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 shiver as with the ague. Besides, if the ascending path was more arduous and painful to clamber, I had one source of secret consolation and delight. It was to all appearance taking us back to the surface of the earth. That of itself was hopeful. Every step I took confirmed me in my belief, and I began already to build castles in the air in relation to my marriage with my pretty little cousin. About twelve o'clock there was a great and sudden change in the aspect of the rocky sides of the gallery. I first noticed it from the diminution of the rays of light which cast back the reflection of the lamp. From being coated with shining and resplendent lava, it became living rock. The sides were sloping walls, which sometimes became quite vertical. We were now in what the geological professors call a state of transition, in the period of Silurian stones, so called because this specimen of early formation is very common in England in the counties formerly inhabited by the Celtic nation known as Silures. "I can see clearly now," I cried; "the sediment from the waters which once covered the whole earth formed during the second period of its existence these schists and these calcareous rocks. We are turning our backs on the granite rocks, and are like people from Hamburg who would go to Lubeck by way of Hanover." I might just as well have kept my observations to myself. My geological enthusiasm got the better, however, of my cooler judgment, and Professor Hardwigg heard my observations.