CONNECTION OF ELECTRICITY AND MAGNETISM. 263 



This velocity is very great, from 175,000 to 200,000 miles per second, 

 according to clifiFerent experiments. Now, the velocity of light, accord- 

 ing to Foucault's experiments, is 185,000 miles per second. In fact^ the 

 different determinations of either velocity differ from each other more 

 than the estimated velocity of light does from the estimated velocity of 

 propagation of small electro-magnetic disturbance. But if the luminif- 

 erous and the electro-magnetic media occupy the same place, and trans- 

 mit disturbances with the same velocity, what reason have we to distin- 

 guish the one from the other ? By considering them as the same, we 

 avoid at least the reproach of filling space twice over with different 

 kinds of ether. 



Besides this, the only kind of electro-magnetic disturbances which 

 can be propagated through a non-conducting medium is a disturbance 

 transverse to the direction of propagation, agreeing in this respect with 

 what we know of that disturbance which we call light. Hence, for all 

 we know, light also may be an electro-magnetic disturbance in a non- 

 conducting medium. If we admit this, the electro-magnetic theory of 

 light will agree in every respect with the undtilatory theory, and the 

 work of Thomas Young and Fresnel will be established on a firmer 

 basis than ever when joined with that of Cavendish and Coulomb by 

 the keystone of the combined sciences of light and electricity — Farad^ay's 

 great discovery of the electro-magnetic rotation of light. 



The vast interplanetary and interstellar regions will no longer be 

 regarded as waste places in the universe, which the Creator has not 

 seen fit to fill with the symbols of the' manifold order of his kingdom. 

 We shall find them to be already full of this wonderful medium ; so full 

 that no human power can remove it from the smallest portion of space, 

 or produce the slightest flaw in its infinite continuity. It extends 

 unbroken from star to star ; and when a molecule of hydrogen vibrates 

 in the Dog-star, the medium receives the impulses of these vibrations ; 

 and after carrying them in its immense bosom for three years, delivers 

 them in due course, regular order, and full tale into the spectroscope of 

 Mr. Huggins, at Tulse Hill. 



But the medium has other functions and operations, besides bearing 

 light from man to man, and from world to world, and giving evidence 

 of the absolute unity of the metric system of the universe. Its minute 

 parts may have rotary as well as vibratory motions, and the axes of rota- 

 tion form those lines of magnetic force which extend in unbroken conti- 

 nuity into regions which no eye has seen, and which by their action on 

 our magnets are telling us, in language not yet interpreted, what is 

 going on in the hidden under-world from minute to minute and from 

 century to century. 



And these lines must not be regarded as mere mathematical abstrac- 

 tions. They are the directions in which the medium is exerting a ten- 

 sion like that of a rope, or rather like that of our own muscles. The 

 tension of the medium in the direction of the earth's magnetic force is 



