Canfield.

"Oh, we can line the walls of some little cubby-hole with canvas if necessary, and you can string a wire in so as to give us electricity for heating and lighting, and we can live as comfortable as four bugs in a rug. If we keep out of sight during the day time, no one will ever suspect that we are here."

"Have it your own way!" replied Canfield. "I'll see that you get plenty to eat and plenty of bed clothing."

"That'll help some!" laughed Tommy. "During the night we can travel through the mine with our lights, and during the daytime we can crawl into our little beds and sleep our heads off!"

"When do you want your first load of provisions?" asked Canfield.

"Right now, tonight!" replied Sandy.

"Well, come along then," Canfield said, rising from his chair, "and I'll let you pick out a spot for your camp, as you call it."

After quite an extended search through the breaker the boys selected a small room on the ground floor, from which one window looked out on the half-deserted yard where the weigh-house stood. The room was perhaps twenty feet in size each way, and the walls were of heavy planking. The whole apartment was sadly in need of a scrubbing, but the lads concluded to postpone that until some future date.

"I can bring in cot beds and bedding," the caretaker announced, "and string the electric wire for heating, lighting, and cooking before I go to bed. That will leave you all shipshape in the morning, and you can then begin your cleaning up as soon as you please."

The caretaker was as good as his word, and before ten o'clock the cots and bedding were in place, also an electric heater and an electric plate for cooking had been moved into the apartment.

Not considering it advisable to go out for supper, Canfield had also brought in provisions in the shape of bacon, potatoes, eggs, bread, butter, coffee, and various grades of canned goods, so the boys had made a hearty meal and had plenty left for breakfast. While cooking they had covered the one window with a heavy piece of canvas.

"Now you're all tight and snug for the night," the caretaker smiled, as he turned back from the door and glanced over the rather cozy-looking room. "If I'm about here during the night, I'll look in upon you again."

Canfield stepped out and closed the door behind him. Then he came back and looked in again with a half-smile on his face.

"Do you boys know anything about mines?" he asked.

"Not a thing!" replied Tommy.

"Then don't you go climbing down the ladders and wandering around in the gangways tonight!" the caretaker warned.

"Say, there's an idea!" Tommy said to Sandy, with a wink, as Canfield went out. "How do you think one of these mammoth coal mines looks, anyway?"

"Cut that out, boys!" exclaimed Will. "If I catch one of you attempting the ladders tonight, I'll tie you up!"

"Who said anything about going down the ladders tonight?" demanded Tommy.

Chapter II

THE CALL OF THE PACK

It was somewhere near midnight when the boys sought their beds. Will and George were soon asleep, but Tommy and Sandy had no notion of passing their first night in the mine in slumber. Ten minutes after the regular breathing of the two sleepers became audible, Tommy sat up in his bed and deftly threw a pillow so as to strike Sandy in the face.

"Cut it out!" whispered Sandy. "You don't have to do anything to wake me up! I've been wondering for a long time whether you hadn't gone to sleep! You looked sleepy when the light went out."

"Never was so wide awake in my life!" declared Tommy.

"Well, get up and dress," advised Sandy. "If we get into the mine tonight, we'll have to hurry!"

"Have you figured out how we're going to get into the mine?" asked Tommy. "It will be the ladders for us, I guess."

"Of course it'll be the ladders!" replied Sandy. "Do you suppose Canfield is coming here in the middle of the night to turn on the power?"

"I wonder how deep the shaft is?" asked Tommy.

"I guess this one must be about five hundred feet."

"Is that a guess, or a piece of positive information?"

"It's a guess," laughed Sandy, drawing on his shoes and walking softly across the bare floor in the direction of the shaft.

The boys passed out of the sleeping chamber into a passage which led directly to the shaft of the mine. This shaft was perhaps twenty feet in width. It included the air shaft, the division where the pumps were operated, and two divisions for the cages which lifted the coal from the bottom of the mine. The pumps were not working, of course, and no air was being forced down.

One of the cages lay at the top so the other must have been at the bottom of the shaft. As the boys looked down into the shaft, Tommy seized his chum by the arm and whispered:

"Did you see that light down there?"

"Light nothing!" declared Sandy.

"But I did see a light!" insisted the other.

"Perhaps you did," replied Sandy, "but if there's any light there it's merely a reflection from our electrics. There may be a metallic surface down there which throws back the light rays."

"Have it your own way!" grunted Tommy. "You know yourself that the caretaker said there were lights in the mine which no one could account for, and he especially mentioned the light in Tunnel Six."

"All right!" Sandy grinned. "We'll sneak down so quietly that any person who happens to be at the bottom of the shaft with the light will never suspect that we are within a hundred miles of the place. We may be able to geezle the fellow that's making the ghost walk around here nights."

The boys took to the ladders and moved down as silently as possible. Now and then a rung creaked softly under their feet, but they got to the bottom without any special mishap.

Tommy drew a long breath when at last they landed at the bottom of the shaft. He threw his light upward, then, and declared that in his opinion they were at least ten thousand feet nearer the center of the earth than they were when they started down.

"I remember now," Sandy said with a grin, "that the Labyrinth mine is only about five hundred feet deep. If I remember correctly, there are three levels; one at three hundred feet; one at four, and one at five."

"And which level is this?" asked Tommy.

"Why, we're on the bottom, ain't we?"

"Of course," laughed Tommy. "I ought to have known that!"

"Well come along if you want to see the mine!" urged Sandy. "All we have to do is to push our searchlights ahead and walk down the gangway. We'll come to something worth seeing after a while."

As the boys advanced they found the gangway considerably cluttered with "gob," or refuse, and the air was none of the best.

"I wish we could set the air shaft working," suggested Sandy.

"Well, we can't!" Tommy answered with a scornful shrug of his shoulders. "We can't set the whole works going in order to give us a midnight view of the Labyrinth mine. What gets me is, how are we going to find our way back? There seem to be a good many passages here."

"I've got that fixed all right!" Sandy exclaimed.

As the lad spoke he took a ball of strong string from his pocket and tied one end to the cage which lay at the bottom of the shaft.

"Now we can go anywhere we please," he chuckled "and when we want to return, all we've got to do is to follow the string."

"Quite an idea!" laughed Tommy.

The boys proceeded along the gangway, walking between the rails of the tramway by means of which the coal was delivered at the bottom of the shaft. The experience was a novel one to them. The dark walls of the passage, the echoes which came from the counter gangways, the monotonous dripping of water as it seeped through seams and crevices in the rock, all gave a weird and uncanny expression to the place.

After walking for some distance the boys came to a