Finally, I came to a spot where the Roman tunnel opened into a water-worn cavern--a huge hall, hung with long white icicles of lime deposit. From this central chamber I could dimly perceive that a number of passages worn by the subterranean streams wound away into the depths of the earth. I was standing there wondering whether I had better return, or whether I dare venture farther into this dangerous labyrinth, when my eyes fell upon something at my feet which strongly arrested my attention.
The greater part of the floor of the cavern was covered with boulders of rock or with hard incrustations of lime, but at this particular point there had been a drip from the distant roof, which had left a patch of soft mud. In the very centre of this there was a huge mark--an ill-defined blotch, deep, broad and irregular, as if a great boulder had fallen upon it. No loose stone lay near, however, nor was there anything to account for the impression. It was far too large to be caused by any possible animal, and besides, there was only the one, and the patch of mud was of such a size that no reasonable stride could have covered it. As I rose from the examination of that singular mark and then looked round into the black shadows which hemmed me in, I must confess that I felt for a moment a most unpleasant sinking of my heart, and that, do what I could, the candle trembled in my outstretched hand.
I soon recovered my nerve, however, when I reflected how absurd it was to associate so huge and shapeless a mark with the track of any known animal. Even an elephant could not have produced it. I determined, therefore, that I would not be scared by vague and senseless fears from carrying out my exploration. Before proceeding, I took good note of a curious rock formation in the wall by which I could recognize the entrance of the Roman tunnel. The precaution was very necessary, for the great cave, so far as I could see it, was intersected by passages. Having made sure of my position, and reassured myself by examining my spare candles and my matches, I advanced slowly over the rocky and uneven surface of the cavern.
And now I come to the point where I met with such sudden and desperate disaster. A stream, some twenty feet broad, ran across my path, and I walked for some little distance along the bank to find a spot where I could cross dry-shod. Finally, I came to a place where a single flat boulder lay near the centre, which I could reach in a stride. As it chanced, however, the rock had been cut away and made top-heavy by the rush of the stream, so that it tilted over as I landed on it and shot me into the ice-cold water. My candle went out, and I found myself floundering about in utter and absolute darkness.
I staggered to my feet again, more amused than alarmed by my adventure. The candle had fallen from my hand, and was lost in the stream, but I had two others in my pocket, so that it was of no importance. I got one of them ready, and drew out my box of matches to light it. Only then did I realize my position. The box had been soaked in my fall into the river. It was impossible to strike the matches.
A cold hand seemed to close round my heart as I realized my position. The darkness was opaque and horrible. It was so utter one put one's hand up to one's face as if to press off something solid. I stood still, and by an effort I steadied myself. I tried to reconstruct in my mind a map of the floor of the cavern as I had last seen it. Alas! the bearings which had impressed themselves upon my mind were high on the wall, and not to be found by touch. Still, I remembered in a general way how the sides were situated, and I hoped that by groping my way along them I should at last come to the opening of the Roman tunnel. Moving very slowly, and continually striking against the rocks, I set out on this desperate quest.
But I very soon realized how impossible it was. In that black, velvety darkness one lost all one's bearings in an instant. Before I had made a dozen paces, I was utterly bewildered as to my whereabouts.