“You are the youths who guide airships, I believe?”

This interrogation straight at the boys.

“That is our business,” modestly advanced Billy.

“You know also of their construction?”

“Yes, sir,” replied the Bangor boy, “we are factory trained.”

Then followed a series of questions relating to the heavier-than-air machines, the rapid improvement thereof, the various types in use, the duration of flight, carrying capacity, and so forth.

Warming to a subject so near to their hearts and so familiar by constant contact and continuous practice, the boys alternated in detailing what experience had taught them about modern aeronautics. They forgot to feel like a cat in a strange garret, as at first entrance into the palace. They also forgot mention that they had, not so long since, flown over Constantinople in a Russian airship that left a stream of fire behind it.

The man on the divan, the only one seated in the room, during the practical exposition of the past, present and future of air mastery, had listened attentively for some twenty minutes or more, when he indicated by a slight movement of the hand that the statements already made would suffice.

The boys backed out through the doorway, held to that movement by a significant pressure on their elbows from behind.

Once outside the palace, and putting two and two together, the young aviators might have guessed that they had not been very far away from the first caliph of the Moslem world—the sultan himself.