“Heigho!” shouted Frank. “What are you doing down there, captain?”

“That’s what I’ve been asking myself, mate,” replied the mariner, “give me a lift before I fall.”

“All right!”

Frank lowered the same rope with which he had hauled Barney up.

In a few moments the captain was safe on the air-ship’s deck.

His story was a remarkable one.

“How did I get there?” he exclaimed. “I couldn’t tell ye. I only know that I went to sleep in the little camp with Barney. When I woke up I was hanging on out there.”

“Somnambulism!” suggested Frank.

“I reckon so; I am subject to that. Sure to walk in my sleep if I go to bed with too much on my mind.”

“Whew!” exclaimed Frank. “You are hardly a safe man aboard an air-ship then.”