now about to become certainty.

But the way was rougher now, and at one place they had to make a long
detour. But they made no complaint. As long as no impassable barrier
of rock loomed up before them they could feel that they were getting
nearer and nearer to freedom and life.

But before long both became conscious of a steadily-growing heat in the
air of the cave. The perspiration flowed from them in streams. At
first they were inclined to attribute this to their strenuous exertions
and the mental strain under which they were laboring.

"Strange it should be so frightfully hot," remarked Drew, as he stopped
for a moment to wipe his brow.

"It's no wonder," responded Ruth. "It's hot enough on this island even
when you're in the outer air, and it would naturally be worse still in
this confined place."

"But we didn't feel that way ten minutes ago," objected Drew.

"We've done a good deal of walking since then," said Ruth, though
rather doubtfully. "But let's get along, Allen. I'm just crazy to get
to the outlet."

They were about to resume their journey, when a great flame of fire
leaped to the very roof of the cave about a hundred yards in front of
them.

They stopped abruptly, and in the smoky light of the torch both of
their faces were white as chalk, as they faced each other with a
question in their eyes.

"Fire!" gasped the man.

"Yes," assented Ruth quietly but bitterly. "What we thought was
daylight is nothing other than fire."

"Shall we keep on?" debated Allen.

"We're so close that we might as well," advised Ruth. "Perhaps we may
be able to get around it somehow."

They went forward, though with excessive care, and a moment later stood
on the brink of the most awe-inspiring spectacle they had ever
witnessed.

In a deep pit perhaps six hundred feet in circumference was a lake of
liquid fire! The molten lava twisted and writhed as though a thousand
serpents were coiling and uncoiling. A vapor rose from the fiery mass
that glowed with a hideous radiance in all the colors of the spectrum.

At intervals, huge geysers of living flame spurted up from the surface
to a height of many feet and fell back in a glistening of molten gold
and coruscating diamonds.

It was a scene that if it could have been viewed with safety would have
drawn tourists in thousands from every corner of the globe.

But to the two spectators the thought that they were looking on one of
the marvels of the world