348 



GEOLOGY OF THE COMSTOCK LODE. 



Table XVI., finally, contains the data nece.ssaiy for the approximate 

 representation of earth-potential as a function of distance. By arbitrarily 

 assuming- the potential of Point VIII. as zero the final means in Table XV. 

 are identical with the potential of the ))oints to which the data refer. Tlie 

 third and fourth columns of Table XVI. contain tlie length and bearing of 

 the imaginary lines joining I. with the succeeding points. 



Table XVI. 



Discussion. — From the results in Table XIII. for the resistance of differ- 

 ent circuits similar conclusions to those on page 341 are deducible. Wherever 

 the structure of the rock and coexisting circumstances are favorable to the 

 absorption of moisture, there also minimal values for this quantity are found. 

 Unusually high values were obtained for the holes XV. and XVI. But the 

 rock at these points was so tough and tenacious that the miners complained 

 of the slow progress made in drilling. 



Remarks analogous to the above are applicable to the values for inten- 

 sity on this level. 



The results for earth-potential in Table XV. harmonize much better 

 than those for the preceding levels. The individual values in the two series, 

 as well as the means of the series themselves, are in fixir accordance. 

 This might be ascribed to the fact that the holes were mostly in rock of 

 the same variety, and that strong salt solutions were discarded in completing 

 the contact between the terminal bags and the earth. 



By a method of procedure similar to that already employed the relation 

 between potential and distance may be represented graphically. It will also 



