Returning now to the ruins of Melfi, as no building, even among the strongest and best, escaped uninjured, we cannot say whether the earthquake had more power in high or in low places; yet we are of opinion that houses built on a declivity must have fallen sooner than those built on a level surface, and in general we remarked this in all endangered districts. Houses built on a level surface, with a square or rectangular foundation, not much longer than wide, of a moderate height, especially if provided with beams and iron chains (i.e., chain bars built into the walls), at least allowed egress to their inmates, and although injured were for the most part left standing. The house of Signore Calvino is an apparent exception to this rule, it being the only private house in the district of Venosa which buried any person beneath its ruins, and yet it is recently built on a large, level, and almost square foundation; but on attentive examination we find that its devastation must be attributed to faults of construction, for the roof had no tye-bars, whilst the floors were covered a volta a velœ with a very weak arch very thin at the top; the quoins were made of hewn stone, wretchedly bonded into the rest of the fabric, so that at the occurrence of the earthquake, the front wall, by the motion of the arches, was easily shaken from its vertical position, and then some fragments of the roof falling on the arch of the upper story, which had already lost its equilibrium by the displacement of one of its abutments, caused it to fall on the story beneath, burying all the people who were in it. We take this opportunity to state that the inhabitants of Vulture, availing themselves of the lava, which is sufficiently porous and capable of taking a good bond with cement, built their walls of unhewn stone of lava rubble-work; and as the cement which they use is not very good, owing either to the small proportion of lime which is mixed with it, or the want of selection of the Pouzzolana, it does not, as good cement, harden with time, but loosens, and crumbles into dust, so that the walls do not offer much resistance to the convulsions of the ground. The ceilings are also made of lava, and are easily destroyed by the vibration of the walls. In Melfi little skill is displayed in uniting the fragments of lava; we have seen a wall, the inner side of which was left standing, while the outer had
