In the year 1687, when NI. La Loubere returned from his embassy to the king of Siam, he brought along with him a Siamese manuscript, containing astronomical ta bles, and the method of employing them in calculating the places of the sun and moon. These tables were ex plained by the celebrated Cassini, who found that their epoch corresponds to the 21st of March 638 of our xra, and that they are founded on the supposition that the tropical year is 365d 5h 50' 40", a determination which differs only 1' 53" from that which is employed in the new solar tables of Delambre. These tables involve also the equation of the sun's centre, the two chief equations of the moon, and the Metonic cycle of 19 years. Two other sets of astronomical tables, one from Chrisna bouram, and the other from Narsapour, were sent to Paris by the missionaries in Hindostan ; but they did not excite the notice of astronomers till M. Gentil returned from India, possessed of the new tables of Tirvalore, and instructed by the Brahmins in their methods of cal culation. These precious remains of antiquity have been diligently examined and compared by the celebrated M. Bailly, in his Traite De l'4stronomie Indienne et Orientate, with that sagacity and eloquence which characterise all the writings of that illustrious but unfortunate astrono mer. He has found that the epoch of the Tirvalore tables coincides with the year 3102 before the Christian xra, and has shown, by a train of sound and convincing argu ment, that this epoch is not fictitious, but founded on real observations, which must have been made even be fore the commencement of the Caly-Yug. These high pretensions to antiquity, which M. Bailly has claimed for the Indian astronomy, have been admitted by many distinguished philosophers, and have been recently de fc nded by our countryman Professor Playfair, with an acuteness of reasoning, and a clearness of illustration, peculiar to that eloquent writer. On this subject, how ever, a difference of opinion still exists among astrono mers. La Place has endeavoured to prove, though not with his usual success, that the epoch of 3102 was in vented for the purpose of giving a common origin in the zodiac to all the motions of the heavenly bodies, and that the tables have either been constructed or corrected in modern times ; but he at the same time allows, that the remarkable accuracy of the mean motions assumed in their construction, could have arisen only from very ancient observations. Other astronomers, less candid than La Place, and less entitled to pronounce a decided opinion, have ascribed the astronomy of the Indians to the instructions which they received from Pythagoras ; while another class has maintained, that astronomy was carried to India by the Arabs, about the middle of the ninth century. The merits of these different opinions our readers will be able to appreciate, from a general view of the reasoning employed by Bailly and professor Playfair.
If the epoch of 3102 is fictitious, and has been deter mined by calculation, from observations of a modern date, the mean places of the sun and moon assumed at that period, the inequalities in the mo of these lu minaries, the obliquity of the ecliptic, ngth of the tropical year, and the places of the fix stars, must all differ from their real values, or those which would have been ascertained from actual observation, by quan tities depending in some measure on the errors of the modern epoch, but chiefly on those minute variations arising from the theory of gravity, which the elements themselves have undergone, and which were discovered only towards the close of the 18th century. If we should therefore find that all these elements, as assumed at the epoch of 3102, are nearly the same as if they had been then determined by observation, or as if they had been deduced from a modern epoch, by calculations in volving the acceleration of the moon, the variation in the precession of the equinoxes, the change of the obli quity of the ecliptic, &c. we have only two alternatives, either to believe that the epoch of 3102 is real, and the Indian astronomy of high antiquity ; or, that the Brah mins, at the period of the modern epoch, were com pletely acquainted with the theory of gravity, and with all the refinements of modern analysis.
From the delineation of the zodiac, for example, which La Gentil brought from India, it appears that the star Aldebaran was 40 minutes before the vernal equinox in 3102. Now if we take the precession of the equinoxes at 50.r, and employ the inequality in the precession dis covered by La Grange, we shall find, by calculating from the place of Aldebaran in 1750, that in the year 5102 this star was 13 minutes beyond the vernal equinox, a result differing only 53 minutes from the Indian zodiac. But the force of this argument does not terminate here : even if the Brahmins had been acquainted with the in equality of precession, and had applied it to the modern epoch of 1491 B. C., the 3 seconds of excess which they
gave to the precession itself, would have produced an error of 49' 39" at the epoch of 3102.
