I do not suppose even the most obsessed geologist would have studied the nature of the rocks that we were pa.s.sing under such circ.u.mstances. As for me, I hardly troubled myself about them. Pliocene, Miocene, Eocene, Cretaceous, Jura.s.sic, Tria.s.sic, Permian, Carboniferous, Devonian, Silurian, or Primitive was all one to me. But the professor, no doubt, was pursuing his observations or taking notes, for during one of our stops he said to me: "The farther I go the more confident I am. The order of these volcanic formations absolutely confirms Davy's theories. We're now in the midst of primordial soil in which the chemical reaction of metals catching flame through the contact of water and air occurred. I absolutely reject the theory of heat at the center of the earth. We'll see, in any case."

Always the same conclusion. Of course, I was not inclined to argue. My silence was taken for consent, and the descent continued.

After three hours, and I still did not see bottom of the chimney. When I raised my head I noticed how the opening was getting smaller. Its walls, due to their gentle slope, were drawing closer to each other, and it was beginning to grow darker.

Still we kept descending. It seemed to me that the stones breaking loose from the walls fell with a duller echo, and that they must be reaching the bottom of the chasm promptly.

As I had taken care to keep an exact account of our maneuvers with the rope, I could tell exactly what depth we had reached and how much time had pa.s.sed.

We had by that time repeated this maneuver fourteen times, each one taking half an hour. So it had been seven hours, plus fourteen quarter of an hour or a total of three hours to rest. Altogether, ten hours and a half. We had started at one, it must now be eleven o'clock.

As for the depth we had reached, these fourteen rope maneuvers of 200 feet each added up to 2,800 feet.

At that moment I heard Hans' voice.

"Stop!" he said.

I stopped short just as I was going to hit my uncle's head with my feet.

"We've arrived," said the latter.

"Where?" I said, sliding down next to him.

"At the bottom of the vertical chimney," he answered.

"Is there any way out?"

"Yes, a kind of tunnel that I can see and which veers off to the right. We'll see about that tomorrow. Let's have dinner first, and afterwards we'll sleep."

The darkness was not yet complete. We opened the bag with the supplies, ate, and each of us lay down as well as he could on a bed of stones and lava fragments.

When I lay on my back, I opened my eyes and saw a sparkling point of light at the extremity of this 3,000-foot long tube, which had now become a vast telescope.

It was a star without any glitter, which by my calculation should be of Ursa minor. Ursa minor.

Then I fell into a deep sleep.

XVIII.

AT EIGHT IN THE morning a ray of daylight came to wake us up. The thousand facets of lava on the walls received it on its pa.s.sage, and scattered it like a shower of sparks.

There was light enough to distinguish surrounding objects.

"Well, Axel, what do you say?" exclaimed my uncle, rubbing his hands. "Did you ever spend a quieter night in our little house in the Konigstra.s.se? No noise of carts, no cries of merchants, no boatmen vociferating!"

"No doubt it's very quiet at the bottom of this well, but there's something alarming in the quietness itself."

"Now come!" my uncle exclaimed; "if you're frightened already, what will you be later on? We've not gone a single inch yet into the bowels of the earth."

"What do you mean?"

"I mean that we've only reached the ground level of the island. This long vertical tube, which terminates at the mouth of the crater, has its lower end at about sea level."

"Are you sure of that?"

"Quite sure. Check the barometer."

In fact, the mercury, which had gradually risen in the instrument as we descended, had stopped at twenty-nine inches.

"You see," said the professor, "we only have a pressure of one atmosphere, and can't wait for the manometer to take the place of the barometer."

And indeed, this instrument would become useless as soon as the weight of the atmosphere exceeded the pressure at sea level.

"But," I said, "isn't there reason to fear that this steadily increasing pressure will become very painful?"

"No; we'll descend at a slow pace, and our lungs will become used to breathing a denser atmosphere. Aeronauts lack air as they rise to high elevations, and we'll perhaps have too much. But I prefer that. Let's not waste a moment. Where's the packet we sent down before us?"

I then remembered that we had searched for it in vain the evening before. My uncle questioned Hans who, after having looked around attentively with his hunter's eyes, replied: "Der huppe!"

"Up there."

And so it was. The bundle had been caught by a projection a hundred feet above us. Immediately the agile Icelander climbed up like a cat, and in a few minutes the package was in our possession.

