"I don't know. Be careful. There's a lot of rubbish under foot ahead. I don't like the looks of it at all. Stand where you are."
After proceeding a few paces, their guide halted, holding a match high above his head. He turned toward them slowly.
"The rocks have caved in, boys. There's a solid wall in front of us."
"Which means," asked Tad hesitatingly.
"That we are imprisoned far under the surface," answered the miner impressively.
CHAPTER XXII
THE BOYS FACE A MYSTERY
"Then how are we going to get out?" asked Ned Rector as the guide's match went out.
"That depends upon how long it takes to dig us out," answered Mr.
Phipps.
"Then they know we are here?" questioned Tad.