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natives when it has cooled sufficiently. As it issues the heat is 
so intense that a stick held in it cracks as if placed in the fire. It 
would appear as if there were caverns of no very great depth or 
extent, but subject to considerable permanent heat : that these 
caverns are filled with water through an aperture from the sea, 
which gradually heating till it boils over, is replaced by cold 
water, the process taking always about four hours. If deprived 
of the relief afforded by the opening through which the steam 
and water escape, no doubt explosions would ensue. This is 
evidently one of those cases in which steam alone is concerned. 
I believe that a vast number of so-called dynamic effects might 
be traced to the same cause, their irregularity being consequent 
on the variation of subterranean heat. It is noteworthy that 
these disturbances are frequently repeated in the seme exact 
localities. 
In attributing to steam the actual force in operation in most 
cases of earthquake, may we not go still further and imagine its 
having some connection with the generation of electricity ? 
But this is going beyond the scope of a mere glance at the sub- 
ject, which is all I have attempted to take. In doing which I 
have simply endeavoured to form some conclusions, based on the 
opinions of those who appear to me to be the most reliable 
authorities, corroborated, to a small extent, by my own very 
slight experience. But I am open to conviction, and shall listen 
with pleasure to any observations and corrections which may be 
made, and which may throw more light upon the apparent 
causes of these abnormal conditions of what we are wont to call 
terra firma. 
