ITS EAELIEST STAGES. 123 



nearly than lie could ascertain from any evidence and calculation 

 known to him. It is so exact that it is still used in calculating tin- 

 new moon for the time of Easter; and the Golden Number, which is 

 spoken of in stating such rules, is the number of this Cycle correspond- 

 ing to the current year. 24 



Metou's Cycle was corrected a hundred years later (330 B. c.), by 

 Calippus, who discovered the error of it by observing an eclipse of the 

 moon six years before the death of Alexander." In this corrected 

 period, four cycles of 19 years were taken, and a clay left out at the 

 end of the 76 years, in order to make allowance for the hours by which, 

 as already observed, 6940 days are greater than 19 years, and than 

 235 lunations : and this Galippic period is used in Ptolemy's Almagest, 

 in stating observations of eclipses. 



The Metonic and Calippic periods undoubtedly imply a very con- 

 siderable degree of accuracy in the knowledge which the astronomers, 

 to whom they are due, had of the length of the month ; and the first 

 is a very happy invention for bringing the solar and lunar calendars 

 into agreement. 



o 



The Roman Calendar, from which our own is derived, appears to 

 have been a much less skilful contrivance than the Greek ; though 

 scholars are not agreed on the subject of its construction, we can hardly 

 doubt that months, in this as in other cases, were intended originally 

 to have a reference to the moon. In whatever manner the solar and 

 lunar motions were intended to be reconciled, the attempt seems alto- 

 gether to have failed, and to have been soon abandoned. The Roman 

 months, both before and after the Julian correction, were portions of 

 the year, having no reference to full and new moons ; and we, having 

 adopted this division of the year, have thus, in our common calendar, 

 the traces of one of the early attempts of mankind to seize the law of 

 the succession of celestial phenomena, in a case where the attempt was 

 a complete failure. 



Considered as a part of the progress of our astronomical knowledge, 

 improvements in the calendar do not offer many points to our observa- 

 tion, but they exhibit a few very important steps. Calendars which, 

 belonging apparently to unscientific ages and nations, possess a great 

 degree of accordance with the true motions of the sun and moon (like 



34 The same cycle of 19 years has been used by the Chinese for a very great 

 length of time ; their civil year consisting, like that of the Greeks, of mouths of 23 

 and' 80 days. The Siamese also have this period. (Astron. Lib. U. K.) 



25 Delamb. A. A. p. 17. 



