ELECTRICAL ACTIVITY OF ORE BODIES. 



349 



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be seen, from an inspection of Table XVI , that the considerations involved 

 in constructino- Fig. 2S are more pertinent in this case, as the main drift itself 

 is more nearly linear. Laying off potential as or- 

 dinate, distance as abscis.sa (Tal)le XVI.), Fig. 30 I g S, 

 is obtained. = = ? 



Both Fig. 28 and Fig. 30 demonstrate the ° 

 remarkable result that the region of ore bodies 

 coincides with a region of low potential. This is 

 all the more striking, as in the first case, taking I 

 in general a northerly course, the ore bodies are 

 approached from barren rock (400-foot level). In ? 

 the second the course of survey, while passing '^ = 

 toward the ore region, was mainly in an easterly 5 

 direction. The two lines of survey may, roughly | 

 speaking, be said to be at right angles to each ^ 1 

 other. In one case, moreover, the sequence of | 

 points tapped intersects the ore bodies, whereas in | 

 the other it remains exterior to them throughout w -- 

 its whole extent. i 



Comparing the results of the two surveys, the ^ ^ 

 indications on the 600-foot level are found to be g 1 

 much the more pronounced; in fact, they transcend f 

 values which can be accounted for as an aggregate of ^ ^ 

 incidental errors. It may be remarked here, that it ^ 

 is a very improbable chance which would place the 

 region of greatest electrical disturbance in coinci- 

 dence with the region of ore bodies, if the latter °- 

 were without influence in producing the former. 

 There is no reason apparent why the part of the 

 main drift on the 600-foot level, between Points I. -- 

 and X., should not be just as active as that between 

 Points X. and XXL, unless it be that these points lie nearest to ore, and 

 consequently that we are here rapidly approaching the seat of an electro- 

 motive force. 



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