332 CLASSICS OF MODERN SCIENCE 

 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 force of the ether, and it will be necessary to 

 supply 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 greater if the currents are in the same di- 

 rection and near together. The energy to be furnished the counter 

 electomotive force of induction will be greater. This is what we ex- 

 press 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 opposite. 



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 currents have the same direction and are 

 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 would 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 were brought together. 



Finally, the centrifugal force tends to increase the distance between 

 the balls, which would augment the living force were the angular ve- 

 locity to be maintained. 



In like manner, when the currents have the same direction, they 

 attract each other — that is to say, they tend to approach each other, 

 which would increase the living force if the intensity were maintained. 

 If their directions are opposed they repel one another and tend to sep- 

 arate, which would again tend to increase the living force were the in- 

 tensity kept constant. 



Thus the electrostatic effects would be due to the elasticity of the 

 ether and the electrodynamical phenomena to the living force. Now, 

 ought this elasticity itself to be explained, as Lord Kelvin thinks, by 

 rotations of small parts of the fluid? Different reasons may render 



