CHAPTER VIII. 



INCREASE OF TEMPERATURE WITH DEPTH. 



Some measurements were made by Mr. Leon Dominian, field assistant, under 

 the direction of the writer, with a view to ascertaining the increment of temperature 

 with depth in this district. 



METHOD OF MEASUREMENT. 



The best opportunities were offered by the Mizpah Extension and the Ohio 

 shafts, both fairly deep shafts with (at that time) very little side workings and no 

 through system of ventilation. Holes were drilled dry into the rock at the sides 

 of the shafts at the points where the temperature was to be taken, deep enough 

 to take in the thermometers, which were especially procured for this purpose. 

 After the thermometer was inserted the hole was stopped up, and the reading 

 was taken after fifteen to twenty-five minutes in some cases twenty-four hours. 

 Check measurements were taken in every case. In the Ohio Tonopah the holes 

 were driven 18 inches; in the Mizpah Extension not so deep. 



The Ohio Tonopah. shaft is perfectly dry. The Mizpah Extension encountered 

 a very little water on a contact zone at a depth of 300 feet, but is otherwise 

 quite dry. 



TEMPERATURES 



THE MIZPAHT EXTENSION AND THE OHIO 

 TONOPAH. 



The results of the measurements of temperatures are given in the following 



table: 



Temperatures in Mizpah Extension and Ohio Tonopah shafts. 



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