“What are you going to do now?” asked Tom of Jack, who, with the receivers clamped over his ears, was seated at the wireless apparatus.

It was the middle of the afternoon, the storm had blown itself out and the sun was shining cheerfully.

About the young inventors pressed the castaways,—for they had been awakened,—Captain Andrews, so that he might make an observation and get their exact position, and the rest to be on hand if need arose.

Jack had just flashed out the location of the island, and with it a fervent appeal for help. From the balloon-supported wires above him, the message had gone shooting forth into space.

But as yet no answer had come, though the lad sat with the transmitting switch open, waiting for a reply.

“Maybe there are no ships in this part of the Gulf,” said Tom.

“Well, with the power we have from that dynamo we ought to have gotten into communication with something before this,” said Jack impatiently. He turned his head toward the dynamo of the Flying Road Racer, which had been connected with the wireless apparatus and was whizzing away merrily. The motor, fed by a fresh supply of gas obtained by dumping in a new lot of crystals, of course supplied the motive power for the current maker.

“Try again,” suggested Professor Chadwick.

Jack threw over the switch to connect the transmitting appliances, and began manipulating the key once more.

The message of distress crackled and flashed, like the snapping of a whip lash,—or, more truly, a thousand of them.

Jack was utilizing every atom of power he could obtain. He calculated that he had at least one hundred and ten volts of current, which should be ample to send his messages for a great distance.

After sending for a while he stopped and listened. But no message came beating against his ears, breathing a spirit of hope.

“Try sending out a C. Q. D.,” said Abner Jennings.

“You mean S. O. S.,” rejoined Jack. “C. Q. D. isn’t used as an urgent call any more. Too many would-be jokers used to send it out and cause endless confusion.”

He threw the switch again into a sending position, and began to flash out another message.

“o o o —— —— —— o o o” “S. O. S.”

It was the most urgent call known to seamen. The despairing cry of the wrecked the lost.

Again and again Jack volleyed it out, and the far-flung appeal went skyrocketing off on the electric waves, spreading like the ripples on a pond from the tightly stretched aerials. It was signed “The Chadwick Party.”

Then the lad tried listening again.

Suddenly a look of joy flashed over his face.

“He’s getting an answer!” yelled Tom in huge excitement. Ned Banks, hardly less enthusiastic, capered about.

Jack’s pencil traced the message from space on a pad of paper placed on an empty box before him.

“What is it? What’s the matter?”

Once more he began sending furiously.

“We have been driven on a desert island off the Mexican coast.”

“Where is it?” came the reply. “Give latitude and longitude.”

Jack swiftly flashed back the required information. Then he asked a question.

“Who is this?”

“The Sea King,” was the astonishing reply.

“We are coming to your aid. Have you got the gems?”

“Yes. They are safe, and we are all well, but in need of help,” the lad sent back with a joyous heart.

He listened for a reply, but none came. In fact, there was no need for more communication. The castaways knew what they wanted to know most of all, namely, that they would be taken off the island as soon as possible. In the meantime. Professor Chadwick ordered Jupe to prepare a royal spread in celebration of the event.

“We look like a lot of pirates,” commented Jack, as, after a hearty meal, they lay stretched about the fire.

“I suppose that, like most boys, you have a sort of admiration for those gentry?” inquired Captain Andrews.

“Well, he’s stuffed his head with enough books about them,” chuckled Tom.

“Guess that applies to you, too,” parried Jack, with a grin.

“I don’t suppose, though, that either of you ever saw a real pirate,” commented the captain quietly. “I can tell you they are mighty different beings from the red-sashed, romantic sort of chaps you read about.”

“Why, have you ever seen any?” asked Jack, sitting up eagerly.

“Yes, and fought with ’em, too. Care to hear the yarn?” responded the seaman.

The boys’ prompt affirmative removed all doubts on this score and Captain Andrews, without further preliminaries, struck into his tale.

“It was a good many years ago,” he said, “when I wasn’t much bigger than you lads. But for all that I was acting as third mate on a sailing packet running from Liverpool to the West Indies. The skipper, whose name was David Munson, was a stern man, but kind enough. He had a curious way of keeping to himself, though, and the men said that some time before he had been attacked by sea-robbers, who had cut him down and captured his wife and child, who sailed with him. But the rascals had not thought it worth while to take him and left him for dead on his burning vessel. For they, according to their usual custom, had set it on fire before they sailed away.

