266 Prof. A. Anderson on KircKhojf s 

 i 9 a [(n — 3)(n — 4)ron — 2'Zn J 



w(n-l)(n — 2) 

 1.2.3 



^ [(n-3)(7i-4)n 2 ro n " 6 -2-3r n - 4 ] 



n(n — l)(n — 2)(n — 3) r/ . JX/ -.3 »-7 o./i n ~ 5 i 

 -± ± n 2 3 2 ^-[(n-4)(n-5>ori -3*4^! ] 



, n(n— l)(n — 2)(n — 3) r/ A> K n 3 »-* q.u m b - 5 t 

 + -^ 1 2~3 4 [(n — 4)(w— 5)r 1 r -3'4n^o J 



+ • 



which vanishes identically. 



Thus we have proved that the surface integral 



J J L\^i^o " n r o r i °m/ V a / 



ar 2 r Vdn dnJ'dt^K a /J 



for any closed surface S, ^ and r being the distances 

 of a point P of the surface from two points A and B 

 both lying outside it, <f>(t) being such that, in the interval 



(i_H±^ * + !!±!J?\ the conditions for the validity of 



Taylor's series are satisfied. 



Fig. 2. 

 5 



Now let A, fig. 2, be inside the surface and B outside it, 

 and surround A by a small sphere of radius p and centre A. 

 A and B are both outside the space between the surface 

 of the sphere and the surface S. The part of the 



