there are their empty gasolene tins. Guess my hunch wasn’t so far wrong after all.”

“Hmm,” muttered Mr. Pauling, as he examined the marks on the beach and sniffed at the empty tin cans. “I’ll have to admit your hunch was right, but it doesn’t do us much good. Our birds have flown.”

“Yes, hang it all!” exclaimed Rawlins. “They probably saw us coming and cleared out, but they’ll have to land again somewhere.”

“That’s quite true and all very well,” agreed Mr. Pauling, “but we haven’t the least idea where or when. No, it’s no use trying to chase all over the Caribbean after them. There’s nothing to do but go back and await future developments. I’m willing to admit we’ve been beaten.”

“Yes, the gang’s broken up and the tramp and their big submarine destroyed. I doubt if they’ll give further trouble,” said Mr. Henderson. “I think we’ve succeeded in accomplishing a great deal as it is.”

While they were talking, they approached the waiting cutter. Suddenly a screeching roar from the destroyer’s siren drowned the clamor of the birds.

“Jove! What’s that for?” exclaimed Mr. Henderson. “Hello, Disbrow’s signaling. Can you read the wigwag message, Rawlins?”

The diver stared fixedly at the figure of a sailor standing clearly outlined on the destroyer’s bridge and rapidly waving the little flags in an endeavor to convey some message to those on the island.

“Come a-b-o-a-r-d,” translated Rawlins, as the flags flashed up and down. “I-m-p-o-r-t-a-n-t n-e-w-s.”

“By glory!” he ejaculated, as the sailor finished and the message ended. “What in blazes has he seen?”

Rapidly, they hurried to the boat, scrambled in, and were soon speeding towards the destroyer, all impatient to learn what had occurred to cause them to be summoned and utterly at a loss as to what the “important news” could be.

“Great Scott, but he’s in a hurry!” cried Rawlins, as the sound of the anchor winch and the rattle of incoming cable reached them. “He’s getting in his anchors already. And he’s pacing up and down as if the deck were red hot. I wonder what’s up!”

“It’s an S. O. S.!” announced the Commander, as Mr. Pauling gained the deck, “and it might mean anything. Came in ‘S. O. S.--submarine’ and then stopped short. Not another word.”

Before he had ceased speaking, the destroyer’s screws were churning the water and the island was rapidly slipping away.

“By Jove!” exclaimed Mr. Pauling. “Looks as if these men were up to their old game! But where was the ship when she called? Do you know her position?”

“No, only in a general way,” replied the Commander. “Bancroft got the message by accident--was overhauling the radio compass when he picked it up. That’s the only way we know even the direction. They’re southwest, that’s all we know.”

“I’ll say that’s important news!” cried Rawlins. “That shows the sub’s still afloat, but I’d like to know what the dickens became of the plane.”

“Do you think they really sank a ship?” asked Tom. “Why, they can’t expect to get away with that sort of thing!”

“Of course, they did,” declared Mr. Pauling. “Otherwise the vessel would not have sent the S. O. S. and the very fact that the message was cut off shows they did. Poor fellows! They never had a chance and we may be too late to save them now. As for getting away with it, these men are desperate--utterly unprincipled, as you know. Nothing they can do will make their plight any worse. They’ve sunk ships before--so why not again?”

“But why should they?” persisted Tom. “I should think they’d just be trying to get away, not stopping to sink ships.”

“That’s what I’ve been thinking,” declared Rawlins. “The whole thing’s blamed funny. I’ve a hunch it’s all a blind. I’ll bet that message was sent by the sub or the plane just to get us away from here--or something.”

“Hunches or not, I’m not taking chances,” declared the Commander stiffly. “If I get an S. O. S. I answer.”

“Righto!” exclaimed the diver. “Glad you do. And, if luck’s with us, we may get there in time to sight the sub and kill two birds with one stone.”

But to find a ship or its survivors when its exact latitude and longitude are known and to find such a tiny speck upon the broad ocean when only its general direction is known are two very different matters. So meager had been the sudden call for aid which had reached the destroyer that no one could say whether the ship that sent it had been five or fifty miles away and as there had been no time in which to move the loop antenna of the radio compass about until the exact direction was determined, the chances of the destroyer’s finding the vessel or any of her company were very remote. Throughout the day and all through the night the destroyer searched, steaming in circles and with her powerful searchlights sweeping the sea.

In the hopes that another signal might yet come in, men were kept constantly at the radio instruments listening and sending forth messages, but the only replies received were from far distant ships asking what the trouble was. To all of these the operators gave what little information they had and asked if others had heard the frenzied call for help. But only one had, a tramp bound from Cuba for Curacao, and unlike the destroyer she had received the S. O. S. by her regular antenna and so could not know the direction whence it came.

“Well, some of those ships may pick up the poor rascals,” said Mr. Henderson when on the following morning Commander Disbrow reported the messages which had been exchanged. “But it’s odd none of them heard the call except that tramp.”

“I think that proves the vessel was near us,” declared Tom. “If Mr. Bancroft got it on the loop and they couldn’t hear it on their regular aerials, the message must have been sent from very close.”

“Yes, that’s quite true,” agreed Mr. Henderson. “But it doesn’t make matters much simpler. Even a few square miles of sea is a big place.”

“You said it!” exclaimed Rawlins. “And a blamed sight bigger to the poor beggars hanging on to wreckage or in a small boat than to us. But I still have an idea it was a blind. That would account for those ships not getting it.”

“I don’t just see what you mean,” said Mr. Pauling.

“Why, if it was sent from the sub or the plane, it would be a weak message and wouldn’t go far and it may have been sent from within half a mile of the island. Yes, by glory!--Come to think of it, they might have been right there alongside and just sent that message from underwater!”

“Jove, I hadn’t thought of that!” admitted Mr. Pauling. “I wonder--”

Before he could complete his sentence, the deep-throated cry of the lookout rang through the little ship, and at his words all crowded to the rails and peered ahead.

“Small boat two points off the starboard bow!” was the sailor’s shout.

CHAPTER III—THE CASTAWAYS

Very small and pitiful appeared the tiny speck bobbing up and down upon that wide expanse of restless sea in the faint morning light. But rapidly it took on form as the destroyer slid hissing through the sparkling water toward it. Through their glasses the boys could see that it was a ship’s lifeboat filled with men and that one of the occupants was standing up and wildly waving a bit of cloth fastened to an oar.

“I’ll say they’re mighty glad to see us!” exclaimed Rawlins. “By gravy, it makes me think of war times again! Confound those sneaking Bolsheviks, they’re as bad as the Huns.”

“Worse,” declared Mr. Pauling tersely. “The Germans had the excuse of war and these rascals are merely cutthroats. I wonder if this boat’s the only one that escaped.”

“We’ll know in a moment,” said Mr. Henderson. “Lucky