y the
electrical storm, with lightning bolts discharging so close, was too
much for the "ghost."

In another instant it looked as if the whole place about where the
diamond seekers stood, was a mass of fire. Great forked tongues of
lightning leaped from the clouds, and seemed to lick the ground. There
was a rattle and bang of thunder, like the firing of a battery of guns.
Tom and the others felt themselves tingling all over, as if they had
hold of an electrical battery, and there was a strong smell of sulphur
in the air.

"We are in the midst of the storm!" cried Mr. Parker. "We are standing
on a mass of iron ore! Any minute may be our last!"

But fate had not intended the adventurers for death by lightning. Almost
as suddenly as it had begun, the discharge of the tongues of fire ceased
in the immediate vicinity of our friends. They stood still--awed--not
knowing what to do.

Then, once more, came a terrific clap! A great mass of fire, like some
red-hot ingot from a foundry, was hurled through the air, straight at
the face of the mountain, and at the spot where the figure in white had
stood but a few minutes before.

Instantly the earth trembled, as it had at Earthquake Island, but it was
not the same. It was over in a few seconds. Then, as the diamond seekers
looked, they saw in the glare of a score of lightning flashes that
followed the one great clap, the whole side of the mountain slip away,
and go crashing into the valley below.

"A landslide!" cried Mr. Parker. "That is the landslide which I
predicted! The lightning bolt has split Phantom Mountain!"

CHAPTER XVI--THE VAST CAVERN

For a time the roiling, slipping, sliding and tumbling of the mass of
earth and stones, down the side of the mountain, effectually drowned
all other sounds. Even the thunder was stilled, and though Tom and his
companions called to one another in terror, their voices could not rise
above that terrific tumult.

Finally, when they found that the direction of the slide was away from
their tent, and that they were not likely to be engulfed, they grew more
calm.

Gradually the noise subsided. The great boulders had rolled to the
bottom of the valley, and now only a mass of earth and stones was
sliding down. Even this stopped in about five minutes, and, as though
satisfied with what it had done, the electrical storm passed. Not a drop
of rain had fallen.

"Bless my shirt studs!" exclaimed Mr. Damon, who was the first to sp