"That must be the shaft opening," said Frank. "We're on the track now."
The boys descended into the pit. The going was precarious, for the rocks were slippery and the snow concealed crevices and holes, so that they were obliged to proceed cautiously. But at length they reached the bottom and made their way across to the mouth of the cave.
Frank produced his flashlight as he prepared to enter.
"Stick close behind," he advised his brother. "We don't know what we're liable to run into here."
The snow flung itself upon them and the wind shrieked with renewed fury as they left the unsheltered pit and entered the half darkness of the cave mouth. It was as though they were entering a new world. They had become so accustomed to the roaring of the gale and the sweep of the storm that the interior of the passage seemed strangely peaceful and still.
The flashlight sliced a brilliant gleam of light from the blackness ahead.
Step by step they advanced across the hard rock. The dampness and cold became more pronounced. As they went on the passage widened and in a few minutes they found themselves in a huge chamber in the earth, a chamber that extended far on into darkness, and they could not see the opposite walls.
A curious rustling sound attracted their attention as soon as they entered the place, and Frank stood still.
"What was that?"
They remained motionless and silent. Away off in the darkness of this subterranean chamber they could hear a scuffling and rustling, and sounds that the boys judged were caused by pattering feet. Frank directed the beam of the flashlight toward them, but the light fell short and they could see nothing.