General observations on the Theory of Concentric Spheres, with a few suggestions to the Congress of the United States, to authorize and fit out an Expedition for the discovery of the Interior Regions; or, at least, to explore the northern parts of the continent of America.
Of the many various and conflicting theories which have been advanced, relative to the form, structure, and motion of the earth, the theory of Concentric Spheres deserves to rank as one of the most important: for, should it hereafter be found correct, the advantages resulting to the civilized and learned world, must cause it to stand pre-eminent among the improvements in philosophy. The habitable superfices of our sphere would not only be nearly doubled; but the different spheres of which our earth is probably constituted, might increase the habitable surface ten-fold.
That such may be the construction of the earth, every law of matter with which I am acquainted, seems to admit, at least of the possibility; the different appearances of the other planets render it probable; and the various concurring terrestrial facts existing in the arctic regions, to my mind, render such a conclusion almost certain. And further, that matter and space are never uselessly wasted, is an axiom, not only of sound philosophy, but of natural religion, and of common sense.
Many of the theories which have been advanced respecting the earth, are vague and uncertain, and will remain so forever; being predicated on deductions drawn from certain premises that can never be established with certainty; consequently they must rest wholly on the strength of the arguments drawn from the premises, as they are not susceptible of being demonstrated by experiment. Not so with the theory of concentric spheres. Its correctness admits of ocular demonstration. The interior of the sphere is declared accessible, and the whole extent capable of being accurately explored; thereby establishing the theory, or disproving and putting it at rest forever.
The celebrated Dr. Halley, in the year 1692, in his attempt to account for the change of the variation of the magnetic needle, advanced a novel hypothesis, as respects the internal structure of the earth. He supposes that there is an interior globe, separated from the external sphere by a fluid medium; or that there may be several internal spheres, separated from each other by atmospheres, and that the concave arches may in several places shine with a substance similar to that which invests the body of the sun, producing light and heat for the accommodation of those internal regions which he alleges may possibly be inhabited by animate beings.[45]
However, he suggests no idea of Polar Openings, nor of any communication from the outer surface to those interior regions; consequently their existence must have remained forever a matter of mere conjecture.
We find that Dr. Halley, in the wisdom of his philosophy, believed those internal regions to be lighted, though situated many thousand fathoms beneath the surface, and without any aperture to communicate light from without. Why not, then, believe that the interior of the spheres, according to Symmes's theory, may be lighted, when he lays down such vast openings at either pole for that purpose?
Euler was also an advocate for the theory of Dr. Halley. He believed, with him, that the earth is hollow, with a ball, or nucleus, included in the centre; he, however, differed from Halley as to the nature of the nucleus. Halley believed it to be constituted of the same materials of the exterior crust of the earth. Euler believed it to be a luminous body formed of materials similar to the sun, and adapted to the purpose of illuminating and warming the interior surface of the crust, which he supposed might be inhabited equally with the exterior surface. He fancied that this luminous ball had no rotary motion, and that the outer shell revolved around it. However, neither he nor Dr. Halley left any opening by which the internal regions could be explored; their existence was therefore left to rest on vague hypothesis.[46]
These different theories, however extravagant they may appear to us, were believed and supported by those men, whom we must acknowledge were among the most learned of the age in which they lived; and among the mathematicians in Europe they have yet some warm supporters. Why not then give Symmes's theory of open poles, and concentric spheres, a serious investigation, the correctness of which is so much more probable, and the demonstration of its truth or falsehood so much more practicable? At all events a voyage to the polar regions, with an eye to the accomplishment of Symmes's purpose, might be productive of incalculable advantages to the cause of science in general. With respect to astronomy and geography, it would afford many new lights, and perhaps discover and establish many new principles, not thought of at this day.
"Knowledge is power," and so far as an individual acquires a knowledge of literature and science, above his contemporaries, so far does he possess a power and influence over those among whom he resides. So does a nation, when she becomes characterized for the acquisition of knowledge in the sciences and the arts. Those nations which have made great and important advances in the improvement of science, or in new discoveries, have acquired a pre-eminence of character and standing, among other nations of the world.