"I guess I'm doomed to go to the bottom," he thought. "If I only fall into deep water it won't be so bad. I can swim out. But if I land on the rocks--"
Fenn did not like to think about it. In fact his heart was full of terror at his strange situation, and only his natural courage kept him from giving way to despair. But he was filled with a dogged determination to save himself if he could, even at the end.
Though it has taken quite a while to describe Fenn's queer mishap, it did not take him long to accomplish it. He was slipping along at considerable speed, being shunted from side to side as the tunnel widened or narrowed, but, on the whole, being carried onward and downward in a fairly straight line.
Suddenly the blackness was illuminated the least bit by a tiny point of light below and in front of him. It looked like an opening.
"There's daylight ahead," thought the boy. "That must be where the fresh air comes from," for he had noticed that the tunnel was not close, but that a current of air was circulating through it. Fenn was wrong as to the source of this supply, as he learned later, but he had little time to speculate on this matter, for, much sooner than he expected, he had reached the spot of the light.
He saw, suddenly looming before him, an opening that marked the end of the tunnel. The shaft gave a sharp upward turn and Fenn was shot up and out, just as are packages that are sent down those iron chutes from the sidewalk into store basements.
A moment later the boy, covered with mud from head to foot, found himself on a narrow ledge on the face of a cliff overlooking Lake Superior. He lay, partly stunned for a moment, and blinking at the strong light into which he had come from the darkness of the shaft.
Below him rolled the great lake, on which he and his chums had so recently been sailing in the _Modoc_. Fenn arose to his feet, and gave a glance about him.
"It's the same place!" he murmured. "The same place where we saw the men who so mysteriously disappeared! I'm on the track of their secret!"
He looked at the ledge on which he stood. It was long and narrow, and, not far from where he was, he saw a partly-round opening, that seemed to be the mouth of another shaft, leading straight down.