ADVANCES IN OIL PROSPECTING 119 
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VALUC OF §F 






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QGUIABIISSTTTOTITIMTTOTIODIE : 
Horizontol Tank 
Vertical Tank 
Fic. 14.—A : Arrangement of 4 electrodes crossing vertical boundary (after Tagg). 
B: Apparent resistivities for various electrode positions (after Tagg). C: Tanks used 
for model resistivity experiments. 
449 
