Page:Great Neapolitan Earthquake of 1857 Vol 2.djvu/112

Rh plumb towards the west; but the east and west movement has been by far the greater. Upon the whole, I conclude that the wave-path and direction, of the great primary shock, are given very accurately by the cathedral; that, standing, as the town does, upon an elongated ridge, which received the impulse of the primary wave obliquely, the ridge itself vibrated, in many different directions, by transverse and reflex waves; and that from the lofty ridges to the south and S.E. of the city, a reflected wave, or oblique echo, was delivered back, and produced a powerful secondary shock, nearly orthogonal to the primary. I am hence disposed to reject all wave-paths, given by other buildings than the cathedral, as respects the primary wave, and view them as evidences chiefly of the secondary waves.

The clergy of the cathedral informed me, that they had learned from others of their cloth, at Brindisi and at Tricarico, that at both these places, the direction of shock had been exactly west to east.

At Vignola, also, they said it had been felt from west to east exactly, but of course such statements cannot be relied upon within 5° or even 10° either way. Signor D'Errico after I had explained my views to him, considered the direction from, as evidenced by the injuries done, to the churches of Sta. Maria Maggiore, and D'Annuziata (Photogs. No. 314 and No. 315, Coll. Roy. Soc), as about 70° or 80° W. of north, and from the S.E.

I was unable to get any reliable information, as to the instant of time of the first shock. They all spoke here of three shocks. The first great one, which they thought, continued vibrating more or less, for about twenty or thirty seconds, and was succeeded very soon, (after a moment of