III. I shall conclude with the moral use we ought to make of these
prodigies of nature.
I. The struggles of subterraneous winds and fires, that should heave
up the ground like animal convulsions, seem to me impossible: Their
powers, and manner of acting (if such there be) is quite incapable of
producing the appearance of an earthquake. That these should operate
instantaneously, in one minute, thro' a circle of 30 or 40 miles diameter,
or more, I could not conceive. Nor that there should be any possible, much
less ready passage thro' the solid earth, for such nimble agents, as every
one is apt to imagine that speak of this appearance; without sufficiently
reflecting on the insuperable difficulties in that _hypothesis_.
We cannot pretend to deny that there may be such vapours, and
fermentations, inflammable substances, and actual fires, in the bowels of
the earth; and that there may be some caverns under-ground, as well as we
find some few above ground: such as _Pool_'s-_Hole_, _The Devil_'s-_Arse
in the Peak_ of _Derbyshire_, and _Okey-Hole_ in _Somersetshire_.
These, I believe, to have been so from the creation, never were made by
earthquakes. We know, there are hot springs running continually: There
are some vulcano's frequently belching out flames and smoke, and to these
perhaps some earthquakes may be owing, tho' not according to the vulgar
notion; as we shall see, by and by.
But these matters are very rare, much rarer than earthquakes, both as to
time and place. _Vesuvius_ in _Italy_, and in that part of it abounding
with mines of sulphur: _Ætna_ in _Sicily_, and _Heckla_ in _Iceland_;
these are all we know of, in the old world. In the _Andes_ mountains of
_America_, there are some. The scarcity of these appears to me a strong
argument against the common deductions made therefrom, as to their being
the cause of earthquakes.
Nor can I enter into the sentiments of those that hold the cavernous
state of the earth, so as to contribute to the forming an earthquake by
vapours running from place to place under ground. How many thousand acres
of coal-mines do they daily work in _England_, and have done for ages? I
have been myself 2 or 300 feet deep in a solid rock of native salt: I have
walked a mile lengthwise directly into the earth, and descending all the
way, in the proportion of one yard in five, 'till we came under the bed of
the very ocean, where ships were sailing over our heads. This was at Sir
_James Lowther_'s coal-pit, at _Whitehaven_. We were at this time deeper
under ground by the perpendicular, than any part of the ocean, between
_England_ and _Ireland_.
We never hear, from the many hundreds of thousands of workmen in this
kind, at _Newcastle_, _Nottinghamshire_, _Yorkshire_, _Derbyshire_,
_Staffordshire_, _Somersetshire_, and _Wales_: from the infinite numbers
of workmen in the mines of lead, tin, and the like, of the cavernous
state of the earth, so as to give any colour for this _hypothesis_ of
earthquakes. The earth is generally of solid rock; in which there must be
now, and then, some clefts, and vacuities, small in compass, as naturally
so many heterogeneous _strata_ of the earth consolidate together. But
there can be no imagination of vapours breaking through, uniting,
traversing so suddenly, a large space of earth, so as to produce those
earthquakes, we have seen, and felt; much less such as we read of. The
workmen in all sorts of mines confess by their hard labor, that the earth
is not cavernous; nor are there mines of sulphur, nitre, and the like
inflammable materials in _England_. Or if there were, could they burn,
and cause convulsions of the earth, without proper cavities, pipes, and
conveyances of air; as vulcano's, and coal-pits, when set on fire. But
even from these coal-pits, when fired, do we ever find any thing like
an earthquake produced. Nor do we find earthquakes frequent in those
countries, that abound with coal-mines, as certainly would be the case,
if that _hypothesis_ was just. How easy would it be, on the slightest
occasion for earthquakes to happen in the countries abounding with
coal-mines, which are so full of artificial cavities communicating with
one another, for many miles together: The very thing supposed, by those
who hold the old opinion, of vapours traversing the earth for that purpose.
