lighter
than the dark cave.

"I should say it was a storm!" cried Tom Swift. "See, it is striking
every minute, and all around us!"

In fact, lightning bolts were falling on every side of the adventurers.
Every time the balls of fire struck, they burst open great stones,
or seared a livid scar on the face of some cliff. As for Tom and the
others, they stood on a dry dirt hill, in which, fortunately, there was
no iron ore. To this fact they undoubtedly owed their lives, though
had there been rain, to moisten the ground and make the earth a good
conductor of electricity, they probably would have been badly shocked.
But the electrical outburst was not accompanied by rain.

Tom looked up. He saw a compact mass of cloud moving toward the summit
of the mountain on the slope of which they stood. From this cloud there
played shafts of reddish-green fire.

"Look!" called the young inventor to Mr. Parker. The instant the latter
saw the cloud, he cried:

"We must get away from here by all means! That is the center of the
storm. As soon as it gets over the mountain, where that lightning rod
is, all the electrical fluid will be discharged in one bolt at the
mountain, and it will be destroyed! We must run, but keep on the dirt
places! Run for your lives!"

They needed no second warning. Turning, they fled down the steep side of
the mountain, slipping and stumbling, but taking care not to step on any
iron ore. Behind them flashed the lightning bolts.

Suddenly there was a most awful crash. It seemed as if the end of the
world had come, and the ear drums of Tom and his companion almost burst
with the fearful report. The concussion knocked them down, and they lay
stunned for a moment.

Following the terrible report there was a low, rumbling sound. Hardly
knowing whether he was dead or alive, Tom opened his eyes and looked
about him. What he saw caused him to cry out in terror.

The whole mountain seemed bathed in fire. Great blue, red and green
flashes played around it. Then the towering cliff seemed to melt and
crumble up, and the great peak, the top of it containing the diamond
makers' cave, from which they had fled but a few minutes before, the
entire summit was toppled over into the valley on the other side, and in
the direction opposite to that where the adventurers stood.

Then came a profound silence, and the lightning ceased. The storm was
over, and only the rattle of stones and boulders, as they came to rest
in th