PHYSICS 75 



be correct, we have reduced two unknowns — matter and 

 electricity — to but one, electricity. 



But what is this electricity? Or, as we say, what is an 

 electrical charge? One view is to regard it as a strained 

 condition of the ether, or possibly a system of whirls or at 

 most a mechanical disturbance of the ether. But this is 

 merely guessing. No definite experimental line of attack 

 has as yet opened up. But these theories all regard the ether 

 as the fundamental substance. 



The discovery of the electron has opened up a number 

 of questions and such things as the conduction of heat and 

 the flow of electricity through metals are being reduced to 

 much simpler problems. By the aid of the electron we can 

 form a mechanical explanation of the origin of light waves. 

 Light waves are short electrical waves. A vibrating electri- 

 cal charge can produce electrical waves. Since an electron is 

 a charge of electricity, if it is vibrating, \t can send out these 

 short electrical waves, or light waves. Experiments showing 

 that magnetic fields will change the frequency and other char- 

 acteristics make it seem probable that a source of light is a 

 collection of vibrating electrons. 



Some of the problems connected with sources of light 

 are very complex. I may refer to the character of the light 

 given off by different substances as shown by an examina- 

 tion of their spectra. The element hydrogen whose atomic 

 and molecular structure is one of the simplest radiates, when 

 incandescent, a great many waves of different frequencies. 

 So intricate is this that many have despaired of ever being 

 able to work out the mechanical details of this radiation. 

 However, with the advent of the electron renewed interest 

 in this very beautiful line of work should yield results. 



Of great interest to the physicists is the question: Shall 

 we, by methods that I have explained, succeed in cataloguing 

 all physical facts? At time hopes have run very high. Then 

 has come an inundation of new facts. Usually most of these 



