and Tom, after going down quite a way, left off work, and walked over to one of the big ice caves.
"What's up?" asked Ned, resting from his labors.
"I was thinking whether it would be safe to put the Red Cloud in this ice cave for a shelter," replied Tom. "There may come up a hail storm at any time, and damage it. The caves would be just the place for it, only I'm afraid the roof might collapse."
"It looks strong," said Ned. "Let's ask Mr. Parker his opinion."
"Good idea," agreed Tom.
The scientist was soon taking measurements of the thickness of the cave roof, noting its formation, and looking at the frozen floor.
"I see no reason why this cave should collapse," he finally announced. "The only danger is the movement of the whole valley of ice, and that is too gradual to cause any immediate harm. Yes, I think the airship could be housed in the ice cave."
"Then I'll run her in, and she'll be safer," decided Tom. "I guess we three can do it, Ned, and leave Mr. Damon and Abe to keep on digging for gold." The airship was so bouyant that it could easily be moved about on the bicycle wheels on which it rested, and soon, after the
