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 elevate 
ata 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 
€se 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 voleanic 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. 
aubeny says,* “That (the supporters of my views) should 
explain to us why primary rocks, traversed, as they so frequently 
“re, with fissures of all descriptions, should not in every part o 
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 
hoticed in Ischia, as being unaccompanied with gaseous pro- 
ducts,” 
* Report, p. 70. 
