350 



GEOLOGY OF THE COMSTOCK LODE. 



Chambers No. M and No. 15 connected electrically. 111 tllG SUl'Vey OH tllG 400 aud 500" 



Ibot levels, two ore bodies, Nos. 12 and 15, were indirectly connected, 

 but the indications obtained were much smaller than was anticipated. It 

 appeared desirable therefore to test this matter still more carefully by 

 connecting- the huge ore-masses in chambers No. 14 and No. 15. Ac- 

 cordingly a P. C. in a large breast of ore (lead carbonate) in cham- 

 ber No. 15 was placed successively in contact with three different points, 

 at a distance of about 100 feet one from another, in chamber No. 14. Each 

 of these was also in ore, the first in lead carbonate, the second in lead car- 

 bonate and earthy sulphide, the third finally in a mixture of carbonate, 

 sulphide, and ferruginous earth. Table XVII. contains the results of the 

 electrical measurements. A single set of observations, with one exchange 



for each, was made. 



Table XVIL 



FIRST SERIES. 



In considering these results, it is strikingly apparent that the evidences 

 of electric action are almost altogether absent. It is true that in all proba- 

 bility chambers Nos. 1 4 and 1 5 are but parts of one and the same large 

 ore-mass, but in the place where the experiments were made they are to 

 some extent, at least, locally disconnected. The results lead to the inference 

 either that the ore of both chambers is remarkably similar in character, so 

 as to present no appreciable electric difference, or that it is here without 



