Penny Blood: Serial Sensation and Working-Class Entertainment — page 252: what you’re looking at

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

cH. xvu.] ZHEORY OF VOLCANIC ENERGY. 235 force’, viz. the weight of a column of rock 2000 miles. high and 1 mile im sectional area and of the density of the crust, which we will term P, and by giving to P, the value zero. A superior limit to the whole work on a vertical section of the strip of crust will therefore be — k’e; be and upon a square mile of this section, 2 e ke. je Mr Mallet, at p. 8 of his paper in the “Philosophical Maga- zine” for July 1875, states that the friction may be as great as 2 of the pressure. Let us, then, suppose first that the nucleus 1s solid, and that the force requisite to move a column of the crust horizontally over the nucleus is ? of the weight of the column; and P is the weight of a column 2000 miles long. Hence w=EP SGa6 whence, if k = 400 miles’, which is the thickness suggested by Mr Mallet, | aa? P=%4 5° Hence the work upon a square mile of section cannot be so great as 4 Poke, which = 4 Pe x (2000 miles), To assign a value for P, we use the weight of a cubic foot of granite, given by Mr Mallet as 178°3392 pounds (say 200 pounds). And for the supposed value of e, which we may obtain from the radial contraction during one year as given by the same Physi- cist in his Addition, &c., Tab. 11.° for 400 miles thickness of crust, 1 ¢= 10° ce) 1 p. 36. | 2 We must recollect that the crust is assumed to be thick, 8 “ Addition to the paper on Volcanic Energy.” ‘Phil. Trans, Roy. Soc.” Vol. 165, Part 1. -D> GONG oOo SS (CO)