782 



ELECTRICAL METHODS 



[Chap. 10 



gives the in-phase and quadrature components of the field, the former 

 being obtained by adjustment of the sUde wire, the latter on the secondary 

 of a variometer. When the bridge is balanced, the in-phase voltage drop 

 ri on the resistor R, plus the quadrature e.m.f. induced in the secondary of 

 the mutual inductance M, is equal to the voltage Vx induced in the pickup 

 coil: 



M I + n = F. 

 at 



(10-52) 



HeUand Research Corp. 

 Fig. 10-104. Compensator with amplifier and receiving coil. 



with i = V/(R -\- jLu)). A complete compensator arrangement with coil 

 on tripod and instrument case containing network and amplifier is shown 

 in Fig. 10-104. 



In the ring-induction method compensation is accomplished by creating 

 in-phase and out-of-phase fields outside the detector coil. When alter- 

 nating current is passed through the primary loop in Fig. 10-105, a quadra- 



•«J. Koenigsberger, Phys. Zeit., 31, 487-498 (1930), 36(1), 6-8 (1934); Beitr. 

 angew. Geophys., 3(4), 392-407 (1933), 4(2), 201-216 (1934), 7(2), 112-161 (1937). 

 W. Nunier, Beitr. angew. Geophys., 3(4), 370-391 (1933); Phys. Zeit., 35(1), 8-10 

 (1934). A. Graf, Beitr. angew. Geophys., 4(1), 1-75 (1934). S. Stefanescu, Beitr. 

 angew. Geophys., 6(2), 182-192 (1935), 6(2), 168-201 (1936). 



