Penny Blood: Serial Sensation and Working-Class Entertainment — page 291: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

274 SUMMARY. (cH. XXII. say how much it would have cooled at any specified depth from the surface, since the whole became solid. If then we know the amount of contraction on cooling for such rocks as exist near the earth’s surface, we shall have the means of calculating how great the contraction would have been; and consequently what amount of inequalities this cause could have produced. Again, Mr Mallet has made a series of careful experiments on a large scale, on the contraction through cooling of silicious slags from a state of fusion, and his results are sufficiently applicable to our problem. These we have used, and calculated the amount of inequalities of the earth’s surface, which would have been formed had they been due to a hot solid globe cooling by con- duction, and we have found the amount to be very far smaller than that which actually exists. For whereas, as we have seen, the actual inequalities, if levelled down, would form a layer of about 10,000 feet thickness, those which would be formed on the present hypothesis would form a layer not exceeding 900 feet in thickness on the most extravagant supposition. But if we adopt a more moderate basis of computation, 200 feet would be nearer the mark. VII. The large discrepancy between these quantities shows that the hypothesis, that the inequalities of the surface have been caused by the cooling, and consequent contraction of the earth regarded as a solid globe, is untenable. We appear then to be compelled to accept one or both of the alterna- tives, (1) either the inequalities of the surface are not altogether, or even chiefly, due to lateral compression, or (2) there has been some other cause involved in producing the inequalities of the crust, other than the contraction of a solid globe through mere cooling. In the estimate we have made of the inequalities of the surface, which might arise through compression from the cool- ing of a solid globe, we have included the basins of the oceans. If these be due at all to the contraction of the materials of the globe, there does not appear to be any other way of accounting for them except by compression: because, if they had been caused by direct radial contraction, they would require a. differ- COMIC OOOKS.EO > — _— .