458 COSMOS. 



Uranus 0-0466108 



Neptune 0-00871946 



The motion of the major axis (line of apsides) of the 

 planetary orbits by which the place of the perihelion is 

 changed, is a motion which goes on perpetually in one 

 direction, and proportionally to the time. It is a change in 

 the position of the major axis, which requires more than a 

 hundred thousand years to complete its cycle, and is to be 

 distinguished as essentially different from those alterations 

 which the planetary orbits undergo in their form their 

 ellipticity. The question has been raised as to whether the 

 increasing value of this ellipticity, is capable during thousands 

 of years of modifying, to any considerable extent, the tem- 

 perature of the Earth, in reference to the daily and annual 

 quantity and distribution of heat ? Whether a partial solution 

 of the great geological problem of the embedding of tropical 

 vegetable and animal remains in the now cold zones may not 

 be found in these astronomical causes proceeding regularly 

 in accordance with eternal laws ? The same mathematical 

 arguments which excite apprehensions as to the position of 

 the apsides, the form of the elliptical planetary orbits (accord- 

 ing as these approach the circular form or a cometary eccen- 

 tricity), as to the inclination of the planetary axes, changes 

 in the obliquity of the ecliptic, the influence of precession upon 

 the length of the year, also afford in their higher analytical 

 development, cosmical grounds for reassurance. The major 

 axes and the masses are constant. Periodic recurrence hinders 

 the unlimited augmentation of certain perturbations. In 

 consequence of the mutual and at the same time compensating 

 influence of Jupiter and Saturn, the excentricities of their 

 orbits, in themselves slight, are alternately in a state of in- 

 crease and decrease, and are also comprised within fixed and 

 for the most part narrow limits. 

 The point in which the Earth is nearest to the Sun falls in 



