_Facts tending to illustrate and prove the existence of a_
mid-plane-space, _situated between the concave and convex surfaces of
the sphere._
According to Symmes's Theory, each sphere has an intermediate cavity,
or _mid-plane-space_, of considerable extent, situated between the
convex and concave surfaces of the sphere, filled with a very light and
elastic fluid, rarified in proportion to the gravity, or condensing
power of the exposed surfaces of the respective spheres: and also,
various other less cavities or spaces between the larger or principal
one, and the outer and inner surfaces of the spheres, each filled with
a similar fluid or gas, most probably partaking much of the nature of
hydrogen. This fluid is lighter than that in which the sphere floats;
and has a tendency to poise it in universal space. The spheres, in many
parts of the unfathomable ocean, is believed to be water quite through
from the concave or convex surfaces to the great mid-plane-space, and
probably the earthy or solid matter of the sphere, may in many places
extend quite through from one surface to the other, tending, like ribs
or braces, to support the sphere in its proper form. Such a formation
of spheres appears to be supported by various facts and phenomena;
amongst the most prominent of which are Volcanoes and Earthquakes. Many
volcanic mountains burst out and burn for ages, discharging from the
bowels of the earth immense quantities of lava, pumice, and various
substances of various kinds. Some of these mountains have been burning
for thousands of years, at least as far back as the records of history
have been made known to us.
Had the earth, at its formation, been a solid globe, four times as hard
as hammered iron at the centre, and gradually lessening in density
towards the surface, we must admit that it would still be solid matter.
Governing ourselves by these principles, how can we imagine that such
immense caverns, filled with combustible matter, as would be necessary
to supply those volcanoes from time immemorial, could have existed?
However, that they do exist is certain, which I think is in no way
more easily accounted for, than on the plan of a _mid-plane-space_,
or of spaces, filled with a certain hydrogenous gas, which being much
lighter than atmospheric air, if there should be any small aperture or
crevice extending from the surface to the space beneath, the gravity of
the outer part of the sphere pressing on it would occasion a portion
of this gas to escape through the aperture; and as it comes in contact
with the oxygen of the atmosphere would take fire and occasion those
tremendous explosions which we know do sometimes take place and cause
those mountains to burn for years, until the cavity which supplied the
volcanic matter, becomes exhausted; or until some shock or convulsion
consequent on the burning, may have loosened rocks or earth of the
denser part of the sphere, which falling into the aperture, choke it
up. Hence the gas ceasing to escape, the volcano would cease to burn,
until some shock or accident should again open the aperture.
The elastic fluid, with which the _mid-plane_ cavities are filled,
being forced out into the common atmosphere, the greater degree of
gravity would condense and set free its latent heat or caloric, and be
resolved into its original base, somewhat as coal-gas, out of the tube
of a gas-light apparatus, yields up its latent heat by condensation.
Hence steam burns when mixed with coal-gas.
If the earth be a solid globe, I am at a loss to account for the
principles on which earthquakes occur. Long before I heard of Symmes's
theory, or perhaps before it had an existence in the mind of man,
when reading accounts of earthquakes, it appeared to me altogether
unaccountable, that such violent concussions could take place in one
part of the world, and not be felt throughout the globe. It appears
altogether inconsistent, that one part of a solid piece of matter,
would be shaken so violently, without affecting the whole mass. We are
informed by authentic history, that whole islands, and vast sections
of country, have been sunk by earthquakes, and never more heard of. On
the other hand, islands which are now inhabited, and productive, have
been raised, apparently, from the bottom of the unfathomable ocean.
How such things occur, I am unable to divine. If the globe be solid,
on what principle could a large portion of its surface, which is said
to be lighter than the parts beneath, sink into a dense medium? How
could a heavy mass, lying a thousand fathoms deep at the bottom of the
ocean, rise, and be suddenly elevated above the surface of the water,
when all below is so compact, and governed by an opposite and immutable
tendency? It appears to be a solecism in nature.
The writer had once an opportunity of witnessing some of the effects
of earthquakes. It was his fortune to be on the Mississippi river
in the year 1812, at the time when that country was so violently
convulsed with an earthquake. He saw and heard innumerable explosions,
as though a large quantity of air had been confined in the bowels of
the earth, and, seeking vent, rushed out with a tremendous sound;
forcing up considerable quantities of sand through the apertures, in
many instances mixed with black muddy water, and a substance resembling
stone coal, or carbonated wood, which emitted a strong bituminous
odour, when exposed to fire.
