204 



Fig. A. 



which becomes evident when the retarded potentials i.e. the integrals 

 of the differential eqnation 



1 ÖV/ 



de 



- Lr/ :=Q 



for /?, are compared with those for the higher R->„-^i's. 

 For R,: 



*=^JJJ*"?' 



Foi\R, 



For R, 



''MiJj'-n 



[(>]_j_i 



dt 



[Q] , 1 



(c ■= 1 . • • 1 (^^o) ) ^ 4- 



dt 





c r^ 



c r 



(see appendix IV). 



Here C, — 4.Tr, C\ = | rt% C\ = ^ .-r\ are the areas of spheres 

 with a radius equal to unity in R^, R^, R- respectively. The symbol 



M. 



"do" 

 dt 





expresses that the values must be taken at the 



