al 
on 
co 
C. A. HETLAND 
The writer knows of only two! instances where it is claimed that 
it was possible to recognize a direct effect of the oil in the resistivity 
data (in this paper we shall not deal with the claims which have been 
. Village 
ac 
\ “ bberg 


(leg. scale) 
Fic. 40 a and 6.—Results of some potential-drop-ratio measurements, and corre- 
sponding geologic section, in Oberg oil field, Germany. (Plotted after data published by 
J. Koenigsberger.) c: Potential-drop ratios as function of conductivity ratio. 
made in that respect for the electromagnetic Elbof method). The first 
of the two instances in question has been published by Lee and Swartz, 
the second by Koenigsberger (ref. list Nos. Ilig, I1Is7, and IV2). 
1 As a possible third instance may be mentioned the measurements carried out by 
Swartz and others to determine the depth of rock asphalt in very shallow depth (ref. 
list No. IIIx9, p. 114). The observations were made in the same area in which indica- 
tions from oil-bearing strata in 5-800 feet depth, to be described later, were obtained. 
488 
