On the thirteenth of August we were up betimes. There was no time to be lost. We now had to inaugurate a new kind of locomotion, which would have the advantage of being rapid and not fatiguing.

A mast, made of two pieces of wood fastened together, to give additional strength, a yard made from another one, the sail a linen sheet from our bed. We were fortunately in no want of cordage, and the whole on trial appeared solid and seaworthy.

At six o'clock in the morning, when the eager and enthusiastic Professor gave the signal to embark, the victuals, the luggage, all our instruments, our weapons, and a goodly supply of sweet water, which we had collected from springs in the rocks, were placed on the raft.

Hans had, with considerable ingenuity, contrived a rudder, which enabled him to guide the floating apparatus with ease. He took the tiller, as a matter of course. The worthy man was as good a sailor as he was a guide and duck hunter. I then let go the painter which held us to the shore, the sail was brought to the wind, and we made a rapid offing.

Our sea voyage had at length commenced; and once more we were making for distant and unknown regions.

Just as we were about to leave the little port where the raft had been constructed, my uncle, who was very strong as to geographic nomenclature, wanted to give it a name, and among others, suggested mine.

"Well," said I, "before you decide I have another to propose."

"Well; out with it."

"I should like to call it Gretchen. Port Gretchen will sound very well on our future map."

"Well then, Port Gretchen let it be," said the Professor.

And thus it was that the memory of my dear girl was attached to our adventurous and memorable expedition.

When we left the shore the wind was blowing from the northward and eastward. We went directly before the wind at a much greater speed than might have been expected from a raft. The dense layers of atmosphere at that depth had great propelling power and acted upon the sail with considerable force.

At the end of an hour, my uncle, who had been taking careful observations, was enabled to judge of the rapidity with which we moved. It was far beyond anything seen in the upper world.

"If," he said, "we continue to advance at our present rate, we shall have traveled at least thirty leagues in twenty-four hours. With a mere raft this is an almost incredible velocity."

I certainly was surprised, and without making any reply went forward upon the raft. Already the northern shore was fading away on the edge of the horizon. The two shores appeared to separate more and more, leaving a wide and open space for our departure. Before me I could see nothing but the vast and apparently limitless sea—upon which we floated—the only living objects in sight.

Huge and dark clouds cast their grey shadows below—shadows which seemed to crush that colorless and sullen water by their weight. Anything more suggestive of gloom and of regions of nether darkness I never beheld. Silvery rays of electric light, reflected here and there upon some small spots of water, brought up luminous sparkles in the long wake of our cumbrous bark. Presently we were wholly out of sight of land; not a vestige could be seen, nor any indication of where we were going. So still and motionless did we seem without any distant point to fix our eyes on that but for the phosphoric light at the wake of the raft I should have fancied that we were still and motionless.

But I knew that we were advancing at a very rapid rate.

About twelve o'clock in the day, vast collections of seaweed were discovered surrounding us on all sides. I was aware of the extraordinary vegetative power of these plants, which have been known to creep along the bottom of the great ocean, and stop the advance of large ships. But never were seaweeds ever seen, so gigantic and wonderful as those of the Central Sea. I could well imagine how, seen at a distance, tossing and heaving on the summit of the billows, the long lines of algae have been taken for living things, and thus have been fertile sources of the belief in sea serpents.

Our raft swept past great specimens of fucus or seawrack, from three to four thousand feet in length, immense, incredibly long, looking like snakes that stretched out far beyond our horizon. It afforded me great amusement to gaze on their variegated ribbon-like endless lengths. Hour after hour passed without our coming to the termination of these floating weeds. If my astonishment increased, my patience was well-nigh exhausted.

What natural force could possibly have produced such abnormal and extraordinary plants? What must have been the aspect of the globe, during the first centuries of its formation, when under the combined action of heat and humidity, the vegetable kingdom occupied its vast surface to the exclusion of everything else?

These were considerations of never-ending interest for the geologist and the philosopher.

All this while we were advancing on our journey; and at length night came; but as I had remarked the evening before, the luminous state of the atmosphere was in nothing diminished. Whatever was the cause, it was a phenomenon upon the duration of which we could calculate with certainty.

As soon as our supper had been disposed of, and some little speculative conversation indulged in, I stretched myself at the foot of the mast, and presently went to sleep.

Hans remained motionless at the tiller, allowing the raft to rise and fall on the waves. The wind being aft, and the sail square, all he had to do was to keep his oar in the centre.

