"Get into the boat," said my eyeless pilot, "and we will proceed to the farther edge of the lake, over the barrier of which at great intervals of time, the surface water flows, and induces the convulsion known as Mount Epomeo."
We accordingly embarked, and a gentle touch of the lever enabled us rapidly to skirt the shore of the underground sea. The soft, bright, pleasant earth-light continually enveloped us, and the absence of either excessive heat or cold, rendered existence delightful. The weird forms taken by the objects that successively presented themselves on the shore were a source of continual delight to my mind. The motion of our boat was constantly at the will of my guide. Now we would skim across a great bay, flashing from point to point; again we wound slowly through tortuous channels and among partly submerged stones.
"What a blessing this mode of locomotion would be to humanity," I murmured.
"Humanity will yet attain it," he replied. "Step by step men have stumbled along towards the goal that the light of coining centuries is destined to illuminate. They have studied, and are still engaged in studying, the properties of grosser forces, such as heat and electricity, and they will be led by the thread they are following, to this and other achievements yet unthought of, but which lie back of those more conspicuous."
We finally reached a precipitous bluff, that sprung to my view as by magic, and which, with a glass-like surface, stretched upward to a height beyond the scope of my vision, rising straight from the surface of the lake. It was composed of a material seemingly black as jet, and yet when seen under varying spectacular conditions as we skirted its base it reflected, or emitted, most gorgeously the brilliant hues of the rainbow, and also other colors hitherto unknown to me.
"There is something unique in these shades; species of color appear that I can not identify; I seem to perceive colors utterly unlike any that I know as the result of deflected, or transmitted, sunlight rays, and they look unlike the combinations of primary colors with which I am familiar."
"Your observations are true; some of these colors are unknown on earth."
"But on the surface of the earth we have all possible combinations of the seven prismatic rays," I answered. "How can there be others here?"
"Because, first, your primary colors are capable of further subdivision.
"Second, other rays, invisible to men under usual conditions, also emanate from the sun, and under favorable circumstances may be brought to the sense of sight."
"Do you assert that the prism is capable of only partly analyzing the sunlight?"
"Yes; what reason have you to argue that, because a triangular bit of glass resolves a white ray into seven fractions that are, as men say, differently colored, you could not by proper methods subdivide each of these so-called primary shades into others? What reason have you to doubt that rays now invisible to man accompany those capable of impressing his senses, and might by proper methods become perceptible as new colors?"
"None," I answered; "only that I have no proof that such rays exist."
"But they do exist, and men will yet learn that the term 'primitive' ray, as applied to each of the seven colors of the rainbow, is incorrect. Each will yet be resolved, and as our faculties multiply and become more subtle, other colors will be developed, possessed of a delicacy and richness indescribable now, for as yet man can not comprehend the possibilities of education beyond the limits of his present condition."
During this period of conversation we skirted the richly colored bluff with a rapid motion, and at last shot beyond it, as with a flash, into seeming vacancy. I was sitting with my gaze directed toward the bluff, and when it instantly disappeared, I rubbed my eyes to convince myself of their truthfulness, and as I did so our boat came gradually to a stand on the edge of what appeared to be an unfathomable abyss. Beneath me on the side where had risen the bluff that disappeared so abruptly, as far as the eye could reach, was an absolute void. To our right, and before and behind us, stretched the surface of that great smooth lake on whose bosom we rested. To our left, our boat brushing its rim, a narrow ledge, a continuation of the black, glass-like material, reached only a foot above the water, and beyond this narrow brink the mass descended perpendicularly to seemingly infinite depths. Involuntarily I grasped the sides of the boat, and recoiled from the frightful chasm, over which I had been so suddenly suspended, and which exceeded anything of a similar description that I had ever seen. The immeasurable depth of the abyss, in connection with the apparently frail barrier that held the great lake in its bounds, caused me to shudder and shrink back, and my brain reeled in dizzy fright. An inexplicable attraction, however, notwithstanding my dread, held me spell-bound, and although I struggled to shut out that view, the endeavor failed. I seemed to be drawn by an irresistible power, and yet I shuddered at the awful majesty of that yawning gulf which threatened to end the world on which I then existed. Fascinated, entranced, I could not help gazing, I knew not how long, down, down into that fathomless, silent profundity. Composing myself, I turned a questioning glance on my guide.
