"We can find the wall of the cave and then feel round it till we discover the opening," said jack in a firmer voice than when he had last spoken.
"Hurray! Here it is!" exclaimed Sandy after they had groped about for several minutes.
"Then, forward march!" cried Jack, "and let's get out of this place as quick as we can. I wish we had never come into it."
"So do I," agreed Sandy, "but it's crying when the milk is spilt."
Through the darkness the two boys advanced into the tunnel whose entrance they had discovered. They tramped briskly on for some time and at last a feeble glimmer of light began to show. This heartened them, and they quickened their steps. At last they reached the mouth of the tunnel they had been traversing.
But at its end a cruel shock awaited them.
Instead of the rocky plateau they had expected to find, they discovered that they had emerged on the lip of a cliff. Peering over the edge, they could see that they were standing on a sort of shelf, a good hundred feet above the bottom of a steep-sided ravine.
The opposite side of the abyss was not more than twenty feet distant, but how were they to cross it?
"We must turn back," said Jack in a voice tinged with despair.
But Sandy shook his head.