"But it's impossible," insisted the young engineer. "No one, let alone a woman, could get near enough to this chamber to be heard as distinctly as that."
"I—I think it must be somebody who can go right through a rock," stammered Ned.
"Ghosts," nodded Walter.
"That's what I thought at first. But I knew it couldn't be after I had time to think twice. And I—"
"He-l-l-l-o-o-o!"
"There it goes again," fairly shouted Tom Phipps. "I'm going to find out what this means before I'm another minute older."
Hastily lighting a match he made a tour of the chamber, every corner of which he examined carefully, ending by a long, critical survey of the hole in the roof.
"It is just as impossible for anyone to be up there as it is to expect to see some one walk through the solid rocks here beside us," he decided, throwing the spent match on the floor where it glowed briefly and went out, leaving the darkness more dense than before.
Tad struck a fresh match.
"Hello, what's this?" he cried, reaching for a small package that lay wrapped in a piece of newspaper on the floor near him. "I didn't see that before."