t was
moving off; but with a leap Tom was back upon it and drew it ashore by a
piece of line, which he tied to one of the poles after forcing it well
down into the sand.

"That won't get away now, Mas'r Harry," he said.

And then stepping cautiously along over the sand, which gave way and
seemed to shiver beneath our feet, we reached the end of the vault, and
with very little difficulty climbed from cranny to cranny till we gained
the opening--a mere slit between two masses of rock--through which we
had to squeeze ourselves, and then wind up and up between block after
block, that looked as though they had been riven asunder in some
convulsion of nature.

Two or three times we were for going back, so arduous was the ascent;
but determined to see our adventure to the end we pressed on and on,
ever higher, till the noise became almost deafening, a cold dank wind
too made our lights to flutter, and once they threatened to become
extinct. But five minutes after the passage widened and the draught was
not so fierce, while bright veins running through the rock at my side
whispered of some rich metal or other for him who would venture thus far
in its search.

"We're a-coming to it now, Mas'r Harry," said Tom shouting, for the
noise was deafening.

The very next moment we were standing in a vast vault stretching out as
far as our feeble light would show us, while about fifty feet to our
left, in one black, gloomy, unbroken torrent, fell from some great
height above, a cascade of water, black as night, till it reached the
basin below us, which, even with our trembling lights, shone forth in a
silvery, iridescent foam.

We could hardly hear the words we uttered from time to time, but we felt
but little inclination to speak, so awe-inspiring was the scene before
us; and it was not until we had been gazing for some time that we
ventured to climb down lower and lower, to find that the bottom of the
cavern was a basin of restless water, from which it was evident some
portion escaped through a natural conduit to the vault below, while
probably the rest made its way to the vast gulf we had before seen.

Then up and down--now near the great foaming basin, then with arduous
climbing close to the dome that formed the roof--I searched about, well
aided by Tom, who seemed to think that I was looking for something
precious, though he said nothing. At one time we approached so near the
waterfall that we could distinguish, high up, t