Old Tunnel and Giant's Chapel, two fine cave-rooms, were next explored.
On entering the latter, Bob favored us with the rehearsal of an old
story from the Arabian Nights, which--unfortunately, not one which will
bear repetition--he wished us to believe actually happened in this very
locality.

I may here confess that, when we came to 'the dark hole in the ground,'
I felt some slight reluctance to trust myself therein. Bob, observing
this, immediately drew from his lively imagination such an astonishing
increase of the perils of the way, looking complacently at me all the
while, that my alarm, strange to say, took flight at once, and I pushed
onward defiantly. The journey is, however, one that might justly inspire
timidity. Above our heads, and on each side, frowned immense rocks,
threatening at every instant to fall upon us; while the dash and babble
of a stream whose course we followed, increasing in volume as we
progressed, came to our ears like the 'sound of many waters.' We crossed
this stream a hundred times, at least, in our journey. Sometimes it
murmured and fretted in a chasm far below us; again, it spread itself
out in our very path, or danced merrily at our side, until it seemed to
plunge into some distant abyss with the roar of a cataract.

We emerged from the windings of our tortuous path into Harlem Tunnel, a
room six hundred feet in length. In its sides were frequent openings,
leading into hitherto unexplored parts of the cave; but we did not
venture to enter many of these. Never have I seen such rocks as we here
encountered; at one time piled up on one another, ready to totter and
fall at a touch; at another, jutting out in immense boulders, sixty feet
above our heads, while, in the openings they left, we gazed upward into
darkness that seemed immeasurable.