Penny Blood: Serial Sensation and Working-Class Entertainment — page 64: what you’re looking at

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

r CH. V.] ELEVATIONS AND DEPRESSIONS. 47 or, denoting the sums of the quantities in like positions by the symbol, 2, we get kl (1 +e) =k + & (a) — 3 (b) +E (8) — 5 (a). , kle = % (a) —& (b) + (B) —Z (a). .ceceeceveeee (1), which we shall call a “datum-level equation.” - Since the pressure is supposed to take place in a horizontal direction, it will not have any direct effect to raise the centre of gravity of the portion of the crust under consideration; so that, if the layer in question rest upon a liquid substratum, we may expect some portions of the disturbed crust to dip into the superheated rocks. But in that case, if the datum- level be unaffected in position, a corresponding volume of such subjacent rock must rise into the anticlinals. Hence, > (a) = & (8). And the equation becomes kle = % (a) — 3 (6). In order to render this reasoning applicable to the section of a surface of any form it is only necessary that the pressure, which causes the compression, should be everywhere tangential to the surface, and that gravity should be perpendicular to it. Hence it is applicable to the earth’s surface, although that surface is not strictly regular, and may contain local elevations and depressions affecting the mean figure (that is the figure as unaffected by corrugation), which, though of small amount as compared to the dimensions of the earth, may be large as com- pared with the quantities of which we have to take cognizance in this investigation. But the above suppositions cannot represent accurately what has occurred in nature. For they assume the upper and under parts of the crust of the earth to have been. compressed _hori- zontally by the same amount. In reality compression must have gone on gradually ever since a solid crust was first formed, and must be greatest at the upper datum level. We must therefore consider e to be the mean coefficient of compression. In the next place it will be necessary to extend our considera- GONG oOo SS (CO)