The present volume is a sequel to my Orion or Researches into the Antiquity of the Vedas, published in 1893. The estimate of Vedic antiquity then generally current amongst Vedic scholars was based on the assignment of arbitrary period of time to the different strata into which the Vedic literature is divided; and it was believed that the oldest of these strata could not, at the best, be older than 2400 B.C. In my Orion, however, I tried to show that all such estimates, besides being too modest, were vague and uncertain, and that the astronomical statements found in the Vedic literature supplied us with far more reliable data for correctly ascertaining the ages of the different periods of Vedic literature. These astronomical statements, it was further shown, unmistakably pointed out that the Vernal equinox was in the constellation of Mṛiga or Orion (about 4500 B.C.) during the period of the Vedic hymns, and that it had receded to the constellation of the Kṛittikâs, or the Pleiades (about 2500 B.C.) in the days of the Brâhmanas. Naturally enough these results were, at first, received by scholars in a skeptical spirit. But my position was strengthened when it was found that Dr. Jacobi, of Bonn, had independently arrived at the same conclusion, and, soon after, scholars like Prof. Bloomfield, M. Barth, the late Dr. Bulher and others, more or less freely, acknowledged the force of my arguments. Dr. Thibaut, the late Dr. Whitney and a few others were, however, of opinion that the evidence adduced by me was not conclusive.