He informed me that this hard, glass-like dam, confined the waters of the slowly rising lake that we were sailing over, and which finally would rise high enough to overflow the barrier.
"The cycle of the periodic overflow is measured by great intervals," he said; "centuries are required to raise the level of the lake a fraction of an inch, and thousands of years may elapse before its surface will again reach the top of the adamantine wall. Then, governed by the law that attracts a liquid to itself, and heaps the teaspoon with liquid, the water of the quiet lake piles upon this narrow wall, forming a ledge along its summit. Finally the superimposed surface water gives way, and a skim of water pours over into the abyss."
He paused; I leaned over and meditated, for I had now accustomed myself to the situation.
"There is no bottom," I exclaimed.
"Upon the contrary," he answered, "the bottom is less than ten miles beneath us, and is a great funnel-shaped orifice, the neck of the funnel reaching first down and then upward from us diagonally toward the surface of the earth. Although the light by which we are enveloped is bright, yet it is deficient in penetrating power, and is not capable of giving the contour of objects even five miles away, hence the chasm seems bottomless, and the gulf measureless."
"Is it not natural to suppose that a mass of water like this great lake would overflow the barrier immediately, as soon as the surface reached the upper edge, for the pressure of the immense volume must be beyond calculation."
"No, for it is height, not expanse, which, as hydrostatic engineers understand, governs the pressure of water. A liquid column, one foot in width, would press against the retaining dam with the force of a body of the same liquid, the same depth, one thousand miles in extent. Then the decrease of gravity here permits the molecular attraction of the water's molecules to exert itself more forcibly than would be the case on the surface of the earth, and this holds the liquid mass together more firmly."
"See," he observed, and dipping his finger into the water he held it before him with a drop of water attached thereto (Figure 27), the globule being of considerable size, and lengthened as though it consisted of some glutinous liquid.
"How can a thin stratum of water give rise to a volcanic eruption?" I next queried. "There seems to be no melted rock, no evidence of intense heat, either beneath or about us."
"I informed you some time ago that I would partially explain these facts. Know then, that the theories of man concerning volcanic eruptions, in connection with a molten interior of the earth, are such as are evolved in ignorance of even the subsurface of the globe. The earth's interior is to mankind a sealed chamber, and the wise men who elucidate the curious theories concerning natural phenomena occurring therein are forced to draw entirely upon their imagination. Few persona realize the paucity of data at the command of workers in science. Theories concerning the earth are formulated from so little real knowledge of that body, that our science may be said to be all theory, with scarcely a trace of actual evidence to support it. If a globe ten inches in diameter be covered with a sheet of paper, such as I hold in my hand, the thickness of that sheet will be greater in proportion to that of such a globe than the depth men have explored within the earth is compared with the thickness of the crust of the earth. The outer surface of a pencil line represents the surface of the earth; the inner surface of the line represents the depth of man's explorations; the highest mountain would be represented by a comma resting on the line. The geologist studies the substances that are thrust from the crater of an active volcano, and from this makes conjectures regarding the strata beneath, and the force that casts the excretions out. The results must with men, therefore, furnish evidence from which to explain the cause. It is as though an anatomist would form his idea of the anatomy of the liver by the secretion thrown out of that organ, or of the lung texture by the breath and sputum. In fact, volcanoes are of several descriptions, and usually are extremely superficial. This lake, the surface of which is but one hundred and fifty miles underground, is the mother of an exceptionally deep one. When the water pours over this ledge it strikes an element below us, the metallic base of salt, which lies in great masses in some portions of the earth's crust. Then an immediate chemical reaction ensues, the water is dissociated, intense heat results, part of the water combines with the metal, part is vaporized as steam, while part escapes as an inflammable gas. The sudden liberation of these gases causes an irregular pressure of vapor on the surface of the lake, the result being a throbbing and rebounding of the attenuated atmosphere above, which,in gigantic waves, like swelling tides, dashes great volumes of water over the ledge beside us, and into the depth below. This water in turn reacts on fresh portions of the metallic base, and the reflex action increases the vapor discharges, and as a consequence the chamber we are in becomes a gasholder, containing vapors of unequal gas pressures, and the resultant agitation of the lake from the turmoil continues, and the pulsations are repeated until the surface of the lake is lowered to such a degree as at last to prevent the water from overflowing the barrier. Finally the lake quiets itself, the gases slowly disappear by earth absorption, and by escape from the volcanic exit, and for an unrecorded period of time thereafter the surface of the lake continues to rise slowly as it is doing now."