“Captain Munson recovered consciousness in the nick of time to stagger out of the path of the flames. A boat lay astern of his craft and he had just strength enough left to slide down a rope into this and cast off. Then he lost consciousness once more.

“For three days he drifted in this way, lying all the time in a dead swoon. On the third day he was picked up, more dead than alive, by a Bristol line clipper, which brought him back to England.

“It was many a long day before he got about again and it was then found that he had lost all recollection of the tragedy and appeared to think that his vessel had perished in a storm. But, except for this, his mind was clear enough and he found little difficulty in getting a new command. This was the West Indiaman Cambrian Hills, of which I was third mate. Captain Munson’s story was related to me by the first mate, a man named Sterling, a fine seaman and a good fellow. This Sterling had been on board the ship that the pirates had captured and had been made prisoner by them. But later he had managed to make his escape from the South American city to which they had taken him to be sold as a slave.

“Reaching England, he found that his former skipper, whom he had thought dead, was alive and in good health, but that his mind was hopelessly clouded as to the past. In fact, he did not recognize Sterling, and Sterling, fearing the consequences of reminding him of what had occurred on the Spanish main, made no move to awaken his slumbering memory. This was the strange story Mate Sterling told me one stormy night on watch.

“Well, on this particular voyage the Cambrian Hills came in for the buffeting of their life. Heavy gales, head seas, and violent squalls beat the craft about day after day. And at last up came a terrific gale from the northeast, which carried us away off our course and down off the coast of Brazil.

“Now, as it so happened, this was the very worst place we could have been driven to at this particular time. One of those little wars that were then eternally harassing the South American republics had just come to an end and the seas thereabouts were swarming with piratical craft. These gentry called themselves privateers and carried government papers, but were, to all intents and purposes, pirates and nothing more nor less.

“Following the gale, the weather fell into a regular condition of doldrums. Sometimes it blew a light wind, but more often a dead calm till it seemed that we were doomed to haunt the Brazilian coast for the rest of our lives. The men grew restive. It was insufferably hot and the calking in the deck seams fairly bubbled and boiled.

“Thus passed an entire week and the only man or board whose nerves were not on edge was Captain Munson. He appeared not to worry or chafe over our situation in the least. This was the more curious, inasmuch as Sterling had informed me that the seas in which we lay were the very identical ones in which the fatal battle with the pirates who had looted Captain Munson’s last command had taken place.

“One morning just after breakfast I was standing against the taffrail, with Sterling by my side, idly gazing horizonward for a sign of coming wind. All at once I saw Sterling clap his telescope to his eye and gaze intently off into the southeast.

“‘Wind?’ says I.

“‘No,’ says he.

“‘Well, what then?’ says I.

“‘A sail,’ says he.

“‘Then they must be getting more wind than we are,’ says I. ‘What do you make her out to be?’

“‘Can’t tell yet; but somehow I don’t much like the look of her.’

“He handed me the glass.

“‘Take a look yourself,’ he said.

“I squinted through the telescope and at last made out the distant sail. She was a black brigantine, low in the water and with a rakish sort of look about her masts and spars. The water over around her was dark blue—of a deeper tinge than the ocean surrounding us—showing that the wind was blowing off in that direction.

“‘She doesn’t show any colors,’ says I, handing the glass back to Sterling. ‘What do you make her out to be?’

“He shrugged his shoulders.

“‘I don’t know, laddie,’ he said, ‘but she looks to me like a war vessel of some sort. Maybe a Brazilian craft.’

“‘Well, whatever she is,’ says I, ‘she’s got the wind with her and it’ll hit us in a minute.’

“‘That’s right,’ says he, coming out of a sort of a reverie. ‘Get your yards squared and your courses braced up.’

“I hastened to put these orders into execution, and hardly had they been completed when the long awaited wind struck us. The Cambrian Hills heeled over and began to move through the water.

“The crew set up a cheer as we began to get under way and the noise brought the skipper on deck. He looked more than usually grave and had a Bible, which he had evidently been reading, in his hand.

“‘Wind at last, Mr. Sterling?’ he said quietly.

“‘Aye! aye, sir,’ said the mate. ‘I knew the luck was bound to turn,’ he added.

