“Yes, I see now,” said Vane. “I shall not forget that.”

Their visitor laughed.

“Then you will be a very exceptional fellow, Vane Lee. But, there, I hope you will not forget. Humph!” he continued, looking round, “You have a capital lot of material here: machinery and toys. No, I will not call them toys, because these playthings are often the parents of very useful machines. What’s that—balloon?”

“An attempt at one,” replied Vane.

“Oh, then, you have been trying to solve the flying problem.”

“Yes,” cried Vane excitedly; “have you?”

“Yes, I have had my season of thought over it, my lad; and I cannot help thinking that it will some day be mastered or discovered by accident.”

Vane’s lips parted, and he rested his elbows on the workbench, placed his chin in his hands, and gazed excitedly in his companion’s face.

“And how do you think it will be done?”

“Ah, that’s a difficult question to answer, boy. There is the problem to solve. All I say is, that if we have mastered the water and can contrive a machine that will swim like a fish—”