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.

At this moment Hans came, he saw my hand in my uncle's, and I may safely say that there was joy in his countenance.

"_God dag,_" said he.

"How do you do, Hans? How are you? And now, uncle, tell me where we are at the present moment?"

"To-morrow, Axel, to-morrow. Now you are too faint and weak. I have bandaged your head with compresses which must not be disturbed. Sleep now, and to-morrow I will tell you all."

"But do tell me what time it is, and what day."

"It is Sunday, the 8th of August, and it is ten at night. You must ask me no more questions until the 10th."

In truth I was very weak, and my eyes involuntarily closed. I wanted a good night's rest; and I therefore went off to sleep, with the knowledge that I had been four long days alone in the heart of the earth.

Next morning, on awakening, I looked round me. My couch, made up of all our travelling gear, was in a charming grotto, adorned with splendid stalactites, and the soil of which was a fine sand. It was half light. There was no torch, no lamp, yet certain mysterious glimpses of light came from without through a narrow opening in the grotto. I heard too a vague and indistinct noise, something like the murmuring of waves breaking upon a shingly shore, and at times I seemed to hear the whistling of wind.

I wondered whether I was awake, whether I dreaming, whether my brain, crazed by my fall, was not affected by imaginary noises. Yet neither eyes, nor ears could be so utterly deceived.

It is a ray of daylight, I thought, sliding in through this cleft in the rock! That is indeed the murmuring of waves! That is the rustling noise of wind. Am I quite mistaken, or have we returned to the surface of the earth? Has my uncle given up the expedition, or is it happily terminated?

I was asking myself these unanswerable questions when the Professor entered.

"Good morning, Axel," he cried cheerily. "I feel sure you are better."

"Yes, I am indeed," said I, sitting up on my couch.

"You can hardly fail to be better, for you have slept quietly. Hans and I watched you by turns, and we have noticed you were evidently recovering."

"Indeed, I do feel a great deal better, and I will give you a proof of that presently if you will let me have my breakfast."

"You shall eat, lad. The fever has left you.