Penny Blood: Serial Sensation and Working-Class Entertainment — page 164: what you’re looking at

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

cH. x1.] THE REVELATIONS OF THE PLUMB-LINE, 147 It will be at once seen that this reasoning produces an arrangement of the crust upon the subjacent fluid exactly analogous to that which has been arrived at in the preceding chapter. Of course we from our point of view cannot contem- plate the independent formation of a table-land apart from the downward projection, so that it should afterwards break and form one. But it does not seem that it concerned Sir G. B. Airy to show that the one cannot be formed without the other. The object he had in view was to explain how this arrange- ment of matter would produce a smaller deviation of the plumb- line. He says, “It will be remarked that the disturbance depends on two actions; the positive attraction produced by the elevated table-land, and the diminution of attraction produced by the substitution of a certain volume of light crust (in the lower projection) for heavy lava. The diminution of attractive matter below, produced by the substitution of light crust for heavy Java, will be sensibly equal to the increase of attractive matter above. The difference of the negative attraction of one and the positive attraction of the other, as estimated in the direction of a line perpendicular to that joining the centres of attraction of the two masses (or as estimated in a horizontal line), will be proportional to the difference of the inverse cubes of the distances of the attracted point from the two masses.” A D @) “Suppose then that the point C is at-a great distance, where nevertheless the positive attraction of the mass A, considered alone, would have produced a very sensible effect on the astro- nomical latitude, as ten seconds. The effect of the negative : 8 attraction of B will be 10” x CA’ and the whole effect will be CB’ 8 10” x si , which probably will be quite insensible. “But suppose that the point D is at a mueh smaller I0O—2 GONG oOo SS (CO)