Astronomy is the most ancient of all the sciences. The Chaldeans, the Egyptians, the Chinese, the Hindoos, Gauls, and Peruvians, each regarded themselves as the inventors of astronomy, an honour which Josephus deprives them of by ascribing it to the antediluvian patriarchs. From the few facts to be gleaned out of the vague accounts by ancient authors regarding the Chaldeans, it may be inferred that their boasted knowledge of this science was confined to observations of the simplest kind, unassisted by any instruments whatever. The Egyptians, again, though anciently considered the rivals of the Chaldeans in the cultivation of this science, have yet left behind them still fewer records of their labours, though it is so far certain that their astronomical knowledge was even greater than that of the Chaldeans. The Phoenicians seem to have excelled in the art of navigation, and would no doubt direct their course among the islands of the Mediterranean by the stars; but if they had any further speculative notions of astronomy, they were probably derived from the Chaldeans or Egyptians. In China, astronomy has been known from the remotest ages, and has always been considered as a science necessary and indispensable to the civil government of the Celestial Empire. On considering the accounts of Chinese astronomy, we find it consisted only in the practice of certain observations, which led to nothing more than the knowledge of a few isolated facts, and they are indebted to foreigners for any further improvements they have since adopted. The Greeks seem to have made the most early advances in astronomy; for notwithstanding that the art of observation was still in its infancy, we are indebted to the labours and speculations of ancient Greek philosophers for raising astronomy to the dignity of a science. The complicated but ingenious hypotheses of the Greek Ptolemy prepared the way for the discovery of the elliptic form of the planetary orbits and other astronomical laws by the German Kepler, which again conducted our English Newton to the discovery of the law of gravitation. I am not, however, desirous of giving this meeting a lecture on astronomy--I shall leave that to Professor Grant. But it is singular that I should have come here on a day on which one of the now known observations and movements of the planets has taken place--the transit of Mercury. This was calculated to occur this day by the science of astronomy, and it is also known when it will again occur, namely, on the 6th of May 1878. I will end this subject by saying, that the discoveries in astronomy in the last and present centuries have been so many and interesting, that it would be quite impossible for me to enter here minutely upon them.