Penny Blood: Serial Sensation and Working-Class Entertainment — page 297: what you’re looking at

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

280 SUMMARY. [cH. xxII. tendency will be for fissures to form, chiefly along the shore line on the steeper side of the ridge. The depressions, in which the deep water lies, will also by the same action be moved further away from the ridge on both sides. XI. We apply to the downward protuberance of the crust into the substratum, under any elevated tract, the popular expression of “roots of the mountains.” The existence of these roots of the mountains are not a mere matter of speculation. They have been felt by aid of the plumb-line in the following manner. The great mass of the Himalaya mountains was, during the Indian Trigonometrical Survey, found to attract the plumb-line. But upon its being calculated how much attraction ought to be attributed to this mountainous mass, it was found that, though they attracted the plumbline, yet they ought to have attracted it still more than they did. Sir G. B. Airy explained this anomaly by the existence of downward protuberances of a lighter crust into a heavier sub- stratum ; which 1s exactly the same supposition to which our reasoning has just led us. This then is a strong confirmation of our theory of the constitution and arrangement of the crust. Another point to be‘ observed is, that the floatation of a crust, thus dipping downwards into a heavier fluid at the places where it rises upwards into the air, precludes the transmission of any unequal stresses to the parts below, and renders unneces- sary the supposition of extreme rigidity, either in the crust itself or in the subjacent matter, in order to support such stresses. XII. Again, the existence of the roots of the mountains ought to be revealed by phenomena of underground tempera- ture; and we find such to be the case. Whether the crust be thick or thin at any given locality, the temperature of its under surface ought to be the melting temperature. This tempera- ture may practically be considered the same everywhere. Accordingly any difference in the rates of increment of tem- perature in descending at two localities ought to depend only upon the thicknesses of the crust, and upon the mean surface COMIC OOOKS.EO