The day of the big race in which the various air-craft had been entered dawned fair and cloudless. There was not a breath of wind and the conditions seemed propitious for making ideal flights.

The big crowds that early thronged the grounds thought so too. They strolled about, poking their heads into various sheds and making conditions almost unbearable for the various flying-men who were busily preparing their machines within.

A band had been engaged and was blaring away at popular tunes. All the aerodromes were draped with flags, and bunting of all kinds made the grounds gay indeed.

But the gayety did not extend inside the boys' aerodrome where, in fact, dismay reigned.

To explain its cause we must go back a little and recount some happenings of the preceding night.

While the boys and Le Blanc had been sound asleep, the figure of Sanborn had upraised itself from his cot and quietly sneaked over to the aeroplane. Softly he worked with a wrench and screw-driver for some time, and then with an exclamation of:

"That will fix you," he had softly tiptoed out of the tent carrying the detached main guiding lever of the ship. He rapidly traversed the deserted aviation grounds and flung the important part of the air-craft's mechanism into a clump of bushes. Thus did Sanborn carry out his promise to Malvoise and Luther Barr to cripple the Golden Eagle.

"There, that's done," he said, with an evil sneer, "and now I'll make myself scarce. I came too near to being caught by that whiskered old Apache, Bluewater Bill, the other night, to make it healthy for me round here when it is discovered that the lever is gone. However, I managed to overhear all the details of the treasure galleon and if old man Barr doesn't make the knowledge worth my while he's not so greedy after gold as I thought he was."

Thus musing, Sanford walked rapidly off in the direction of the village.

When the boys awoke on the eventful day, naturally their first thoughts were of the machine in which they hoped so ardently to win the aviation trophy. Their dismay may be better imagined than put into words when they discovered their loss.

"It puts us out of the race," was Harry's despairing cry.

"We can never replace it by two o'clock, the time set for the start,"

was Frank's despairing exclamation.

Suddenly they realized that Sanborn also was missing. Like a flash Frank realized that it must have been their mechanic who had done the damage. It would have been impossible for any one to enter the shed from the outside without leaving traces, as the lock was on the interior of the door.

Le Blanc raged round the shed like a wild man. It would have fared ill with Sanborn had he fallen into the hands of the Frenchman just then.

Le Blanc regarded the Golden Eagle like his own child and his rage would have been comic from the antics it made him perform if the situation had not been so serious.

What was to be done?

Frank tried device after device in his anxiety to provide a subst.i.tute lever, but they all proved too frail. It was impossible to get a duplicate at such short notice, as the levers were especially made for the Golden Eagle.

"Well, boys, it looks as if we will have to disqualify," finally p.r.o.nounced Frank, after his fifth endeavor at a subst.i.tute lever had broken off short when a strain was placed on it.

"I wish I could get hold of that fellow for just five minutes,"

groaned Harry.

"I was foolish not to discharge him when I made up my mind to do so,"

rejoined Frank. "I felt all along that the fellow was a scoundrel."

Bluewater Bill had entered the shed while the boys were discussing the situation and Le Blanc was tearing his hair. He was soon made acquainted with what had happened.

"Say," he said finally after due consideration, "that was a pretty heavy lever, wasn't it, boys?"

"Yes," was the reply.

"Then he didn't carry it very fur. This fellow Sandboy, I mean."

"I don't suppose so," rejoined Frank.

"In that case he must have hidden it somewhere."

"That's true, but that doesn't put us any nearer to finding it."

"Have you tried?"

"No."

"Well, then, here's what you do. Announce your loss on the grounds by posting a notice and offering a reward. Maybe someone will show up who has found it."

"That's a pretty slim chance," despairingly said Frank.

"Worth trying. I had a pretty slim chance when I was in that launch.

It's slim chances that win out lots of times."

"Well, perhaps, as you say, it is worth trying. Anyhow I'll write out a notice and post it on the outside of the shed."

Frank rapidly wrote out a description of the missing aeroplane lever and soon it was tacked up on the door of the shed. An eager crowd surrounded it at once and soon a score of men and boys were searching over the grounds in the hope of being able to claim the reward.

As the time wore on and there seemed to be no chance of their contesting in the race, the boys grew more and more angry at the thought of Sanborn's treachery.

"We ought to have him locked up if we can get hold of him," was Harry's indignant exclamation.

"That's just the trouble, that little 'if,'" put in Billy Barnes.

"I'll bet he's a long way off by this time. What motive can he have had in removing the lever?"

"Somebody must have put him up to the job, that's certain to my mind,"

said Frank.

"I think so, too," agreed Harry, "I have it," he cried suddenly. "I'll bet that fellow Malvoise is in this some way. He'd do anything to see us lose."

"I wish we could prove it on him," sighed Frank.

At this point a gray head stuck itself into the shed and the boys, as they recognized its possessor, shouted:

"Come in, Mr. Joyce."

A rapidly healing scar was all that remained of the injury that had sent the old man to the hospital. He had found work on the grounds and was fast recovering his health.

"Well, I suppose you boys are going to win the cup," he said, smilingly, as he came in. "I had a letter from my daughter to-day in which she asked to be remembered to you and to convey to you her best wishes for your success."

"Thank you," politely answered Frank, "but I am afraid we are out of the race."

He hastily explained the loss of the lever and the old man shook his head sympathizingly. He examined the aeroplane carefully but was unable to suggest a subst.i.tute for the missing lever.

"If you had been able to race, I had some advice for you," he said.

"As I told you when you visited me at the hospital, I am the inventor of the Buzzard and the plans and patents were wrongfully obtained from me by a trick. I know the Buzzard's strong points but I also know her weak ones. When going at full speed she cannot steer round into the wind which is, I hear, one of your aeroplane's good features. Now, if you had gone into the race to-day, with the direction in which the wind is blowing, you could have outgeneraled Malvoise by forcing him to make such a maneuver. I would give anything to see the man who robbed me of my designs robbed, in his turn, of the cup."