118 NOMOS. 



to differences on the surface of the Sun which are 

 analogous to the differences met with on the sur- 

 face of the Earth. On the contrary, there is some 

 reason for believing that these differences are 

 not met with upon the Sun; and this reason is 

 in the fact that the perihelia and aphelia of the 

 different planets and comets are related almost 

 indiscriminately to different regions of the Sun, 

 and not to particular regions, as would certainly 

 be the case if the surface of the Sun did present 

 these differences. Indeed, this almost indiscri- 

 minate relation of the perihelia and aphelia of 

 the planets and comets to all parts of the Sun, is, 

 according to the premises, a certain proof that 

 the orbital eccentricities of the planets are not due 

 to differences in the surface of the Sun; and, 

 being so, we are compelled to seek for the cause of 

 the orbital eccentricity of each planet in some pecu- 

 liarity of the planet itself. 



And if the orbital movements of the planets 

 are to be explained upon these principles, it follows, 



as a matter of course, that their rota- 

 pianetsmust tory movements must be explained upon 



the same principles. 



Nor is there any reason why the same principles 

 should not apply to the motion of all other heavenly 

 bodies, comets, satellites, and the Sun himself. 



There are two particular difficulties in the move- 

 ments of comets, but these are not insuperable. The 

 The law of ^ rst ' l8 *ke extreme eccentricity of the 

 the labora- orbit, the second is the retrograde move- 



