Penny Blood: Serial Sensation and Working-Class Entertainment — page 139: what you’re looking at

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

122 DISTURBED TRACT. [cH. x. At A, x=0; and f has some constant value; and there 1s no extrinsic pressure at A; Again, if p’ be the force at P’ which resists the downward motion of ZP, dp’ = — gpda + fadz ; Now, at the neutral zone, the forces which resist the upward motion must be equal to those which resist the downward motion. If then A be the depth of the zone, the integral (1), taken from 0 to h, must be equal to (2) taken from fh to &, when to the second we have added the extrinsic force gpk, arising from the pressure of the fluid; h ke ‘ gph + | fc =— gp (e—h) + | fila + gph; “ [. file = [ fae. This result shows that the position of the ‘neutral zone depends solely upon the condition, that the friction upon the column above it shall be equal to that upon the column below it. Let us first of all make the assumption that the friction is constant at all depths, and equal to A. Then Nhe n(k—-h); _k 9 P or the neutral zone is aiteated in the middle region of the crust. But if we consider the plasticity of the material to be increased by heat in the lower parts of the crust, we must (CO) conniclsoolkks