“‘There is no such thing as luck, Mr. Sterling,’ said the captain in his quiet, grave way. ‘All is the doings of Providence.’

“Then he turned and moved away, but Sterling was at his side in a minute.

“‘There’s a sail off there to windward, sir. Will you take a look at her and tell us what you think of her? You know it pays to be suspicious in these waters, and I don’t much like her looks.’

“In his usual serious manner the skipper took the glass and gazed through it at the brigantine, which, to my eye, was sailing two feet to our one, and overhauling us fast. He gazed at her a long time and when he set the glass down his face was working curiously. He clapped his hand to his forehead as if something there hurt him.

“‘I—I—There’s something strangely familiar about that craft, Mr. Sterling,’ says he, ‘but, for the life of me, I can’t tell what it is.’

“‘Looks to me like a man-o’-war of some sort, sir,’ says Sterling.

“He took up the glass again and scrutinized the stranger. Then I saw the color begin to die out of his red, good-natured face till it grew white as a corpse.

“‘It’s an armed vessel, sir,’ he grated out through his clenched teeth, ‘and—and she’s just broken out the Black Flag,—the skull and cross bones, sir!’

“‘A pirate, eh?’ said Munson quietly, and I noticed the same curious expression pass across his face. It was the strained look of a man trying to recall something that eludes him persistently. ‘Well, Mr. Sterling, she’s faster than us. We must fight for it, sir,’ he said at length.

“‘Aye, sir,’ says Sterling gravely, ‘I’ll call the men aft and explain to them. Andrews, my lad, you attend to distributing the weapons.’

“Every West Indiaman in those days carried a small arsenal of weapons—blunderbusses and cutlasses—for attacks by roving bands of sea-robbers were not infrequent. The men took the news well enough, although one or two of them went white. But there were enough old veterans among them to keep them steady and prevent a panic.

“I guess the resolute bearing of Captain Munson and Mr. Sterling had a good deal to do with putting heart into them. As for myself, I was horribly scared inside, but I trust that my alarm did not appear too conspicuously on my countenance.

“The men gave a cheer as Captain Munson concluded his little speech and I summoned three of them below to assist in the distribution of the arms. In the meantime Mr. Sterling gave orders to the men to rig up as many dummies as possible and station them along the bulwarks so that we might seem to be more in number than we actually were. This was a common enough trick in those days.

“I have to smile even now when I think of it, but one good fellow in his zeal even clapped a cap on top of the galley chimney, although what a man would have been doing poking his head out of ‘Charley Noble’—as the cook-house stack is called by seamen—is hard to say. By the time all our preparations were completed the craft that was overhauling us was not more than half a mile astern.

“She was a handsome craft and a witch at sailing. The Cambrian Hills was accounted a fast vessel; but we weren’t in it with our pursuer. If we had had any doubt as to her intentions toward us till then she soon dispelled it. From her bow came a flash and a puff of smoke and a ball screamed through our rigging. It did no harm—wasn’t meant to, probably—but it showed us that they ‘meant business.’

“The Cambrian Hills carried an old brass cannon, more for saluting purposes than anything else. But we had slugs on board and the piece of artillery was loaded up. But the enemy, as we now rightfully regarded her, was too far off for our carronade to be effective as yet. She, on the other hand, appeared to have a serviceable heavy gun. All this was not encouraging, but the prospect grew worse as we swept their decks with the glass. Fully forty men lined her bulwarks and we numbered only twenty, including the cook, who was not accounted a first class fighting man. Of him, however, more anon.

“I was a young fellow then and had always thought of pirates as being chaps all covered with finery, gold lace and jewels and such. I was stricken with astonishment to see that no such men appeared on the brigantine. They were all filthy, wretched looking things, many of them being coal-black negroes. Among them were even one or two Chinese. Such a mixture of races I never saw before or since.

“Suddenly Captain Munson, to my astonishment, snatched up his speaking trumpet and hailed the pirate, who was now almost alongside and to windward.

“‘Ship ahoy!’

“His voice was as bold as if he had been skipper of a man-o’-war hailing a sea criminal. It was a bold move, but it was successful in producing some confusion among the pirates. All at once a giant of a man with a black beard stepped up on the pirate’s rail, holding on by the lee forestays.

“‘Hullo!’ he hailed in a foreign accent.

