Penny Blood: Serial Sensation and Working-Class Entertainment — page 194: what you’re looking at

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

CH. XIII] AMOUNT OF COMPRESSION. 177 We then shall have d’v—(D), or the water displaced, equal to a layer of the area of the land, and of the mean depth of the ocean, or equal to L6, as already assumed. To calculate the second term, we may assume wat L 82, 268 » and 7 197? and we obtain 0:083; whence _ e = 0254 — 0-083, = 0171. The contraction indicated by this result is greater than can be admitted ; remembering that e is the mean compression for the whole thickness of the crust, and that the contraction of the outer surface of the globe, and therefore of its radius, is probably nearly the same, it would require that the radius of the earth should have been shortened by nearly 700 miles since a crust began to be formed. If we suppose the substratum of lesser density as compared with the crust than the density of basalt as compared with that of granite, then, owing to the smaller value of o—p, this contraction would have to be put higher. Nevertheless on our conclusions regarding a fluid sub- p stratum, we cannot put the ratio = at a less estimate than we have done; for even that is probably too small, since it is not likely that the density of the substratum should not be lessened both by its exalted temperature, and possibly by the combined water; so that o will be more nearly equal to p than the density of basalt is to that of granite. Our hypothesis must therefore be in fault. Now in obtaining the above estimate, we have taken the crust to be of the same density beneath the oceans as beneath the continents. But we have shown* that that cannot be the case, for that it must be there more dense, and that the equili- brium of the ocean is due to that circumstance. We must 1 See ch. v., p. 55, note. | 2 ch. xuz., p. 165. F. 12 NOO SS (CO) COMMUC