48 



ON MATTER, FORCE, AND MOTION IN SPACE. 



THOUGH this topic has close kindred with that of the 

 preceding paper, it embraces certain special questions 

 in relation to the great phenomena of the natural 

 world, which this general title may serve to designate. 

 In using the three words, Matter, Motion, and Space, 

 we touch upon the most profound problems of physical 

 science, verging in part on metaphysics, yet open to 

 research under those stricter methods which belong to 

 the inductive philosophy of our day. The expression 

 of c matter moving in space ' includes actions which 

 range from the movements of suns and planets in the 

 seeming void of the universe, to those motions and 

 changes which pervade matter in its ultimate atomic 

 forms, and which are possible only through this in- 

 finitesimal minuteness. The unity of science requires, 

 even now, that these phenomena, however seemingly 

 diverse, should be brought into some common relation. 

 And the connexion so required is ever becoming closer 

 and more apparent. 



Nevertheless, parts of the subject may be viewed 

 separately, and the remarks I here make relate chiefly 

 to those motions in miter space which connect our 

 globe with other portions of the universe, and more 

 especially with the planetary system to which we 