"Now," said my uncle, "let's have breakfast, but let's have it like people who may have a long route in front of them."

The biscuit and extract of meat were washed down with a draught of water mingled with a little gin.

Breakfast over, my uncle drew from his pocket a small notebook, intended for scientific observations. He consulted his instruments, and recorded: Monday, July 1Chronometer: 8.17 a.m.

Barometer: 29 7/12".

Thermometer: 6C.

Direction: E.S.E.

This last observation applied to the dark tunnel, and was indicated by the compa.s.s.

"Now, Axel," exclaimed the professor with enthusiasm, "we're really going into the bowels of the globe. At this precise moment the journey begins."

That said, my uncle took the Ruhmkorff device that was hanging from his neck with one hand; and with the other he connected the electric current with the coil in the lantern, and a rather bright light dispersed the darkness of the pa.s.sage.

Hans carried the other device, which was also turned on. This ingenious electrical appliance would enable us to go on for a long time by creating an artificial light even in the midst of the most inflammable gases.

"Let's go!" exclaimed my uncle.

Each of us took his package. Hans pushed the load of cords and clothes before; and, myself going last, we entered the tunnel.

At the moment of penetrating into this dark tunnel, I raised my head, and saw for the last time through the length of that vast tube the sky of Iceland, "which I was never to behold again."

The lava, in the last eruption of 1229, had forced a pa.s.sage through this tunnel. It still lined the walls with a thick and glistening coat. The electric light was here intensified a hundredfold by reflection.

The only difficulty in advancing lay in not sliding too fast down an incline of about forty-five degrees; fortunately certain abrasions and a few blisters here and there formed steps, and we descended, letting our baggage slip before us from the end of a long rope.

But what made steps under our feet had turned into stalact.i.tes overhead. The lava, porous in some places, had taken the shape of small round blisters; opaque quartz crystals, decorated with limpid drops of gla.s.s and suspended like chandeliers from the vaulted roof, seemed to light up at our pa.s.sage. It seemed as if the spirits of the abyss were illuminating their palace to receive their earthly guests.

"It's magnificent!" I exclaimed spontaneously. "My uncle, what a sight! Don't you admire these hues of lava, which blend from reddish brown to bright yellow by imperceptible gradations? And these crystals that seem to us like globes of light?"

"Ah! you're coming around, Axel!" replied my uncle. "So you find this splendid, my boy! Well, you'll see many others yet, I hope. Let's go! Let's go!"

He had better have said "slide," for we did nothing but drop down the steep slopes. It was the facilis descensus Averni facilis descensus Averni of Virgil. of Virgil.ao The compa.s.s, which I consulted frequently, gave our direction as southeast with inflexible steadiness. This lava stream deviated neither to the right nor to the left. The compa.s.s, which I consulted frequently, gave our direction as southeast with inflexible steadiness. This lava stream deviated neither to the right nor to the left.

Yet there was no sensible increase in temperature. This justified Davy's theory, and more than once I consulted the thermometer with surprise. Two hours after our departure it only showed 10, an increase of only 4. This was reason to believe that our descent was more horizontal than vertical. As for the exact depth we had reached, it was very easy to ascertain that; the professor measured the angles of deviation and inclination accurately on the road, but he kept the results of his observations to himself.

At about eight in the evening he signaled to stop. Hans sat down at once. The lamps were hung on a projection in the lava; we were in a sort of cavern where there was no lack of air. On the contrary. Certain breezes reached us. What caused them? That was a question I did not try to answer at the moment. Hunger and exhaustion made me incapable of reasoning. A descent of seven consecutive hours is not accomplished without considerable expenditure of strength. I was exhausted. The word 'stop' therefore gave me pleasure. Hans spread some provisions out on a block of lava, and we ate with a good appet.i.te. But one thing troubled me; our supply of water was half consumed. My uncle counted on a fresh supply from underground sources, but so there had been none. I could not help drawing his attention to this issue.

"Are you surprised at this lack of springs?" he said.

"More than that, I'm anxious about it; we have only water enough for five days."

"Don't worry, Axel, I guarantee you that we'll find water, and more than we'll want."

"When?"

"When we have left this layer of lava behind us. How can springs break through such walls as these?"

"But perhaps this pa.s.sage runs to a very great depth. It seems to me that we've not yet made much progress vertically."

"Why do you suppose that?"

