The slab of rock tilted to one side, as if on a pivot, revealing a square opening which seemed to lead through solid stone. And at the far end of the opening Tom Swift saw a glimmer of light.
Stooping down, he looked through the hole thus strangely opened and what he saw caused him to cry out in wonder.
"It's the tunnel!" he cried. "I can look right down into the tunnel. It's the incandescent lights I see. I can look right at the ledge of rock where I kept watch that day, and where I saw—where I saw the face of Waddington!" he cried. "It wasn't a dream after all. This is a shaft connecting with the tunnel. We didn't discover it because this rock fits right in the opening in the roof. It must have been there all the while, and some blast brought it to light. Is this how the men got out, or were taken out of the tunnel, Masni?" Tom asked.
"This how," said the Indian woman. "See, here rope!"
She pawed aside a mound of earth, and disclosed a rope buried there, a rope knotted at intervals. This, let down through the hole in the roof of the tunnel, provided a means of escape, and in such a manner that the disappearance of the men was most mysterious.
"I see how it is!" cried Tom. "Some one interested, Waddington probably, who knew about this old secret shaft going down into the earth, used it as soon as our blasting was opened that far. They got the men out this way, and hid them in the secret valley."
"But what for?" cried Mr. Damon.
"To cripple us! To cause the strike by making our other workers afraid of some evil spirit! The men were taken away secretly, and, doubtless, have been kept in idleness ever since—paid to stay away so the mystery would be all the deeper. Our rivals finding they couldn't stop us in any other way have taken our laborers away from us."
"Bless my meal ticket! It does look like that!" cried Mr. Damon.
"Of course that's the secret!" cried Tom. "Blakeson & Grinder, or some of their tools—probably the bearded man or Waddington—found out about this shaft which led down into our tunnel. They induced the first ten men to quit, and when Tim went to get the fuse the rope was let down, and the men climbed up here, one after the other. Those Indians can climb like cats. Once the ten were out the shaft was closed with the rock, and the ten men taken off to the valley to be secreted there.