142 PHYSICS OF THE ELECTRON 



The more important values from the point of view of choice of 

 equations are those corresponding to values of the velocity very near 

 to that of light, and which amounted to ninety-five per cent of it in 

 Kaufmann's experiments. But the /? rays are then very little devi- 

 ated, and exact measurements are extremely difficult. 



It would be extremely important to determine the longitudinal 

 mass by the use of an intense electric field parallel to the velocity of 

 the electron, furnishing to it a known energy and producing a variation 

 of the velocity, which if measured would give the longitudinal mass. 



(29) Matter and Electrons. But if the accuracy of experiment is 

 not sufficient to determine completely the law, the agreement with 

 the equations, obtained by supposing the mass to be entirely electro- 

 magnetic, is so good that we can reasonably conclude that cathode 

 particles constituting the /? rays have no mass other than that due 

 to their electric charges or the train which they carry with them in 

 their motion through the ether. 



It is interesting to extend the same result to ordinary matter by 

 conceiving it as made up of an aggregation of electrons of both 

 signs; it is unreasonable on the other hand to apply to two phe- 

 nomena so nearly identical as inertia of ordinary matter and that 

 of the cathode particles, two entirely distinct explanations, of which 

 the one, the electromagnetic explanation, is definite and confirmed 

 by experiment, while the other remains entirely unknown. 



The inertia of a similar aggregation of electrons should be equal to 

 the sum of the partial inertias because of the great distance of the 

 electrified centres from one another compared to their radii, which 

 one can calculate by supposing all their inertia electromagnetic. 



In these conditions, the trains of the different electrons do not 

 interfere appreciably, and we find thus the law of the conservation 

 of inertia as a consequence of the conservation of the electrons in the 

 transformations to which matter is subject. But the theory is not 

 incompatible, on account of the interference of trains, with a slight 

 disagreement between the inertia of an assemblage and the sum of 

 the partial inertias. 



The complexity of the atomic system to which we are led, each 

 atom of the molecule containing probably a very great number of 

 electrons, seems also to be a necessary consequence of the com- 

 plexity of the luminous spectrum sent out from the atoms, by the 

 electrons which they contain, when an external disturbance displaces 

 the system from its state of stable periodic motion. In such a state 

 the radiations emitted by the various electrons on .account of the 

 acceleration which keeps them in their intermolecular orbits com- 

 pensate one another almost completely from the point of view of 

 energy radiated ; so that there is in general no decay of the periodic 

 intermolecular motion. 



