Among the Jews there are traditions of a very high antiquity for their astronomy. Josephus assures us that it was cultivated before the Mosaic Deluge. According to him it is to the public spirit and the labour of the antediluvians that we owe the science of astrology: "and since they had learnt from Adam that the world should perish by water and by fire, the fear that their science should be lost, made them erect two columns, one of brick the other of stone, on which they engraved the knowledge they had acquired, so that if a deluge should wash away the column of brick, the stone one might remain to preserve for posterity the memory of what they had written. The prescience was rewarded, and the column of stone is still to be seen in Syria." Whatever we may think of this statement it would certainly be interesting if we could find in Syria or anywhere else a monument that recorded the ancient astronomical observations of the Jews. Ricard and others believe that they were very far advanced in the science, and that we owe a great part of our present astronomy to them; but such a conjecture must remain without proof unless we could prove them anterior to the other nations, whom, we have seen, cultivated astronomy in very remote times. One observation seems peculiar to them, if indeed it be a veritable observation. Josephus says, "God prolonged the life of the patriarchs that preceded the deluge, both on account of their virtues, and to give them the opportunity of perfecting the sciences of geometry and astronomy which they had discovered; which they could not have done if they had not lived for 600 years, because it is only after the lapse of 600 years that the _great year_ is accomplished." Now what is this great year or cycle of 600 years? M. Cassini, the director of the Observatory of Paris, has discussed it astronomically. He considers it as a testimony of the high antiquity of their astronomy. "This period," he says, "is one of the most remarkable that have been discovered; for, if we take the lunar month to be 29 days 12h. 44m. 3s. we find that 219,146-1/2 days make 7,421 lunar months, and that this number of days gives 600 solar years of 365 days 5h. 51m. 36s. If this year was in use before the deluge, it appears very probable it must be acknowledged that the patriarchs were already acquainted to a considerable degree of accuracy with the motions of the stars, for this lunar month agrees to a second almost with that which has been determined by modern astronomers." A very similar argument has been used by Prof. Piazzi Smyth to prove that the Great Pyramids were built by the descendants of Abraham near the time of Noah; namely, that measures of two different elements in the measurement of time or space when multiplied or divided produce a number which may be found to represent some proportion of the edifice, and hence to assume that the two numbers were known to the builders.