g to throw the switch."

He did so. A moment later the man who had before given warning of the
storm came dashing in. He was very much excited.

"It's awful!" he cried. "The lightning is striking all over! Big rocks
are being split like logs of wood!"

"Well, it can't do any damage in here," said Munson. "We are well
protected. Get on one of the plates," and he motioned to one of the
hard-rubber platforms that was not occupied. The roar and rumble of the
storm outside had given place to short terrific crashes. In their small
cave the adventurers could feel the solid ground shake.

A bluish light began dancing about the electrical wires. There was a
smell of sulphur in the air. Crash after crash resounded outside. A
flash of flame lit up the whole interior of the cave. It came from the
copper switch.

"Something's wrong with the insulation!" cried Munson.

"Don't go near it!" yelled Folwell. "If you value your life, stand
still!"

Hardly had he spoken than inside the cavern there sounded a report like
that of a small cannon. A big ball of fire danced about the middle of
the cave and then leaped on top of the steel box.

"This is a fearful storm," cried Munson.

The adventurers in the cave did not know what to say or do. They were in
deadly peril.

Suddenly there came a crash louder than any that had preceded it. The
whole side of the cave where the switches were was a mass of bluish
flame. Then came a ripping, tearing sound, and a tangle of wires and
copper connections were thrown to the floor. At the same time the steel
box, containing the materials from which diamonds were made, turned
blue, and flames shot from it.

"It's all up with us!" cried Munson. "Run for it, everybody! The wires
are down, and this place will be an electric furnace in another minute!"

He leaped toward the exit from the cave.

"What about those fellows?" asked Folwell, indicating the place where
Tom and the others had been tied.

"They'll have to do the best they can! It's every man for himself, now!"
yelled Munson. There was a wild scramble from the cavern.

"Come on!" cried Tom. "We must escape! It's our only chance!"

He leaped into the big cave, followed by the others. Already long
tongues of electrical fire were shooting out from the walls and roof as
Tom Swift and his companions, evading them as best they could, sought
safety in flight.

CHAPTER XXV--THE MOUNTAIN SHATTERED--CONCLUSION

"Can't we get some of the