“But you made sure it was Percy’s biplane?” asked Frank, interested somewhat, for somehow the other rival flier was always doing such bold stunts that he could not help feeling as though it might pay to keep track of what he was doing, lest their interests clash unexpectedly, in midair perhaps.

“I ought to know the way it glides, and the whole general look; and I’d be willing to take my affidavy that was the Canvas-back, as he calls his biplane.”

“And he was in it, of course, with Sandy too?” Frank went on.

“I could just make out that there were two aboard,” said Andy, “but somehow it seemed to me that Percy had altered his whole way of piloting his airship, or else he was drunk, and hardly knew what he was doing.”

Frank whistled to indicate his surprise and consternation: 

“When it gets as rough as that you can take it from me that Percy’s mother will hear something simply awful about him before long.  He’s bound to go from bad to worse; and everybody knows what the end of such an aviator is going to be.”

“But what under the sun could he be off at daylight this morning for?” Andy went on to remark, as though that thing had been bothering him ever since the moment he lost track of the biplane among the teetering, cawing crows.

Frank shrugged his shoulders as he replied: 

“Did you ever know any reason for half the things Percy does?  He just acts from a sudden impulse.  Remember all that happened when he followed us down there to Columbia in South America, and tried to give us all the trouble he could make up.  And there have been lots of other times too, we can look back at, all of which prove what I am saying that he is often like a ship without a rudder.  Now, perhaps, he’s got the crazy notion in his head that we might prosecute him either for what he tried to do up here to our hydroplane, or on account of breaking into our hangar, and doing a certain amount of damage, if the vandal was Percy Carberry.”

“That sounds a little reasonable, anyhow, Frank.  Queer that I never seem to get hold of these things, and they just float along as easy as anything to you.  But it looks as if we had her all primed up now as steady as a church.  How about it, Frank?”

For answer the other touched several taut wire guys with a peculiar little movement of finger and thumb, and each one responded with a musical note that was the sweetest possible sound in the responsive ear of the young aviators.

“All done, and let’s be off,” he said, presently, after the last test had been applied.

Accordingly they shook hands with Farmer Quackenboss, his good wife, and Felix, in the palm of which latter Andy made sure to leave a greenback that made the boy grin broadly.

Three minutes later Frank sang out the word, and both the farmer and Felix ran along with the machine for a dozen paces or so, when it left them behind, taking on speed, and finally rushing over the ground at a tremendous pace.