166 THE GREEK ASTRONOMY. 



not be accepted as a real event: for during the 

 next ten centuries, we find no single observation, 

 or fact, connected with astronomy, in the Chinese 

 histories ; and their astronomy has never advanced 

 beyond a very rude and imperfect condition. 



We can only conjecture the mode in which the 

 Chaldeans discovered their period of 18 years; and 

 we may make very different suppositions with re- 

 gard to the degree of science by which they were 

 led to it. We may suppose, with Delambre 54 , that 

 they carefully recorded the eclipses which hap- 

 pened, and then, by the inspection of their registers, 

 discovered that those of the moon recurred after 

 a certain period. Or we may suppose, with other 

 authors, that they sedulously determined the mo- 

 tions of the moon, and having obtained these with 

 considerable accuracy, sought and found a period 

 which should include cycles of these motions. This 

 latter mode of proceeding would imply a consider- 

 able degree of knowledge. 



It appears probable rather that such a period 

 was discovered by noticing the recurrence of 

 eclipses, than by studying the moon's motions. 

 After 6585J days, or 223 lunations, the same 

 eclipses nearly will recur. It is not contested that 

 the Chaldeans were acquainted with this period, 

 which they called Saros ; or that they calculated 

 eclipses by means of it. 



54 A. A.; P . 212. 



