( 143 ) 



the whole space, in which C may be found is divided into volume- 

 elements AT', we have to determine 



B 



N 



As 1 is known as function of /;, AT^ must also be given as de- 

 pendent on h. 



If we represent the angle which CM forms with FG by (p^ the 

 annular volume-element, in wicli C lies, is to be represented by 



2 It dcp dh {h -\- a cos cpf . 



If we take (p between and the value which it has, when Clies 

 on the distance-sphere of ^1, twice the value of this integral is to 

 be taken. 



As the value of ^ is quite determined by /(, when C lies on the 

 sphere of A^ the integration must be done with respect to /(, and the 

 limits are to be determined, between which h is to be taken. 



The highest value of h is of course j/ [R~ j; the lowest 



value may be found from 





^K^^-t) 



The lowest value, however, cannot descend below — i/(s* j 



which would be the case if ?•"> 72^/3. This is the cause that the 

 integration, must be done in two tempo's, and that we have to 

 calculate 



RVS -2 E »/(/^-4) 



I dr j dh + j dr j dh 

 K RV3 -l/(^ij._^) 