“‘What ship’s that?’ hailed Captain Munson again.

“‘None of your business. Heave to. I want to board you,’ was the reply in an insolent voice.

“‘You go plumb to blazes!’ came from Sterling, who was a hot-tempered chap and could contain himself no longer.

“At that very instant a puff of wind blew the man’s black beard aside. He clutched at it desperately, but somehow he bungled the job, and to my utter astonishment—it came off! He stood revealed as a man of huge frame with a brutal bull-dog jaw and unmistakable Latin cast of features. But I had little time to notice this, for a strange cry had broken from Captain Munson’s lips as the man’s disguise blew off. He turned deathly pale and staggered like a drunken man.

“Sterling and I rushed to his side. We thought for a minute that he was about to faint. But he rallied and stared at us for a moment wildly.

“‘Good Lord!’ exclaimed Sterling, ‘it’s all come back to him!’

“Then I understood. That man who had hailed us was the captain of the same piratical band that had attacked Captain Munson’s other ship and carried off his wife and child. The next instant following Sterling’s exclamation was a dramatic one.

“‘You know me, sir?’ asked the mate.

“‘Yes! Yes! You’re Robert Sterling,’ burst from the captain’s lips. ‘I recall it all now. The fight! That ruffian struck me down. I woke up to find you all gone. But, Sterling, how do you come to be here,—and—and where are Bess and the baby?’

“I felt sorry for Sterling then. His face went as white as the captain’s visage and he actually shook as if from cold. But he had to answer.

“‘Better off than if they were in the hands of those ruffians, sir,’ he replied in a low voice which shook perilously, ‘they are——’

“‘Dead!’ burst out the captain, with a terrible cry.

“Sterling bowed his head.

“‘Your wife leaped overboard rather than be sold down the coast as a slave,’ he said slowly, ‘and—and she took the baby with her.’

“I did not dare to look at Captain Munson’s face. But I could hear his breath come short and quick, just like a man breathes after a long, hard swim. But the next instant we had other things to think of. A volley of small arms from the pirate craft whistled about our ears. She was up to windward and evidently meant to grapple and board us. What followed is hard to describe. I don’t know how most men feel in a fight of that character, but it seemed to me that I was in a dream. I fired and loaded, and fired and loaded, while all about me bullets were flying and fallen men groaning. Splinters flew as the pirate’s volleys raked our rails. I was suddenly conscious of being wounded, but I fought on, actually hardly knowing what I was doing.

“Suddenly the pirate’s sails loomed close alongside. Our yardarms locked with his. Grappling irons were thrown aboard us and the whole horde of ruffians tried to board us by main force. But they met with such desperate resistance that they were compelled to retreat for the time. Right here is where the cook figured. Just as things looked most critical he turned the tide for us. Attached to a huge boiler in his domain was a hose, used for washing stains out of the decks.

“While we had been arming he had made up a roaring fire. By the time the pirates boarded us there was enough boiling water in the boiler to make that hose an effective weapon. Yelling like an Indian, the cook turned it on the scrambling mass of rascals. The stream of boiling water was more effective than bullets. With yells and cries they fell back, some of them scalded horribly.

“All this time I had lost sight of Captain Munson. Now I glimpsed him, just in time to see him leap into the main chains and from thence on to the bulwarks of the pirate ship. His face was fixed and terrible and held an expression of desperate resolve. Cutlass in hand, he fought his way through the demoralized pirates and at last I saw, in a flash of understanding, his purpose. His object was to find out, and kill with his own hands, the pirate chief. Hardly had I realized this before the men encountered each other. Apparently the pirate recognized Munson instantly, for I saw him recoil as if he had seen a ghost. But the next instant he had recovered and began to fight desperately for his life.

“In the meantime some of our crew had cut the two vessels apart, and before any of us recovered his wits and started to the captain’s rescue the two craft had drifted so far asunder that it was impossible. With horrified fascination we watched the fight, and if it held us spellbound it appeared to have the same effect on the pirate crew; at any rate, none of them interfered.

“Such a furious fight could not, in the nature of things, last long, but it came to an altogether unexpected conclusion. Captain Munson’s cutlass had broken off short and he closed with his enemy, grasping him about the waist. They both reeled backward—and suddenly vanished from sight. A hatchway had been left open, and in their blind fury neither had noticed it. Tripping on the coaming, they had plunged into it.

