188 ON FARADAY'S LINES OF FORCE. 



form that its nature and properties may be clearly explained without reference 

 to mere symbols, and therefore I propose in the following investigation to use 

 symbols freely, and to take for granted the ordinary mathematical operations. 

 By a careful study of the laws of elastic solids and of the motions of viscous 

 fluids, I hope to discover a method of forming a mechanical conception of this 

 electro-tonic state adapted to general reasoning*. 



PART II. 

 On Faraday's "Electro-tonic State." 



When a conductor moves in the neighbourhood of a current of electricity, 

 or of a magnet, or when a current or magnet near the conductor is moved, or 

 altered in intensity, then a force acts on the conductor and produces electric 

 tension, or a continuous current, according as the circuit is open or closed. This 

 current is produced only by changes of the electric or magnetic phenomena sur- 

 rounding the conductor, and as long as these are constant there is no observed 

 effect on the conductor. Still the conductor is in different states when near a 

 current or magnet, and when away from its influence, since the removal or 

 destruction of the current or magnet occasions a current, which would not have 

 existed if the magnet or current had not been previously in action. 



Considerations of this kind led Professor Faraday to connect with his 

 discovery of the induction of electric currents the conception of a state into 

 which all bodies are thrown by the presence of magnets and currents. This 

 state does not manifest itself by any known phenomena as long as it is undis- 

 turbed, but any change in this state is indicated by a current or tendency 

 towards a current. To this state he gave the name of the " Electro-tonic 

 State," and although he afterwards succeeded in explaining the phenomena 

 which suggested it by means of less hypothetical conceptions, he has on several 

 occasions hinted at the probability that some phenomena might be discovered 

 which would render the electro-tonic state an object of legitimate induction. 

 These speculations, into which Faraday had been led by the study of laws 

 which he has well established, and which he abandoned only for want of experi- 



* See Prot W. Thomson On a Mechanical Representation of Electric, Magnetic and Galvanic 

 Forces. Camb. and Dub. Math. Jour. Jan. 1847. 



