362 Mr. H. N. Allen on Energy Movements in the 



; i 6. If H e is the intensity of the electrostatic field, or the force 



acting upon a particle with unit charge ; 

 B e the number of tubes of induction per sq. centim., 



or the induction in the direction of the line of force; 

 D e the number of polarization tubes per sq. centim., or 



the polarization or displacement in the same 



direction ; 

 K the dielectric constant of the medium ; 



i tj B e -p. KH,_B, 

 we have ri e = ^' D = — — . 



K 4-7T 4:77 



The length of an energy-cell is yt or . y. . 

 The area of section of the cell is ty 

 Thus the volume of the cell is 



47rD/ 



r n , .. • 27rD e 2 B e 2 KH.» 



Hie enerorv-ciensitv is — yt~ = r, — Jr = — ; — . 



The volume of an energy-cell is proportional to the square 

 of its length measured along a line of force. Figs. 1 and 2 

 show how in general the portion of the line of force inter- 

 cepted between two equipotential surfaces diminishes as the 

 movement proceeds. The volume of the energy-cell con- 

 stantly tends to diminish, though in some cases, as in fig. 2, 

 the volume of some of the cells has to increase for a while to 

 allow the rest to contract. During this contraction the length 



of the cell bears to its area the constant ratio -r— . 



47r 



It has seemed worth while to trace roughly the curves of 

 equal energy-density in the aether about equal unlike and 

 equal like particles. These are shown in figs 3 and 4. The 

 numbers apply to masses of 100 with a distance 10 between 

 them. 



7. Maxwell has discussed (Scientific Papers, vol. i. pp. 570- 

 571) the modifications which must be made in the theory to 

 make it fit in with the observed facts of gravitation. 

 , The energy diagram for two gravitational particles is the 

 same as that for two like electrified particles. The polari- 

 zation tubes go off to infinity, and do not, as far as we know, 

 end on negative gravitational matter. 



The properties of the cells between the polarization tubes 

 and the^ equipotential surfaces are exactly opposite in the two 

 cases of electricity and gravitation. 