“Suddenly we heard a shot from the pirate craft, and then came a great cry. I could not make out what all the yelling was about, and turned to Sterling who seemed equally spellbound at the horror of the thing we had just witnessed.

“‘What is it? What are they saying?’ I demanded.

“‘They are shouting that the magazine is on fire!’ he exclaimed, ‘that a shot fired by the Englishman has ignited the powder!’”

“The words had hardly left his lips before a hot blast rushed full at me. I was knocked from my feet, saw a vast sheet of flame before me, and knew no more. When I came to I discovered Sterling bending over me. His face was very grave and serious.

“‘What has happened?’ I asked weakly.

“‘The pirate ship is blown up,’ he replied; ‘not a vestige of her is left.’

“‘And Captain Munson?’ I demanded, although I knew what the reply would be.

“Sterling removed his cap; a last tribute to a brave man.

”‘Has gone with her to Jones’ locker,’ he rejoined; ‘maybe it was better so. It would be just about here that his wife and baby died.’”

Captain Andrews paused. So ended his story, which cast a gloom over the party that was not to be dispelled. Soon after, therefore, they retired, with the picture of the sea captain’s tragic death still vividly before their eyes.

Before joining the others. Jack tried to get into communication with the Sea King by wireless once more. But he failed. However, this did not worry them, as they knew that their friends must know where to find them.

“I wonder when they’ll arrive here,” said Professor Chadwick, as they prepared to spend as comfortable a night as they could on the sand. “Those repairs were surely effected quickly,” he added.

“Very quickly,” said Captain Andrews, who alone of the party had not been almost wild with delight at the prospect of the rescue. “By the way. Jack, you are quite sure that it was the Sea King that you were in communication with?”

“Of course,” rejoined the lad rather impatiently, “who else could it have been? Who would have had any object in trying to pass themselves off as the Sea King unless they——”

He stopped short and looked rather blank all of a sudden. The idea of Herrera had just crossed his mind. And then that ship that they had seen laboring in the stormy sea that afternoon?

“Pshaw!” said the lad to himself; “she had two masts and a yellow funnel, there’s no chance of that being the Tarantula.”

When he voiced this belief aloud later on, the others agreed with him. But Captain Andrews, still suspicious, determined, he said, to keep watch. The others, almost too tired to keep their eyes open, rather ridiculed this precaution, and soon sleep enwrapped every one on that desolate island.

Every one? Yes; for tired nature had asserted herself and Captain Andrews, after a hard struggle to keep awake, dozed off, woke with a start, dozed off again and finally slumbered profoundly.

Had he kept his eyes open a while longer he would have seen something approaching the island that would have caused him to keep awake with a vengeance. This object was nothing more nor less than the Tarantula, disguised cunningly by a canvas smokestack painted yellow, and two masts.

Herrera early that day had ascended the river and heard of the flight of the prisoners and the destruction of his hemp-drying plant. Half crazy with fury he kept a watch on the skies and saw the Flying Road Racer, high in air as she was driven seaward after her perilous experience in the circular storm.

In defiance of the wild weather he at once prepared to put to sea disguising his ship, as he had done on other occasions, as she dropped down the river.

Me had seen the storm-racked air craft as she flew above him. He had observed her, in fact, at the very moment that the adventurers espied his tossing craft. To his chagrin, however, she passed out of sight. But he held on in the direction she had vanished determined not to give up the chase of those precious stones till he had exhausted every means of trying to obtain them.

Just as he was despairing of ever hearing of the Flying Road Racer again. Jack’s “S. O. S.” message had come winging across the sea. As soon as his operator gave him the despatch the rascal conceived the daring plan of impersonating the Sea King and in this guise he flashed back the message inquiring the position of the castaways. He took care to ascertain that the gems were safe.

While profound and peaceful sleep wrapped the party of adventurers, a boat landed on the beach, crowded with men. It came from the Tarantula, which had anchored about two hundred yards to seaward. Every man was armed and among them was Herrera with one or two of his chosen aides.

Their plans had been formed before they landed and they silently sneaked up on the castaways’ camp. They were agreeably surprised to find no sentries posted.

