But we enjoyed absolute safety and utter seclusion; no savages or wild beasts infested these silent depths.
Next morning, we awoke fresh and in good spirits.

The road was resumed.

As the day before, we followed the path of the lava.

It was impossible to tell what rocks we were passing: the tunnel, instead of tending lower, approached more and more nearly to a horizontal direction, I even fancied a slight rise.

But about ten this upward tendency became so evident, and therefore so fatiguing, that I was obliged to slacken my pace.
"Well, Axel ?" demanded the Professor impatiently.
"Well, I cannot stand it any longer," I replied.
"What! after three hours' walk over such easy ground." "It may be easy, but it is tiring all the same." "What, when we have nothing to do but keep going down!" "Going up, if you please." "Going up!" said my uncle, with a shrug.
"No doubt, for the last half-hour the inclines have gone the other way, and at this rate we shall soon arrive upon the level soil of Iceland." The Professor nodded slowly and uneasily like a man that declines to be convinced.