Page:Great Neapolitan Earthquake of 1857.djvu/330

270 angle of elevation of the projectile which is here equal to the angle of emergence, we have, in which $$H$$ is the height due to $$\mathrm{V}$$, and finally obtain $$e = 68^\circ 25'$$, for the angle of emergence, or that of the wave-path with the horizon; but as the tiles were fastened more or less, some force was expended in detaching them, so that the angle $$e$$, was rather less than this, and may be estimated about 60° or 64°.

The house was approached by an arched gateway, of rubble stone-work plastered, as seen in Photog. No. 138, looking south from the military road. This arched structure is heavily fissured, right through the crown of the arch, showing most at the south side, and in three diagonal fissures on the north side of the structure. The largest fissure is about 4 inches wide at top. The gateway is 12 feet wide and the height to the soffit is 16 feet; each pier is equivalent to about 4$$\tfrac{1}{2}$$ feet square in horizontal section, and buttressed by the fragments of walls proceeding from them at each side. These fissures, like those of the main building, indicate a wave-path not far from E. and W., and a direction from the eastward—on the whole, about 100° west of north. The gateway fissures have had their directions mainly determined by those of the voussoirs of the arch, which is of brick; by the relative support given by the side walls as buttresses; and by the rocking of the piers as the shock passed through them; so that no inference can be drawn from them as to the angle of emergence.

In the Photog. No. 138 the rere or north front of the villa is seen, and above the projection at the central part