According to previous plans, each man of the crew carried ropes and gags. The sleeping party was surprised without warning and tied and gagged without a chance of their presenting any opposition. Each of the Chadwick party, as they awakened under the rough handling of the henchmen of Herrera, was given a strong hint not to resist, in the form of a pistol barrel pressed to the nape of his neck.

As resistance would have been worse than useless all submitted quietly to the outrage, and Herrera’s triumph appeared to be complete. When they all had been secured the marauders commenced a frantic search for the great silver jewel casket. They found it without much difficulty under the professor’s coat which he had used as a pillow. Not expecting any attack he had not taken much pains to conceal it.

Herrera burst into a loud laugh as he opened the casket and took out the three great flashing stones it contained.

“So you thought that you could trick Herrera, eh, you stupid Yankee,” he snarled, “but I caught your message by wireless, you dogs of gringos. I spit on you and despise you. The jewels you thought to steal are now mine. But see—Herrera is generous. He leaves you the box!”

As he spoke the ruffian flung the silver casket to the sand and then, with some gruff orders to his men, strode off across the beach. A few minutes later the splash of oars informed the marooned castaways that their foe had departed taking with him the gems they had gone through so much to save intact; and not only that, he took with him also their hopes of being rescued. From what he had said about the wireless, it was clear that he had intercepted the message for aid, and thus been guided to the island. The Sea King had not received word from them at all.

With what bitter feelings they reviewed the situation may be imagined. And it did not relieve the misery of their present position, as they lay gagged and helpless, to reflect that if they had kept a guard, the disaster might not have happened. They had been trapped like so many unthinking children.

Jack struggled and strained at his bonds, as, in fact, all the rest of the party were doing. To his delight, after a brief period of struggling, he managed to loosen them considerably. The work of tying up the party had been done hastily, and, consequently, the knots were not very hard to loosen. In fact, all that Herrera had wanted, was to keep them quiet till he had looted the treasure of the gems.

When Jack had worked his hands free he pulled the gag out of his mouth, and then, after undoing his ankle bonds, he drew out his knife and rapidly liberated his companions.

“Well, a fine mess I’ve made of it,” grumbled out Captain Andrews, as soon as he was free.

“I don’t see that you were any worse than the rest of us,” said Professor Chadwick; “in fact, it was you who had a keen enough mind to guess that our message might have been received and answered by another craft than the Sea King.”

“Which it was,” put in Mr. Jesson.

“Yes; but I kept watch for a while,” contritely said the captain, “and—I’m bitterly ashamed to say it,—I fell asleep at my post of duty.”

“For which we don’t attach a bit of blame to you,” said Professor Chadwick; “what we had passed through was enough to exhaust a giant. To tell you the truth, I almost feel relieved now that the gems are gone.”

“The natives had a legend that they brought bad luck,” said Mr. Jesson, “and indeed they seemed to.”

“I hope they bring evil fortune to that greaser who has them now,” struck in Abner Jennings.

The two sailors added their growling assent to this wish, nor could any of the party refrain from echoing it.

[Illustration: Jack liberated Captain Andrews.]

“I suppose he’s got clear away,” hazarded Ned presently.

“Of course he has,” grunted Captain Andrews. “I’ll bet there’s twenty miles between him and this island right now. And, incidentally, I’m ready to bet as to his future.”

“What will it be?” asked Jack, with some curiosity.

“Why, he’ll throw up his governorship,—the Diaz government is on its last legs, anyhow,—and skip out to Paris. He’ll sell those gems over there and—live happy ever afterward.”

“Why Paris?” asked Mr. Jesson.

“Oh, all those scallywags go over there when they’ve made their graft,” laughed Ned; “they won’t tolerate them any other place, I guess. When I was over there with my folks two years ago we saw more princes and exiled presidents from South America than you could shake a stick at. You couldn’t have thrown a brick on the main boulevards without hitting some ruler who had left his country for his country’s good.”

“All of which disquisition,” said Professor Chadwick dryly, “doesn’t solve our problem.”

“No, indeed,” said Mr. Jesson; “we are as badly off as before.”

“Worse,” exclaimed Jack.

“How’s that?” asked Tom.

“Well, haven’t we lost those gems?”

“Oh, bother the old gems,” said Tom, “we’ve got the box, haven’t we? If any one in the States doesn’t believe we ever had the three gems we can show them the casket as proof that we really did have them once.”

As he spoke he picked up the box from the sand where Herrera had flung it, and handed it to the Professor.

