But just as he reached the far end of the long passage, Fritz felt a fresher breath of air, and at the same moment his ear detected a continual whistling sound.
“Wind!” he muttered. “That’s wind!”
He put his face near the wall, and his hand found several fissures in it.
“Wind!” he said again. “It certainly is wind! It gets in here when it blows from the north. So there is a passage, either on the side or at the top of the cliff! But then, on this side, it would mean that there is a communication with the northern flank of the cliff!”
Just at that moment the candle which Fritz was passing along the wall went out suddenly, in a stronger draught blowing through one of the fissures.
Fritz did not wait for anything more. He was convinced. If one got through this wall one would have free access to the outside!
To crawl back to the cave where all were waiting for him, to tell them of his discovery, to take them back again with him, and make sure that he was right, was only the work of minutes.
In a few minutes more Fritz, followed by Captain Gould, John Block, and James, went from the first cave into the second. They lighted their way by candles which, on this occasion, they were careful not to put too near the wall at the far end.
Fritz was not mistaken. Fresh air was blowing freely through the passage.
Then the boatswain, passing the light along the level of the ground, noticed that the passage was closed only by a heap of stones which had no doubt fallen right down a kind of natural shaft.