railroad wreck?"

"Looks like--" began Mark, when he was interrupted by a voice calling:

"Hurry up, Perfessor! De boys has awakened from de unconsciousability!"

And, to the astonishment of Jack and Mark, the old man and his negro
helper hurried from the inner room and stood in front of the bed.




CHAPTER IV

THE AIRSHIP


"Do you feel better?" asked the professor, anxiously, as he came forward
and felt of the boys' pulses.

"A great deal," answered Jack. "But what has happened? Where are we?
What are all these wheels for?"

"Slowly, slowly," said the old man with a pleasant laugh. "One question
at a time. For the first: what happened was a railroad wreck."

"I remember now," said Jack, slowly. "We tried to stop the cars."

"And you didn't succeed very well," went on the old man. "However, the
sand bank did it for you, and stopped you two at the same time. As for