him he perceived what he was sure were regular joints of masonry, but on
the sides of the cave he saw nothing of the sort. For some minutes he
stood and reflected, his brain in a whirl. Presently he exclaimed:

"Yes, this cave is man's work! I am sure of it. It is not natural. I
wondered how there could be such a cave on the top of a hill. It was
originally a gorge, and they have roofed it over, and the bottom of the
basin has been cut out to make it deeper. It was made so that it could be
filled up with water, and roofed over so that nobody should know there
was any water here, unless they came on it by means of the passage from
our caves. That passage must have been blocked up. As for the great
opening in the side of the cave, the rocks have fallen in there--that is
easy enough to see. Yes, men made this cave and filled it with water, and
if the water were high enough to cover the handle of that machine, as it
was when I struck it, it must also have been high enough to cover up this
stone mound. The lake was intended to cover and hide that mound. And
then, to make the hiding of it doubly sure, the men who built all this
totally covered up the lake so that nobody would know it was here. And
then they built that valve apparatus, which was also submerged, so that
they could let out the water when they wanted to get at this stone
thing, whatever it is. What a scheme to hide anything! Even if anybody
discovered the lake, which would not be likely until some part of the
cave fell in, they would not know it was anything but a lake when they
did see it. And as for letting off the water, nobody but the people who
knew about it could possibly do that, unless somebody was fool enough to
take the cold bath I was obliged to take, and even then it would have
been one chance in a hundred that he found the lever, and would know how
to turn it when he did find it. This whole thing is the work of the
ancient South Americans, and I imagine that this stone mound is the tomb
of one of their kings."