IS THE CENTRE OF THE EARTH A SOLID MASS.

Pelorus Guardian and Miners' Advocate., Volume 18, Issue 41, 21 May 1907, Page 2

IS THE CENTRE OF THE EARTH A SOLID MASS.

There is a popular belief that this earth on which we live is composed of a surface crust ; that within this crust there is a molten mass heated to a degree beyond anything the human mind can conceive, much less measure by degrees, or describe in figures. We have been told that this crust eon only be compared to tho shell of the egg, and that even this comparison does not do the subject justice, so much thinner is our earthcrust, or shell, than is the shell of the egg, when the thickness of both is measured by the respective vollung of the contents of each. If the existing theory is a mistaken one, it must be admitted that it may yet be possible for man to descend to depths far below any he has yet attained.■ The one fact upon which scientists base the theory that the interior is a liquid mass of intense heat is that in or other deep borings hitherto made in the earth's surface, it has been found that heat increases in a degree proportionate to the depth descended. It lias been found that this heat increases one degree Fahrenheit for every fifty-one feet below the surface, and that at a depth of two miles the temperature is equal to that of boiling water. But there are those who question all this. They even question whether tho interior of the earth is in any degree warmer than its surface, and if these sceptics should be right the ingenuity of man may yet devise means to -make exploration far beyond any on which he has yet ventured. The objection will arise that it is a fact that it does grow rapidly warmer as descent from the earth's surface is made. Mr. Frank Harris, an English geologist, in replying to this objection, says, that instead of the increasing heat perceptible when -'descent into tho earth to any considerable depth is made being causod by much greater heat further below, it is, in reality, caused by the pressure of the air from above. He cites . two well known instances t© prove .this. One is that in valleys in Switzerland when a cold wind descends upon them tho pressure of the upper air, cold as it is, upon the lower strata of 'air, causes great heat. Another place where similar effect is produced by similar cause, he says, is at Melbourne, Austra4ia, where, when a cold wind blows in from tho South Antarctic the air exercises a pressure upon the warmer .northern air below- and produces oppressive heat that continues until the cold current of air has obtained mastery over the warmer air beneath.

And further, say those, who do not agree with the generally accepted theory, if "the interior of the earth was composed of an intensely heated liquid mass, enclosed within a shell as thin as we have been taught to believe the earth's crust to be, it it would long since have found veut and over whelmed both land and sea. Berosford Ingram, B.A , F C.S., who has given much thought to this subject without having reached a conclusion to which he will commit himself, very fairly states the theory held by some geologists that the ea*rth is a cooling body, with a thin crust and an interior composed of a molten, liquid mass of some unknown substance, but, presumably, melted rocks, while others hold that the pressure in the interior of the earth must be so great that through the greater proportion of its diameter it must necessarily be solidified, leaving only a comparatively small strata of intensely heated liquid between this nucleus and the outer crust.

One objection he sees to this theory, however. "If," says Mr. Ingram, ''the earth's crust is so thin it would yield to the deforming influences of the sun and of the moon, in which case the water would be drawn up with the earth, and 'thus no sensible tidal effectscould b£ produced. In order to counteract the attraotion it would bo necessary to admit that the thickness of the' earth's crust is at least two thousand miles.-" He- cites another theory that the earth, having passed through the stage of alternate solidity and fluidity, is now solid throughout, but with large fluid cavities existing in the mass, which, would go far to account for volcanoes and earthquakes.