Church — Underground Temperatures on the Comstock Lode. 293 
linked chain of heat phenomena, extending from rocks that are 
sensibly cold to the touch, and may not have a temperature 
above 50° or 60° F., through rocks that have the average 
atmospheric temperature, and those which are as hot as sur- 
face rocks ever become in Nevada, to those which have a tem- 
perature of 157° F. There is no reason to doubt that the 
gradation is quite regular, and the transition from the lower 
to the higher temperature is made through a much larger series 
of intermediate steps than the accidental thermometer readings 
taken show. 
he rock is usually dry. Wet portions exist, but these are 
os tain in comparatively narrow bands parallel with the lode 
and separated by thick masses of rock; the lode is usually per- 
fectly dry, and never exhibits more than the average leakage 
of mines. Wet rock is the exception, and dry rock the rule, 
through the whole lode. In the drifts cut through this hot, 
dry rock, the walls of the freshly exposed surfaces are painful 
to the hand, and the air is often filled with dust. The rock is 
both hard and tough, but, in spite of its strength, it gives an 
impression of fine porosity to the touch, due erg | to its 
trachytic character. It often has the odor of clay, but not 
ways. It may be slightly adherent, or the impression of 
dryness upon the tongue may be due to its heat. 
The plan of the Yellow Jacket mine is simple and such as to 
eliminate complications from the single problem of heat absorp- 
tion by moving currents of air from rock surfaces. From the 
1,531 level two parallel winzes are sunk on the lode, inclining 
with it. They are four hundred and thirteen feet apart, and 
connected on every lower level by the main north and south 
drift. The Yellow Jacket is a downcast mine, and the air cur- 
rent passes down the vertical shaft to the 1,119-foot level, 
thence down the incline to the 1,531 level, through a dri 
the south winze, and thence down tbis winze to the 2,200 
level, the bottom of the mine. On its way from the 1,531 it 
sends a current through the 1,732, 1,935 and 2,040 levels, these 
currents being reunited in the north winze, which is the upcast. 
he north winze does not reach to the surface, and no air rises 
‘to day” in the mine, the entire current flowing into the Im- 
aarp and Bullion mines, both north of the Yellow Jacket, and 
th of them exclusively upcast. i 
_ Captain Taylor has placed Fahrenheit thermometers of the 
_ common kind, with japanned tin cases, at the surface, foot of 
the vertical shaft (1,119 level), 1,782 south and north winzes, 
1,935 north winze, and 2,040 south and north winzes. The 
_ south winze is downcast, and the thermometers placed here on 
_ the different levels measure the increase of heat in the winze 
: itself, while those which are hung at the north winze measure 
