indows were not screened, because
I could see the moonlight streaming through the far side. Yet, surely,
the hut must be their objective, I thought. Where else could they be
going to? Fascinated, I crawled on my hands and knees till I could
touch the walls of the smoking-room by putting out my arm. I heard a
great commotion coming, it seemed, from the very ground beneath my
feet.

I laid my ear to the ground and listened. The noise grew louder, and
the voices seemed to be shouting against a more powerful sound--the
waterfall, possibly. I thought perhaps the floor of the hut would give
me more opportunity to locate the source of the disturbance. I threw
caution to the winds and slipped through the wide windows into the
room. I moved as carefully as I could, however, once my feet found the
floor, for if there should be anyone below they would probably hear me
up above. I turned back the carpet in order to hear more distinctly,
and as I did so I noticed a rectangular shaft of light which trickled
through the floor. There was a trap-door. I knelt down and lifted it
cautiously by a leather tab which was attached to one side of it and
peered through. I can never understand how it was I did not drop that
hatch again with a self-confessing crash when I realised the
extraordinary nature of the sight that greeted my eyes. There was I in
the smoking-hut of a peaceful American citizen, where only a few hours
before I had spent a pleasant hour in friendly conversation, and now I
was lying on the edge of the entrance to a great cavern.

Below me there was a confused mass of machinery and men. Some were
working on scaffolding, others were many feet below. The nearest of
them was so close to me that I could have leaned down and laid my hand
on his head. I tried to make out what they were doing, but except that
they were dismantling the machinery, whatever it might be, I could
make nothing of it. I watched them breathlessly, trembling lest at any
moment one of them should look up and detect my presence.

The place was lighted by electricity, though there were not enough
lamps to illuminate the cavern very brightly, and as my eyes got
accustomed to the lights and shadows I was able to make out the cause
of this.

Evidently there was a turbine engine below, driven by the water from
the falls, which supplied the necessary power. After a moment or two
it dawned on me how the cavern came to be there; it was, or had been,
the course of a