262 



I. I. Krolenko 



An analysis of the extensive experimental data led to a number of interest- 

 ing conclusions on the dependence of the induced e.m.f. on the number 

 of turns of the receiving circuit, on the AB dimensions, frequency of the 

 pulsating current, the mutual disposition of the collector rings of the 

 pulsator, etc. 



To study the depth of reach of the method of e.m.f. corresponding to 

 the final stabilizing stage of the field in the earth, tables were compiled 

 giving the ranges of observations for various values of delay time of the 

 start of e.m.f. reception relative to the time of connecting the current 

 for the 1st and 2nd pulsators and also tables of the time for stabilizing the elec- 

 tromagnetic field according to the dimensions of the --45 line ^sere employed. 



On the basis of these tables a graph was drawn showing the disposition 

 of the intervals of the record on the curves for stabilizing the electrical 

 and magnetic fields for various values of a and AB (Fig. 14), 



On the graph along the ordinate are plotted the relative deviations of the 

 stabiHzing field {E, H) from the field which is stabilized {Eg^, Hg^), i.e. 

 Ei E — £"00 Hi H—Hoo 



and along the abscissa axis the ratio of the time of observation t to the so- 

 called constant of time 



abV 



^1" 



where C is the speed of light; 



Q is the specific resistance of the investigated rocks. 

 A comparison of the time for stabilizing the field for various values of AB 

 with the time for recording the e. m. f. when working with the No 2. pul- 

 sator led to the conclusion that with the existing design of pulsator, only 



Fig. 13. A comparison of the e.m.f. curves with various vakies of df^ (single turn 



contours); ^5=200 m; /=2a; iV =600 rev/min; o=+3 mm; J„ is the distance of 



earthing from the AB line. 



