4332.58 days; while those for Saturn come out 6.55 days more than the present period of 10,759.22 days.
The methods of calculation and tables connected with the Sûrya-Siddhânta were rigorously applied by M. Bailly to an observed interval extending from the epoch in 3102 b. c. to a certain moment on May 21, 1282 of our era, at Benares—a period of 4383 years and 94 days; and the mean place of the Moon thus found was less than a minute of arc different from that calculated for the same interval by the modern tables of Cassini. An astronomy which could achieve a result like this by methods and tables at least five thousand years old, points to the enormous duration of some prior high civilization.