The boys continued to signal back and forth until the situation was fairly well understood. Will and Ed knew that Bert had been found and that all three were barricaded in the cave.
They were disposed to make their way to the rescue of the boys without further delay, but George advised them to wait until it became darker, as Cameron might return at almost any moment. The news that Bert had regained consciousness was very welcome and, confident of their ability to thwart the plans of the miner, the boys looked forward to quiet hours in the cabin.
Of course the boys had no suspicion that their enemies were close at hand watching every movement. Cameron and Fenton became impatient, after a time, and began advancing slowly toward the boys, who were now not very far from the mouth of the outer cavern.
Something better than an hour passed, and then George signalled from the interior of the cavern that it might be well for the boys to come up and begin the work of removing the rocks which barred their egress.
"Sneak In," George signalled. "Don't show yourself more than you have to. Cameron may be about! It may be that he has seen our signals already!"
Sandy replied that he had not discovered any indications of the presence of the miner, and the two boys advanced to the shelf of rock which faced the opening. It was nine o'clock then.
"What's that strange noise?" asked Will as they moved along the shelf.
"You've got me!" replied Ed, "The ground's tipping!"
There came a deafening crash and the whole face of the cliff fell away! When Will and Ed regained their feet and looked through the dust which was rising over the scene, they saw that there was no longer any cavern in view. The rock on which they stood was sliding down the slope.
"Buried alive!" cried Will with a sob, "Buried alive!"