Central Heat of the Earth, and Volcanic Phenometia. 137 



spheroidized, — the stream continues, till, in course of time, 

 an immense volume of water is there rolling and tossing 

 about, but not yet touching the metallic surface ; ultimately, 

 however, the balance is overturned, the liquid touches the 

 metallic basin. An immense volume of water is thereby 

 quickly converted into steam ; while at the same moment 

 chemical action on a large scale speedily ensues between the 

 liquid and the metallic bodies, — the latter action giving rise 

 to heat quite sufficient to fuse large portions of mineral mat- 

 ter. The almost instantaneous generation of large volumes 

 of vapours and gases, and these promptly augmented in bulk 

 for some time, would soon produce a force quite able to raise 

 large tracts of land, and, when a vent was made or obtained, 

 would eject the fused mass, as seen from the craters of some 

 modern volcanoes during the term of an eruption. 



By the above theory we are put in possession of a method 

 by which a very powerful and long-continued force can be 

 generated, and brought to bear upon volcanic phenomena. 

 When the vapours began to be produced, the water-course 

 would be dammed up, so that during the term of an erup- 

 tion no additional quantity of water could be projected into 

 the basin-shaped cavity from the water-stream : when, how- 

 ever, the whole of the water in the cavity had been converted 

 into the gaseous condition, and the force had gradually spent 

 itself, then the water would once more begin to percolate into 

 the cavity. Of course, some time would elapse after the last 

 drop of water was rendered gaseous before the pressure of 

 the gases would allow the water to issue from its course ; 

 during this time the basin-shaped cavity would be regaining, 

 from the surrounding hot matter, any heat which it had lost 

 during the eruption. Matters would thus again resume 

 their former aspect; the water would once again become 

 spheroidized in the subterranean cavity, there rolling and 

 tossing about, but waiting the appointed time, when the 

 balance will be overturned, and the striking phenomena cha- 

 racteristic of a volcanic eruption will again shew themselves. 



