Both these circumstances
perfectly agree with the general idea of the undulations having
come from the south-west; in which quarter subterranean noises were
also heard; for it is evident that the walls running south-west and
north-east which presented their ends to the point whence the
undulations came, would be much less likely to fall than those
walls which, running north-west and south-east, must in their whole
lengths have been at the same instant thrown out of the
perpendicular; for the undulations, coming from the south-west,
must have extended in north-west and south-east waves, as they
passed under the foundations. This may be illustrated by placing
books edgeways on a carpet, and then, after the manner suggested by
Michell, imitating the undulations of an earthquake: it will be
found that they fall with more or less readiness, according as
their direction more or less nearly coincides with the line of the
waves. The fissures in the ground generally, though not uniformly,
extended in a south-east and north-west direction, and therefore
corresponded to the lines of undulation or of principal flexure.
Bearing in mind all these circumstances, which so clearly point to
the south-west as the chief focus of disturbance, it is a very
interesting fact that the island of S.
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