VERTICAL AND INCLINED SURFACES OF SEPARATION 



275 





(6) 



If the expression in braces is denoted by gj^ and the value (^^ ^)^ is substi- 

 tuted in equation (5) we obtain 



H^V 



Qh^iQi.k)LQk -QiQkQk 



or 



6k 6k •> 



Qi 



(7) 



where gj^ is the value of the ordinate of the curve on an SN-1 reference 

 graph for each spacing of the probes ; q^ is the corresponding value of the 

 ordinate of the curve on a CV-2S or CV-3S reference graph. 

 Taking logs of expression (7) we obtain 



i,(f)=i,rf+i,rf- 



When, therefore, we are constructing a desired curve on a bilogarithmic 

 paper we sum the ordinates of the curves given above graphically. 



1-0 



p-\n.m N' /7 :/>, =00(99/?.m) 



y / 



/ /'.■ 



^.mi 



@ © 



A 







-^ 





f ■' / ■/ / . 



J/ / ///./> 







(a) (b) c'ia^Cc) 



<(d) 



y / .-/ 



-^ 



'/ / / 



X^ 



/qnnr).-nnnnnnonO[g^ 



(T) Values of -p- 

 I 00 I Values of ^ 



(e) 



AB 

 2d 



Fig. 2. a— approximately constructed VEP curves; b — VEP curves for a horizontally 

 homogeneous medium; c — curves of the CV-2S reference graph; d — curves of the HVC 

 reference graph; e — Hne connecting the points on VEP curves for the maximum 

 separations oi AB used in practical work. 



