64 Natural History of Volcanos and Earthquakes. 



tend, that these processes take place near to the surface, else how 

 could we explain the fact, that, in boring Artesian wells, the 

 greater the depth, from which the water rises, the higher is its 

 temperature. As little explanation could be gi^en of the circum- 

 stance, that springs rising in a small district near one another, 

 often present no inconsiderable difference in their average tem- 

 perature. In proof of the former assertion, I will cite out of 

 many other instances that of the hole bored at Rudersdorf near 

 Berlin, where water at 74^.3 F. was drawn by boring to a 

 depth of 880 feet ; and in proof of the latter, the numerous 

 springs in Paderhorn, whose temperature varies from 49° to CP. 

 P. In the former case, then, these presumed chemical processes 

 must take place far below the depth of 880 feet; in the latter 

 they must be supposed to be going on, either entirely below the 

 situation of the springs at a nearly equal depth, or at various 

 depths beneath each separate spring. In the previous 

 different temperatures would be occasioned by one spring run- 

 ning nearer, the other at a greater distance from, the common 

 source of heat. 



case 



Daubeny speaks, in general terms only, of chemical processes ; 

 if we may, however, judge from a note,* he seems to allude to 

 the same processes as those which he assumes as the cause of 

 volcanic phenomena, viz., the oxidation of metals of alkalies and 

 earths by water. We may pause a little to consider these 

 hypothetical chemical processes, as they ought to inform us 

 whence the agent, viz., heat, is derived, which is the point in 

 question. 



As the presence of thermal springs is so universal, these met- 

 als must be equally so. This hypothesis, especially in the ex- 



tent given it by those who maintain it, viz., that the whole nu- 

 cleus of the earth consists of an unoxidized mass, cannot be rec- 

 onciled with the proportionate density of our earth, as I have al- 

 ready shown. Yet, let us admit for a moment the existence of 

 these metals in a more limited proportion. Their oxidation re- 

 quires the access of water; we must, therefore, suppose as many 

 channels to conduct the water from the surface as there are ther- 

 mal springs, or at least groups of thermal springs. Granting all 

 this, the question yet remains to be answered, why the effects of 



Report, «fcc., p. 68 and 69. 



