184 THEOltY OF THE EARTH. 



had for many ages applied themselves to such in- 

 vestigations. 



In order to determine the force of this argu- 

 ment, it is necessary that we should here enter 

 upon some explanations. 



The solstice is the moment of the year at 

 which the rise of the Nile commences, and that 

 which the Egyptians must have observed with 

 most attention. Having, at the beginning, made, 

 from imperfect observations, a civil or sacred year 

 of three hundred and sixty-five days complete, 

 they would preserve it from superstitious motives, 

 even after they had perceived that it did not agree 

 with the natural or tropical year, and did not 

 bring back the seasons to the same days *. How- 

 ever, it was this tropical year which it behoved 

 them to mark for the purpose of directing them 

 in their agricultural operations. 



They would, therefore, have to search in the 

 heavens for an apparent sign of its return, and 

 they imagined they had found this sign when the 

 sun returned to the same position, relatively to 

 some remarkable star. Thus they applied them- 

 selves, like almost all nations who are beginning 



* Geminus, who was cotemporary with Cicero, explains 

 their motives at length. See M. Halma's edition at the end 

 of the Plolomee, p. 43. 