"But what has this phenomenon to do with the volcano?"
"It produces the eruption; the water that rushes down into the chasm, partly as steam, partly as gas, is forced onward and upward through a crevice that leads to the old crater of the presumed extinct but periodically active Mount Epomeo. These gases are intensely heated, and they move with fearful velocity. They tear off great masses of stone, which the resultant energy disturbances, pressure, gas, and friction, redden with heat. The mixture of gases from the decomposed water is in large amount, is burning and exploding, and in this fiery furnace amid such convulsions as have been described, the adjacent earth substance is fused, and even clay is melted, and carried on with the fiery blast. Finally the current reaches the earth's surface through the funnel passage, the apex of which is a volcano—the blast described a volcanic eruption."
"One thing is still obscure in my mind," I said. "You assert that the reaction which follows the contact of the flowing water and metallic bases in the crevice below us liberates the explosive gases, and also volumes of vapor of water. These gases rush, you say, and produce a volcanic eruption in a distant part of the crust of the earth. I can not understand why they do not rush backward as well, and produce another eruption in Kentucky. Surely the pressure of a gas in confinement is the same in all directions, is it not?"
"Yes," he replied, "but the conditions in the different directions are dissimilar. In the direction of the Kentucky cavern, the passage is tortuous, and often contracts to a narrow crevice. In one place near the cavern's mouth, as you will remember, we had to dive beneath the surface of a stream of water. That stratum of water as effectually closed the exit from the earth as the stopper prevents water escaping from a bottle. Between the point we now occupy and that water stopper, rest thousands of miles of quiescent air. The inertia of a thousand miles of air is great beyond your comprehension. To move that column of air by pushing against this end of it, and thus shoving it instantly out of the other end, would require greater force than would burst the one hundred and fifty miles of inelastic stone above us. Then, the friction of the sides is another thing that prevents its accomplishment. While a gradually applied pressure would in time overcome both the inertia of the air and the friction of the stone passages, it would take a supply of energy greater than you can imagine to start into motion the elastic mass that stands as solid and immovable as a sentinel of adamant, between the cavern you entered, and the spot we now occupy. Time and energy combined would be able to accomplish the result, but not under present conditions.
"In the other direction a broad open channel reaches directly to and connects with the volcanic shaft. Through this channel the air is in motion, moving towards the extinct crater, being supplied from another surface orifice. The gases liberated in the manner I have described, naturally follow the line of least resistance. They turn at once away from the inert mass of air that rests behind us, and move with increasing velocity towards the volcanic exit. Before the pressure that might be exerted towards the Kentucky cavern would have more than compressed the intervening column of air enough to raise the water of a well from its usual level to the surface of the earth, the velocity in the other direction would have augmented prodigiously, and with its increased rapidity a suction would follow more than sufficient to consume the increasingly abundant gases from behind."
"Volcanoes are therefore local, and the interior of the earth is not a molten mass as I have been taught;" I exclaimed.
He answered: "If men were far enough along in their thought journey (for the evolution of the mental side of man is a journey in the world of thought), they would avoid such theories as that which ascribes a molten interior to the earth. Volcanoes are superficial. They are as a rule, when in activity but little blisters or excoriations upon the surface of the earth, although their underground connections may be extensive. Some of them are in a continual fret with frequent eruptions, others, like the one under consideration, awaken only after great periods of time. The entire surface of this globe has been or will be subject to volcanic action. The phenomenon is one of the steps in the world-making, matter-leveling process. When the deposit of substances that I have indicated, and of which much of the earth's interior is composed, the bases of salt, potash, and lime and clay is exhausted, there will be no further volcanic action from this cause, and. in some places, this deposit has already disappeared, or is covered deeply by layers of earth that serve as a protection."
"Is water, then, the universal cause of volcanoes?"
