308 SPECIAL RESULTS IN THE UEANOLOGICAL 



Mars, and between Jupiter, Saturn, and Uranus, is very far 

 from being a regular one. We see that, in general, the 

 absolute magnitudes, as Kepler had already remarked (Har- 

 monice Mundi, V. iv. p. 194 ; Kosmos, Bd. i. S. 389 ; 

 Eng. ed. p. xvi. Note 38), increase with the distance ; but 

 this, though generally true, is not true of each case in par- 

 ticular, for Mars is less than the Earth, Uranus less than 

 Saturn, Saturn less than Jupiter, and Jupiter, the largest 

 of all the planets known to us, is immediately preceded by 

 a group of planets whose disks are scarcely measurable 

 from their minuteness. The velocity of rotation does 

 indeed increase generally with the solar distance ; but yet 

 the rotation of Mars is slower than that of the Earth, and 

 that of Saturn slower than that of Jupiter. 



The world of forms can, I repeat, be only depicted accord- 

 ing to the actual relations of space existing in nature, not as 

 the necessary object of intellectual deduction or of an already 

 recognised causal sequence. In this respect no natural law 

 has been discovered in celestial space, any more than in the 

 geographical position of the culminating points of mountain 

 chains, or in the particular configuration of continents on 

 the surface of our globe. They are facts in Nature which 

 have issued from the conflict of tangential and attracting 

 forces of manifold character, acting under conditions which 

 remain unknown to us. We here find ourselves approach- 

 ing with eager but unsatisfied curiosity the mysterious do- 

 main of formation. The questions before us relate, in the 

 strict sense of the words, to universal events, to cosmical 

 processes taking place in intervals of time to us immeasura- 

 bly small. 



If the planets have been gradually formed from revolv- 

 ing rings of vaporous matter, when this matter began to 



