"You've got to explanation me," George laughed, as the caretaker left the room, and the boys began picking up their clothing, preparatory to the alleged journey. "I can't understand what you mean by saying that you'll watch out for a boy tramp in the railroad yards."

"It's a sure thing, isn't it?" Will asked, "that the boys we are in search of are in the mine? We don't know what they're in there for. They may be hiding there because of some fool notion they have in their heads, or they may have been sent here for some definite purpose."

"You bet they've been sent here for some definite purpose," George replied. "They never came here to work on the breaker without having some well-defined motive. Boys answering to their description don't accept such jobs as they accepted here!"

"Well, the boys are in the mine," Will continued. "As stated, we don't know what they're there for, but we know they're there. Now, this third boy comes to the mine and works just long enough to get in touch with the other two. Then he disappears."

"Buys a lot of provisions and goes down the river to leave his hat on the bank!" laughed Tommy. "I guess that was a pretty poor imitation of a suicide or a drowning accident, either!"

"But this boy didn't get to be intimate with the two breaker boys,"

contended George. "He talked with them about two minutes after the fight, according to Canfield, but paid no further attention to them after that. If he had any secret understanding with them, he must have done a whole lot of talking in a mighty short s.p.a.ce of time."

"The right kind of a boy can say a good deal in a minute and half!"

laughed Tommy. "But suppose we let Will go on and explanation us about that boy tramp in the railroad yards. I think I know what he's getting at, but I'm not quite certain. Go on, Will, it's up to you."

"In order to make the connection," laughed Will. "I'll state for the third time that we know that the boys are in the mine. It may also be well to state, once more, that we are reasonably certain that this third boy came to the mine for the specific purpose of communicating with the other two. Now, this boy didn't drop into the river. He dropped the provisions he bought for the boat into the coal mine, and left them there for the consumption of the two boys inside. That's reasonable, isn't it?"

"Fine deduction, as Sherlock Holmes would say to Watson!" laughed George.

"But this third boy," Will went on, "doesn't go into the mine. He stays outside to serve as a means of communication between the boys who are hiding in the mine and some interested person or persons on the outside.

That's perfectly clear, isn't it?"

"That'll do very well for a theory," replied George.

"I'll go you a plate of cookies," argued Sandy, "that Will is right, and that this third boy is hanging around taking messages from the two boys in the mine and also to the two boys in the mine."

"Didn't I say it was all right for a theory?" chuckled George.

"Now, the point is this," Will continued. "What are those boys in the mine for? What do they want there? Why didn't they answer our Boy Scout challenge when we replied to their call of the pack?"

"If you don't ask so many questions, you won't get so many negative answers," Sandy advised. "We're here to find the boys, and I don't see that it makes any difference to us what they're in there for."

"But we've found the boys now," contended Tommy. "We haven't got our hands on them yet, of course, but we know they're in there, and we know it's only a question of time when we get hold of them."

"Well," Will insisted, "I'm going to find a motive before I quit the case. I'm going to know who sent those boys here, and all about it, before I make any report to Mr. Horton."

"Go as far as you like," laughed Tommy. "My b.u.mp of curiosity is growing half an inch a day, and will continue to spread out until I find out exactly what those boys are doing burrowing in a deserted mine."

"Now, we'll get back to the point we started from," Will explained.

"This boy who is undoubtedly doing duty outside the mine in the interests of the persons who sent the two boys in, furnishes the clue to the whole situation! When we find him, and find out what he's up to, and trace any communications he may make back to their original source, we'll have the whole case tied up tight!"

"That's right!" declared Tommy. "We'll have the case tied up tight if we succeed in getting hold of this third boy."

"Oh, go on!" laughed Sandy. "We'll be picking third boys and fourth boys and fifth boys out of the air, first thing you know. We never went away on a Boy Scout expedition yet that we didn't find all manner of kids hanging around on purpose to be discovered. We found them on Old Superior; and in the Everglades; and on the Great Continental Divide; and up in the Hudson Bay country, we began to think we had stumbled on the center of population so far as Boy Scouts were concerned!"

"There's just one thing that's likely to make us trouble," Will resumed.

"And that is the fact that Canfield very foolishly slopped over to Ventner when explaining the purpose of our visit here. That b.u.m detective knows now that we're here to search the mine. Of course he might have received, as Canfield says, the most of his information from outside sources, but the caretaker should have thrown him off the track instead of telling him exactly what our mission here was."

"But Ventner came here to search for the boys himself!" George broke in.

"At least, he says that he did."

"There's a mystery about the whole matter," Sandy declared, "and I'd like to help clear it up from beginning to end!"

"We're likely to have a chance!" laughed Tommy.

"What are we going to do all the afternoon?" George asked.

"Wander around town," smiled Will, "and find out about the evening train, and ask fool questions about the pumps and the mine, and laugh at the idea of anybody living in there. That'll give Ventner the idea that we're going for good, I reckon. He's a pretty b.u.m skate to pose as a detective!"

"I'll tell you what I'm going to do most of the afternoon!" Tommy declared. "I'm going to the hay! I never felt so bunged up for want of sleep in my innocent life."

"Haven't you forgotten something?" asked Sandy.

"Sure!" shouted Tommy. "I'm forgetting to eat!"

"And you're forgetting something else!" insisted Sandy.

"Nix on the forget!" declared Tommy. "When I forget my eatings and sleepings, the world will come to an end!"

"You forgot to read a chapter in your dream book!" said Sandy.

"Never you mind that dream book," Tommy replied. "Whenever you want to find the answer to any puzzle, you look in that dream book!"

After eating another hearty meal the boys, having already packed their wardrobes, locked the door of their room and addressed themselves to slumber.

They were awakened about five o'clock by a loud knocking on the door, and presently they heard the voice of Canfield calling to them.

"Wake up, boys!" he cried. "I have good news for you!"

"All right, let her go!" shouted Tommy.

"The pumps are working, and the water is lowering in the mine!"

"That's nice!" laughed Sandy.

"And we've found out what caused the sudden flooding," the caretaker went on. "It seems that a part.i.tion, or wall, between the Labyrinth and the Mixer mines unaccountably gave way. The Mixer mine has been flooded for a long time and, as it lies above the level of the Labyrinth, the water naturally flowed into our mine as soon as the wall was down."

"But what caused the part.i.tion to fall?" asked Will, opening the door for the admission of the caretaker.

"No one knows!" was the answer.

"If you look about a little," Tommy suggested, "I think you'll find traces of dynamite. Who discovered the break in the dividing wall?"

"A gang under the leadership of Ventner, the detective!" was the reply.

The caretaker was very much surprised and not a little annoyed at the effect his answer had upon the four boys.

"I don't see anything humorous about that!" he said as the lads threw themselves down on the bunks and roared with laughter.