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grounds, the deepest boring in the world (at Sperenberg, near 
Berlin), being only three-quarters of a mile deep, which is a very 
insignificant distance compared with the 4,000 miles radius of the 
earth, from which to draw conclusions. Various theories, mechani- 
eal, chemical, and electrical, have been broached to account for the 
undoubted fact of fluid lava, or melted rock at a high temperature, 
existing beneath volcanic vents; none of them, however, are quite 
satisfactory. It is presumptuous in me to bring forward a theory 
of my own when so many scientific men are in doubt on the 
subject, and yet the thing seems so clear to my mind. Admitting 
that the temperature rises in geometrical ratio as we go beneath 
the surface and towards the centre of the earth, we must, of course, 
soon reach a point at which all ordinary rocks would liquify from 
the heat, but beyond that point again we should come to a region 
where the superincumbent pressure would be so enormous as to 
counteract the effects of the highest conceivable temperature, and 
from there to the earth’s centre all would be solid. So that ata 
certain depth, which would vary widely according to different 
physical conditions of pressure, &c., there must exist a layer of 
liquified or melted rock, which only requires the addition of water 
to generate steam and became so highly explosive as to force its 
way through any weak place in the overlying strata. Now itis a 
curious fact that all voleanoes are situated close to the sea shore, 
or on islands, and in the one or two apparently exceptional cases 
they are not far distant from water. It has been argued that 
volcanoes cannot derive the steam which they generate in such 
vast volumes during eruptions, from the subjacent seas, because 
the fissures or rents in the earth communicating with the waters, 
could only have been caused by the eruptive force, so that the com- 
munication would only exist after, instead of before the explosion. 
But every one knows the enormous distance to which water will 
percolate through the earth, and it is only necessary to imagine it 
reaching the liquified rock by this means, to understand the sudden 
and immense evolution of steam which would take place. If other 
proof were wanting, it would be found in the fact that fish have 
been frequently ejected from volcanoes, as well as the chemical 
constituents of sea water. I am often asked if it is likely we should 
ever have severe earthquakes in England, and ifit is possible for a 
volcano to spring up in our midst. Of course we might have other 
and more severe earthquakes than we have yet had, for although 
they are almost invariably associated with volcanic eruptions, they 
are often felt at enormous distances from the volcanic orifice, often 
indeed more severely than near the vent. Nor is this surprising 
when we remember that earthquakes generally subside in violence 
as soon as a free outlet is afforded to the pent-up forces. We are 
