ight, 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 f