ADVANCES IN OIL PROSPECTING 107 
We shall first discuss briefly the electrode arrangements and ap- 
paratus used in the resistivity methods proper. 







p = ray IE 
p= ‘ray VA 
pao eee ove) a 
I (— 2a)? + al 
V. — Va(l — a) 2a 
Ba oF enum (i= 120) Ww 
p = 2xa at Mi VT 
vye& We 
e= 27 Cc 6b 
é= fad 7 jae Vi A 
CEs Vole as dre &, ar 
Cate inn ihapomed seek egy Seal 
= 
Fic. 7.—Electrode arrangements in resistivity prospecting. 
I, ELECTRODE ARRANGEMENTS 
a. POSSIBLE ARRANGEMENTS 
Five possible electrode arrangements which can be used in re- 
sistivity work are described in detail, and formulae are given for each 
arrangement, in J. N. Hummel’s publication (reference list No. Iie) 
and Figure 7. They are summarized briefly as follows. 
437 
