"Then I will have time to go out and make some observations, will I not?" asked Mr. Parker. "I think this cave is a very old one, and I may be able to find some evidences in it that the sea of ice is slowly working its way down from the polar regions."
"I hope you don't," whispered Ned to Tom, who shook his head dubiously as the gloomy scientist left the cave.
The weather was very cold, but, in the cavern it was hardly noticed. The adventurers were warmly dressed, and when they did get chilly from working over the airship, they had but to go into the well-heated and cozy cabin to warm themselves.
It was on the third day of their habitation in the cave, and work on putting the patches on the gas-bag was almost finished. Mr. Parker had gone out to make further observations, his previous ones not having satisfied him. Tom was on an improvised platform, putting a patch on top of the bag, when he heard a sudden yell, and some one dashed into the cavern.
"They're coming! They're coming!" cried a voice, and Tom, looking down, saw Mr. Parker, apparently in a state of great fear.
"What's coming?" demanded the young inventor, "the icebergs?"
