cii KANT'S UNIVERSAL NATURAL HISTORY 



really be a positive addition to them. M. Wolf puts the 

 objection thus : * In every isolated nebula the internal 

 actions are held to be sufficient to produce a regular motion 

 of rotation in the whole mass. This conclusion is absolutely 

 contrary to the laws of mechanics ; the actual motions of 

 the revolution and rotation of the sun and planets, can be 

 only the equivalents, without augmentation or diminution, 

 of the motion of rotation communicated originally to the 

 nebula by an external cause.' This is practically to fall 

 back upon Newton's position, and to discard entirely the 

 ingenious explanation suggested by Kant. But the matter 

 cannot rest there ; nor does Laplace's assumption really 

 lighten the difficulty. After all, we know too little of the 

 action of the force of repulsion to justify us in either 

 dogmatically asserting, or dogmatically rejecting, Kant's 

 view; and the new theory of the 'vortex-atom,' and the 

 tendency, in consequence, to revive in modified form the 

 Cartesian vortices, point on the whole in Kant's direction. 

 Moreover, other explanations of the rotatory motion, not 

 inconsistent with Kant's process generally, have been 

 suggested, such as the modification of the Impact Theory 

 suggested by Lord Kelvin, according to which, if two solid 

 globes collided with each other in space and ' if each had a 

 transverse motion, in opposite directions, of 1-89 metre per 

 second, the result would be a globe like our sun rotating in 

 twenty-five days.' 1 It has occurred to me, although I 

 cannot quote an authority in favour of the idea, that the 

 objection would be met, if we supposed the generating 

 nebula to be not simple and one, but compound and made up 

 of two or more nebulae which, by their mutual attraction had 

 met and blended with each other in space, as may be the 

 case with the Spiral Nebulas, which seem to suggest such a 

 formative condition. But the discussion of a multinebular 



l Good Words, April, 1887. 



