The next day was Tuesday, the 30th of June—and at six o'clock in the morning we resumed our journey.  
We still continued to follow the gallery of lava, a perfect natural pathway, as easy of descent as some of those inclined planes which, in very old German houses, serve the purpose of staircases. This went on until seventeen minutes past twelve, the precise instant at which we rejoined Hans, who, having been somewhat in advance, had suddenly stopped.
 
"At last," cried my uncle, "we have reached the end of the shaft."
 
I looked wonderingly about me. We were in the centre of four cross paths—somber and narrow tunnels. The question now arose as to which it was wise to take; and this of itself was no small difficulty.
 
My uncle, who did not wish to appear to have any hesitation about the matter before myself or the guide, at once made up his mind. He pointed quietly to the eastern tunnel; and, without delay, we entered within its gloomy recesses.
 
Besides, had he entertained any feeling of hesitation it might have been prolonged indefinitely, for there was no indication by which to determine on a choice. It was absolutely necessary to trust to chance and good fortune!
 
The descent of this obscure and narrow gallery was very gradual and winding. Sometimes we gazed through a succession of arches, its course very like the aisles of a Gothic cathedral. The great artistic sculptors and builders of the Middle Ages might have here completed their studies with advantage. Many most beautiful and suggestive ideas of architectural beauty would have been discovered by them. After passing through this phase of the cavernous way, we suddenly came, about a mile farther on, upon a square system of arch, adopted by the early Romans, projecting from the solid rock, and keeping up the weight of the roof.
 
Suddenly we would come upon a series of low subterranean tunnels which looked like beaver holes, or the work of foxes—through whose narrow and winding ways we had literally to crawl!
 
The heat still remained at quite a supportable degree. With an involuntary shudder, I reflected on what the heat must have been when the volcano of Sneffels was pouring its smoke, flames, and streams of boiling lava—all of which must have come up by the road we were now following. I could imagine the torrents of hot seething stone darting on, bubbling up with accompaniments of smoke, steam, and sulphurous stench!
 
"Only to think of the consequences," I mused, "if the old volcano were once more to set to work."
 
I did not communicate these rather unpleasant reflections to my uncle. He not only would not have understood them, but would have been intensely disgusted. His only idea was to go ahead. He walked, he slid, he clambered over piles of fragments, he rolled down heaps of broken lava, with an earnestness and conviction it was impossible not to admire.
 
At six o'clock in the evening, after a very wearisome journey, but one not so fatiguing as before, we had made six miles towards the southward, but had not gone more than a mile downwards.
 
My uncle, as usual, gave the signal to halt. We ate our meal in thoughtful silence, and then retired to sleep.
 
Our arrangements for the night were very primitive and simple. A traveling rug, in which each rolled himself, was all our bedding. We had no necessity to fear cold or any unpleasant visit. Travelers who bury themselves in the wilds and depths of the African desert, who seek profit and pleasure in the forests of the New World, are compelled to take it in turn to watch during the hours of sleep; but in this region of the earth absolute solitude and complete security reigned supreme.
 
We had nothing to fear either from savages or from wild beasts.
 
After a night's sweet repose, we awoke fresh and ready for action. There being nothing to detain us, we started on our journey. We continued to burrow through the lava tunnel as before. It was impossible to make out through what soil we were making way. The tunnel, moreover, instead of going down into the bowels of the earth, became absolutely horizontal.
 
I even thought, after some examination, that we were actually tending upwards. About ten o'clock in the day this state of things became so clear that, finding the change very fatiguing, I was obliged to slacken my pace and finally come to a halt.
 
"Well," said the Professor quickly, "what is the matter?"
 
"The fact is, I am dreadfully tired," was my earnest reply.
 
"What," cried my uncle, "tired after a three hours' walk, and by so easy a road?"
 
"Easy enough, I dare say, but very fatiguing."
 
"But how can that be, when all we have to do is to go downwards."
 
"I beg your pardon, sir. For some time I have noticed that we are going upwards."
 
"Upwards," cried my uncle, shrugging his shoulders, "how can that be?"
 
"There can be no doubt about it. For the last half hour the slopes have been upward—and if we go on in this way much longer we shall find ourselves back in Iceland."
 
My uncle shook his head with the air of a man who does not want to be convinced. I tried to continue the conversation. He would not answer me, but once more gave the signal for departure. His silence I thought was only caused by concentrated ill-temper.
 
However this might be, I once more took up my load, and boldly and resolutely followed Hans, who was now in advance of my uncle. I did not like to be beaten or even distanced. I was naturally anxious not to lose sight of my companions. The very idea of being left behind, lost in that terrible labyrinth, made me shive............