MODERN VIEWS AND PROBLEMS OF PHYSICS. 515 



our powers ever to conceive of the ultimate nature of matter. Of 

 the structure of matter this is not the case. Various hypotheses 

 have been offered regarding the structure of matter all, save 

 one, have been charged with some fatal objection and have 

 broken down. This one, the suggestion of that powerful mind. 

 Lord Kelvin's, is known as the vortex-ring theory. We can not 

 give it here in any detail, but the gist of it is that the ether is 

 universal and for the most part formless, but that some parts are 

 differentiated from the remainder by being in motion in the shape 

 of vortex rings. These parts in such rotational motion are mat- 

 ter in the ordinary forms. A remarkable thing about it, and one 

 which exhibits the very spirit of modern physics, is that those 

 properties of ordinary matter which emphasize its stability of 

 form and position, especially inertia, elasticity, and rigidity, can 

 he a result of viotion. Yet Lord Kelvin has shown that with 

 ordinary matter a limp system of bodies could be made a rigid 

 system by merely putting them into gyroscopic rotation, and also 

 that elasticity itself might properly be regarded as a mode of mo- 

 tion. The vortex-ring theory is as yet only a speculation, but 

 when its adaptability to occult as well as to plainer properties of 

 matter are considered, we need not wonder that it has been 

 thought so beautiful that " it deserves to be true." At any rate 

 it stands in such an attitude toward modern views concerning the 

 structure of matter that "it is either that theory or nothing. 

 There is no other one that has any degree of probability at all " 

 (Dolbear). We can see how such a theory might reconcile con- 

 flicting views such as those above given concerning matter and 

 ether separately. 



Without waiting for a decisive answer as to the nature of 

 ether or the structure of matter, attention is being concentrated 

 on the relations of one to the other, the extent to which and the 

 manner in which any change in either substance affects the 

 other ; and this examination may throw light upon the greater 

 question regarding the nature of the substances. Do material 

 bodies moving in the ether of space for example, the earth and 

 its atmosphere move through the ether, or carry with them the 

 ether that is distributed throughout the matter that is moving ? 

 Experiments of extraordinary precision by Prof. Michelson have 

 led him to conclude that most probably the earth carries with it 

 all the ether in its immediate neighborhood ; that certainly the 

 relative motion of the earth and the ether in it is exceedingly 

 small. If he can repeat his experiments and get a different re- 

 sult on the top of a mountain, that conclusion may be considered 

 established. Those conclusions were drawn from experiments in 

 which the earth's velocity in its orbit is involved. Prof. Lodge 

 has experimented for effects due to slower motion of bodies upon 



