212 On Earthquakes — thdr causes and eff'eets, 



known volcanoes are siluated near the sea. Cotopaxi is 

 said to be farthest from it, at one hundred and forty miles 

 distance. Thus it is that inlands are so much more prolific 

 of volcanoes than continents. In Europe there is but one 

 on the continf^nt, and twelve on its islands; in Asia eight, 

 and on its islands fifty-eight ; in America ninety-seven, and 

 on its islands nineteen. Water therefore is an essential 

 portion of the volcano, and we may safely conclude that it 

 is its most powerful agent. We are all acquainted with the 

 astonishing elasticity of this fluid when surcharged with ca- 

 loric, and may imagine with what an enormous power it must 

 act through the subterraneous channels. The immense and 

 numerous masses ejected to an enormous height, fully illus- 

 trate this. A rock ejected from Vesuvius has been found 

 to measure twelve feet long and forty-five in circumference. 

 During an eruption of Vesuvius a hill one thousand feet high 

 was thrown up in one single night. 



Whether the earth was created with its internal mass in an 

 ignited state, or whether (he action of fire commenced since 

 that period, we are not to decide, — we must examine it as 

 we find it, and endeavour to show how this fire is kept up. 



In descending through the exterior strata of the earth we 

 find the heat to increase as we recede from its surface, and 

 if it continue to increase in the same ratio beyond the depth 

 man has been able to attain, we should have at a compara- 

 tively short distance, a state of ignition almost beyond our 

 conception. If such be really the fact, the centre of this 

 mass must assume a fluid form presenting a heterogenous 

 mass of metalloids ; but it is diflicult to suppose that it could 

 remain in a state of ignition without a large supply of air: 

 yet, on the contrary, the great density of the earth's mass 

 urges strongly in favour of such a belief. Dr. Maskelyne has 

 proved this density to be 9 a 2 water, and [) a 5 common 

 stone. 



If we admit of channels extending to, and connecting vol- 

 canoes, and branching into countries not possessed of them, 

 they must be independent of, and superincumbent to the 

 fluid mass. They may be considered, in fact, as a species 

 of horizontal volcanoes, their walls and roofs furnishing them 

 with combustible matter, aided by oxygen supplied by 

 ihe influx of the sea. That volcanoes are connected with 

 the ocean, cannot admit of a reasonable doubt. Inde- 

 pendent of what I have «aid on the subject, we have sub- 



