density of the air.
The word cavern does not convey any idea of this immense space; words of human tongue are inadequate to describe the discoveries of him who ventures into the deep abysses of earth.
Besides I could not tell upon what geological theory to account for the existence of such an excavation. Had the cooling of the globe produced it? I knew of celebrated caverns from the descriptions of travellers, but had never heard of any of such dimensions as this.
If the grotto of Guachara, in Colombia, visited by Humboldt, had not given up the whole of the secret of its depth to the philosopher, who investigated it to the depth of 2,500 feet, it probably did not extend much farther. The immense mammoth cave in Kentucky is of gigantic proportions, since its vaulted roof rises five hundred feet11 above the level of an unfathomable lake and travellers have explored its ramifications to the extent of forty miles. But what were these cavities compared to that in which I stood with wonder and admiration, with its sky of luminous vapours, its bursts of electric light, and a vast sea filling its bed? My imagination fell powerless before such immensity.
I gazed upon these wonders in silence. Words failed me to express my feelings. I felt as if I was in some distant planet Uranus or Neptune - and in the presence of phenomena of which my terrestrial experience gave me no cognisance. For such novel sensations, new words were wanted; and my imagination failed to supply them. I gazed, I thought, I admired, with a stupefaction mingled with a certain amount of fear.
The unforeseen nature of this spectacle brought back the colour to my cheeks. I was under a new course of treatment with the aid of astonishment, and my convalescence was promoted by this novel system of therapeutics; besides, the dense and breezy air invigorated me, supplying more oxygen to my lungs.
It will be easily conceived that after an imprisonment of forty seven days in a narrow gallery it was the height of physical enjoyment to breathe a moist air impregnated with saline particles.
I was delighted to leave my dark grotto. My uncle, already familiar with these wonders, had ceased to feel surprise.
“You feel strong enough to walk a little way now?” he asked.
“Yes, certainly; and nothing could be more delightful.”
“Well, take my arm, Axel, and let us follow the windings of the shore.”
I eagerly accepted, and we began to coast along this new sea. On the left huge pyramids of rock, piled one upon another, produced a prodigious titanic effect. Down their sides flowed numberless waterfalls, which went on their way in brawling but pellucid streams. A few light vapours, leaping from rock to rock, denoted the place of hot springs; and streams flowed softly down to the common basin, gliding down the gentle slopes with a softer murmur.
Amongst these streams I recognised our faithful travelling companion, the Hansbach, coming to lose its little volume quietly in the mighty sea, just as if it had done nothing else since the beginning of the world.
“We shall see it no more,” I said, with a sigh.
“What matters,” replied the philosopher, “whether this or another serves to guide us?”
I thought him rather ungrateful.
But at that moment my attention was drawn to an unexpected sight. At a distance of five hundred paces, at the turn of a high promontory, appeared a high, tufted, dense forest. It was composed of trees of moderate height, formed like umbrellas, with exact geometrical outlines. The currents of wind seemed to have had no effect upon their shape, and in the midst of the windy blasts they stood unmoved and firm, just like a clump of petrified cedars.
I hastened forward. I could not give any name to these singular creations. Were they some of the two hundred thousand species of vegetables known hitherto, and did they claim a place of their own in the lacustrine flora? No; when we arrived under their shade my surprise turned into admiration. There stood before me productions of earth, but of gigantic stature, which my uncle immediately named.
“It is only a forest of mushrooms,” said he.
And he was right. Imagine the large development attained by these plants, which prefer a warm, moist climate. I knew that the Lycopodon giganteum attains, according to Bulliard, a circumference of eight or nine feet; but here were pale mushrooms, thirty to forty feet high, and crowned with a cap of equal diameter. There they stood in thousands. No light could penetrate between their huge cones, and complete darkness reigned beneath those giants; they formed settlements of domes placed in close array like the round, thatched roofs of a central African city.
Yet I wanted to penetrate farther underneath, though a chill fell upon me as soon as I came under those cellular vaults. For half an hour we wandered from side to side in the damp shades, and it was a comfortable and pleasant change to arrive once more upon the sea shore.
But the subterranean vegetation was not confined to these fungi. Farther on rose groups of tall trees of colourless foliage and easy to recognise. They were lowly shrubs of earth, here attaining gigantic size; lycopodiums, a hundred feet high; the huge sigillaria, found in our coal mines; tree ferns, as tall as our fir-trees in northern latitudes; lepidodendra, with cylindrical forked stems, terminated by long leaves, and bristling with rough hairs like those of the cactus.
“Wonderful, magnificent, splendid!” cried my uncle. “Here is the entire flora of the second period of the world - the transition period. These, humble garden plants with us, were tall trees in the early ages. Look, Axel, and admire it all. Never had botanist such a feast as this!”
“You are right, my uncle. Providence seems to have preserved in this immense conservatory the antediluvian plants which the wisdom of philosophers has so sagaciously put together again.”
“It is a conservatory, Axel; but is it not also a menagerie?”
“Surely not a menagerie!”
“Yes; no doubt of it. Look at that dust under your feet; see the bones scattered on the ground.”
“So there are!” I cried; “bones of extinct animals.”
I had rushed upon these remains, formed of indestructible phosphates of lime, and without hesitation I named these monstrous bones, which lay scattered about like decayed trunks of trees.
“Here is the lower jaw of a mastodon,”12 I said. “These are the molar teeth of the deinotherium; this femur must have belonged to the greatest of those beasts, the megatherium. It certainly is a menagerie, for these remains were not brought here by a deluge. The animals to which they belonged roamed on the shores of this subterranean sea, under the shade of those arborescent trees. Here are entire skeletons. And yet I cannot understand the appearance of these quadrupeds in a granite cavern.”
“Why?”
“Because animal life existed upon the earth only in the secondary period, when a sediment of soil had been deposited by the rivers, and taken the place of the incandescent rocks of the primitive period.”
“Well, Axel, there is a very simple answer to your objection that this soil is alluvial.”
“What! at such a depth below the surface of the earth?”
“No doubt; and there is a geological explanation of the fact. At a certain period
