THE AGE OF ELECTRICITY. 169 



said of him that, without figuring out any computation and without 

 writing down an equation, he had proved himself a great geometrician. 



Faraday's mind carried him further. He imagined that the very 

 notion of action from a distance could not stand, and that in every 

 instance the intervening medium plays the leading part. To electrify 

 a body, to produce a magnet, is but to modify the conditions of the 

 medium by which they are surrounded, and the forces that may be 

 brought out in the field of action are but a manifestation of the elastic 

 properties of the intervening medium. 



The condition of the fluid theory, then, appears considerably dam- 

 aged; it was even worse when Faraday discovered after numerous 

 attempts — the secret of which he kept— that a ray of light is altered 

 in passing through a magnetic field produced by magnets or currents; 

 so that there is a connection among them all — electricity, magnetism, 

 light, and consequently heat. We have no longer before us isolated per- 

 sonages acting independently of one another, but the several actors in 

 the great drama of nature which each one renders under a particular 

 form; whose passions come in conflict and undergo transformations as 

 the plot i^rogresses; the spectator, human intellect, at first listened to 

 the several i>arts in turn ; he is aware to-day of a commou action and 

 of a general bond which will probably remain the great mystery. 



Universal gravitation itself, which was held to be the type of action 

 from a distance, must be subject to the common rule and find its true 

 exi)lanation in the structure of the medium which fills the celestial 

 space. 



One of our best-beloved masters, before whom the examjile of the sun, 

 which attracts the earth, was given as an objection to these ideas, said : 

 " Have you seen his hands ? If the sun attracts the earth, he must have 

 hands and a string." 



The adoption of a system of interdependent measures for electric and 

 magnetic phenomena which worked invaluable good in industrial appli- 

 cations had previously been the starting point of immense progress 

 in the province of pure science. It has been ascertained that if the 

 same (quantity of electricity is measured by Coulomb's law on recipro- 

 cal actions or by the magnetic properties of currents the ratio of the 

 two values is a physical velocity, and it was found by experiment 

 to be virtually at the same rate as the velocity of the propagation of 

 light. Such a coincidence could not be the effect of mere accident; it 

 bespoke a close connection between electricity and light. 



Clerk Maxwell, who had made a profound study of Faraday's works 

 on the action of the mediums, thought that they were the actual seat 

 of electrical phenomena. In a learned mathematical analysis he proved 

 that luminous undulations maybe explained by means of currents whose 

 frequent alternations excite other currents in the adjacent parts and 

 propagate from place to i^lace, in which case the velocity of propaga- 

 tion would be nothing else than the celebrated ratio of units of measure- 



