Astronomy.--The knowledge of the ancients as to astronomy was great and accurate. Callisthenes, who accompanied Alexander the Great to Babylon, sent to Aristotle a series of Chaldean astronomical observations which he found preserved there, recorded on tablets of baked clay, and extending back as far as 2234 B.C. Humboldt says, "The Chaldeans knew the mean motions of the moon with an exactness which induced the Greek astronomers to use their calculations for the foundation of a lunar theory." The Chaldeans knew the true nature of comets, and could foretell their reappearance. "A lens of considerable power was found in the ruins of Babylon; it was an inch and a half in diameter and nine-tenths of an inch thick." (Layard's "Nineveh and Babylon," pp. 16, 17.) Nero used optical glasses when he watched the fights of the gladiators; they are supposed to have come from Egypt and the East. Plutarch speaks of optical instruments used by Archimedes "to manifest to the eye the largeness of the sun." "There are actual astronomical calculations in existence, with calendars formed upon them, which eminent astronomers of England and France admit to be genuine and true, and which carry back the antiquity of the science of astronomy, together with the constellations, to within a few years of the Deluge, even on the longer chronology of the Septuagint." ("The Miracle in Stone," p. 142.) Josephus attributes the invention of the constellations to the family of the antediluvian Seth, the son of Adam, while Origen affirms that it was asserted in the Book of Enoch that in the time of that patriarch the constellations were already divided and named. The Greeks associated the origin of astronomy with Atlas and Hercules, Atlantean kings or heroes. The Egyptians regarded Taut (At?) or Thoth, or At-hotes, as the originator of both astronomy and the alphabet; doubtless he represented a civilized people, by whom their country was originally colonized. Bailly and others assert that astronomy "must have been established when the summer solstice was in the first degree of Virgo, and that the solar and lunar zodiacs were of similar antiquity, which would be about four thousand years before the Christian era. They suppose the originators to have lived in about the fortieth degree of north latitude, and to have been a highly-civilized people." It will be remembered that the fortieth degree of north latitude passed through Atlantis. Plato knew ("Dialogues, Phædo," 108) that the earth "is a body in the centre of the heavens" held in equipoise. He speaks of it as a "round body," a "globe;" he even understood that it revolved on its axis, and that these revolutions produced day and night. He says--"Dialogues, Timæus"--"The earth circling around the pole (which is extended through the universe) be made to be the artificer of night and day." All this Greek learning was probably drawn from the Egyptians.