The awful and destructive concussions which sometimes are produced at
great depths beneath the surface of the soil, would seem to indicate
that no force but that of electricity is adequate to account for the
almost instantaneous desolation of wide tracts of the earth's surface.
But we do not mean to say that the action of the terral vortices,
combined with the internal conditions of our planet, is the only cause;
although it is far from improbable that the same activity of the ether,
which generates through these vortices, the full fury of the hurricane
in the tropics, may be simultaneously accompanied by a _subterranean_
storm. And physicists are too rash to reject the evidence on which the
connection of the phenomena rests.
In the extract given by Colonel Reid, in his "Law of Storms," from Sir
George Rodney's official report of the great hurricane of 1780, it is
stated, that, "Nothing but an earthquake could have occasioned the
_foundations_ of the strongest buildings to be rent; and I am convinced
that the violence of the wind must have prevented the inhabitants from
feeling the earthquake which certainly attended the storm."[33] Again,
in the Savannah-la-Mar hurricane, which occurred the same year and
month, the Annual Register, published at Jamaica, states, that at the
same time, "a smart shock of an earthquake was felt." The general
serenity of equatorial regions is due to the fact that they are beyond
the limit of the vortices, as in Peru, where neither rain nor lightning
nor storm is ever seen. Thunder and rain, without storms, however, are
common in other tropical countries, also out of the reach of the
vortices. But even in those parts, (as the Antilles,) lying in the track
of these vortices, the weather is not as _frequently_ disturbed as in
higher latitudes. The storms of the Antilles, when they do occur,
however, are fearful beyond any conception, showing the presence of some
cause, auxiliary to the ordinary disturbing action of the vortices,
which, when simultaneously occurring, adds tremendously to their force.
That earthquakes are preceded _sometimes_ by a peculiar haziness and
oppressiveness, similar to that which sometimes precedes a storm, is a
current opinion in volcanic countries. And Humboldt, who doubts the
connection, has to confess that sudden changes of weather have
_succeeded_ violent earthquakes, and that "during the great earthquake
of Cumana, he found the inclination of the needle was diminished 48'."
He also mentions the simultaneous occurrence of shocks, from
earthquakes, and a clap of thunder, and the agitation of the
electrometer during the earthquake, which lasted from the 2d of April to
the 17th of May, 1808; but concluding that "these indications presented
by clouds, by modifications of atmospheric electricity, or by calms,
cannot be regarded as _generally_ or _necessarily_ connected with
earthquakes, since in Peru, Canada, and Italy, earthquakes are observed,
along with the purest and clearest skies, and with the freshest land and
sea breezes. But if no meteorological phenomena indicates the coming
earthquake, either on the morning of the shock or a few days previously,
the influence of certain periods of the year, (the vernal and autumnal
equinoxes,) the commencement of the rainy season in the tropics, after
long drought, cannot be overlooked, even though the genetic connection
of meteorological processes, with those going on in the interior of our
globe, is still enveloped in obscurity."[34]
It is at the equinoxes that the earth changes her distances from the sun
most rapidly, and whether she is passing from her perihelion or from
her aphelion, the density of the ether externally is changing in the
subduplicate ratio of these distances and consequently at these times
there will be the greatest disturbance of the electric equilibrium. How
far our views of the internal structure of our globe, (considered along
a diameter as a solid crust, then a fused mass separated from the lower
ocean by another solid crust, and separated from a similar arrangement
on the opposite side by an interposed mass of water, perhaps also
possessing a solid nucleus,) may affect this question, is difficult to
say; but that the agent is electric, appears highly probable; and very
recently it has been discovered, by M. Ratio Menton, that a piece of
iron, suspended by attraction to a magnet, will fall on the approach of
an earthquake; thus indicating that the power of the magnet is
temporarily weakened by the action of some disturbing force.