238 SCIENCE AND METHOD. 



to the motion of the positive electrons and the field 

 due to the motion of the negative electrons, and 

 consider only the algebraic sum of these two fields — 

 that is to say, the resultant field. 



In the new theory, on the contrary, the action upon 

 the positive electrons of the electro-magnetic field due 

 to the positive electrons takes place in accordance 

 with the ordinary laws, and the same is true of the 

 action upon the negative electrons of the field due 

 to the negative electrons. Let us now consider the 

 action of the field due to the positive electrons upon 

 the negative electrons, or vice versa. It will still 

 follow the same laws, but with a different coefficient. 

 Each electron is more sensitive to the field created 

 by the electrons of opposite denomination than to 

 the field created by the electrons of the same de- 

 nomination. 



Such is Lorentz's hypothesis, which is reduced to 

 Franklin's hypothesis for low velocities. It agrees 

 with Newton's law in the case of these low velocities. 

 More than that, as gravitation is brought down to 

 forces of electro-dynamic origin, Lorentz's general 

 theory will be applicable to it, and consequently the 

 Principle of Relativity will not be violated. 



We see that Newton's law is no longer applicable to 

 great velocities, and that it must be modified, for 

 bodies in motion, precisely in the same way as the 

 laws of Electrostatics have to be for electricity in 

 motion. 



We know that electro-magnetic disturbances are 

 transmitted with the velocity of light. We shall 

 therefore be tempted to reject the foregoing theory, 

 remembering that gravitation is transmitted, according 



