Penny Blood: Serial Sensation and Working-Class Entertainment — page 168: what you’re looking at

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

CHAPTER XII. THE REVELATIONS OF THE THERMOMETER. Recapitulation of results of previous chapter—Roots of mountains should be revealed by phenomena of underground temperature—Conditions upon which the mean rate of increase of temperature will depend—Rate greater in plains and less in mountains—Dr Stapff—His observations on temperature of rocks an St Gothard tunnel—His explanation of the smaliness of the rate—Why not satisfactory—LEffect of convexity of mountain upon the rate—The rate may be considered uniform above—The conclusion from the premises is that the mountain has roots—The rate may be regarded as nearly uniform throughout —General method of determining the thickness of the crust at the sea-level, and the melting temperature, from the rates beneath the mountain and the usual rate—Application to St Gothard—Thickness of crust at sea-level and melting temperature deduced numerically from the data—The like for Mont Cenis—Results confirmatory of previous conciusions—Considerations about the oceanic areas—How the water is retained there—The thickness of the sub-oceanic crust and its density. WE have seen in the preceding chapter that certain results of geodesy agree well with the conclusion arrived at in the tenth chapter, that mountains have “roots,” that 1s that there is, for all regions elevated above the mean level of the crust, a corresponding downward protrusion of the lighter material of the crust into the heavier substratum. This is in substance the same thing which Herschel expressed by saying that, “the force by which continents are sustained 1s one of tumefaction’.” According to our theory these roots will consist of the lighter material of the crust, in an unmelted state, projecting into a heavier molten fluid. The amount of this projection may be roughly determined by the relative densities of the crust and fluid, in the same way as if the crust floated without constraint in equilibrium. For although, as we have argued in the tenth 1 See p. 76. GONG oOo (CO)