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local chemical action, and water coming into contact with it in 
large quantities? The sudden flashing into steam that would 
follow would, in a confined space, unquestionably cause a violent 
explosion. When a small quantity of water finds its way through 
a leak into a blast furtiace the consequences are sometimes serious: 
how much greater might be the effect of a large volume of water 
on molten lava of considerable extent ! 
Though in some volcanic regions the ground, even near the 
surface, is much more honeycombed than I believe people in 
general imagine, yet I do not, of course, suppose that the 
vibrations felt through an extended area are produced by the 
passage of steam through a suecession of chambers: we must trace 
in this the course and action of the electric wave. But that very 
considerable subterranean communications do in places exist there 
seems no doubt. There is every reason to suppose, for example, 
that there is direct communication between Vesuvius and Solfa- 
terra, about thirty miles apart; the tiny outlet is evidently in 
such close sympathy with its great neighbour. 
The undoubted fact that maritime regions are more subject to 
volcanic disturbance than inland districts seems to add weight to 
the opinion of those who assert that steam is the most potent 
agent in this matter, for it is easy to imagine what vast quantities 
of water may be ever finding its way into the bowels of the earth 
from the bed of the ocean, to return to the surface again only by 
the action of intense heat. It is not often that we have an 
opportunity of noticing this inpour of the sea, but a remarkable 
instance exists in the Island of Cephalonia, where some con- 
siderable streams, large enough to turn mills, flow continually 
inland from the tideless sea, and, falling into deep chasms, 
disappear. In the same island I descended into some of the 
many caverns, and when our further progress was stopped by the 
narrowness of the fissures, we could still judge of their immense 
extent by hearing the roar of underground torrents still far away 
below us. 
