I believe there are but few theories, which do not contain much that is profitable. The man who has the ingenuity to advance new ones, will be likely, in the course of reasoning necessary to support them, to say something that is useful to be known. In his very reveries and wanderings, he will often point out land-marks, which may be useful to the future traveller. Whether then is it better to crouch under the tyranny of prejudice, or employ our thoughts and reasoning powers in the search of truth, though at the risk of deceiving ourselves, as our predecessors have done? Had it not been for a prudent boldness in advancing and defending new doctrines, the human mind must have remained to this day, the sport of all the chimeras of the ancients.
The exact shape and formation of the earth are admitted not to be well understood. The laws of gravity, and the admeasurements which have been made in different places on the same meridian, have demonstrated to us, that the greatest mathematicians have mistaken its real figure. Various theories have at different times been published and refuted, and others substituted in their stead. Yet still a shade of darkness and mystery appears to hang over the subject; for many principles, attractions, and apparent variations from the established laws believed to exist in the economy of nature, have been discovered, particularly in the polar regions, which remain unexplained and unaccounted for. Let us, therefore, examine and investigate any theory which proposes to explain them. Let us not be so tenacious of our own opinions, and hereditary prejudices, as to stop at the very point where every thing invites us to proceed. Let us rather push our researches after knowledge to the utmost, and exercise our reason, and every means in our power that may tend to the advancement of science and knowledge. In the pursuit, let us not be retarded by the cry of prejudice, or the sarcastic whispers of the narrow minded, and selfish.
Let us, therefore give Captain Symmes a "gentle meeting," and a candid hearing, in the following short chapters; ascertain what his theory is, and on what principles he supports it; and then adopt or reject it, as our reason may dictate.
CHAPTER II.
Symmes's Theory; comprehending his description of the form of the earth, and of the other orbs in the Universe; his principles of gravity, and the points wherein he differs from the old or generally received theories.
According to Symmes's Theory, the earth, as well as all the celestial orbicular bodies existing in the universe, visible and invisible, which partake in any degree of a planetary nature, from the greatest to the smallest, from the sun, down to the most minute blazing meteor or falling star, are all constituted in a greater or less degree, of a collection of spheres, more or less solid, concentric with each other, and more or less open at their poles; each sphere being separated from its adjoining compeers by space replete with aerial fluids; that every portion of infinite space, except what is occupied by spheres, is filled with an aerial elastic fluid, more subtile than common atmospheric air; and constituted of innumerable small concentric spheres, too minute to be visible to the organ of sight assisted by the most perfect microscope, and so elastic that they continually press on each other, and change their relative situations as often as the position of any piece of matter in space may change its position: thus causing a universal pressure, which is weakened by the intervention of other bodies in proportion to the subtended angle of distance and dimension; necessarily causing the body to move towards the points of decreased pressure.
It is a sound principle of philosophy, that the particles of the common air of our atmosphere are of a repellant quality, and mutually repulse each other. The whole system of pneumatics goes to prove that air presses equally in all directions. Not a single experiment in this branch of natural science can be performed that does not depend on such a property. This being the case, if the boundless extent of the universe, beyond the limits of our atmosphere, be an entire vacuum, why should the atmosphere be retained in its present circumscribed form, and not expand, by virtue of its repellant quality, far beyond its known height? To prevent this, Symmes believes universal space to be filled with an elastic fluid, inconceivably rare, and uniformly distributed throughout; differing from common air, and from the elastic fluids (which also are known to be repellant) existing in our atmosphere. This tendency is what Symmes believes should be understood by the term gravity; the laws of action governing which he holds to be true, as defined by Newton: and he moreover holds that the application of the laws of gravity, as laid down by Newton, leads a reasoning mind to the belief of concentric spheres, with open poles, as all planetary bodies are in his opinion formed.
In regard to the effects of gravity, he pretends not to differ from the generally received opinion of the age; but the application of them, as to the inner parts of insulated bodies, has enabled him to improve in a knowledge of the formation of planets; and finally led him to form a correct idea of what constitutes gravity.