Page:Great Neapolitan Earthquake of 1857.djvu/425

Rh inch. The chord of vibration of the frames on the wall $$\mathrm{B}$$ in plane of that wall (or north and south), was 7.50 inches,



and the semichord corresponding from and back to this wall $$\mathrm{A}$$, was about 4 inches.

It was obvious, therefore, that here two wave-paths almost coincident in time had crossed each other, at a sharp angle, the one arriving first, being transmitted with more or less of an east and west direction, from the north and south axis of the great range of mountains to the eastward, and having an horizontal amplitude not exceeding 2 inches; the other, which almost instantly followed, having a north to south direction, and an horizontal amplitude of 6 or 7 inches.

Nothing observed, except the chocolatière, gave any approximation to the extent of vertical movement or altitude of the wave which appeared by it, about half an inch at most.

Upon rushing out of the house, Signor Calvoso said, he was struck with the quietude of the night, and the general serenity of the sky for the season. The night was not a dark one, but he had observed nothing himself, of any unusual luminous appearance; of having remarked which, however, numbers of persons had spoken to him since the shock. He however stated that having on the