stones?"

Panton held up his light as they turned round a bend of the rocky side
on their left, and pointed to the coloration of the rocks and the half
loose fragments, which still clung in their place, while other bits had
fallen down.

"There," he said, "those are as bright as anything in Aladdin's cave."

"And as valuable?"

"That depends on the value people put upon them. From a geological
point of view, and the study of the formation of crystals by volcanic
heat they are priceless."

"But how much farther are you going?" said Drew.

"As far as the candles will let us," said Panton. "Hallo!"

His voice was echoed from a distance as loudly as he had spoken, and the
"Hallo!" went reverberating away in the gloom.

"We must be in a big opening," he said, and again his voice echoed, and
then went on repeating itself and dying away.

Panton thrust a hand into his pocket and brought out a roll of magnesium
wire, gave Wriggs his gun to hold, and then lit one end which flashed
out into a brilliant whitish light, surrounded by dense fumes of smoke,
and illuminating the vast hall in which they stood, for here the tiny
river ran in a wide-spreading plain of smooth lava which must at one
time have been a lake of molten stone, now hard, cold, and dry, save
where the water glided on like so much steel in motion.

As the magnesium wire burned out, the candles which were getting short
looked like so many yellowish sparks in the midst of utter blackness,
and it was some minutes before even Panton showed any disposition to
stir. But at last the eyes of all began to lose the dazzled sensation
caused by the white glare, and Panton proposed that they should go on.

"What for?" said Drew. "There are specimens enough for you here without
going farther, and the place seems to be all alike."

"Oh, no: all variety. You are not afraid, are you?"

"Well, I don't know so much about that," replied Drew, quietly. "I have
no wish to seem cowardly, but it is not very pleasant moleing along here
in the darkness. I keep expecting to step down into some bottomless
pit."

"If we come across one, you'll see me go down first. But hark! What's
that?"

"I don't hear anything," said Drew.

"Don't you, Lane?" cried Panton.

"Well, yes, I fancy I can hear a dull sound as of falling water."

"There must be a cascade, then, farther in. Come on, I must see that.
I've got some more wire."

Holding his candle well on high, he strod