"No, I'll use a rock to pound with if they get near enough. There's no hurry, however. It will be a long time before there's any occasion to communicate."
Turning back, Tom led the way through the passage to the large chamber which they had but recently left. Arriving there, he directed each of the lads to light a match at the same time so he could make a survey of the room to determine whether it were safe for them to remain there or not.
"See that hole up there?" he exclaimed.
"Yes, what is it?" asked Tad.
"It's a check. You see there must have been a weakness in the strata at that point—perhaps it had already started to check there, when the force of the explosion split it wide open. The opening is large enough to admit a man's body. Hold your lights down here while I examine this rubbish that has fallen through."
They did so, and Mr. Phipps dropping to his knees sorted over the stones and dirt that had fallen from above.
At a muttered exclamation from him, the lads crowded closer.
"Queer, very queer," he mused.
"What's queer?" asked Ned.
"Why, this stuff. It appears to be surface material mixed with pieces of rock of about the same quality as that of which the Ruby Mountain is composed."