"I'll chance it at any rate," returned Brown, and presently he stood beside his friend.
Morton told him of the strange sound he had heard, and both stood by the edge of the hole and listened. Once more the blast of cold air came and with it the melancholy and mysterious noise.
"That's no human or animal noise," said Brown; "it seems more like water or air escaping."
"The atmosphere does not seem so bad now," said Morton. "I suppose it was the contrast with the pure air above."
"It was getting light to the eastward when I came down just now," returned Brown; "we had better wait for full daylight—half an hour cannot make much difference."
"It might make all the difference," replied Morton; "however, I suppose there is no help for it."
At that moment there was a sudden cry from above.
"Wonder what's up?" said Morton, scrambling back. "Hang it all!" he exclaimed as he laid hold of the surcingles and they came tumbling down, showing that the blacks above had let go of them.
Presently they were heard jabbering at the edge of the hole, and Morton shouted to them and threw a coil of the surcingles up. Apparently they understood what was wanted, for the line tautened once more and Morton scrambled up, and then assisted Brown. The dawn was rapidly breaking, and the blacks, pointing to the candle Morton still held in his hand and then towards the memorable cliffs, chattered volubly.
"They must mean that they saw a light in that direction," said Brown. "It's too light for us to see now."