20 C THE NEBULAE HYPOTHESIS. 



But now let us inquire whether, besides these most con 

 spicuous peculiarities of the Solar System, sundry minor ones 

 are not .similarly explicable. Take first the relation be 

 twcen the planes of the planetary orbits and the plane of 

 the sun s equator. If, when the nebulous spheroid extend 

 ed beyond the orbit of Xeptune, all parts of it had been 

 revolving exactly in the same plane or rather in parallel 

 planes if all its parts had had one axis; then the planes 

 of the successive rings would have been coincident with 

 each other and with that of the sun s rotation. But it 

 needs only to go back to the earlier stages of concentration, 

 to see that there could exist no such complete uniformity 

 of motion. The llocculi, already described as precipitated 

 from an irregular and widely-diffused nebula, and as start 

 ing from all points to their common centre of gravity, must 

 move not in one plane but in innumerable planes, cutting 

 each other at all angles. 



The gradual establishment of a vortical motion such as 

 we saw must eventually arise, :md such as we at present 

 sec indicated in the spiral nebula&quot;, is the gradual approach 

 toward motion in one plane the plane of greatest momen 

 tum. But this plane can only slowly become decided. 

 Flocculi not moving in this plane, but entering into the 

 aggregation at various inclinations, will tend to perform 

 their revolutions round its centre in their own planes ; and 

 only in course of time will their motions be partly destroy 

 ed by conflicting ones, and partly resolved into the general 

 motion. Especially will the outermost portions of the ro 

 tating mass retain for long time their more or less indepen 

 dent directions; seeing that neither by friction nor by the 

 central forces will they be so much restrained. Hence the 

 probabilities are, that the planes of the rings first detached 



bavc put the question to an astronomer scarcely second in authority to tin 

 cnc above referred to, and he agrees that this would probably be the pro 

 cess. 



