r walls, where, as its wonderful
hardness and texture and its enamel-like surface showed, it had been
roasted for years probably.

Nor do I believe in the _sudden_ blowing away of one-half the crater and
cone of Vesuvius, or of any other volcano, at one effort, however
affirmed.

Nothing more than conjecture as to the nature of the impulse producing
great or small Earthquakes can, I believe, as yet be produced. That
there is some one master mechanism productive of most of the impulses of
great shocks is highly probable, but that more causes than one may
produce these impulses, and that the causes operative in small and long
repeated shocks, like those of Visp-Comrie and East Haddam, differ much
from those producing great Earthquakes, is almost certain.

We shall be better prepared to assign all of these when we have admitted
a true theory of volcanic action, and so are better able to see the
intimate relations in mechanism between seismic and volcanic actions.

It is not difficult meanwhile to assign the very probable mechanism of
those comparatively petty repercussions which are experienced in close
proximity to volcanic vents when in eruption, and which, though
certainly seismic in their nature, and powerful enough, as upon the
flanks of Etna, to crack and fissure well-built church-towers, can
scarcely be termed Earthquakes.

In my First Report I stated that almost nothing was known then of the
distribution of recorded Earthquakes in time or in space over our
globe's surface, and I proposed the formation and discussion of a
complete catalogue of all recorded Earthquakes, with this in view.

This was approved by the Council of the British Association and at once
undertaken by me, with the zealous and efficient co-operation of my
eldest son, Dr. J. W. Mallet. Nearly the whole of the Second British
Association Report, of 1851, is occupied with the account of the
experiments as to the transit rate of artificially made shocks in sand
and granite, as already referred to.

The Third Report, of 1852-1854, contains the whole of this, "The
Earthquake Catalogue of the British Association" (of which, through the
liberality of that body, more than one hundred copies were distributed
freely), in which are given, in columnar form, the following
particulars, from the earliest known dates to the end of 1842:

1. The date and time of day, as nearly as recorded.

2. The locality or place of occurrence.

3. The