In the coal-pits, some small natural cavities now and then are found;
which when opened, send forth a pestiferous vapor and a fire-damp which
runs for a long time together. And tho' there are many substances that
may generate air, within the bowels of the earth; yet these matters are
infinitely unable to produce an earthquake: Never would have force to open
a passage for themselves thro' the solid rock, of perhaps many hundred
feet in thickness. Nor did we observe in these last earthquakes any fire,
vapour, smoke, or smell, any kind of eruption, in the least; as must
certainly have been, in so great a struggle of the superfice, as affected
a circle of so large a diameter. Were there such, we could scarce hope any
otherwise, than that they would be too sensibly felt; to the destruction
of many thousands, by their pestiferous qualities.
Indeed this consideration alone, of the extent of that surface, is
sufficient to overthrow any supposition, of earthquakes being chiefly
owing to subterraneous vapours: They cannot momentarily fly under so large
a tract of ground, if they were near the outward shell of the earth. They
could not do it without breaking ground, and discovering themselves to
the sight, or smell; and that for a long time after. It cannot possibly
be imagin'd, they could have so immense a force, as to lift up the city
of _London_, and never be perceived by our organs, and outward senses. We
have frequent accounts of a little fire-ball bursting in the air, at a
distance; yet it instantly propagates a sulphureous smell around.
If the movement of a superficies of 30 miles diameter was owing to fumes,
and vapours; we ought reasonably to find some great discharges of them,
belching out smoke and fire, for a long time after, like vulcano's,
and coal-pits fir'd. The operation of the shock ought to be of hours
continuance, not instantaneous; and the evaporation of so vast a quantity
of matter, must darken the whole region of the air for a long time
after; or require a long time, if gradually it discharges itself. We see
how immense a volume of smoke is produc'd by a very small quantity of
gun-powder; and no vapour could be so subtle, that produc'd such effects,
and not be very obvious to our senses.
Even in vulcano's, it is the opinion of the learned _Italian_ philosopher
_Borelli_, and of other great naturalists, that they are kindled first
from the surface, where there is a possibility of ventilation from the
air. They imagine, it begins at the top of the mountains; not by any
fancied fermentation of the _pyrites_ and sulphureous vapours arising from
subterraneous caverns, in the lower parts of mountains.
There is another consideration, which utterly overthrows these
suppositions, of earthquakes being caused by anything under-ground; and
that is a due consideration of springs, and fountains perpetually flowing;
and that from the creation of the world to this day. If we would form any
tolerable idea of their nature, we must needs conceive, that God Almighty
has laid their pipes, and canals in the earth, from a great depth, even to
the surface; like as he has planted the veins, arteries, and glands in an
animal body. And likewise that they are more and more ramify'd, as they
nearer approach the outward shell of the earth; just so our veins, and
arteries, as they come nearer the skin.
The workmen in coal-mines, and those of metals, minerals, and
stone-quarries, never fail to meet with springs, and currents of water,
every where. Often they ruin, and divert springs another way, only by
digging into the earth for foxes, and the like. Whenever they dig for
wells, in any kind of earth, they commonly find springs. The colliers,
and workers of mines, are oblig'd to drain the waters off with very great
expence.
These are circumstances not favorable to subterraneous fires being in the
earth in abundance; much less to their being the cause of earthquakes.
And further, we cannot possibly think of earthquakes doing their work
that way, without absolutely ruining the whole system of springs, and
fountains, throughout the whole country, where they pass. But all this is
quite contrary to fact; even where an earthquake has been repeatedly. For
an instance from home.
On _Wednesday, April_ 6, 1580, about six in the evening, just such another
earthquake was felt in _London_ and around it, as these two we have seen.
Another exactly similar 1692. In all these four, no houses thrown down, no
springs disturb'd thereby, no sensible eruptions nor smells.
These considerations I apply only to this little inconsiderable space,
of a circle 30 miles diameter; as with us. But what is that to the
earthquakes we read of in history? In the year of our Lord 17, no less
than thirteen great and noble cities in _Asia minor_, were destroyed in
one night. _Tacitus_, _Pliny_, and many other authors mention it. The fact
is so notorious, that some persons here present, have seen a vast block of
white marble now standing near _Naples_; being the pedestal of a coloss
statue of _Tiberius_ the emperor; having carv'd on it the _genius's_, or
pictures of all those cities, with their names. The accurate _Bulifon_ and
others have wrote treatises upon it. These cities were rebuilt by that
emperor. But without going so far, we may see another evidence of it, a
coin of that emperor struck upon the occasion, with this inscription,