"Because if we had advanced far into the crust of earth, it would be hotter."

"According to your theory," said my uncle. "What does the thermometer say?"

"Hardly 15C, which means an increase of only 9 since our departure."

"So, draw your conclusion."

"This is my conclusion. According to exact observations, the temperature in the interior of the globe increases at the rate of 1 Celsius for every hundred feet. But certain local conditions may modify this rate. For example, at Yakutsk in Siberia it's been observed that the increase of 1 takes place every 36 feet. This difference clearly depends on the heat-conducting power of the rocks. Moreover, in the neighborhood of an extinct volcano, through gneiss, it's been observed that the increase of 1 is only attained every 125 feet. Let's therefore a.s.sume this last hypothesis as the most appropriate for our situation, and calculate."

"Do calculate, my boy."

"Nothing's easier," I said, putting down figures in my notebook. "Nine times a hundred and twenty-five feet adds up to a depth of eleven hundred and twenty-five feet."

"Very accurate indeed."

"Well?"

"By my observation we are 10,000 feet below sea level."

"Is that possible?"

"Yes, or numbers aren't numbers anymore!"

The professor's calculations were accurate. We had already reached a depth of six thousand feet beyond that so far reached by the foot of man, such as the mines of Kitzbuhl in Tyrol, and those of Wuttemberg in Bohemia.

The temperature, which should have been 81C in this place, was scarcely 15. This was serious cause for reflection.

XIX.

THE NEXT DAY, TUESDAY, June 30, at six in the morning, the descent began again.

We continued to follow the tunnel of lava, really a natural, gently sloping ramp like those inclined planes which are still found in old houses instead of staircases. And so we continued on until seventeen minutes past noon, the precise moment when we rejoined Hans, who had just stopped.

"Ah! here we are," exclaimed my uncle, "at the very end of the chimney."

I looked around me. We were standing at the intersection of two roads, both dark and narrow. Which one should we take? This was a difficulty.

But my uncle did not want to seem hesitant, either before me or the guide; he pointed to the Eastern tunnel, and all three of us were soon deep inside it.

In any case, any hesitation about this double path would have prolonged itself indefinitely, as there was no indicator to guide our choice of one or the other; we had to leave it absolutely to chance.

The slope of this tunnel was scarcely perceptible, and its sections very unequal. Sometimes we pa.s.sed a series of arches succeeding each other like the majestic arcades of a gothic cathedral. Medieval artists could have studied all the forms of sacred architecture here that derive from the ogival arch. A mile farther we had to bow our heads under low arches in the Roman style, and ma.s.sive pillars growing from the rock bent under the burden of the vaults. In certain places, this magnificence gave way to low structures which looked like beaver dams, and we had to crawl through narrow tubes.

The temperature remained bearable. Involuntarily I thought of the heat when the lava ejected from Snaefells was boiling and working through this now silent pa.s.sage. I imagined the torrents of fire breaking at every turn in the tunnel, and the acc.u.mulation of overheated steam in this close environment!

"I only hope," I thought, "that this old volcano doesn't come up with any belated fantasies!"

I did not convey these fears to Professor Lidenbrock; he would not have understood them. His only idea was to move on. He walked, he slid, he even fell with a conviction that one could only admire.

By six in the evening, after an undemanding walk, we had gone two leagues south, but scarcely a quarter of a mile down.

My uncle gave the signal to rest. We ate without talking, and went to sleep without reflection.

Our arrangements for the night were very simple; a travel blanket into which we rolled ourselves was our only bedding. We had neither cold nor intrusive visits to fear. Travelers who penetrate into the wilds of central Africa, and into the pathless forests of the New World, are obliged to watch over each other by night. But here, absolute safety and utter seclusion. Savages or wild beasts, we did not need to fear any of these wicked species.

We awoke the next morning refreshed and in good spirits. We resumed the road. As on the previous day, we followed a lava path. Impossible to identify the nature of the rock it pa.s.sed through. The tunnel, instead of leading down into the bowels of the globe, gradually became absolutely horizontal. I even thought I noticed that it rose again toward the surface of the earth. This tendency became so obvious at about ten in the morning, and therefore so tiring, that I was forced to slow down our pace.

"Well, Axel?" said the professor impatiently.

"Well, I can't stand it any longer," I replied.

"What! after three hours' walk over such easy ground."

"It may be easy, but it's tiring all the same."