At one place the river was stopped in its course a short time: the
water rose to a considerable height above its common level; and, on
the west side of the channel of the river, there was a counter-current
for a few minutes of an astonishing velocity. So great was its force,
that for some distance the cotton wood and willows on the margin of the
river, were either prostrated or bent up the stream; and their branches
looked as if they had been dragged a long way on the ground. The waters
of the river soon subsided, and flowed in their natural direction.
So tremendous were those explosions, that when happening under large
trees, the tenacity of their texture yielded at once to their force;
and the largest in the forest were split and fractured from root
to top. During these convulsions, the ground on which the town of
New-Madrid is situated, together with the country for several miles
round, sunk about five feet below its former elevation; in which
situation it has remained. Eight years afterwards the writer was again
on the same spot. The desolate aspect, which the country presented at
the time he witnessed those scenes, was measurably obliterated: but the
banks of the river were still in their sunken situation.
How could all those violent convulsions take place at this point, and
not be felt at New-Orleans, along the sea coast of the United States,
and other places? Whence came this water and air, which issued from
those apertures in the earth? And why did the river for a few minutes
flow in a contrary direction, and then resume its natural course? If
the earth be a compact and solid globe, I can account for none of
these things; but admitting the formation of the sphere to be such as
I contend for, they are all resolved into the most simple principles;
and what would otherwise be impenetrable mystery, is made as plain
as noon-day. If the sphere be formed as I allege, those concussions
were doubtless occasioned by the gas or fluid in the _mid-plane_ or
some intermediate space, near the surface, which, by being suddenly
rarified, would make it expand, and cause the upper part of the sphere
to be suddenly elevated in the neighbourhood of the Little Prairie;
and hence the waters of the river, pursuing the laws of gravity, would
flow in a contrary direction. This sudden expansion, and elevation of
the surface, would cause apertures, through which the rare gas would
escape, and the surface would then settle down again, not only to its
former level, but, as a considerable portion of this gas had escaped,
the remaining part would occupy less space; hence the surface of the
country, around New-Madrid, would be below its former situation.[31]
The fluid, or gas, which fills the mid-plane and intermediate cavities,
is most probably the same, or partaking of the same nature, (though
perhaps in a purer state,) with that which oozes out of fissures
in the earth, at the bottom of deep mines, called by chemists,
_hydro-carbonate_; which being highly inflammable, takes fire from the
lamps used by workmen, and explodes with such violence as to destroy
both men and horses employed in the mine. This is a frequent occurrence
in the deep coal mines of England; and great numbers annually have lost
their lives in this way, before the introduction of Sir Humphrey Davy's
lamp. I am also informed, from good authority, that the miners, in some
of the deep coal mines in England, once felt, or heard an earthquake,
which happened in Italy, whilst those on the surface of the ground had
no knowledge of it. This would be the case, if the intermediate cavity,
which caused the earthquake, extended in that direction, and near the
bottom of the mine; as it is presumed the rare gas with which those
spaces are filled, is better adapted to the conveyance of sound, or
vibratory motion, than the more solid parts of the sphere, or even the
atmosphere around us.
On the supposition that the globe is solid, and the matter composing
it at rest, as respects itself, on what principle can boiling and hot
springs be accounted for; some of which issue out several thousands
of miles distant from where any volcano or subterranean fire is known
to exist; particularly as to those on the waters of Red river, in the
state of Louisiana, which are sufficiently hot to cook meat in a few
minutes.
Phenomena which occur in various lakes in Europe, may be adverted to in
support of this theory. The waters of lake Zirchnitzer, in the Dutchy
of Carniola, in Germany, flow off, and leave the basin empty; and again
fill it, in an extraordinary and impetuous manner; bringing up with
its waters fish and even sometimes wild water fowl.[32] In the same
country, there is a subterranean lake, in the Grotto Podspetschio, of
considerable extent; the whole of this vast body of water, at certain
times, will disappear in a few minutes, and leave the basin dry; and
after a few weeks, it again suddenly returns, with a frightful noise.
