260 1. 1. Krolenko 



relatively deeply lying deposits. To solve the second problem use was made 

 of the receiving frame circuit. 



With the usual loop method, the e.m.f. is measured with a field potentio- 

 meter having a high -inertia galvanometer. In practice, this permits the 

 measurement of only a certain average e.m.f. The value of the measured 

 e.m.f. apparently depends to a considerable extent on its initial value, 

 determined by stabilizing the field in the upper layers of the section. 

 Corresponding to this, the arrangement for the commutation of the AB and 

 MN circuits mth the old method of working on the PU pulsator (in fu- 

 ture it will be referred to as the No. 1 pulsator) provided an observation 

 mainly in the initial stage of stabilization only (Fig, 10). 



Fig. 10. 1 — Observed stabilizing phase Fig. 11. 1 — recorded phase; 2 — stabi- 

 of field; 2 — stabilizing phase excluded lizing phase excluded by pulsator. 



by pulsator. 



For experimental work a No. 2 pulsator, suggested by Yu. A. Dikgof, 

 was made and tested; this pulsator did not transmit the initial phase 

 into the receiving channel, which made it possible to take the e.m.f. cha- 

 racteristic of the structure of the deeper layers (Fig. 11). For this purpose 

 the connection and disconnection of the MTV line somewhat lagged behind 

 those of the AB fine. 



The quantity characterizing the order of such a shift of collector rings 

 of the No. 2 pulsator Avill later be referred to by the letter a mth positive or 

 negative signs depending on whether the connection of the MTV line lags 

 behind or precedes the connection of the AB line. One of the cases of 

 displacement of the collector rings of the No. 2 pulsator is showir in Fig. 12. 



The receiving frame circuit is a 2 in square frame with 2500 turns. The 

 frame is tapped off at certain points (500, 600 and 1400 turns). The effective 

 area of this frame is 10,000 m^. Thus, the frame is equivalent to a square 

 loop of 100 m aside. 



The frame was mounted on a 0.5 m high support; the AB cable was 

 folded on top of the frame and divided it into two symmetrical halves. The 

 position did not change very much when the frame was set up on a two- 



