OUTLINES OF NATURAL PHILOSOPHY. 



the earth's rotation. The decisive facts have not 

 yet occurred, which are to determine, whether or 

 not a motion of translation belongs also to that 

 body. 



In order that the theory of the elliptical motion may 

 have its conclusions extended either to the future 

 or the past, a very accurate measure and reckon- 

 ing of time are necessary, and we are now in pos- 

 session of the data by which these may with cer- 

 tainty be obtained. 



Of the Equation of time 9 and of the Kalendar. 



The arrival of the Sun in the meridian, being a more 

 conspicuous phenomenon than that of a Star, has 

 been taken to mark the beginning and end of the 

 day, used for the purposes of civil life. Solar time, 

 consists of days measured in this manner, and is 

 used by astronomers, as well as by the people at 

 large. Astronomers begin the day at noon, and 

 reckon 24< hours round to noon again : in the com- 

 mon reckoning, the day begins at midnight, and 

 is divided into 24 hours, which are counted by 12 

 and 12. LA PLACE has proposed, that in this 

 the astronomers should follow the people, as, by 

 beginning the day at midnight, the whole of the 

 sun's stay above the horizon falls in the same day. 



104. The 



