UNDERGROUND TEMPERATURE 
9 
BY E. WETHERED, RC.S,, F.G.S. 
EOLOGY and Chemistry have revealed to us a mass of infor- 
'^mation concerning the nature and composition of the crust of 
our earthy but how far that crust extends, and what it encloses, is 
even at the present day a matter of considerable doubt. 
The inconsistency between the known specific gravity of the 
rocks which compose the crust of the earth, and what would be 
the specific gravity of a similar solid globe, renders it clear, that the 
earth is not a solid, or, that there must be a nucleus, composed of 
a substance, or substances, of a much less density than those which 
compose the crust. 
With a view of gaining information on this matter, we naturally 
turn to volcanoes, hot springs and geysers ; these phenomena all 
indicate the presence of heat But if we agree thus far, we may 
not concur as to the direct cause or source of this heat : are we 
to consider that the water of springs and geysers derives its heat 
from chemical action within the crust of the earth, or from the 
substances contained in the water, or is that heat derived from a 
lower region ? 
With regard to the first,— chemical action within the crust of 
the earth, Professor John A. Church, of Ohio, North America, 
recently contributed a paper at the Chetauooga Meeting of the 
American Institute of Mining Engineers on the ^^Heat of the 
Comstock Mines f he states that the rocks in the lowest levels of 
the mines appear to have a pretty uniform temperature of 130° f. 
