For an instant Tom and his friends paused at the entrance to the wonderful cavern, and looked at the raging storm. It seemed madness to venture out into it, yet they had been driven from the cave by those who had every right of discovery to say who, and who should not, partake of its hospitality.  
"We can't go out into that blow!" cried Ned. "It's enough to loosen the very mountains!"
 
"Let's stay here and defy them!" murmured Tom. "If the—if what we seek—is here we have as good a right to it as they have."
 
"We must go out," said Professor Bumper simply. "I recognize the right of my rival to dispossess us."
 
"He may have the right, but it isn't human," said Mr. Damon. "Bless my overshoes! If Beecher himself were here he wouldn't have the heart to send us out in this storm."
 
"I would not give him the satisfaction of appealing to him," remarked Professor Bumper. "Come, we will go out. We have our ponchos, and we are not fair-weather explorers. If we can't get to the lost city one way we will another. Come my friends."
 
And despite the downpour, the deafening thunder and the lightning that seemed ready to sear one's eyes, he walked out of the cave entrance, followed by Tom and the others.
 
"Come on!" cried Tom, in a voice he tried to render confident, as they went out into the terrible storm. "We'll beat 'em yet!"
 
The rain fell harder than ever. Small torrents were now rushing down the trail, and it was only a question of a few minutes before the place where they stood would be a raging river, so quickly does the rain collect in the mountains and speed toward the valleys.
 
"We must take to the forest!" cried Tom. "There'll be some shelter there, and I don't like the way the geography of this place is behaving. There may be a landslide at any moment."
 
As he spoke he motioned upward through the mist of the rain to the sloping side of the mountain towering above them. Loose stones were beginning to roll down, accompanied by patches of earth loosened by the water. Some of the patches carried with them bunches of grass and small bushes.
 
"Yes, it will be best to move into the jungle," said the professor. "Goosal, you had better take the lead."
 
It was wonderful to see how well the aged Indian bore up in spite of his years, and walked on ahead. They had left their mules tethered some distance back, in a sheltering clump of trees, and they hoped the animals would be safe.
 
The guide found a place where they could leave the trail, though going down a dangerous slope, and take to the forest. As carefully as possible they descended this, the rain continuing............