78 DEFINITE INTEGRALS. [INT. III. 



/~\ 



dr _ x a dr _y b dr z c 

 dx r ' dy r ' dz r 



f-\- ----- x ~ a 



dx \rj r 2 ox r 3 



- _ _ 



g^l^-J- ~ 3 + ^4 3^- ^ 



a ' 2 3 (y - 6) 3 - r 2 a 2 / 1\ _ 3 (z - c) 2 - r 2 > 



2 a 2 / 1\ _ 

 ' dz*(r)~ 



r 5 ' dz*r r 5 



82 KS a>2 



> + "ap" + 1^ 2 " 



3 {(as - cbf + (y- &) 2 + (z- c) 2 } - 3r 2 



r 5 



and is harmonic, except where r = 0. 

 r 



