232 SCIENCE AND METHOD. 



120,000 miles a second, the body in its relative motion 

 in relation to the observer can attain the same velocity; 

 its absolute velocity will then be 240,000 miles, which 

 is impossible, since this is a figure higher than that of 

 the velocity of light. But this is only an appearance 

 which vanishes when we take into account Lorentz's 

 method of valuing local times. 



't> 



VII. 

 The Wave of Acceleration. 



When an electron is in motion it produces a dis- 

 turbance in the ether which surrounds it. If its 

 motion is rectilineal and uniform, this disturbance is 

 reduced to the wake I spoke of in the last section. 

 But it is not so if the motion is in a curve or not 

 uniform. The disturbance may then be regarded as 

 the superposition of two others, to which Langevin 

 has given the names of wave of velocity and wave of 

 acceleration. 



The wave of velocity is nothing else than the wake 

 produced by the uniform motion. 



As for the wave of acceleration, it is a disturbance 

 absolutely similar to light waves, which starts from 

 the electron the moment it undergoes an acceleration, 

 and is then transmitted in successive spherical waves 

 with the velocity of light. 



Hence it follows that in a rectilineal and uniform 

 motion there is complete conservation of energy, but 

 as soon as there is acceleration there is loss of energy, 

 which is dissipated in the form of light waves and 

 disappears into infinite space through the ether. 



