You've gone and done it now!" he said.

"There's some one in here all right!" Sandy explained. "Did you hear the
call of the pack a minute ago? There are Boy Scouts in there, and what
we hear are the signals of the Wolf Patrol."

"That's right!" cried Tommy excitedly. "That's right!"

CHAPTER III

WHO CUT THE STRING?

"Do you suppose he would understand the call of the Beaver Patrol?"
asked Sandy. "I'm going to try him, anyway!"

The boy brought his hands together in imitation of the slap of a
beaver's tail on the water, and listened for some reply.

"He'll understand that if he's up on Boy Scout literature," suggested
Sandy. "He ought to be wise to the signs of the different patrols if
he's a good Boy Scout."

There was a short silence, broken only by the constant drip of the water
in an adjoining chamber, and then the call of the pack came again,
clearly, sharply and apparently only a short distance away.

"What did Mr. Canfield call those two boys we are looking after?" asked
Sandy, after waiting a short time for the repetition of the sound.

"Jimmie Maynard and Dick Thompson," replied Tommy.

Sandy threw out his chest and cried out at the top of his lungs:

"Hello, Jimmie! Hello, Dick!"

The lad's voice echoed dismally throughout the labyrinth of passages,
but there was no other reply. Tommy and Sandy gave the call of the
Beaver Patrol repeatedly, but the call of the Wolf pack was heard no
more.

"I'll bet it's some trick!" exclaimed Sandy after waiting in the chamber
for a long time in the hope of hearing another call from the boys who
were hidden somewhere behind the cribbing.

"What do you mean by trick?" demanded Tommy.

"Why, I mean that some of the breaker boys, out of work because of the
stoppage of operations, may have sneaked into the mine on purpose to
produce the impression that there are ghosts here."

"But ghosts wouldn't be giving signals of the Wolf Pack, would they?"
asked Tommy.

"Not unless they were Scouts," replied the other.

"Oh well, of course the kids would want to test us, wouldn't they,
seeing that we were only boys?"

"Well, we've discovered one thing by coming down," said Tommy, "and that
is that there really are people in the mine who have no business here."

"Then we may as well go back to bed," advised Sandy.

"Do you know how many corners we've turned since we came in here?" asked
Tommy.

"About a thousand, I guess," replied Sandy.

"Yes, and we'