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 th