Penny Blood: Serial Sensation and Working-Class Entertainment — page 189: what you’re looking at

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

172 AMOUNT OF COMPRESSION. [CH. XIII. and Jet the distance between the two circles, that is the distance between the lower mean and the lower datum level, be er, where r is the radius of the sphere to the upper datum level. Then if & be the mean thickness of the crust, 4crer (r — k)* is very nearly the volume of the shell between these two levels. And so it is easily seen from the figure, that 4rrer (r —k)? = 3 (X)—-3 (X)4+2%(Y’) -—2%(Y¥). But we know that, by the datum level equation, % (X)—-% (Y) =0'; *, 4orer (r —k)® =3(Y’) —% (X’), and _3(¥)- 3 (X") fern (r—k)t * | Secondly, suppose the outer circle to be the upper mean level, and’ the inner one the upper datum level. Then the volume of the shell between these two levels is nearly 4arr’er. Aud from the figure, S (A) -3 (4) +3 (B) — 3 (B) = darren ; & (A) —> (B) = 4arr’er + & (A’) — & (B).......(A). But, by the datum level equation, > (A) — & (B) = 8ar'ke. And the value of ¢ has just now been found. Hence, substituting for > (A) — > (B) and e in (A), op ECP) — S(2)} + 8(4) -2B)...B) We suppose for the present that the crust beneath the oceans 1s of the same density as elsewhere, and attribute their presence to depressions of the surface, owing to the crust being thinner beneath them. This is the particular case in the last chapter* when p’ is put equal to p. Srr'ke = 1 This follows from the relation Z (a)== (8); p. 47. 2 p. 164. COMIC OOOKS.EO DP tin - ny alpen ee OO ene Oa nS ) ES et Ca ee