"What are you so busy over, my lad?" inquired Lieutenant De Frees one morning, stopping in front of the Dreadnought Boys' hangar.
Ned looked up from the sheet of paper over which he had been poring. It was covered with figures and geometrical scrawlings made by a stumpy lead pencil.
The lad was a bit abashed. Herc was busy tuning up his aeroplane, and Ned, by this time, should have been busy on his machine, for it was a clear, calm day, ideal for a flight. But Ned had not yet even donned his aviation togs. Instead, he had been putting in the best part of an hour on his figuring, bending over it with a puckered brow. A moment before the officer had poked his head in at the door, the boy had started up with a glad cry:
"Herc, I've got it!"
"Catching?" inquired Herc, as he tightened the turnbuckle of a slack stay-wire.
"I hope so," laughed Ned. "I hope it proves catching enough for Uncle Sam to adopt. You see, an aeroplane fitted with pontoons——"
"Oh, choke it off. I've heard it all a hundred times," began Herc, and then, dropping his bantering expression, the freckled lad went on:
"It's a great thing, Ned, not a doubt of it. But are you sure you've got it at last?"
"Certain sure," smiled Ned confidently; "it was to attain cubic capacity, combined with strength and lightness, that bothered me. But I think I've figured it out now so that it will work."