The lake of Geneva, and some others in Switzerland, at certain times
rise and fall several feet without any cause, which has as yet been
satisfactorily explained; and some writers inform us, that those lakes,
particularly Geneva, send forth, at times, a grumbling noise. In the
Saian mountains, near the source of the Yenisei, is a lake, called
Boulamy-Koul, which, at the approach of winter, emits strange sounds,
somewhat similar to those which precede the eruption of a volcano, and
which are compared by the neighbouring inhabitants to howling. The
inhabitants on the borders of Baikal, also state, that they have often
heard dreadful and terrific howlings proceed from that lake.[33] The
lake, Agnano, in Italy, sometimes, especially when the waters are
high, appears to boil at its borders. This ebullition is supposed to be
occasioned by some gaseous fluids, discharged into the bottom, which
traverse the waters of the lake.[34] These various phenomena, which
cannot be easily accounted for, might be best explained perhaps, on the
principles of _mid-plane-spaces_. In various parts of the north, thick
strata of ice are found, under a thick soil; and on ice-bergs, floating
in the ocean, have been discovered masses of earth, of granite, and of
other rocks.[35]
On the shores of Greenland the ebb tide flows towards the coast,
apparently as though it passes under the land, and the flood tide
recedes from the shore; and in those regions the sea is almost
universally found deeper as you approach the shore.[36] When the
whales become scarce, experience has taught the whalers to seek for
them near the shore, as if at certain seasons they retired to it,
and then disappeared. Captain Symmes imagines that the sea extends
quite through the spheres, about Greenland, and that the whales
suddenly migrate either to the _mid-plane-space_, or to the seas
on the opposite side; which he alleges to be the case with several
other species of fish, as well as seals; all of which, he supposes,
breed in the _mid-plane-space_. The reasons that induce him to adopt
this conclusion are various; such as, that fish have been thrown up
by the eruption of a volcano in South America[37]――herring appearing
in such immense numbers at certain seasons of the year――the whales
seeming to pass under Greenland――two seals having been once caught in
Lake Ontario, which is said to be unfathomable, although this lake
is many degrees south of where the seals have ever before been known
to come――and the various species of fish in our northern lakes which
appear and disappear at certain periods. That the exterior seas in
some places communicate with the interior seas, is rendered probable
by various other circumces; such as currents running continually into
the Mediterranean, and no visible outlet to the water thus continually
flowing in. It is scarcely probable that evaporation could carry off
all the water supplied by the straits of Gibraltar――the white sea being
more salt at the head than at the foot――the tides being higher in the
Baltic than the Mediterranean――white foxes having been forced up by
the waters of the sea (as Symmes undertakes to prove) in the northern
regions――the peculiarities of the tremendous whirlpool on the coast
of Norway, called the Maalstroom, which sucks in, and discharges the
waters of the sea with great violence――and those observable in the Bay
of Biscay, which are said to be unfathomable.
FOOTNOTES:
[31] EARTHQUAKES.――M. Biot, after detailing the phenomena of the
earthquake, on the 22d of February, 1822, concludes an interesting
paper with these observations:――
In the infancy of Chemistry and Natural Philosophy, it was imagined
that earthquakes might be easily explained; in proportion as these
sciences have become more correct and more profound, this confidence
has decreased. But by a propensity, for which the character of the
human mind sufficiently accounts, all the new physical agents which
have been successively discovered, such as electricity, magnetism,
the inflammation of gases, the decomposition and recomposition of
water, have been maintained in theories as the causes of the great
phenomena of nature. Now all these conjectures seem to be insufficient
to explain convulsions so extensive, produced at the same time over
such large portions of the earth, as those which take place during
earthquakes. The most probable opinion, the only one which seems to
us to reconcile, in a certain degree, the energy, the extent of these
phenomena, and often their frightful correspondence in the most distant
countries of the globe, would be to suppose, conformably to many other
physical indications, that the solid surface on which we live is but of
inconsiderable thickness in comparison with the semi-diameter of the
terrestrial globe; is in some measure only a recent shell, covering
a liquid nucleus, perhaps still in a state of ignition, in which
great chemical or physical phenomena operating at intervals cause
those agitations which are transmitted to us. The countries where the
superficial crust is less thick or less strong, or more recently or
more imperfectly consolidated, would agreeably to this hypothesis, be
those the most liable to be convulsed and broken by the violence of
these internal explosions. Now if we compare together the experiments
on the length of the pendulum, which have been made for some years past
with great accuracy, from the north of Scotland to the south of Spain,
we readily perceive that the intensity of gravitation decreases on this
space, as we go from the Pole towards the Equator, more rapidly than
it ought to do upon an ellipsoid, the concentric and similar strata of
which should have equal densities at equal depths; and the deviation
is especially sensible about the middle of France, where too there has
been observed a striking irregularity in the length of the degrees of
the earth. This local decrease of gravity in these countries should
seem to indicate, with some probability, that the strata near the
surface must be less dense there than elsewhere, and perhaps have in
their interior immense cavities. This would account for the existence
of the numerous volcanos of which these strata show the traces, and
explain why they are even now, at intervals, the focus of subterraneous
convulsions.
[32] Cook's Geography, v. 2, p. 250――Also Rees' Cyclopedia, article
Lake.
[33] Rees' Cyclopedia, article Lake Geneva.
[34] Rees' Cyclopedia, article Lake.
[35] Ross' Voyage, v. 1, p. 225.
[36] Ibid, v. 1, p. 144.
[37] Humboldt.