138 LIGHT AND ELECTRICITY. 



Wliile the electrostatic attractions are taken to be due to a multitude 

 of little springs — that is to say, to the elasticity of the ether — it is sup- 

 posed to be the living- force and inertia of the same lluid which produce 

 the phenomena of induction and electrodynamical effects. 



The complete calculation is far too extended for these images, and I 

 shall again content myself with a simile. I shall borrow it from a well- 

 known instrument — the centrifugal governor. 



The living force of this apparatus is i)roportional to the square of the 

 angular velocity and to the square of the distance of the balls. 



According to the hypothesis of Maxwell, the ether is in motion in 

 galvanic currents, and its living force is proportional to the stpiare of 

 the intensity of the current, which thus correspond, in the parallel I 

 am endeavoring to establish, to the angular velocity of rotation. 



If we consider two currents in the same direction, the living force, 

 with equal intensity, will be greater the nearer the currents are to one 

 another. If the currents have opi^osite directions, the living force will 

 be greater the farther they are apart. 



In order to increase the anguljfr velocity of the regulator and con- 

 sequently its living force, it is necessary to supply it with energy and 

 consequently to overcome a resistance which we call its inertia. 



In the same way, in order to increase the intensity of a current, we 

 must augment the living foice of the ether, and it will be necessary to 

 sup[)ly it with energy and to overcome a resistance which is nothing 

 but the inertia of the ether and which we call the induction. 



The living force will be gieater if the currents are in the same direc- 

 tion and near together. The energy to be furnished the counter electro- 

 motive force of induction will be greater. This is what we express when 

 we say that the mutual action of two currents is to be added to their 

 self induction. The contrary is the case when their directions are 

 o]tposite. 



If we separate the balls of the regulator, it will be necessary, in 

 order to maintain the angular velocity, to furnish energy, because with 

 equal angular velocity the living force is greater the more the balls are 

 separated. 



In the same way, if two currcMits have the same direction and 

 brought toward one another, it will be necessary, in order to maintain 

 the intensity to supply energy, because the living force will be aug- 

 mented. We shall, therefore, have to overcome an electromotive force 

 of induction which will tend to diminish the intensity of the currents. 

 It Avould tend on the contrary to augment it, if the currents had the 

 same direction and were carried apart, or if they had opposite direc- 

 tions and Avere brought together. 



Finally, the centrifugal force tends to increase the distance between 

 the balls which would augment the living force were the angular veloc- 

 ity to be maintained. 



