664 Force-Transformation and, FresneV s Coefficient. 



For present conditions, on adding in the second case the 

 " unconverted activity, '"• (2v 1 T- [ ) appears repartition ed thus : 



A = vi~r -(cfi) = 2w 1 T 1 -w 1 T 1 ; 



A, = v,j t (c^ + rn^ = 2v 1 T 1 -ivT'. 



Hence 



A — Aj _ m" dv _ 1 



A + A x 



h . (44) 



i'i 



-A+-r.-s=T-+*»>a-j 



This agrees with one particular (empirical) rearrangement 

 of equation (9), after reducing the working-speed to («)'; 

 exploiting the flexibility of a zero-different 



ice 



And the magnitude of the last item coincides with the 

 time-rate of the corresponding electromagnetic potential. 

 The quoted value of electromagnetic energy-flux rejects, we 

 might say, both extreme suppositions, of (A, A T ) ; it is 

 determined symmetrically between them. How far does 

 this support the assertion of mass in the Lorentz electron ? 



Proper candour can admit this whole system of equations 

 to be finally inconclusive, and yet hold to their present 

 usefulness. So long as aggregates only are accessible, the 

 search for their physical constituents will grope more or less 

 blindly. The close of that period will be hastened by first 

 enlarging the list of possibilities, and at last weighing them 

 impartially. The simple thoughts of this paper do no more 

 than exemplify a method; it is true, without exhibiting it in 

 formal terms or delimiting it. But it can scarcely be 

 doubtful that such a widening of Lagrange's plan is of 

 good promise for the further discussion of energy-fluxes 

 in terms of mechanics. 



University of California. 