Ever since we had taken our departure from the newly named Port Gretchen, my worthy uncle had directed me to keep a regular log of our day's navigation, with instructions to put down even the most minute particulars, every interesting and curious phenomenon, the direction of the wind, our rate of sailing, the distance we went; in a word, every incident of our extraordinary voyage.

From our log, therefore, I tell the story of our voyage on the Central Sea.

Friday, August 14th. A steady breeze from the northwest. Raft progressing with extreme rapidity, and going perfectly straight. Coast still dimly visible about thirty leagues to leeward. Nothing to be seen beyond the horizon in front. The extraordinary intensity of the light neither increases nor diminishes. It is singularly stationary. The weather remarkably fine; that is to say, the clouds have ascended very high, and are light and fleecy, and surrounded by an atmosphere resembling silver in fusion.

Thermometer, +32 degrees centigrade.

About twelve o'clock in the day our guide Hans having prepared and baited a hook, cast his line into the subterranean waters. The bait he used was a small piece of meat, by means of which he concealed his hook. Anxious as I was, I was for a long time doomed to disappointment. Were these waters supplied with fish or not? That was the important question. No—was my decided answer. Then there came a sudden and rather hard tug. Hans coolly drew it in, and with it a fish, which struggled violently to escape.

"A fish!" cried my uncle.

"It is a sturgeon!" I cried, "certainly a small sturgeon."

The Professor examined the fish carefully, noting every characteristic; and he did not coincide in my opinion. The fish had a flat head, round body, and the lower extremities covered with bony scales; its mouth was wholly without teeth, the pectoral fins, which were highly developed, sprouted direct from the body, which properly speaking had no tail. The animal certainly belonged to the order in which naturalists class the sturgeon, but it differed from that fish in many essential particulars.

My uncle, after all, was not mistaken. After a long and patient examination, he said:

"This fish, my dear boy, belongs to a family which has been extinct for ages, and of which no trace has ever been found on earth, except fossil remains in the Devonian strata."

"You do not mean to say," I cried, "that we have captured a live specimen of a fish belonging to the primitive stock that existed before the deluge?"

"We have," said the Professor, who all this time was continuing his observations, "and you may see by careful examination that these fossil fish have no identity with existing species. To hold in one's hand, therefore, a living specimen of the order, is enough to make a naturalist happy for life."

"But," cried I, "to what family does it belong?"

"To the order of Ganoides—an order of fish having angular scales, covered with bright enamel—forming one of the family of the Cephalaspides, of the genus—"

"Well, sir," I remarked, as I noticed my uncle hesitated to conclude.

"To the genus Pterychtis—yes, I am certain of it. Still, though I am confident of the correctness of my surmise, this fish offers to our notice a remarkable peculiarity, never known to exist in any other fish but those which are the natives of subterranean waters, wells, lakes, in caverns, and suchlike hidden pools."

"And what may that be?"

"It is blind."

"Blind!" I cried, much surprised.

"Not only blind," continued the Professor, "but absolutely without organs of sight."

I now examined our discovery for myself. It was singular, to be sure, but it was really a fact. This, however, might be a solitary instance, I suggested. The hook was baited again and once more thrown into the water. This subterranean ocean must have been tolerably well supplied with fish, for in two hours we took a large number of Pterychtis, as well as other fish belonging to another supposed extinct family—the Dipterides (a genus of fish, furnished with two fins only, whence the name), though my uncle could not class it exactly. All, without exception, however, were blind. This unexpected capture enabled us to renew our stock of provisions in a very satisfactory way.

We were now convinced that this subterranean sea contained only fish known to us as fossil specimens—and fish and reptiles alike were all the more perfect the farther back they dated their origin.

We began to hope that we should find some of those saurians which science has succeeded in reconstructing from bits of bone or cartilage.

I took up the telescope and carefully examined the horizon—looked over the whole sea; it was utterly and entirely deserted. Doubtless we were still too near the coast.

After an examination of the ocean, I looked upward, towards the strange and mysterious sky. Why should not one of the birds reconstructed by the immortal Cuvier flap his stupendous wings aloft in the dull strata of subterranean air? It would, of course, find quite sufficient food from the fish in the sea. I gazed for some time upon the void above. It was as silent and as deserted as the shores we had but lately left.

Nevertheless, though I could neither see nor discover anything, my imagination carried me away into wild hypotheses. I was in a kind of waking dream. I thought I saw on the surface of the water those enormous antediluvian turtles as big as floating islands. Upon those dull and somber shores passed a spectral row of the mammifers of early days, the great Liptotherium found in the cavernous hollow of the Brazilian hills, the Mesicotherium, a native of the glacial regions of Siberia.

