Penny Blood: Serial Sensation and Working-Class Entertainment — page 65: what you’re looking at

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

48 ELEVATIONS AND DEPRESSIONS. [cH. v. tions from a section of unit of horizontal width to any pro- posed area of the earth’s surface, and eventually to that of the whole globe. A clear conception of what will then be the upper “datum level” is important, It will be an imaginary surface which occupies the position that the surface of the crust would occupy at the present time, had it been perfectly compressible in a horizontal direction; so that no corrugations would have been formed in it. At present we regard it as affected in position by the contraction of the interior, but not by the compression of the crust. _ As soon as elevated tracts had once been formed by the cor- rugation of the ‘cooled crust, all the material above the datum level, however distributed, must have been derived from matter originally beneath it, and subsequently raised above it. As often as further compression of the crust has taken place, every fresh addition to the sum total of the quantity of matter above the datum level must have accrued by the elevation of matter from below it. For the matter which was already above it, however freshly corrugated, or re-arranged by water action, or otherwise, cannot have been thereby altered in quantity. More- - over each additional contraction will have acted upon a crust thicker than it was before, on account of its having become in the meanwhile solid, or if solid contracted, to a greater depth. We have hitherto confined our symbols to a vertical section of unit of width. We will now extend them as in the diagram to a portion of the crust whose length is / and width w, and the depth k; e and e’ being the mean coefficients of com- pression in the directions of length and width. Then, if we (CO) COMIC OOOKS