I did not delay. I took the burning glass from my pocket and held it up in my left hand to the sun, and when I thought it well filled with the sun’s rays I crawled in through the hole. When I was inside, the opening closed behind me, and I was in utter darkness. It was very cold, and the noise of thunder was louder than before. I was surprised to see at a little distance a single spot of light, which flickered here and there as I crept on; but I soon observed that it came from the burning glass which I was still holding in my left hand. _He Goes Down into the Cave in Thunder Mountain_ I was aware that I was going downward. The farther I went, the louder became the thunder. I must have descended thus for a minute or two, when a gust of cold air swept my face, and, finding the floor level, I stood up. The sound of thunder was now deafening, beyond anything I had yet heard. As I stood there, a great mass of what appeared to be ice, larger than my body, rolled past me and disappeared in the darkness. I jumped aside, and walked on. In another moment a mass of ice like the first fell at my side and rolled away; a rush of the bitterest cold air accompanied it; and as it struck the ground a crash of thunder shook the place, and its sound, as it rolled away into the dark, was the sound of thunder rumbling afar off among the mountains. I now understood the origin of the thunder I had heard in the clear sunlight outside. I pointed my burning glass upward, and I was able to make out dimly, in the ceiling, great numbers of these bodies of ice, hanging there like stalactites, but rounded at the bottom and very slender at the top, so that they appeared to hang by little more than a thread. As I stumbled on, one after another of these fell to the ground with a crash and rolled away with a decreasing rumble. There was no telling when one of them might fall on me, and I could only trust to luck. There was nothing to do but to get forward as quickly as possible; time was flying, and even if I should escape these thunder stones, I had only three or four minutes of my seven left. I darted blindly on, and the ice came crashing about me faster and faster, until I thought my head would split with the noise. Once or twice I was nearly struck. How I escaped I do not know, for it became certain that the thunder stones were dropping closer and closer around me, as if they were trying to halt me. And all the time the cold was becoming so bitter that my feet and legs were already numb. I suddenly found myself walking on a slippery film of ice, and at that moment I knew that I had cleared the chamber of thunder, and had left that danger behind me; the noise abated to a distant rumbling.