G. F. Becker — Kant as a Natural Philosopher. 107 



which in some circumstances supersedes the second. In either 

 event the number of the fundamental principles of natural 

 philosophy would be still incomplete. 



It is possible, however, to imagine the date of this critical 

 period in the universe, the epoch of initial nebulosity, infi- 

 nitely remote, though little intellectual satisfaction is to be 

 attained by this means. If a strictly finite amount of matter 

 were distributed in a space not merely relatively large but 

 absolutely infinite, so that every atom should be at a truly 

 infinite distance from any other, then a strictly infinite lapse 

 of time would be required to produce a finite degree of con- 

 densation. Known laws would therefore account for present 

 conditions if the ratio of space to mass in the universe is not 

 merely large, but (like time itself) absolutely infinite. Such an 

 assumption however seems preposterous, while it is far from 

 incredible that some natural law remains to be discovered, even 

 one which would make a perjtetuum mobile of the universe as 

 a whole. 



The attempt which Kant made to create moment of momen- 

 tum from the impact of nebulous matter is curiously out of 

 accord with the rest of his investigation. In treating of 

 Saturn's rings he avoided any such mistake, and the persistency 

 of moment of momenta follows from his own scheme of the 

 universe. When the solar system collapses, only to be restored 

 to a nebulous state, as he supposed, it will be in rapid rotation, 

 according to his own theory. It is thus only for the very first 

 of the infinite succession of developments that his exposition 

 asserts a fallacious source for rotational movement. 



Kant seems to have anticipated Laplace almost completely 

 in the more essential portions, of the nebular hypothesis. The 

 great Frenchman was a child when Kant's theory was issued, 

 and the Systeme du Monde, which closes with the nebular 

 hypothesis, did not appear till 1796. Laplace, like Kant, infers 

 unity of origin for the 'members of the solar system from the 

 similarity of their movements, the small obliquity and small 

 excentricity of the orbits of either planets or satellites.* Only 

 a fluid extending throughout the solar system could have pro- 

 duced such a result. He is led to conclude that the atmos- 

 phere of the sun, in virtue of excessive heat, originally 

 extended beyond the solar system and gradually shrank to its 

 present limits. This nebula was endowed with the moment of 

 momentum which Kant tried to develop by collisions. Planets 

 formed from zones of vapor, which on breaking agglomerated. 

 He appeals to the rings of Saturn as an illustration of nebular 

 contraction ; he also considers the Zodiacal light as due to a 



* The retrograde satellites of Uranus were discovered by Herschel io 17S7, but 

 Laplace in his hypothesis does not refer to them. 



