284 ANNUAL REPOKT SMITHSONIAN INSTITUTION, 1910. 



theory of the formation of matter and of mechanical phenomena. 

 It is evident that all the facts which we have just reviewed lead 

 logically to this point of view. 



We find that a corpuscle which appears to be nothing but electricity 

 has been isolated from matter, and that the mass of this electron is 

 entirely of electromagnetic origin. We are therefore forced to take 

 electricity^ as a point of departure in building up a theory of physical 

 phenomena, and even of matter itself. 



If matter is made up of an assemblage of electrons, its inertia is 

 entirely of electromagnetic origin; and it is the ether which sur- 

 rounds each of these electrons and not the matter itself which is the 

 seat of all energy. I do not wish to go as far as to say that there is 

 no such thing as matter; this merely signifies that it is not well to 

 depend entirely on appearances, and that it is necessary to view matter 

 in a different light from which it has been viewed up to the last few 

 years. 



If the inertia of matter is electromagnetic, the mass of bodies de- 

 pends on their velocity, yet this result from an absolute point of view 

 is contrar}' to one of the principles on which mechanics are based. 

 It would be well to notice, however, that the problems treated in 

 mechanics are all identified with a particular phase, where the ve- 

 locity is small in comparison with that of light. This is the case not 

 only in all velocities realized on the earth, but also in all velocities 

 in which the stars are concerned. Under such conditions the mass 

 can be considered as practically constant, and nothing in the me- 

 chanics of the past need be affected. 



Persons who are not sufficiently familiar with the ideas which have 

 just been reviewed often object that electricity still remains a mystery 

 and the new theories rest on an unknown basis. That is very true; 

 we are ignorant of the primary cause of electricity and Ave compre- 

 hend but slightly certain properties of the ether. But in the me- 

 chanical theories of the past, is not the word matter wrapped in 

 mystery just as profound? Is the meaning of the word mass any 

 clearer when we speak of a material mass? Is not the origin of 

 matter when considered as independent of the ether still more ob- 

 scure than that of electricity which appears to us to be a modification 

 of ether itself ? 



In any case the electrical theory of matter presents the advantage 

 of simplicity, for it tends toward the unification of all the phenom- 

 ena which are bound up in the manifestations of a single medium, 

 the ether. The electron, which is at the same time ether and matter, 

 serves as a transition means between the ether of space and the 

 matter which is apparent to us. 



The object of electrical theories of matter should be to investigate 

 how the atoms of elements can be made up of an assemblage of 



