ITS EARLIEST STAGES. 139 



can hardly be considered as an improvement in the 

 Greek calendar already described. 



The first cycle which produced any near corre- 

 spondence of the reckoning of the moon and the 

 sun, was the Octaeteris, or period of 8 years: 8 

 years of 354 days, together with 3 months of 30 

 days each, making up (in 99 lunations,) 2922 days ; 

 which is exactly the amount of 8 years of 365^ 

 days each. Hence this period would answer its 

 purpose so far as the above lengths of the lunar 

 and solar cycles are exact ; and it might assume 

 various forms, according to the manner in which 

 the three intercalary months were distributed. The 

 customary method was to add a thirteenth month 

 at the end of the third, fifth, and eighth year of 

 the cycle. This period is ascribed to various per- 

 sons and times; probably different persons pro- 

 posed different forms of it. Dodwell places its 

 introduction in the 59th Olympiad, or in the 6th 

 century, B. c. : but Ideler thinks the astronomical 

 knowledge of the Greeks of that age was too 

 limited to allow of such a discovery. 



This cycle, however, was imperfect. The dura- 

 tion of 99 lunations is something more than 2922 

 days; it is more nearly 2923^; hence in 16 years 

 there was a deficiency of 3 days, with regard to 

 the motions of the moon. This cycle of 16 years 

 (Hecccedecaeteris), with 3 interpolated days at the 

 end, was used, it is said, to bring the calculation 

 right with regard to the moon ; but in this way 



