Mass, Energy, and Radiation. 685- 



have lines of electric force anchored on to electrons or the 

 units of positive electricity ; we only get radiation when we 

 have along with the mass particles, closed lines of electric 

 force. The distribution and movement of the lines of 

 electric force determine the distribution and movement of 

 the mass particles. 



Comparing the "physical universe with a living organism 

 we may regard the mass particles as the flesh, the lines of 

 electric force as the nervous system. Muss and energy are 

 contributed by the mass particles, but the distribution^ 

 localization, and movement of both mass and energy are 

 determined by the lines of electric force. 



The mass particles in a steady electrostatic field, though 

 moving with the velocity of light, are constrained to follow 

 closed paths round the lines' of electric force. This produces 

 a tension along the lines of electric force, and these are only 

 prevented from breaking away by being anchored to the 

 electrons and positive charges, and so being obliged to drag 

 about with them wherever they may go the masses con- 

 densed about these charges. 



In a steady electrostatic field all the lines of electric force 

 have their ends either on electrons or positive charges, none 

 of these lines form closed curves. When, however, the 

 electric field is changing, either by the motion of the positive 

 and negative charges or otherwise, the lines of electric force 

 may get looped, and some of them may form closed curves. 

 These closed curves are not anchored to electrical charges, 

 there is nothing to prevent the mass particles from dragging 

 them away ; thus the mass particles will travel out through 

 space with the velocity of light through a vacuum, dragging 

 after them the closed lines of electric force. This, on the 

 view we are considering, is the way in which radiation is 

 supposed to originate. Since both the energy and mass are 

 due to the mass particles, we see that, on this view, radiation 

 involves a- transference of mass proportional to the trans- 

 ference of energy. The speed with which the radiation 

 travels is the speed of the mass particles, this speed is in- 

 variable and equal to the velocity of light through a vacuum : 

 it is independent of the medium through which the particles 

 are travelling ; the velocity of light, however, depends upon 

 the medium, and we have to show that an invariable velocity 

 of the mass particles carrying the energy is consistent 

 with the variation in the velocity of light with the medium 

 through which it is travelling. When a wave of light passes 

 through a refracting medium the electrons in the medium 

 are set in vibration and give out secondary waves ; the effect 



