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.  
Tom was the first to come to a realization of what was needed to be done.
 
"We must help them!" he exclaimed, and it was characteristic of him that he harbored no enmity.
 
"How?" asked Ned.
 
"We must get a force of Indians and dig them out," was the prompt answer.
 
At Tom's vigorous words Professor Bumper's forces were energized into action, and he stated: "Fortunately we have plenty of excavating tools. We may be in time to save them. Come on! the storm seems to have passed as suddenly as it came up, and the earthquake, which, after all did not cover a wide area, seems to be over. We must start the work of rescue at once. We must go back to camp and get all the help we can muster."
 
The storm, indeed, seemed to be over, but it was no easy matter to get back over the soggy, rain-soaked ground to the trail they had left to take shelter in the forest. Fortunately the earthquake had not involved that portion where they had left their mules, but most of the frightened animals had broken loose, and it was some little time before they could all be caught.
 
"It is no use to try to get back to camp tonight," said Tom, when the last of the pack and saddle animals had been corralled. "It is getting late and there is no telling the condition of the trail. We must stay here until morning."
 
"But what about them?" and Mr. Damon nodded in the direction of the entombed ones.
 
"We can help them best by waiting until the beginning of a new day," said the professor. "We shall need a large force, and we could not bring it up to-night. Besides, Tom is right, and if we tried to go along the trail after dark, torn and disturbed as it is bound to be by the rain, we might get into difficulties ourselves. No, we must camp here until morning and then go for help."
 
They all decided finally this was best. The professor, too, pointed out that their rivals were in a large and roomy cave, not likely to suffer from lack of air nor food or water, since they must have supplies with them.
 
"The only danger is that the cave has been crushed in," added Tom; "but in that event we would be of no service to them anyhow."
 
The night seemed very long, and it was a most uncomfortable one, because of the shock and exertions through which the party had passed. Added to this was the physical discomfort caused by the storm.
 
But in time there was the light in the east that meant morning was at hand, and with it came action. A hasty breakfast, cups of steaming coffee forming a most welcome part, put them all in better condition, and once more they were on their way, heading back to the main camp where they had left their force of Indians.
 
"My!" exclaimed Tom, as they made their way slowly along, "it surely was some storm! Look at those big trees uprooted over there. They're almost as big as the giant redwoods of California, and yet they were bowled over as if they were tenpins."
 
"I wonder if the wind did it or the earthquake," ventured Mr. Damon.
 
"No wind could do that," declared Ned. "It must have been the landslide caused by the earthquake."
 
"The wind could do it if the ground was made soft by the rain; and that was probably what did it," suggested Tom.
 
"There is no harm in settling the point," commented Professor Bumper. "It is not far off our trail, and will take only a few minutes to go over to the trees. I should like to get some photographs to accompany an article that perhaps I shall write on the effects of sudden and severe tropical storms. We will go to look at the overturned trees and then we'll hurry on to camp to get the rescue party."
 
The uprooted trees lay on one side of the mountain trail, perhaps a mile from the mouth of the cave which had been covered over, entombing the Beecher party. Leaving the mules in charge of one of the Indians, Professor Bumper and his friends, accompanied by Goosal, approached the fallen trees. As they neared them they saw that in falling the trees had lifted with their roots a large mass of earth and imbedded rocks that had clung to the twisted and gnarled fibers. This mass was as large as a house.
 
"Look at the hole left when the roots pulled out!" cried Ned. "Why, it's like the crater of a small volcano!" he added. And, as they stood on the edge of it looking curiously at the hole made, the others agreed with Tom's chum.
 
Professor Bumper was looking about, trying to ascertain if there were any evidences of the earthquake in the vicinity, when Tom, who had cautiously gone a little way down into the excavation caused by the fallen trees, uttered a cry of surprise.
 
"Look!" he shouted. "Isn't that some sort of tunnel or underground passage?" and he pointed to a square opening, perhaps seven feet high and nearly as broad, which extended, no one knew where, downward and onward from the side of the hole made by the uprooting of the trees.
 
"It's an underground passage all right," said Professor Bumper eagerly; "and not a natural one, either. That was fashioned by the hand of man, if I am any judge. It seems to go right under the mountain, too. Friends, we must explore this! It may be of the utmost importance! Come, we have our electric torches, and we shall need them, for it's very dark............