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 the valley below, reached the ears of our friends.

“Phantom Mountain has been destroyed, just as I said it would be,” spoke Mr. Parker, solemnly.  Once more he had prophesied correctly.

For a few minutes the adventurers hardly knew what to say.  They arose awkwardly from the ground where the shock had tossed them.  Then Tom remarked, as calmly as possible: 

“Well, it’s all over.  I guess we may as well get back to our airship.”

“What became of Munson and the others?” asked Mr. Damon.

Mr. Jenks pointed to the trail, far below.  The figures of some men, running madly, could be seen.

“There they go,” he said; “I fancy we have seen the last of them.”  And they had, for some time at least.

There was little use lingering any longer on Phantom Mountain—­indeed little of it was left on which to remain.  Looking back toward the place where the cave had been, Tom and the others started forward again.  The diamond-making machinery had all been destroyed.  So, also, had the finished diamonds stored in the cavern and the large supply which had probably been made by the last terrific crash.  No one would ever have them now.  Tom and Mr. Jenks felt a sense of disappointment, but they were glad to have escaped with their lives.  They sought their former camp, but the tent and all their food was buried under tons of earth and rocks.

Three days later, after rather severe hardships, they were near the place where they had left the Red Cloud.  They had suffered cold and hunger, for they had no food supplies, and, had it not been that Bill Renshaw knew the haunts of some game, of which they managed to snare some, they would have fared badly, for they had left their guns in the cave.