ssure in the floor.

Gradually the light grew brighter, till, as they suddenly rounded a
cliff, a grand sight burst upon their view. They found themselves in a
vast dome-shaped cavern, thousands of yards in diameter and height.
And almost in the centre of the floor, from a red and purple mound of
cooling lava, leapt a white stream of molten matter from the floor to
the dome. And in the black dome, where the lava turned to molten spray,
hung countless stalactites of every color known to the artistic eye. And
from the foot of the fountain ran a tortuous rivulet that lighted the
walls and roof of a narrow chamber that extended for miles down toward
the bowels of the earth.

Branasko was delighted.

"The king does not know of this," he declared, "else he would make it
accessible to his people, and call it one of the wonders of Alpha.
By accidentally sinking into the pit we have discovered it. But," he
concluded, "we must at once try to find some way out other than that by
which we came."

They turned from the beautiful fountain, and, holding to each other's
hands, and aided by the light behind them, they stumbled laboriously
through the semi-darkness. Branasko's ears were very acute. He paused to
listen.

"Hark ye!" he cautioned.

The combined roar of the pit and the fountain of lava had sunk to a low
murmur, but ahead of them they now heard a rushing sound like a distant
tornado.

"Come on," said the Alphian, and he drew his companion after him with an
eagerness the American was slow to understand. The light in the
cavern gradually grew brighter. By a circuitous route they were again
approaching the pit of fire, though it was still hidden from sight.

Finally they reached a point where the wind was blowing stiffly, and
further on a volume of cold spray suddenly dashed upon them and wet them
to the skin. And when their eyes had become accustomed to the rolling
mist, they saw a great lake, and pouring into it from high above was a
mighty waterfall.

"Mercy!" ejaculated the Alphian, in great alarm. "If this is salt water
we are lost. All Alpha will come to an end!"

"What do you mean?" And Johnston wondered if Branasko's trials and
struggle could have turned his brain.

"If it be salt water, then it has broken in from the ocean above Alpha,"
he explained. "The king has often said that not a drop of the ocean has
ever entered the great cavern."

Branasko stooped and wet his hand in a little pool at his feet. "I