OUTLINES OF NATURAL PHILOSOPHY. 



for being that to which chronologists refer the 

 creation of the world. At that period, the length 

 of time during which the sun was in the northern 

 signs, that is, on the north side of the equator, 

 was precisely the same with that on which he was 

 on the south, each being exactly half a year. At 

 present, the apogee, where the sun's motion is 

 slowest* being in the ninth degree of Cancer, 

 more time by 7 d 16 b 30 m 8 s is consumed in the 

 northern than the southern signs ; so great is the 

 change which the motion of the apsides has pro- 

 duced. About 464 years ago, the apogee was in 

 the beginning of Cancer. 



d. When we would calculate the place of the sun for 

 any time, (especially if very distant), we must be- 

 gin with determining the position of the line of 

 the apsides ; as it is from the lower apsis that the 

 mean and true anomaly are both computed. 



e. The motion of the sun's apsides being 19' 4" in a 

 century, with respect to the fixed stars, it requires 

 a period of more than 108000 years to complete 

 their siderial revolution. Their tropical revolu-* 

 tion is 20903 years. 



112* By a comparison of distant observations, 

 the equation of the centre, and of consequence 

 the eccentricity of the sun's orbit, are discover- 

 ed to be continually diminishing. 



The 



