398 POPULAR SCIENCE MONTHLY. 



undated among the Greeks from Thales to Aristotle, and also ac- 

 quainted with all the progress in the physical and mathematical 

 sciences that had been achieved by the Alexandrian astronomers in 

 the last centuries before Christ. To comprehend the extent of the 

 influence of Hellenic science, we have only to inquire what Hindu 

 astronomy had bcome again at the time of the restoration of the 

 Brahmans in the sixth century A. D. Aryabha'tta teaches the rota- 

 tion of the earth around its axis ; maintains that the moon, naturally 

 dark, owes its light to the rays of the sun; formulates the true theory 

 of eclipses; assigns an elliptical form to the planetary epicycles; and 

 demonstrates the displacement of the equinoctial and solstitial 

 points. Varaha-Mihira devotes himself especially to astrological 

 labors, but also has the merit of having condensed into a vast ency- 

 clopaedia the Pantcha Siddhantika, the principal astronomical trea- 

 tises that were current in India. And Brahmazoupta is especially 

 famous for his revision of an older treatise, the Brahma Siddhdnta. 



In the opinion of the most competent critics, these works, which 

 are chiefly empirical methods of determining the positions of the 

 stars, are inferior to those which the Alexandrians have left us. 

 Yet, in matters relating to the measurement of arcs and to spherical 

 trigonometry, they reveal a more advanced state of the science. It 

 is impossible to determine at what period this new astronomical sci- 

 ence was constituted in India. Some of its theories squarely betray 

 their indebtedness to Greek science, as, for instance, that of the dis- 

 placement of the equinoctial and solstitial points by a periodical 

 vibration or tremor. We can also say as much of the solar zodiac, 

 the names of the constellations of which strikingly resemble the 

 Greek names in form as well as in significance, and the same of the 

 names of the chief planets. Other expressions are found, notably 

 in the works of Vahara-Mihira, which indicate, if not a borrowing, 

 a contact, at least, with the works of the Greek astronomy, of which 

 Mr. Burgess gives a fairly complete list in his Notes on Hindu As- 

 tronomy and the History of our Knowledge of it, in the Journal of 

 the Royal Asiatic Society. Among these terms, some are Greek 

 words which have been utilized in naming constellations or astro- 

 nomical measures; others have retained the special significations 

 which they had in the works of the Alexandrian astronomers. It 

 would certainly be an exaggeration to insist that the adoption of a 

 foreign term of necessity implies the borrowing of the idea which 

 it expresses. It is, nevertheless, probable that the Sanskrit writers 

 would not have made use of so many of these exotic denominations 

 if the ideas they represent had already found their expression in 

 the languages of India. 



Further, among the fine Siddantas which Varaha-Mihira col- 



