prized possession in good shape, when Andy uttered a sudden exclamation that told of both surprise and disgust.

"What's the matter now?" asked Frank, who had been talking with Felix, and was hence not so wide awake as his chum.

"Just take a look over there, and see what's stopped on the road," remarked Andy.

"Seems to be a car, and I can see two heads raised above the top rail of the fence, as if the people in it had sighted our aeroplane sprawled out there in the field, and were wondering what sort of giant insect it could be," Frank went on.

"Look closer, Frank," the other boy went on to say, while his disgust deepened; "and you'll discover that the two fellows in that car happen to be Percy Carberry and his shadow, Sandy Hollingshead. Did you ever hear of such tough luck? Of all the boys in Bloomsbury they are the last we'd want to know that we'd left our new hydroplane out, unguarded, all night, in an open field. Guess I won't go home tonight, Frank. I'd rather camp out here with Felix. You let my folks know, and turn up in the morning with a new piece for that plane. That's settled and you can't change it."

CHAPTER II

ON GUARD

"Perhaps I'd better stay with you, Andy," the other Bird boy remarked.

"No need of it," replied Andy, resolutely. "Besides, you know one of us ought to get busy in the shop, making that new piece we really need so that our job won't have to be done over again. You go, Frank. Perhaps Mr. Quackenboss would let you have a horse; or if you cared to, you give Percy a hail, and he'd take you back to town, I reckon. Goodness knows he owes you a heap, after the way you saved his life the time he was wrecked up on Old Thundertop."

What Andy referred to was a very exciting event which had occurred not so very long before, and which was fully treated in the volume preceding this.

Frank shook his head in the negative.

"I never want to ask any favor of Percy Carberry," he said, resolutely. "And if Mr. Quackenboss can't let me have a horse to ride, why, the walking is good, and I can make it in less than an hour. So don't mention that again please, Andy."

"It's too late now, anyhow," remarked the other, drily, "because there they go, spinning down the road like wildfire. Percy never does anything except in a whirl. He's as bold as they make them, and the only wonder to me is that he hasn't met with a terrible accident before now. But somehow he seems to escape, even when he smashes his flier to kindling wood. His luck beats the Dutch; he believes in it himself, you know."

"But some day it's going to fail, and then he'll never what happened to him," declared Frank. "Of all the professions in the world, that of a flying machine man is the one where a cool head and quick judgment are the things most needed. And the fellow who takes great chances, depending on his good luck, is bound to meet up with trouble. But if you are bound to stay, Andy, I'd better be off."

Upon entering the barn they found that the farmer had finished his task, and was pitching some new sweet hay to the cows.

Frank suggested hiring a horse from him, but Mr. Quackenboss scoffed at the idea.

"You're as welcome to the use of my saddle hoss as the sunlight is after a spell of rain," he said, heartily. "Here, Felix, get Bob out; and you'll find my new saddle hanging on that peg back of the harness room door. And as for Andy, who's going to stay over with us, we'll find a chair for him at the supper table, and only hope hell tell us some of the many things you two have gone through with, both around this region, and away down in South America, that time you found the lost Professor."

Inside of five minutes Frank was in the saddle, and waving his hand to his chum and cousin, of whom he was more fond than if Andy had been his own brother.

"He'd be back tonight with the part we need, and we could make home in the moonlight," said Andy, as, with the farmer he headed for the house; "only both of us have promised our folks not to travel at night-time when it can be helped. Even if the moon is bright there's always a risk about landing, because it's a tricky light at the best, and even a little mistake may wreck things. And so Frank will work in the shop tonight, and be along in the morning."

Once in the farmhouse Andy was given a chance to wash up, and then met the housewife, as well as little Billie, the small chap whose life good Doctor Bird had saved. Mrs. Quackenboss proved to be a very warm-hearted woman, and any one who answered to the name of Bird could have the very best that the place afforded. There was never a night that she did not call down the blessings of heaven upon the physician who had been instrumental in preventing her darling Billie from being taken away.

The table was fairly groaning under the weight of good things to eat, for when company comes the average farmer's wife never knows when to stop bringing out the most appetizing things to eat ever seen.

"Perhaps I'm the luckiest fellow going to be able to stay over-night with you, Mrs. Quackenboss," laughed Andy, as he sat down to the generous spread.

"Well, you know, we never like anybody to get up from our table hungry," she explained.

"The chances are that I won't be able to get up at all, for if I try to taste half I see here, I'll be foundered, as sure as anything," Andy went on to say.

The farmer was not going to allow much time to pass talking about common every-day topics. Those might do all very well when he had ordinary guests; but when fortune sent him one of the now famous Bird boys for company, he wanted to listen to some thrilling accounts of adventures that had come the way of the young and daring aviators, from the time they built their first aeroplane, after purchasing most of the parts, and found that they had an immediate rival in Percy Carberry.

Andy was willing to oblige, and kept those at the table, including the farm hand, Felix Boggs, thrilled with his stories. But the farmer could not help but notice how modest the boy was, giving most of the credit to his cousin Frank, when everybody about Bloomsbury knew that Andy deserved just as much credit, if not more, than the other Bird Boy.

After supper Andy and Felix prepared to go out to where the hydroplane lay. They meant to take blankets along, and make themselves as comfortable as possible for a night's vigil.

Andy would not have dreamed of doing this only for the fact that he knew Percy and his shadow, Sandy, were aware of the plight of the precious flier. And while Frank was inclined to partly believe that the Carberry boy might let up in his mischief-making ways for awhile at least, after all they had done for him up on Old Thundertop, Andy could not bring himself to trust the other further than he could see him. He believed that the nature of Percy was so "rotten" as he called it, that, given a chance to injure his successful rivals, he would shut his eyes to all sense of gratitude, and just lie awake nights trying to get the better of them, by fair means or foul.

Andy also knew that the other was particularly chagrined, because he did not know what manner of a new flier the Bird boys had in hand now. He had resorted to various expedients in order to find out, but all without success.

On this account, if no other, then, Andy believed that the others would be apt to come out here during the night to examine the hydroplane with the aluminum pontoons under its body for floating on the water; and perhaps to slily injure it in such a fashion that it would break down when next Frank and Andy mounted into the air.

It happened that they had alighted close to one corner of the big field, though in plain view from the pike. Andy had noted a clump of trees conveniently near, and already his mind was made up that he and Felix would camp there, to pass the night in alternately keeping watch and ward over the precious