304 



GEOLOGY OF THE COMSTOCK LODE. 



that part of the thermo-element lying near the hot end was really in action. 

 It was therefore thought desirable to reverse the element, so that the end 

 which was formerly in hot water would now be in cold, and vice versa. 

 Table X. contains the results thus obtained. 



Table X. 



10.51 



a. 23 



6. 54 

 5.65 

 4. G9 



calculated. I «(^"<"'- 



10.51 

 9.19 

 6.58 

 5.66 

 4.68 

 3.59 



The difference between the values of a in Tables IX. and X. lies within 

 the range of unavoidable errors. 



In Table VIII. there is a difference of temperatures between tlie inte- 

 rior and exterior of the rock-chamber analogous to that in preceding tables. 

 The former is, as usual, smaller, but in this case the temperature of the 

 rock apparently decreases as the action continues. 



Between the observations No. 34 and No. 38 there appeared disturbances 

 of a kind which seemed to indicate that a break had occurred somewhere 

 in the insulation. Subsequent inspection showed that the parts of the rubber 

 hose around the platinum terminals, which were in contact both \\ith air and 

 steam, had swollen to a spongy mass of many times their former bidk. It 

 is not improbable that -the wire during the disturbances mentioned had been 

 more or less perfectly in contact with the walls of the boiler, the dough}' 

 rubber protection having either given way or offering imperfect insulation. 

 Though this was partially remedied, yet the last week's observations are 

 nevertheless to be regarded as somewhat suspicious, and were consequently 

 omitted in the calculations below. 



Discussion. — In the following discussion the observations in Tables III. and 

 VI., and the first two weeks in Table VIII., are to be considered. Together 

 these data correspond to an interval of four weeks. In the endeavor to 

 reach the most probable conclusion to be derived from the large number of 

 obsei'vations, the end in view will be attained most speedily, and perhaps most 

 satisfactorily, by assuming for the rehition between the variables some ap- 



