EECEEATIVE SCIENCE. 



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make the tour of tlie world, everywhere we 

 meet with igneous rocks upon the summits of 

 the hills, and on the seaboard of the Pacific 

 active craters accompany the line of the 

 upheaval to awful altitudes of the rocks 

 which occupy the lowest place in the geolo- 

 gical series. 



Let us at this point go back to remote 

 geological antiquity, and picture the earth a 

 rocky and sterile mass, but just cooled suffi- 

 ciently to permit the existence on its surface 

 of water in a liquid form. The soil is yet too 

 hot for life in any of its forms ; many of the 

 more volatile elements are still floating in the 

 atmosphere, still uncondensed and unab- 

 sorbed. The seas boil furiously, and the 

 huge bubbles of ebullition keep up a roaring 

 din, which mingles with the blasts of Vul- 

 canian forges, and the thunderous rumblings 

 of earthquakes on the land. Immense volumes 

 of steam involve the world in terrible dark- 

 ness, and showers of hot water fall upon 

 the hotter soil. As the rains fall, the rocks 

 splinter and sever into zigzag seams, and the 

 water flowing through, reaches the terribly 

 heated mass below. Steam is generated in 

 enormous quantity, every particle of water 

 expanding into 1700 times its former bulk ; or 

 the water itself is decomposed into its com- 

 ponent gases, which occupy many thousand 

 times the space of the water from which they 

 are formed, and these, suddenly produced in 

 confinement and under pressure, will fight 

 fiercely for escape. Then will commence the 

 sharp struggle of gas and vapour fighting for 

 freedom, and in the hour of this terrible 

 convulsion, the rocky crust will be torn and 

 shattered, the fiery tide will be protruded, 

 and the masses ejected will form the granite 

 peaks which now crown the world, and pierce 

 the heavens with their grand pinnacles of 

 snow. 



In thermal springs we find a still further 

 confirmation of the theory. Boiling springs, 

 like earthquakes, are most frequent near vol- 

 canoes. The Geysers of Iceland are in close 



proximity to Mount Hecla, and doubtless de- 

 rive their heat from the rocky reservoirs out 

 of which they flow, the immediate source of 

 the fountain being a portion of the volcanic 

 soil which has an immediate connection with 



Theoretic Section of a Geyser, showing the cavity in 

 which the water collects by percolation, and from 

 whence by the pressure of confined steam it is forced 

 along the pipe at the time of eruption. 



the internal fires. The celebrated springs of 

 Soltaferra — the steam of which is used to 

 drive the mills in the adjacent factories — have 

 more than a chance connection with Vesuvius ; 

 and, indeed, by some geologists, and particu- 

 larly by Professors Phillips and Daubeny, 

 boiling springs are regarded but as a class of 

 volcanoes, in which the product of eruption is 

 water in a comparatively pure form. 



Pallassou first explained that the tempe- 

 rature of springs decreases in proportion to 

 their distance from tha great granite mass, 

 and that springs having their source in lay- 

 ers of sedimentary formation much above 

 the granite, vary in temperature with the 

 seasons and the weather, while the deep- 

 seated springs have a constant heat, which is 

 unafiected by external circumstances. So 

 definitely is this the case, that it is regarded 

 as a law of the Artesian and other wells, that 

 the deeper the source the warmer is the water 

 that flows from it, and this, too, in an ascer- 

 tainable ratio. It is also worthy of remark 

 that thermal springs, though frequent in 

 volcanic districts, are by no means coufine4 



