&2 Notice of Uayden'a Geological Essays. 



these cavities communicate in any manner with the oceans, 

 and are (as if they exist at all, tiiey probably are,) filled 

 with water, there exist, we conceive, agents very competent 

 to expel the water of these cavities, and thi's to deluge, at 

 any time, the dry land. These agents are the aerial fluids 

 ' — the gases — whose competency to any and every degree of 

 energy, which a given mechanical movement may require, 

 is abundantly exhibited, in the rending force of gun powder, 

 and of the other still more potent explosive compositions, 

 and in the phenomena of earthquakes and volcanoes, whose 

 mechanical effects, we conceive, depend principally upon 

 the sudden and abundant evolution of aerial bodies. These 

 bodies, suddenly evolved, and subjected to pressure and re- 

 sistance, are competent not merely to propel cannon balls 

 and bombs, to burst rocks and to explode mines — -they can 

 rend mountams — they can rock them from their bases — 

 they can shake continents, and cause the globe itself to vi- 

 brate and tremble. 



If then, there were occasion to elevate a column of wa- 

 ter even six miles in height, so that it should transcend the 

 highest mountains ; aerial fluids would be equal to the effort. 

 Should they be disengaged, abundantly, in the vast sub- 

 terraneous and subaqueous cavities, they would of course 

 occupy the roof or vaults of the cavity, and would there- 

 fore expel the water, which we suppose they may contain, 

 and this water rising and spreading itself over the dry land, 

 might,, by its abundance, more or less complete, submerge 

 the continents more or less completely. In short, it would 

 be merely a case of compressed air acting to raise a column 

 of water, as in a fire-engine. If ^t be objected, that the 

 pressure would split the incumbent earth, we answer that it 

 would do so did not its counteracting pressure, arising from 

 a specific gravity at least two or three times greater than of 

 water,* resist, with even superfluous energy. 



It is not necessary to shew, that any such agencies have 

 been actually exerted, and have certainly produced these ef- 

 fects. - It is sufficient to evince that they are possible, and 

 that if exerted, they are competent to the supposed effect. 



* Possibly even much greater, according to the deductions of Maskeiyne 

 and Button on Ibe specific gravity of the earth 



