102 REPLIES TO CRITICISMS. 



reach any amount. Similarly, by introducing factor after 

 factor, each at first insensible in proportion to the rest, we 

 arrive, through an infinity of gradations, at a combination 

 of any complexity. 



Thus, then, the Science which deals with the inter-action 

 of hypothetical bodies in space, is absolutely continuous with 

 General Mechanics. We have already seen that it is ab 

 solutely discontinuous with that account cf the heavenly 

 bodies which has been called Astronomy from the beginning. 

 When these facts are recognized, it seems to me that there 

 cannot remain a doubt respecting its true place in a classi 

 fication of the Sciences. 



Passing over minor criticisms, either as met by implication 

 or as demanding space that cannot be here afforded, let me 

 say something by way of enforcing the general argument. 

 I will re-state the case in two ways : the first of them 

 adapted only to those who accept the general doctrine of 

 Evolution. 



We set out with concentrating nebulous matter. Trac 

 ing the re-distributions of this as the rotating contracting 

 spheroid leaves behind successive annuli, and as these sever 

 ally breaking up eventually form secondary rotating spheroids, 

 we come at length to planets in their early stages. Thus 

 far we consider the phenomena dealt with purely astro 

 nomical; and so long as our Earth, regarded as one of 

 these spheroids, was made up of gaseous and molten 

 matters only, it presented no definite data for any more 

 complex ^Concrete Science. In the lapse of cosmical time 

 a solid film forms, which, in the course of millions of years, 

 thickens, and, in the course of further millions of years, 

 becomes cool enough to permit the precipitation, first of 

 various other gaseous compounds, and finally of water. 

 Presently, the varying exposure of different parts of the 

 spheroid to the Sun s rays, begins to produce appreciable 



