treating of the relations of geological formation to shock), and often (as at Saponara) chiefly because the houses that fall at the steep side to the left hand, fall against and upon,
those below them, and the accumulated ruin falls in an avalanche of rubbish down the hill-side.
So also if, in place of a steep angle of emergence, the line of shock were nearly horizontal, as from left to right, in the figure, the whole of the steep side of the town, during the first half vibration, tends to fall from the hill-side, and therefore away from all the natural abutments that their foundations excavated from the hill-side afford to the sides nearest the hill-top, but all of which generally are operative in favour of the houses at the other side of the hill.
This difference may be much compensated by the nature of the rock formation beneath the town, as well as by the form of the hill, &c., but this belongs to a future part of the subject.
