BOILING HEAT AT VARIOUS DEPTHS. 



G3 



which water may acquire, beneath the surface of 

 the earth, from the steam coming up from the 

 depths below. 



Depth 



Highest possible Tem- 



below 



perature in degrees, 



surface 

 in feet. 







Cent. 



Fahr. 







100 



212 



16 



1117 



233 



32 



1207 



249-3 



48 



128 



262-4 



64 



131-2 



2735 



96 



111-4 



292 



123 



1527 



306-8 



182 



1599 



319-9 



224 



166-1 



331 



256 



171-6 



3409 



288 



1767 



350 



320 



1813 



35S3 



It is easy to understand, that steam may force 

 its way even up to the surface of the earth, where- 

 ever the circumstances of the place are favourable 

 to such a result ; especially if the brandling water- 

 veins reach far enough down, and if the flow of 

 cold surface-water into their upper parts is pre- 

 vented. The cooling effected by the walls of the 

 water-channel itself is of little importance, for the 

 solid earth can conduct away the heat but in a very 

 slight degree. 



Jets of steam (fumeroles) and springs of boiling 

 water come up in many places, especially in vol- 

 canic districts. AVe have numerous instances of 



