Penny Blood: Serial Sensation and Working-Class Entertainment — page 161: what you’re looking at

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

144 THE REVELATIONS OF THE PLUMB-LINE. |[cu. xt. mountains, thereupon Archdeacon Pratt set himself what ap- peared the Herculean task of actually calculating what the effect of the attraction of that great mountainous region ought to be, and in a second paper upon the same subject he says, “My calculation has been before the public three years ; and, though some small numerical errors have been detected, they are not of sufficient importance to affect the result; and the data I have every reason for believing to be correctly taken, as the Surveyor-General—who first called my attention to the subject in 1852, as an unsolved difficulty in the operations of the great Trigonometrical Survey of India—has been requested to forward to me any corrections which may appear to him to be advisable, and none have been sent’.” The result at which he arrived was, that the attraction of the mountainous region ought to have made, between the true and astronomically ob- served differences of latitude of the extreme stations, a dis- crepancy of 15885 instead of 5°°286 as it did. That is to say, the effect of the attraction of the mountains was in fact considerably less than it ought to have been, according to what their mass above the sea should produce, taking 2°75 from Maskelyne’s determination for Schehallion for the density of the attracting mass. Thus the mountains’ attraction not only accounted for the discrepancy discovered by the Survey, but accounted for too much. They ought to have attracted the plumb-line more than they did. The Archdeacon then applied himself to explain this un- expected anomaly, and the conclusion he came to in his first 1 3008 Ws too large for the Indian arc, the curvature there having been, as he thought, probably increased by the upheaving of the mountains. This would have the effect of making the difference calculated upon the triangulation larger, so as to compensate for the effect of the mountains’. paper was, that the assumed ellipticity 1 Second Paper by Archd. Pratt. Phil. Trans. of Royal Soc., Vol. 149, p. 746. 2 If \ be the amplitude of the arc (i.e. the difference between the latitudes of its extreme stations), J its length, » the latitude of its middle point, and e the COLA @ NOOKS ACO