Page:Great Neapolitan Earthquake of 1857.djvu/203



a body, $$\mathrm{A}$$ (Fig. 105), such as the coping-stone of a wall, a church bell, a ball or finial, upon a tower summit, &c.,

be thrown from its place by the earthquake wave in its first semiphase (direct shock), in the direction of wave-path $$\mathrm{OC}$$, and be found projected to the ground at $$\mathrm{B}$$, in a direction contrary to the wave transit. It is required, if the angle of emergence $$e$$, of the wave-path at the place, be known, to determine the velocity of projection, and vice versâ. The