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Page:Popular Science Monthly Volume 17.djvu/469

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THE INTERIOR OF THE EARTH.

peacefully coexist. Nothing is surer than that all the inventions, and improvements, and discoveries, of which our time is so fruitful, are tending with irresistible force to carry mere political democracy into anarchy.

All these evidences of growing social and political discontent, all these agitations and disturbances—the more violent talk on the one side, the leaning to repression on the other—are indications of unstable equilibrium, of a maladjustment of powerful forces. It is the necessity of the time—the vital, pressing necessity—that these phenomena receive the careful, conscientious attention of thoughtful men, who will trace them to their source and popularize the remedy. It will not do to leave them to the ignorant poor and the ignorant rich, to politicians and demagogues. They require the scientific spirit and the scientific method; they demand the thought of those who can think, and whose opinions carry weight.

 

THE INTERIOR OF THE EARTH.[1]
By R. RADAU.
II.

ASIDE from the evidences of the earth's internal heat furnished by artificial excavations, we have incontestable proof thereof in hot springs and in volcanic phenomena generally. The temperature of certain springs is nearly 100° at the surface. That of the Chaudes-Aigues is 80°; the Trincheras (Venezuela), 97°; the geysers of Iceland are 85° at the surface and 127° at a depth of twenty metres. But it is plain that the temperature of hot springs does not necessarily indicate the heat of the depths they come from. Aside from purely chemical agencies, there are physical causes sufficient to account for a very high degree of heat. When we consider the size of such caverns as those of Carniola and Istria, it will not be difficult to believe that there may be in the earth's crust fissures ten or twenty kilometres in depth, that may be filled with water, like the cavity that periodically absorbs and expels the water of the Lake of Kirknitz. Even at a depth of two or three kilometres the temperature of this water is 100°, but the pressure of two or three hundred atmospheres which it sustains prevents ebullition, as at 100° steam attains a pressure equal to the weight of only one atmosphere, and it does not form unless the pressure exceeds that. Under stronger pressure a higher temperature is required before ebullition takes place (i. e., the temperature at which the pressure of steam equals the resistance, or pressure on the liquid). Thus, under a

  1. Translated from the "Revue des Deux Mondes," by Guy B. Seely.