178 



E. I. Terekhin 



the source of the field "within the hmits of the first layer: 



47r 





+ 



Vr^ + W 

 1 



yr^ + 4^{nh-ZQY 



+ 2 



+ 





+ 



(16) 



In a special case for an apparatus placed at the bottom of the water we have 



Zn = tin 



and 



Uo = 





1 



+ 



+ 



S^" 



1 



+ 2 



+ 



E 



qn 



1 



+ 



1/^2 + 4^{nh- ho) 2 j/7-2 + 4 (a/i + ho) 2 



(17) 



If we consider the obtained formula from the point of view of the theory 

 of reflection, then it can be readily seen that when the source of the field 

 is at the boundary of the first and second conducting layers, the distribution 

 of the fictitious reflected sources is complicated in comparison mth the case 

 where the source is at the surface of the conducting semispace. 



When the source of the field is at a certain depth, the symmetry is lost 

 in the location of the fictitious sources with respect to the real source, 

 reflected sources of equal power appear at different distances {yr'^+{2nzQ)^, 

 yr^ + 4!{nh—z)^ and yr^ + 4i{nh+ZQ)^ from the point of measurement of the 

 potential. The formation of these fictitious sources is connected with the 

 presence of a boundary of separation with a coefficient of reflection i^ = 1 

 (the water-air boundary), which does not pass through the actual current 

 source. 



AN EXPRESSION FOR THE APPARENT SPECIFIC RESISTANCE FOR AN 

 APPARATUS AT THE BOTTOM OF THE WATER 



The apparent resistance is a complex function, depending both on the 

 parameters of the geoelectrical cross -section and on the mutual disposition 

 of the feeding and receiving electrodes of the apparatus. It is calculated from 

 the formula 



AU 



Q = K- 



(17a) 



