"Down--for this reason: We are in a vast chamber, with endless galleries. Yours must lead into it, for it seems as if all the clefts and fractures of the globe radiated round this vast cavern. So get up, and begin walking. Walk on, drag yourself along, if necessary slide down the steep places, and at the end you will find us ready to receive you. Now begin moving." . . . . These words cheered me up. "Good bye, uncle." I cried. "I am going. There will be no more voices heard when once I have started. So good bye!" . . . . "Good bye, Axel, _au revoir!_" . . . . These were the last words I heard. This wonderful underground conversation, carried on with a distance of four miles and a quarter between us, concluded with these words of hope. I thanked God from my heart, for it was He who had conducted me through those vast solitudes to the point where, alone of all others perhaps, the voices of my companions could have reached me. This acoustic effect is easily explained on scientific grounds. It arose from the concave form of the gallery and the conducting power of the rock. There are many examples of this propagation of sounds which remain unheard in the intermediate space. I remember that a similar phenomenon has been observed in many places; amongst others on the internal surface of the gallery of the dome of St. Paul's in London, and especially in the midst of the curious caverns among the quarries near Syracuse, the most wonderful of which is called Dionysius' Ear. These remembrances came into my mind, and I clearly saw that since my uncle's voice really reached me, there could be no obstacle between us. Following the direction by which the sound came, of course I should arrive in his presence, if my strength did not fail me. I therefore rose; I rather dragged myself than walked. The slope was rapid, and I slid down. Soon the swiftness of the descent increased horribly, and threatened to become a fall. I no longer had the strength to stop myself. Suddenly there was no ground under me. I felt myself revolving in air, striking and rebounding against the craggy projections of a vertical gallery, quite a well; my head struck against a sharp corner of the rock, and I became unconscious. CHAPTER XXIX. THALATTA! THALATTA! When I came to myself, I was stretched in half darkness, covered with thick coats and blankets. My uncle was watching over me, to discover the least sign of life. At my first sigh he took my hand; when I opened my eyes he uttered a cry of joy. "He lives! he lives!" he cried. "Yes, I am still alive," I answered feebly. "My dear nephew," said my uncle, pressing me to his breast, "you are saved." I was deeply touched with the tenderness of his manner as he uttered these words, and still more with the care with which he watched over me. But such trials were wanted to bring out the Professor's tenderer qualities.