Natural History of Volcanos and Earthquakes. 55 



these subterraneous oxidations are seen on the surface, in and 

 near volcanos only ; and why not even a trace of such processes 

 can be detected in other places, which yet present innumerable 

 thermal springs ? Surely no one will bring forward the scanty 

 evolutions of sulphuretted hydrogen gas from sulphurous waters 

 as proofs of such processes. But, were the conditions necessary 

 for volcanic activity fulfilled by the access of water to the inte- 

 rior in each of these channels, then would the occurrence of vol- 

 canic phenomena be much more frequent on our earth. Or, it 

 must at least be assumed that they were at a former period as 

 universally distributed as thermal springs now are ; and that they 

 have left behind a high temperature in the interior, which warms 

 the springs, and, as Daubeny also assumes, extricates from the 

 limestones, in the interior, the carbonic acid gas so universally 

 present. That this is occasionally the case, namely that springs 

 do acquire their heat at the expense of volcanic masses elevated 

 at a distant period, is certainly true, and has probably been of 

 still more frequent occurrence in former times. I have myself 

 already adduced instances of this kind. With the cooling of 

 these masses, however, the thermal springs dependent on them 

 must of course also cool, and whether this cooling take place in a 

 longer or shorter time, must depend on the greater or less extent 

 of those masses. 



After the preceding remarks, the question remains, whether 

 it be necessary to assume, in explanation of the universal distri- 

 bution of thermal springs, a volcanic activity once so universally 

 distributed ; or whether their existence cannot be both more 

 simply and more satisfactorily explained by an increased tempera- 

 ture in the interior, which is by no means merely hypothetical, 

 but is supported by innumerable facts. 



Daubeny says,* " That (the supporters of my views) should 

 explain to us why primary rocks, traversed, as they so frequently 

 are, with fissures of all descriptions, should not in every part of 

 the world, and in every kind of situation, give rise to hot springs, 

 by evolving steam from their interior, and why they never ap- 

 pear to give issue to that class of thermal waters which I have 

 noticed in Ischia, as being unaccompanied with gaseous pro- 

 ducts." 



* Report, p. 70. 



