Chapter 9 

 THE METHOD OF CURVED ELECTRICAL PROBES 



M. N. Berdichevskii 



The method of two-way quadrilateral probes* has been widely accepted by 

 electrical exploration workers carrying out electrometric studies in regions 

 where field sections can travel along long straight profiles (^). However, 

 when working in country where conditions are diflicult, the use of quadri- 

 lateral probes is often impossible since the swampy or wooded sections of 

 the surveyed area hinder movement of field parties along a straight line. 

 In this case, it is desirable to change from measurements with a quadrilateral 

 setting to those with an azimuthal arrangement, which would make it pos- 

 sible to use the so-called curved probe, i.e. probes with the observation 

 points on curved routes. The curved probes can also be carried out with 

 a radial arrangement and an arbitrary two -component arrangement by 

 means of which measurements are made of the mutually perpendicular 

 components of the field. 



The properties of an azimuthal arrangement and the method for carrying 

 out curved azimuthal probes (from the results of studies made in the VNII- 

 Geofizika in 1954-1956 by the author together ^nth. T, N. Zavadskaya and 

 V. P. BoRDOvSKii) are given below. 



AZIMUTHAL ARRANGEMENT 



The azinuithal arrangement is shown in Fig. 1. Here AB is the supply 

 Hne, MN the measuring line, R the distance between centres and Q of 

 the feed and measuring lines, d is the angle formed by the feed line AB 

 and the line OQ. 



A basic condition of the azimuthal arrangement is the perpendicvdarity 

 of the measuring line MN to the section OQ, connecting the centers and 

 Q of the feed and measuring lines. It is apparent that the quadrilateral ar- 



* The quadrilateral [Jiterally equatorial in the Russian edition] probe is one of 

 the modifications of the dipole probes proposed by L. M. Al'pin. He has developed 

 the whole theory of dipole probes^). 



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