3B2 



GEOLOGY OF THE GOMSTOCK LODE. 



IR 



111 Fig. 33 these results are graphically represented. It appears, not- 

 withstanding the different kinds of contact at V., VI., VII., and at^, 5, C, D, 



E, that the progress of the 

 curve in passing from 



VI. to V. is continuous. 

 The experiments, there- 

 fore, failed to detect any 

 specitic action due to the 

 holes. Nos. v., VI., and 



VII. were especially 



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Fui. S.i. — Potential of iutfimediate jioiiits. 



chosen, because, as will be seen from a comparison of Figs. 30 and 32, 

 this part of the curve ])resents a curious and pronounced anomaly, the 

 newer results differing very remarkably from the earlier. It was natural 

 to suppose that, in the time which had elapsed between the two series of 

 measurements, hole No. VI. Iiad in some way been interfered with. The 

 results just cited, however, preclude such a supposition. Even larger masses 

 of metal seem to be without marked effect. Between the date of the earlier 

 and that of the newer observations, for instance, a track had been laid 

 from the vicinity of the hole No. I. to No. XV. 



Terminal bags. — There occur a few cases in my notes in which, though in 

 every other respect the behavior was normal, different results were obtained 

 for the same hole at nearly the same time, by employing different bags, viz.: 

 IV. e = 0:10=* VII. ezr2:10^ 



e = 2:l()^ e = 6:W. 



6 = 5:10' 



These cases are rare, however, and their effect is of minor importance. 

 More worthy of consideration are the successive differences of potential due 

 to the bags alone when employed for a long period of time. The quantity 

 referred to has already been considered on page 357, under the symbol e. 

 It may. readily be derived from the tables for intensity. The following table 

 (XXI.) probably contains good examples of its consecutive states, the data 

 given being deduced from those for the holes I.-XIV. on the 600-foot level. 

 If the bags are called A, B, C, I), the electromotive force e between A and 

 B may be conveniently represented by A \ B, between A and C by A \ C 



