TRANSLATOR'S INTRODUCTION Ixxxiii 



in the fifth objection with Laplace's hypothesis, 

 that he abandons it in its main points, and works 

 out a modification of it which in certain respects 

 approaches the theory of Kant. Other modifications 

 have been ably advocated by Trowbridge, Newcomb, 

 Roche, and others ; but the inevitable consequence 

 has been to bring the hypothesis itself more or less 

 into disrepute, and to determine a reaction towards 

 Kant's view. Newton himself was well aware of 

 the common facts in the motions of the Solar 

 System upon which Laplace founded, but he seems 

 to have been deterred by the contradictions pre- 

 sented in the movements of the comets, from 

 hazarding a conjecture as to a common physical 

 origin of these common motions. Laplace only 

 evaded the difficulty by removing the comets origin- 

 ally from the Solar System, whereas Kant's theory 

 is quite compatible with his view of their primarily 

 belonging to it. Again, Laplace's hypothesis is 

 inconsistent with the later views now generally 

 received as to the more recent origin of the great 

 superior planets. For, according to Laplace, the 

 most distant planets must be the oldest, as first 

 formed in the process of the nebular contraction, 

 whereas, according to Kant, some of them are, like 

 the moon, of more recent origin than the earth, 

 and he was apparently the first to maintain that 

 Jupiter is still in a fluid state. Moreover, Laplace's 

 view is much more incompatible than Kant's with 

 the modern Thermodynamics. It is more assump- 



