Page:Great Neapolitan Earthquake of 1857.djvu/119

Rh plane, and with a smaller transversal vibration performed in a horizontal plane as in Fig. 52. The actual relation of altitude and amplitude, so far as observation yet is afforded, seem more as in Fig. 53, or even in a far higher ratio to each other, and the transversal vibration still smaller, as in Fig. 53 , so that in normal or slightly emergent waves the transversal movement is little noticed, (as, indeed, is true pro tanto of the movement in altitude); hence, as stated, we may neglect for present purposes, the transverse movement altogether as respects such waves.



In the case of vertical emergence, however, the path of a moving particle being in one vertical plane elliptic, and the major axis being the line of transit, will have the form of Fig. 54, in a vertical plane atright angles to the former, and in an horizontal plane at the earth's surface the path will be as in Fig. 55. In ascending through heterogeneous formations even the more complex forms of Fig. 56 and, or Fig. 57  and , may be those of the path of the wave particle, the vertical being the movement of largest range, in every instance. In either of those cases the sensible effect upon the earth's surface must be the same as if bodies, besides being lifted up and down, were alternately whirled