Farther on, the pachydermatous Lophrodon, that gigantic tapir, which concealed itself behind rocks, ready to do battle for its prey with the Anoplotherium, a singular animal partaking of the nature of the rhinoceros, the horse, the hippopotamus and the camel.

There was the giant Mastodon, twisting and turning his horrid trunk, with which he crushed the rocks of the shore to powder, while the Megatherium—his back raised like a cat in a passion, his enormous claws stretched out, dug into the earth for food, at the same time that he awoke the sonorous echoes of the whole place with his terrible roar.

Higher up still, the first monkey ever seen on the face of the globe clambered, gamboling and playing up the granite hills. Still farther away, ran the Pterodactyl, with the winged hand, gliding or rather sailing through the dense and compressed air like a huge bat.

Above all, near the leaden granitic sky, were immense birds, more powerful than the cassowary and the ostrich, which spread their mighty wings and fluttered against the huge stone vault of the inland sea.

I thought, such was the effect of my imagination, that I saw this whole tribe of antediluvian creatures. I carried myself back to far ages, long before man existed—when, in fact, the earth was in too imperfect a state for him to live upon it.

My dream was of countless ages before the existence of man. The mammifers first disappeared, then the mighty birds, then the reptiles of the secondary period, presently the fish, the crustacea, the mollusks, and finally the vertebrata. The zoophytes of the period of transition in their turn sank into annihilation.

The whole panorama of the world's life before the historic period, seemed to be born over again, and mine was the only human heart that beat in this unpeopled world! There were no more seasons; there were no more climates; the natural heat of the world increased unceasingly, and neutralized that of the great radiant Sun.

Vegetation was exaggerated in an extraordinary manner. I passed like a shadow in the midst of brushwood as lofty as the giant trees of California, and trod underfoot the moist and humid soil, reeking with a rank and varied vegetation.

I leaned against the huge column-like trunks of giant trees, to which those of Canada were as ferns. Whole ages passed, hundreds upon hundreds of years were concentrated into a single day.

Next, unrolled before me like a panorama, came the great and wondrous series of terrestrial transformations. Plants disappeared; the granitic rocks lost all trace of solidity; the liquid state was suddenly substituted for that which had before existed. This was caused by intense heat acting on the organic matter of the earth. The waters flowed over the whole surface of the globe; they boiled; they were volatilized, or turned into vapor; a kind of steam cloud wrapped the whole earth, the globe itself becoming at last nothing but one huge sphere of gas, indescribable in color, between white heat and red, as big and as brilliant as the sun.

In the very centre of this prodigious mass, fourteen hundred thousand times as large as our globe, I was whirled round in space, and brought into close conjunction with the planets. My body was subtilized, or rather became volatile, and commingled in a state of atomic vapor, with the prodigious clouds, which rushed forward like a mighty comet into infinite space!

What an extraordinary dream! Where would it finally take me? My feverish hand began to write down the marvelous details—details more like the imaginings of a lunatic than anything sober and real. I had during this period of hallucination forgotten everything—the Professor, the guide, and the raft on which we were floating. My mind was in a state of semioblivion.

"What is the matter, Harry?" said my uncle suddenly.

My eyes, which were wide opened like those of a somnambulist, were fixed upon him, but I did not see him, nor could I clearly make out anything around me.

"Take care, my boy," again cried my uncle, "you will fall into the sea."

As he uttered these words, I felt myself seized on the other side by the firm hand of our devoted guide. Had it not been for the presence of mind of Hans, I must infallibly have fallen into the waves and been drowned.

"Have you gone mad?" cried my uncle, shaking me on the other side.

"What—what is the matter?" I said at last, coming to myself.

"Are you ill, Henry?" continued the Professor in an anxious tone.

"No—no; but I have had an extraordinary dream. It, however, has passed away. All now seems well," I added, looking around me with strangely puzzled eyes.

"All right," said my uncle; "a beautiful breeze, a splendid sea. We are going along at a rapid rate, and if I am not out in my calculations we shall soon see land. I shall not be sorry to exchange the narrow limits of our raft for the mysterious strand of the subterranean ocean."

As my uncle uttered these words, I rose and carefully scanned the horizon. But the line of water was still confounded with the lowering clouds that hung aloft, and in the distance appeared to touch the edge of the water.