"Water and air together cause most of them. The action of water and its vapor produces from metallic space dust, limestone, and clay soil, potash and soda salts. This perfectly rational and natural action must continue as long as there is water above, and free elementary bases in contact with the earth bubbles. Volcanoes, earthquakes, geysers, mud springs, and hot springs, are the natural result of that reaction. Mountains are thereby forming by upheavals from beneath, and the corresponding surface valleys are consequently filling up, either by the slow deposit of the matter from the saline water of hot springs, or by the sudden eruption of a new or presumably extinct volcano."
"What would happen if a crevice in the bottom of the ocean should conduct the waters of the ocean into a deposit of metallic bases?"
"That often occurs," was the reply; "a volcanic wave results, and a volcano may thus rise from the ocean's depths."
"Is there any danger to the earth itself? May it not be riven into fragments from such a convulsion?" I hesitatingly questioned.
"No; while the configuration of continents is continually being altered, each disturbance must be practically superficial, and of limited area."
"But," I persisted, "the rigid, solid earth may be blown to fragments; in such convulsions a result like that seems not impossible."
"You argue from an erroneous hypothesis. The earth is neither rigid nor solid."
"True," I answered. "If it were solid I could not be a hundred miles beneath its surface in conversation with another being; but there can not be many such cavities as that which we are now traversing, and they can not surely extend entirely through its mass; the great weight of the superincumbent material would crush together the strongest materials, if a globe as large as our earth were extensively honeycombed in this manner."
"Quite the contrary," he replied; "and here let me, for the first time, enlighten you as to the interior structure of the terrestrial globe. The earth-forming principle consists of an invisible sphere of energy that, spinning through space, supports the space dust which collects on it, as dust on a bubble. By gradual accumulation of substance on that sphere a hollow ball has resulted, on the outer surface of which you have hitherto dwelt. The crust of the earth is comparatively thin, not more than eight hundred miles in average thickness, and is held in position by the central sphere of energy that now exists at a distance about seven hundred miles beneath the ocean level. The force inherent to this sphere manifests itself upon the matter which it supports on both sides, rendering matter the lighter the nearer it lies to the center sphere. In other words, let me say to you: "The crust, or shell, which I have just described as being but about eight hundred miles in thickness, is firm and solid on both its convex and concave surface, but gradually loses in weight, whether we penetrate from the outer surface toward the center, or from any point of the inner surface towards the outside, until at the central sphere matter has no weight at all. Do you conceive my meaning?"
"Yes," I replied; "I understand you perfectly."
After a pause my pilot asked me abruptly:
"What do you most desire?"
The question caused my mind to revert instantly to my old home on the earth above me, and although I felt the hope of returning to it spring up in my heart, the force of habit caused me involuntarily to answer, "More light!"
"More light being your desire, you shall receive it."
Obedient to his touch, the bow of the boat turned from the gulf we had been considering towards the center of the lake; the responsive craft leaped forward, and in an instant the obsidian parapet disappeared behind us. On and over the trackless waste of glass-like water we sped, until the dead silence became painfully oppressive, and I asked:
"Whither are we bound?"
"Towards the east."
The well-timed answer raised my spirits; I thought again that in this man, despite his repulsive shape, I beheld a friend, a brother; suspicion vanished, and my courage rose. He touched the lever, and the craft, subject to his will, nearly rose from the water, and sped with amazing velocity, as was evident from the appearance of the luminous road behind us. So rapid was our flight that the wake of the boat seemed as if made of rigid parallel lines that disappeared in the distance, too quick for the eye to catch the tremor.
Continuing his conversation, my companion informed me that he had now directed the bark toward a point east of the spot where we struck the shore, after crossing the lake, in order that we might continue our journey downward, diagonally to the under surface of the earth crust.
"This recent digression from our journey proper," said he, "has been made to acquaint you with a subject, regarding which you have exhibited a curiosity, and about which you have heretofore been misinformed; now you understand more clearly part of the philosophy of volcanoes and earthquakes. You have yet much to learn in connection with allied phenomena, but this study of the crude exhibition of force-disturbed matter, the manipulation of which is familiar to man under the above names, is an introduction to the more wonderful study destined yet to be a part of your field, an investigation of quiescent matter, and pure motion."
"I can not comprehend you," I replied, "as I stated once before when you referred to what you designated as pure motion."
212:* This view is supported in theory by a note I believe to have somewhere seen recorded. Elsewhere other bases are mentioned also.—J. U. L.