46 SVEVAIN I PLESOMN 
a 
curves the ratio -5* or the relative apparent resistivity will be studied 
P lv 

as a function of the relative depth 4. 
A few applications of the theorem of the reduction of anisotropic 
conditions to homogeneous conditions are considered here. 
APPLICATIONS 
I. TWO STRATA OF THE SAME ANISOTROPY 
If we suppose that the anisotropy coefficients a; and a, are equal, 
formula IV reduces to the simpler form: 
n=0oo0 




/ ( 
Aa en an § 
an/ ay 
From this formula, we calculated the relative apparent resistivity 
p. : 
— for the following cases. 
P 1» 
1) a,=1 Isotropic conditions 
2) a@,=2 Condition which is often obtained for sedimentary beds 
3) a1=4 Condition obtained for intense compaction and dynamo- 
metamorphism 
We further assumed the following resistivities and thicknesses. 
Pw = 2 h=4 
Pav = O hy = © 
By carrying out the calculations indicated by formula V, the re- 
sistivity curves a, b, and c in Figure 3 are obtained using as coérdinates 
the relative resistivity p./p’1, and the relative electrode spacing h/a. 
The curves obtained for a,=0.5 and a1=0.25 are also indicated in 
Figure 3, although such conditions are seldom encountered in field 
practice. 
706 
