So I turned back to try my luck in the other direction.  But first I shouted and shouted with all my might.  I could not be far away from the ruins, and there was a chance of some one hearing me.  However, I had little faith in my effort, and was too tired to keep it up; so I turned with my lantern toward the other end of the corridor.  And here it was easy going, along a gently-graded descent, covered, as I have said, with white sand, in which shells were here and there embedded.  My heart beat wildly.  Perhaps I had only to walk on a little farther to come out on the sea—­for here certainly the sea had been once, whether or not it came up there any more.  Vain hope!—­for when I had followed the corridor some fifty yards or so, it suddenly widened out for a few yards into something of a cavern, and then as suddenly narrowed into a mere slit, and so came to an end.

The deadening of my spark of hope weakened me.  I slid down, with my back against the rock, and gave way to despair.  As I looked up at the smooth implacable walls that imprisoned me, I felt like some poor insect clinging to the side of a bowl partly filled with water.  How frantically the poor creature claws and claws the polished sides, at each effort slipping nearer and nearer to the fatal flood.

I had sense enough to know that I was too tired to think profitably, and drowsiness coming over me told me that an hour or two’s sleep would give me the strength I needed to renew with a will, and more chance of success, my efforts to escape.

Light was too precious to waste, so I blew out my lantern, and, curling up on the sand, almost instantly fell asleep.  But, before I lapsed into unconsciousness, I had clutched hold of one sustaining thought in the darkness—­the assurance of Calypso’s safety, so confidently announced by her father:  “Don’t be afraid for her.  I know my daughter.”  Whatever happened to me, she would come out all right.  As her brave shape flashed before my mind’s eye, down there under the earth, I could have no doubt of that.

CHAPTER XV

In Which I Pursue My Studies as a Troglodyte.

My instinct had been right in giving way to my drowsiness, for I woke up from my sleep a new man.  How long I had been there, of course, I had no means of knowing; but I fancy I must have slept a good while, for I felt so refreshed and full of determination to tackle my escape in good earnest.

It is remarkable how rest sharpens one’s perceptions.  When we are weary, we only half see what we look at, and the very thing we are desperately seeking may be right under our nose and we quite unaware.

So I had hardly relit my lantern, when its rays revealed something which it seemed impossible for any one with eyes, however weary, to have overlooked.