THE SURFACE OP THE GLOBE. 113 



andria, may have confounded the epochs. Diodorus* and Strabof 

 only give a similar year to the Thebans ; they do not say that it was 

 generally adopted, and they lived long after Herodotus. 



Thus the sothaic year, the great year, may have been but a modern 

 invention, since it results from a comparison of the civil year with 

 this pretended heliac year of Sirius ; and that accounts for its not 

 being spoken of before the writings of the second and third century 

 after Christ +, and that Syncellus alone, in the ninth century, seems to 

 quote Manetho , as having mentioned it. 



Whatever may be said on the subject, we have the same ideas of the 

 astronomical science of the Chaldeans. That a people inhabiting vast 

 plains, under a sky always serene, may have been led to observe the 

 course of the stars even from the times when they were wandering 

 tribes, and when the stars alone could guide them at night, is natural. 

 But since what period did they become astronomers, and how far have 

 the)^ carried the science of astronomy ? That is the question. It is 

 agreed that Callisthenes sent Aristotle observations made by them, 

 which went as far back as 2200 years before Christ. But this is stated 

 only by Simplicius §, according to the authority of Porphyry, and six 

 hundred years after Aristotle. Aristotle himself makes no mention of 

 it; no accredited astronomer spealvs of it. Ptolemseus relates and 

 makes use of ten observations on eclipses really made by the Chal- 

 deans ; but it only goes back to Nebuchadnezzar (721 years before 

 Christ) ; they are incorrect ; the time is only expressed in hours and 

 half hours, and the obscuration only in half or quarter diameters. 

 However, as they had certain dates, the Chaldeans must have had 

 some knowledge of the accurate length of the year, and some method 

 of measuring time. They appear to have known the period of eigh- 

 teen years, which brings back the eclipses of the moon in the same 

 order, and which the mere inspection of their registers would have 

 informed them quickly ; but it is certain that they neither knew how 

 to explain nor foretel the eclipses of the sun. 



Cassini and Bailey, having misunderstood a passage in Josephus, have 

 asserted that they had discovered in it a iuni-solar period of six hun- 

 dred years, which must have been known to the early patriarchs || . 



* Bibl. lib. 1, p. 46. f Geogr. p. 102. 



X See the admirable dissertation of M. Biot, on the probable newness of this 

 period, in his researches on many points of Egyptian Astronomy, p. 148, at seq. 



§ See M. Delambre's Hist, d' Astro, v. J, p. 212. See also his Analysis of Ge- 

 minus. ib. p. 211. Compare with them the Memoirs of M. Ideler, on the Astro- 

 nomy of the Chaldeans, 4th vol. of Halma's Ptolemy, p. 166. 



II See Bailey's Hist, of Ancient Astronomy, and M. Delambre's work on the 

 same subject, v. l, p. 3. 



VOL. I. N 



