19".] OF ELECTRICITY AND MATTER. 325 



carry a negative charge, which is relatively enormous, considering 

 the fact that the approximate electronic diameter can scarcely be 

 more than one one-hundred-thousandth that of the atom. 



When any cause sets up a general movement of the electrons 

 within a body, we have a current of electricity, while the random 

 vibratory heat motion of atom and electron is the cause of continual 

 emission of radiant energy to other objects or to outside space. 



A piece of matter is thus a complex system composed of an in- 

 conceivably large number of ultimate units, atoms and electrons, in 

 ceaseless motion to and fro, and permeating all is the mysterious, 

 matter-like entity which we have called radiant energy, and which 

 ever seeks to escape with an enormous, though perfectly definite, 

 velocity into the space outside. Some of it succeeds in escaping, 

 but there appears to be a vast amount which in some way is im- 

 prisoned in the atom-electron aggregate and thus never becomes 

 " radiant " in the strict sense of the word, though it resembles 

 radiant energy so closely as almost to warrant the same name. 



Having thus obtained an impressionistic view of the structure 

 of a piece of matter, I would like to call attention to the properties 

 of the space surrounding an electron, or, what is the same thing for 

 our present purpose, the space surrounding any body, say a small 

 sphere, possessing an electric charge. This space is the seat of what 

 we call electric force, and is known as an " electric field." Now, it 

 is a well-known conclusion and one which cannot at present be in 

 any way avoided, that the energy which the body possesses, by virtue 

 of its charge, that is, the energy originally required to charge it, 

 resides in the electric field around the body, and not on or in the 

 body itself. The existence, without apparent motion, of this energy 

 in what seems to be empty space is very remarkable, but the con- 

 clusion that it is there is unavoidable, and after all there is no great 

 difiference between the discarnate state of this energy and the state 

 of the radiant energy of the sun on its way to the earth. From 

 the older point of view this energy in the electric field was " strain 

 energy " in the ether, the so-called strain being similar to wdiat we 

 would get in an immense block of rubber if a pin-head embedded at 

 its center were to swell into the size of an egg. The rubber would 

 be pushed back in all directions and the energy of this compression 



