“This is better!” exclaimed Ned, shaking his poncho and getting rid of some of the water that had settled on it.

“Bless my overcoat!” cried Mr. Damon.  “We seem to have gotten out of the frying pan into the fire!”

“How?” asked Tom.  “We are partly sheltered here, though had we stayed in the cave in spite of——­”

A deafening crash interrupted him, and following the flash one of the giant trees of the forest was seen to blaze up and then topple over.

“Struck by lightning!” yelled Ned.

“Yes; and it may happen to us!” exclaimed Mr. Damon.  “We were safer from the lightning in the open.  Maybe——­”

Again came an interruption, but this time a different one.  The very ground beneath their feet seemed to be shaking and trembling.

“What is it?” gasped Ned, while Goosal fell on his knees and began fervently to pray.

“It’s an earthquake!” yelled Tom Swift.

As he spoke there came another sound—­the sound of a mass of earth in motion.  It came from the direction of the mountain trail they had just left.  They looked toward it and their horror-stricken eyes saw the whole side of the mountain sliding down.

Slowly at first the earth slid down, but constantly gathering force and speed.  In the face of this new disaster the rain seemed to have ceased and the thunder and lightning to be less severe.  It was as though one force of nature gave way to the other.

“Look!  Look!” gasped Ned.

In silence, which was broken now only by a low and ominous rumble, more menacing than had been the awful fury of the elements, the travelers looked.

Suddenly there was a quicker movement of seemingly one whole section of the mountain.  Great rocks and trees, carried down by the appalling force of the landslide were slipping over the trail, obliterating it as though it had never existed.

“There goes the entrance to the cavern!” cried Ned, and as the others looked to where he pointed they saw the hole in the side of the mountain —­the mouth of the cave that led to the lost city of Kurzon—­completely covered by thousands of tons of earth and stones.

“That’s the end of them!” exclaimed Tom, as the rumble of the earthquake died away.

“Of——­” Ned stopped, his eyes staring.

“Of Professor Beecher’s party.  They’re entombed alive!”

CHAPTER XXIV

THE REVOLVING STONE

Stunned, not alone by the realization of the awfulness of the fate of their rivals, but also by the terrific storm and the effect of the earthquake and the landslide, Tom and his friends remained for a moment gazing toward the mouth of the cavern, now completely out of sight, buried by a mass of broken trees, tangled bushes, rocks and earth.  Somewhere, far beyond that mass, was the Beecher party, held prisoners in the cave that formed the entrance to the buried city.