Page:Great Neapolitan Earthquake of 1857.djvu/389

Rh throw being 14 feet, and the height from which it had descended 30 feet, i.e., these being ordinates to the centre of gravity of the thrown mass. The portion thrown off from the top, was projected during the second semiphase of the wave, by the velocity impressed during the first, or by the return stroke of the shock.

Let $$a$$ = 30 feet, $$b$$ = 14. Then from the equation

we find tan e = 1.593, and e = 57° 50′, an angle of emergence which is within the limits given, by the fissures (which in this instance are extremely well defined in the Photogs. Nos. 177, 179, and 180, Coll. Roy. Soc.) in several parts of this building, and in that of the sluice-house at the river close by.

I shall recur to this wall when treating of the "camine," thrown in the dining-room.

Throughout the Palazzo, the floors are of beton and tiles, laid upon thick oak planking, crossing over oak and fir joists at about three feet apart: some in the largest rooms at the north wing, have been brought down altogether, the fractured beams showing, that they yielded to the inertia of the mass of beton and tiles, under the emergent wave. All are fissured, in various directions diagonally across, the lines more or less curved, with the hollow sides of the curves towards the centre of the floor, and upon the whole making angles of about 22° 33′ with their respective walls, and crossing each other towards the mid length, nearly at right angles; the great prevailing direction 22° 30′ E. of north, and at right angles to the same. These floor fissures, as nearly as they could be drawn by the eye,