“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 diamonds?” cried Mr. Damon, as he raced along behind Tom.  “Now’s our chance.  Those fellows have all gone!” The odd man made a grab for something as he ran.

“It’s as much as our lives are worth,” declared the young inventor.  “We dare not stop!  Come on!”

“I’d like to investigate some of the machinery,” spoke Mr. Jenks, “but I wouldn’t stop, even for that.”

“The storm is too dangerous,” called Bill Renshaw.  “I can show you a shorter way out than the one those fellows have taken.  Follow me.”

“No way can be too short,” said Mr. Parker, solemnly.  “This mountain will go to pieces shortly, I think!”