Listen to me! Five miles west of New Aberfoyle, under the solid rock which supports Ben Lomond, there exists a natural shaft which descends perpendicularly into the vein beneath.

A week ago I went to ascertain the depth of this shaft.

While sounding it, and bending over the opening as my plumb-line went down, it seemed to me that the air within was agitated, as though beaten by huge wings." "Some bird must have got lost among the lower galleries," replied Jack.
"But that is not all, Jack.

This very morning I went back to the place, and, listening attentively, I thought I could detect a sound like a sort of groaning." "Groaning!" cried Jack, "that must be nonsense; it was a current of air--unless indeed some ghost--" "I shall know to-morrow what it was," said Harry.
"To-morrow ?" answered Jack, looking at his friend.
"Yes; to-morrow I am going down into that abyss." "Harry! that will be a tempting of Providence." "No, Jack, Providence will aid me in the attempt.

Tomorrow, you and some of our comrades will go with me to that shaft.