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lest we should be supposed to be carried away bj crude notions, 

 we have tried to consult authorities respecting the size of extinct 

 or active volcanoes elsewhere. Singularly enough, we do not find 

 so much notice taken of the size of craters as the heights of the 

 volcano ; but we gather that the old crater — now Barren Island — in the 

 Bay of Bengal, had an area of sixteen square miles, or thereabouts; 

 that Santorin, in the Grecian Archipelago, had an area of about 200 

 miles ; that Papandayang, in Java, had an area of the same dimensions ; 

 that, at present, Pichincha, in Peru, has an area of five miles ; 

 Vesuvius, only about a quarter of a square mile ; and Kilhaurea and 

 Mauna Ptoa, an area of about six miles. IVlonte Somma was more 

 than eight times the size of its present repi'esentative ; and it is 

 equally clear that the ancient Posilippo crater was nearly a hundred 

 times larger in area than Monte Xuovo, Avernus, Solfatara, and others 

 that succeeded it. 



Another objection seems to us of great weight. If we are to 

 consider the craters as vents, it is extraordinary that they do not 

 continually run. The hypothesis of a central liquid mass must 

 and does necessarily, assume that the crust is not only cold, but 

 that it is perpetually growing cooler by radiation. We cannot 

 conceive that the process of cooling can go on Avithout contraction ; 

 and, if so, there would always be a considerable pressure exerted 

 upon the central fluid, which could not cool in the same proportion 

 as the outside. If, then, a vent were once to be established, there 

 would be quite sufficient power to keep it constantly open, and we 

 should have the wondrous spectacle of a perpetual incandescent stony 

 fountain, whose streams would gradually overlay the outer world. Such 

 an hypothesis, too, is wholly incompetent to explain the explosions, 

 detonations, earthquakes, and other phenomena which precede or 

 accompany volcanic action, nor does it attempt to account for the reason 

 why ashes, scoriae, &c., are so much more abundant in every eruption 

 than lava. 



Another point of interest is this : A volcano, such as Mauna Roa, 

 which has been recently in eruption, and Skaptar Jokul, iu Iceland, in 

 action 1788, did, iu the course of a comparatively short period, emit 

 three streaiiis of lava, forty, fifty, and sixty miles long, with a breadth 

 of from seven to fifteen miles, and a depth of from one to six hundred 

 feet and more. The molten mass filled up valleys of no mean magni- 

 tude, and chasms of awful grandeur. The area covered by the lava 

 from these volcanoes exceeds that of the Isle of Man, and the whole 

 mass maybe rotighlj' estimated at 1,600 cubic miles. 



The abstraction of such a mass from the earth's centre, we are 



