XC KANTS UNIVERSAL NATURAL HISTORY 



the recent discussions and theories of the pre- 

 nebular condition of the universe as we find them 

 in 'the researches of Prout, Newlands, Mendelejeff, 

 Meyer, Dumas, Clarke, Lockyer, Crookes, Brodie, 

 Hunt, Graham, Deville, Berthelot, Stoney, Reynolds, 

 Carnelley, Mills, and others,' which, according to 

 Dr. Croll, ' clearly show that the very matter forming 

 this nebulous mass passed through a long anterior 

 process of evolution.' l Yet Kant in his later work, 

 Metaphysical Principles of Natural Science, following 

 in the footsteps of Leibnitz and Boscovich, laid down 

 the Dynamical Theory of Matter which is pre- 

 supposed in all these discussions, and which has 

 been developed with such penetration and ingenuity 

 in the theory of the 'vortex-atom' by Helmholtz 

 and Lord Kelvin. 2 Kant must have seen that his 

 whole mechanical theory of the evolution of the 

 world, and even his moving forces of Attraction and 

 Repulsion, must depend upon the potentialities of 

 the primary constitution of matter ; but, under the 

 scientific limitations of the time, he had to leave 

 the dynamical theory in a mere general definition to 



^Stellar Evolution (1890), p. 107. But Dr. Croll does more than 

 merely refer to these names. In an interesting chapter on ' The Pre- 

 nebular Condition of the Universe,' he gives an excellent account of 

 the views of Winchell, Morris, Grove, Brodie, Sterry Hunt, Lodge, 

 Crookes, Clarke, Stoney, as well as of his own Impact Theory, in this 

 relation. 



2 See the admirable account in the last two lectures on the ' Structure 

 of Matter,' in Professor Tait's Lectures (1876) ; and Lord Kelvin's 

 volume on ' The Constitution of Matter,' in his Popular Lectures and 

 Addresses, vol. I., 1889. 