The mean longitude of the sun, according to the Brahmins at the epoch of the tables of Tirvalore, is Do' and according to the modern tables, corrected by the inequality of precession discovered by La Grange, and amounting in the present case to 1° 45' 22", the longitude of that luminary is 10' 2° 51' 19", differing only about 47 minutes from the determination of the Indians. The longitude of the moon at the same epoch, by the Tirvalore tables, is 10' 0', and the same com puted from the tables of Mayer, and corrected by tlif moon's acceleration, is 10' 6° 37; a coincidence so re markable, that it could arise only from actual observa tion. Now if we compute the places of the sun and moon, at the commencement of the Cali-Yug, front the tables of the Greek and Arabian astronomers, or from those of Ulugh-Beigh, which were constructed at Samercand in 1437, we shall find that the tables of Ptolemy give an error of 11° in the place of the sun and moon, while the tables of the Tartar prince produce an error of 30' in the place ol the sun, and of 6° in that of the moon. These results give additional strength to the former argument, and completely prove that the Indian astro nomy is not the offspring ol Greece or Arabia ; and that the epochs of the Tirvalore tables were not deduced from modern observations. Arguments of a similar na ture, and equally strong with the preceding, might be deduced from the obliquity of the ecliptic, the length of the solar year, the aphelion and mean motion of Ju piter, and the mean motion of Saturn and the equation of his centre, as contained in the Indian tables ; but from the limits ol this article, we must refer our read ers for further information to the writings of Bailly and professor Playfair.
From the general view which we have now given of the astronomy of the ancients, the mind is necessarily led to the conclusion which Bailly has drawn, that the rules and facts of the Egyptian, Chaldean, Indian, and Chinese astronomy, are but the wrecks of a great system of astronomical science, which has been carried to a high degree of perfection in the early ages of the world. After those mighty revolutions in human affairs, amid which the principles of the science have been lost, the study of astronomy seems to have revived about the year 3102, when the loose materials which time had spared, were carefully collected and diffused through the different kingdoms of Asia. Hence the striking connection that subsists between the various systems which prevailed among the eastern nations, and hence the numerous fragments of the science which have been transmitted to the present day. In examining these wrecks of the human mind, we every where find me thods of calculation without the principles on which they are founded ; rules blindly followed without being understood ; phenomena without their explanation ; and elements carefully determined, while others more im portant, and equally obvious, are altogether unknown. We cannot therefore regard these unconnected facts as the highest efforts of the ancients in the science of as tronomy, or as results which they have reached without the light of theory, or without the aid of long continued observation. When the traveller contemplates the re mains of ancient cities, and examines the broken sta tues, the shafts, and capitals, and pediments which are dug from their ruins, does he consider these fragments as the highest eflOrts of the sculptor and the architect in the arts which they cultivated ? Does he not rather turn in imagination to the columns and statues which they composed, to the temple which they supported or adorned, and to the living beings that worshipped within its walls ? Whatever objections may be urged against these opi nions, let it not be said that they are inconsistent with the truths of revealed religion. The sacred scriptures are not to be affected by any variations in chronological dates, or by any opinions, however extravagant, respect ing the age of the world ; and surely those men are the greatest enemies of their faith, who fix it on such a slender basis. It is as foreign from the object of reve lation to instruct us in chronology and astronomy, as it is from that of science to teach us how we should act, and what we should believe. The speculations of phi losophy will not be confined within the limits of vulgar theory, nor will the human mind suffer itself to be chain ed down from its noble flight. The attempts which have been made to check its progress, are, we hope, the last efforts of expiring bigotry ; and we trust the hazardous experiment will never be repeated among a civilized people, of attempting to raise an altar to their God upon the ruins of the temple of science.