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Miscellany: Temperature Of The Interior Of The Earth

Miscellany: Temperature Of The Interior Of The Earth image
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The circumstance of the earth's being flattened at the poles, and protuberant at the equator, is the natural result of its rotation on its axis. But in order that it might yield to the force resulting from such a motion, the matter of which it is composed, must have been soft. Now, although water is capable of being comresscd, and so far as we can judge, of aking anydegree of density according to be force exerted upon it, still, the shape of the earth is not that which would have esulted from such a mnss of water. - There may be particular portions of the ea that extend to the depth of several miles, as there are particular points of he solid crust of continents, that rise to hat height above the general level. Still ve have reason to believe that the general depth of the ocean does no much exceed three thousand feet. It is thought hat heat may have been the original cause of the fluidity of the earth, and that here may still remain cnough to keep the nterior portions in the same state. The more this subject has been examined, the ïiore the evidence has accumulated in avor of the position that the temperature ncreases as we descend below the surace. There are numerous instances inwhich we have been able, by means of natural or artificial excavations, to penétrate to the dcpth of from 1,300 to 1,000 feet. The general inference from all these observations, made in different parts of the earth, is that there is an increase of heat amounting to 1 degree of Fahrenheit for every 46 feet in depth ; that at the dcpth of 10,000 feet the heat would be sufficient to boil water, and that at the depth of about 100 miles or 1 40th part of th ; distance to the centre, the heat would be intense enough to melt most of the earths and stones that are known to enter into the composition of the globe. These facts and inferences have an important bearing upon the phenomena of eaathquakes and volcanocs, and open a wide field of speculation to the natural