CHAPTER XXV HIGH WINGS!

If he never did so again, Sandy lived up to his decision to turn over a new leaf for once.

Usually impulsive, generally quick to adopt any new suspicion, he surprised his chums by catching Larry by the coat and dragging him back to the ground as his foot rested on the wing-step bracing.

“No!” he cried. “No! Larry—Dick—you, Mister! Come on, quick—under these trees yonder!”

They stared at him.

“Don’t you understand?” he urged. “Jeff will fly over his crate to see if it’s all right. He may see us. Come on!”

So sound was his argument that the others hurried with him to the concealment of the nearby grove, after Larry had thoughtfully cut out the ignition so that the propeller would not revolve if its observers flew low enough to distinguish its position.
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Well hidden, they learned how wise Sandy had been.

Coming closer as it dropped lower, the amphibian circled in a tight swing over the fairway several times and finally straightened out, flying toward the wind that came from almost due North on this first cool day after a humid July week, and began to grow smaller to the watchers.

“We’d better get that engine started, now.” Dick left the grove.

“Let’s be careful,” commented Sandy. “They may come back.”

“We can be warming it up and watching!” Larry urged.

“We don’t need to hurry,” Sandy insisted. “I think I know—at last!—what this all means.”

Three voices, that of the caretaker no longer grumpy, urged him to explain. Too earnest to be proud of his deductions, Sandy spoke.

“When the hangar was first haunted, and we found chewing gum that the ghost had put there, as we thought,” he told an interested trio, “none of us could work out any answer to the puzzle.
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“But stop and think of these things,” he continued, urging his two friends to use their own imaginations. “The amphibian was old-looking and didn’t seem to be much good, and the gas gauge was broken, and the chewing gum was quite fresh. That might look as though——”

“Some pilot was getting the ‘phib’ ready to fly and chewed gum as he worked and put the gauge out of order to keep anybody from knowing he had filled the gas tanks.”

“Good guess, Larry! It’s the way I work it out,” Dick added.

“Go on, young feller.” The caretaker was absorbed.

“Well,” Sandy grinned, “the chewing gum disappeared! Supposing the fellow we thought we saw vanishing really was there and got out some way. He’d know, from Jeff landing us and our going in, that the amphibian might not be usable when he’d need it——”

“So he went back and got the gum—but why?”

“He was getting that ready, Dick, for the emeralds—remember how Sandy discovered the place the imitations were hidden?”

“That’s so, Larry. Go on, Sandy. You’ve got a brilliant brain!”

“Oh, no,” Sandy protested. “It just flashed over me—putting all the facts together, the way I made up my mind I’d do.”

He outlined the rest of his inference.
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“That was proved—the seaplane coming out to the yacht proved that the passenger who said he was a London agent, and wasn’t at all, had changed his plans. Well, say that he had arranged with Mimi, Mrs. Everdail’s maid, to have her throw over the jewels——”

“But she wouldn’t make the mistake of giving a confederate the wrong ones. She’d seen the real ones.”

They were working on the check-up and warming of the engine as they talked. Dick made the objection to Sandy’s theory.

“She’d know that the man knew the difference too!” Larry added.

That could be true, Sandy admitted. But he argued that the girl must have seen the captain take the stern life preserver to his cabin, and might have guessed, even observed through a cabin port, what he did. In that case she would have thrown over the life preserver knowing that her confederate would put it in the seaplane. And he had done exactly that!

“But the passenger jumped with a different life preserver!” Dick was more anxious to prove every step of Sandy’s argument than to find flaws in it.
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“I think we found the life preserver that they might have had on board the seaplane all the time. And the other one—we never thought of the yacht’s name being painted on its own things. So we took it for granted that we had the real hiding place.”

“You argue real good, young feller.”

“Thank you, sir. Well, if that was true—and if it wasn’t—why is the ghost walking again in the very hangar that the seaplane wreckage is in?”

That was a clinching statement.

“You’re right. And the passenger, who has been out of sight, has been haunting the hangar, trying to find the other life belt,” Larry took up the theory. “Mr. Whiteside must have guessed that, too, and he planned today to make a good search and if he didn’t find what he wanted——”

“He’d fly over that swamp and see if the other belt had fallen out of the seaplane—and he’d need a pilot—so he got Jeff!” Dick put the finishing touch to the revelation. “Larry kept Tommy busy, so Mr. Whiteside got Jeff.”

“Then we ought to be flying—the engine wasn’t very cold—it’s safe to hop.” Larry took a step toward the airplane.

“I still claim we needn’t hurry,” Sandy argued. “If we go too soon, they will be sure to see us and give up.”

“But they may find the life preserver if it’s still there and get away with the emeralds.”
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“If it’s still there, Larry, it will take some hunting. Anyway, we almost know their plans. If they don’t find anything they will come back to the hangar with the crate. If they do——”

“They may go anywhere,” Dick declared.

“Well, I don’t say not to follow them. But I do say let’s take our time. Isn’t there some way we can work out so they won’t be likely to discover us?”

Larry stared. Then he nodded and grew very thoughtful.

At last he delivered a suggestion that met unanimous approval.

The airplane, with a more powerful engine and better flying qualities, could go higher than the amphibian which was both slower and more clumsy. To that argument he added the information that if the binoculars they had first used were still where Dick had put them, in the airplane pocket, they could find the ship’s “ceiling”—the highest point to which power would take it and the air could still sustain it at flying speed—and from that height, in one look downward discover the truth or falsity of their theory.
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“If the ‘phib’ is flying low over the marsh, we can go off as far as we can and still see it,” he finished. “Then if they fly back to the hangar, we can outfly them on a different side of the island and get here in time to leave Jeff’s crate while we go and see what they do. They won’t suspect that we’re near, and if the caretaker goes with us as a witness to check up our story and to help balance the fourth seat, we can either come back if they do or follow them if they go somewhere else.”

Within half an hour, high in air, the airplane found its quarry!

With a cry of delight, unheard in the engine drone, Dick took the powerful glasses from his eyes, passed them to Sandy and then rubbed his hands vigorously to rid them of the chill of the high altitude.

Sandy had only to take one look when he located the object of their flight, to know that his deductions had all been sound.

Close to the grassy, channel-divided marsh, flying in a sort of spiral to cover every bit of ground, the amphibian was moving.

Sandy generously recollected the caretaker and sent back the glass.

Larry, informed by Sandy’s gesture of the discovery, nodded, took a second to jam his cap tighter, glad that it fitted so close that it could partly save his hair from the blasting, pulling wind—he had no helmet!—banked and leveled off into a course that would take them straight away from the locality.
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“I don’t want them to catch us cruising,” he murmured to himself.

After a short flight he came around in a wide swing, so that the airplane was over the Sound and then crossed the marsh again from that direction.

The report he got was that the amphibian was still flying.

But the next approach told a new development.

The ’plane beneath them had set down!

That caused Larry to determine to circle over the place. They had found something, perhaps, down below!

When Sandy waved in an excited gesture, twenty minutes later, and Larry’s keen eyes saw the amphibian, a tiny dot, moving over the Sound, he felt sure that the missing life preserver had been found.

Taking a quick glance at gas gauge, altimeter, tachometer and his other instruments, he nodded.

“All right,” he told himself. “We’ll follow them and see what they do and where they go.”

On high wings the pursuit began.