At last the work seemed to have been accomplished.  Bud said he could fix the rudder of the model so that when once it was in the air, it would continue to make revolutions for a certain time.  He declared it would actually fly around the field slowly until the measured stock of gasoline had been exhausted, when of course it would drop to the ground as the engine ceased to work.

“You see I expect to manage by means of this cord,” he explained.  “I’ll chase along below, and every once in so often try to upset the thing by giving a savage jerk.  Then you’ll discover whether my device is going to work.  If it does half way decently in this clumsy model, it’ll pay to install it on a real aeroplane and either go up myself or else have an air pilot do it for me.  But say, let me tell you right now that I’m shivering all over as if I had the ague!  ’Cause why?  In half an hour or so I’m going to know whether I’m it, or else a lunkhead that ought to be smothered before his fool notions get him into a peck of trouble.”

“Oh!  I wouldn’t put it that way, Bud,” advised Hugh.  “You mustn’t call yourself hard names, even if this invention fails to work.  They say Edison has lots of rank failures that the public never hears about; only his brilliant successes become known.  Suppose this scheme doesn’t do all that you expect it to, why, perhaps you’ll see where it falls short and be able to remedy the fault.  If you have faith in yourself, it’s going to turn out all right every time.  Try seventy times seven, and never give up as long as life lasts.”

“Nil desperandum!” quoted Ralph; “or, as we Americans have it, ’if at first you don’t succeed, try, try again!’”

“You just bet I will, fellows,” said Bud firmly; “and now let’s make the first trial spin.”

He had elevated the model so that it would start in the air without the necessity of leaving the ground.  This was a minor matter, and only intended to hurry things along.

When the little motor got to work there was an immediate movement of the rough miniature monoplane.

“Hurrah! there she goes!” cried Ralph, really excited when he saw the object of Bud’s recent labors actually moving through space, sustained by the extended pair of planes.

Hugh, too, felt a thrill of delight.  He was very fond of Bud, and anything that promised to repay the other scout for his weeks of arduous labor pleased the leader of the Wolf patrol more than he could express in words.

Bud was about the busiest boy any one had ever known.  To run along and keep, up with that hurrying model, hanging on to the long stout cord, was no easy task.  The rudder had certainly been fixed properly to insure a circuit of the field; but as the ground was very rough in places, Bud had great difficulty in keeping from falling many times.  This was partly on account of the fact that he had to fasten his eyes on the scurrying monoplane model pretty much all the time, and could therefore not pay much attention to where he was going, or see the traps lying in the way of his feet.