Page:Great Neapolitan Earthquake of 1857.djvu/455

Rh The vase $$\mathrm{B}$$, however, lay (as in Diagram) so, that its line of direction with its own base, was 30° E. of north, the horizontal range of throw being only=4.75 feet. There was evidence of this vase having rolled, from the point where it first alighted, westward, but the precise point at which it first struck the ground was not decisive. It appears probable that it was first, along with its base, tilted up upon the edge $$f f$$ by the transverse shock through the limestone, and that before it had returned to its former position, the principal or direct shock, in the direction 15° W. of north to south, caught it and threw the vase off the base; but part of the effort of projection was in that case destroyed by the fall back of vase and base, and hence the horizontal distance of projection is less than that of the other vase, and less than that due to the velocity of shock; and the direction of projection became one in some intermediate azimuth between the two wave-paths. We might assume that the vase, $$\mathrm{B}$$, was projected by one shock, and that, $$\mathrm{A}$$, by the other; in which case we could infer that the angle of horizontal intersection of the wave-paths had been = 45°, but that would render no account of the twisting of the base of $$\mathrm{B}$$. We must, therefore conclude, that the vase $$\mathrm{B}$$ was acted on by both shocks, and as it had rolled more or less, the angle of intersection would be less. The supposition made, also gives a solution for the fact otherwise hard to account for, that the part of this vase that rested on its base was towards the south as it lay, while the corresponding part of $$\mathrm{A}$$ faced the north. The latter was a clean throw, in the former the vase was tilted a little towards the N. E. [sic] in the return to its place, of its partly-upturned base, immediately previous to its throw, and the rotation thus commenced, turned it over in a vertical plane during its free descent from its base to the ground.