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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- 

 cal, 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 m 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 

 ffom there to the earth's centre all would be solid. So that at a 

 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 it is a 

 curious fact that all volcanoes 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 if it 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 



