“Oh, come now, Roger, old fellow, you must not think like that!” answered Harry. “Now that they have seen that we know they watch us, they may not attempt it again; and they would surely not do very much to us for a little thing like that. Besides, it is intolerable to think that we are being spied upon all day long, and that whatever we do or say is known. There would be absolutely no chance whatever of our making a successful attempt to escape at any time if we had not closed the hole. At any rate, it is done now, and it is no good our worrying over it; we must just wait and see what happens. If they are going to make a fresh place of observation, or punish us for what we have done, they will not defer it long; so to-day will, in my opinion, decide the matter. Meanwhile we must wait; and, while we are unobserved, we had better make the most of our time.”

“You are right, Harry, old friend,” said Roger; “but for my part I do not feel much like talking, or anything else. If we had something really useful to occupy us to pass the time it would be different; but as it is, well—what can we do?”

“Well, I’ll tell you,” answered Harry. “We will wait for a little while, in order to ascertain whether they mean to do anything about this matter of closing up the spy-hole; and, if no one comes, I think we could not do better than make another attempt to translate that cryptogram of ours. We have made many attempts already, it is true, and it has always got the better of us. But then, we have never, until now, really had the time to spare to attend to it properly. Now would be a very good opportunity; we have plenty of time—which drags heavily enough, God knows. This would serve to make it pass; and if we succeed—and should be able also to effect our escape—we should then be ready to secure that treasure without delay. For although, so far as we are aware, we are the only ones who know anything whatever about the affair, delay is dangerous; someone might easily even get there before us and discover the treasure by accident. One never knows. What think you, Roger?”

“Why, Harry, lad,” said Roger, brightening up considerably, “I think that it’s a very good idea. I am surprised that I never thought of it myself. We had better wait a little, however, and see what happens, before we extract the paper from my jacket; we do not want to be taken by surprise.”

The words were hardly out of his mouth when, from somewhere in the building, evidently some distance away, came a long wailing cry, low at first, then rising gradually higher and higher, until it became a piercing scream—the scream of a man in mortal agony.

The long-drawn shriek continued for some moments, and then died down again to a low, moaning sound; then it rose again, and changed into a series of short yapping cries of anguish, almost like the barking of a dog; then it ceased.

“What on earth is that, Harry?” ejaculated Roger, looking at his friend, on whose forehead the cold perspiration was now standing in beads. “What an awful sound!”

“I am afraid, my friend,” replied Harry, “that it means that some poor mortal is undergoing torture almost greater than he can bear. What devils these inquisitors are! If I could but be at the head of a few hundred English seamen at this moment, would I not pull this place of torture about their ears; and would I not put a few of them to the torture themselves, just to teach them by experience what it feels like, and as a warning to the rest! God help that poor wretch, whoever he may be! What a fearful, awful sound it is! This is getting dreadful,” he went on, as another shrill and blood-curdling scream broke on their ears, quavering as it was with the extremity of fearful agony, yet not quite so loud as before, as though the unfortunate individual were losing his strength.

“To be imprisoned here, and not to be able to do anything to help the poor fellow! Oh, they are fiends in human shape!” cried Roger, stamping his foot on the ground in impotent fury.

Then came a sound which made the lads start and look apprehensively at each other. It was the noise of footsteps approaching down the long passage at the end of which their own cell was situated.