“It will make a handsome relic of our trip at all events,” said that gentleman, with half a sigh. “I guess I’ll present it to some institute interested in such things.”

“Pity those bumps on the cover aren’t precious stones,” said Ned, indicating the three dull-colored knobs on the cover. “Wonder what they are there for?”

“To make the box look nobby,” ventured Tom, a pun which almost cost him a clip on the side of the head.

But they were soon recalled to the seriousness of their situation. In the east the day was beginning to dawn, and a return to sleep was out of the question after all that had occurred.

“I guess I’ll get to work with the wireless,” said Jack, “it’s our only hope.”

“Unless we could swim ashore,” said Captain Andrews. “It isn’t more than five miles off.”

“True. But from what we could see yesterday it is a rugged, inhospitable shore,” said Mr. Jesson.

“Most anything would be better than this, though, so long as it was the mainland,” said Ned.

“Yes, if only the old Flying Road Racer would have kept in the air half an hour longer,” groaned Tom, “we might have used her as an auto to reach some civilized spot.”

“We could easily have done that,” struck in Jack. “The engine and running gear are in perfect order. So far as that is concerned, she is ready for a road trip of a thousand miles right now.”

“You ought to have fixed it so she could swim, while you were about it,” said Ned.

He meant the remark as a joke; but Jack answered quite seriously.

“I’ve been thinking over such a plan,” he said; “maybe some day I’ll get to work and invent something that will make the good old craft as capable in the water as she is on land and in the air.”

“Wish you could invent it right now,” began Ned with a laugh. “I——”

He stopped short with a puzzled look, which, oddly enough, was reflected on all their races the next moment.

“My legs are wobbly!” cried Tom.

“By the trident of Neptune,” roared Captain Andrews, “so are mine!”

“It’s not our legs!” cried Mr. Jesson, “it’s the ground that’s moving!”

“The whole island is quivering like jelly!” cried Ned.

“Good land, what ails de place? It’s done got chills and feber!” shouted Jupe from his pots and pans, which were now rolling in every direction.

The tremor grew stronger. Accompanying it was a queer, moaning sort of sound. All at once there came a violent convulsion, and they were all thrown flat. The roaring noise increased till it was almost deafening.

“It’s an earthquake!” called out Professor Chadwick.

“An earthquake?” cried the others in terrified tones as they rolled about.

Suddenly, not far from them, a great ragged fissure yawned in the earth and almost instantly closed again. From that moment, for the ensuing ten minutes, the castaways were in a condition bordering on panic. With the very earth under their feet refusing them support they felt that they were, indeed, in a sorry plight.

At the conclusion of the period of time mentioned, the shocks stopped as suddenly as they had begun.

“Do you think there’ll be any more of them?” asked Tom in rather a quavery voice.

“Impossible to say,” said Mr. Jesson. “I imagine that this is a continuation of the one that caused that cliff to collapse, which resulted in my escape from those Indians.”

“I suspect that is it,” said Professor Chadwick. “The great storm may have also resulted from the generally disturbed conditions. We may have no more shocks and we may have a dozen.”

“I’ve known cases of whole islands being swallowed in the South Seas——” began Abner Jennings gloomily.

But Professor Chadwick stopped him.

“If you can’t talk of something more cheerful, my man, don’t talk at all,” he said.

“And tidal waves, too, that wiped out whole cities like Galveston,” muttered Jennings, in a low tone, however.

“There is no reason to expect that another shock will occur,” resumed the Professor; “the very nature of these seismic disturbances results in——”

“Wow! Glory to Goshen, here comes annudder one!” bellowed Jupe, dropping a frying pan with a clatter and throwing himself flat on his face.

The others followed his example. Indeed, it was impossible to remain on one’s feet. The mighty earth waves undulated like the billows of the sea.

This shock lasted longer than the other, and was more severe. When it was over they arose to their feet considerably unnerved by the convulsion of nature.

“Do——do you think there is any danger of this island sinking. Professor?” asked Ned in a shaky voice.

“I do not,” rejoined the other with a confidence that he was very far from actually feeling, however. “I see no evidence of any volcanic formation hereabouts.”

“Maybe de ole Mudder Earth done got a bad tummy ache,” hazarded Jupe.

“I wish she’d get it in her foot, then,” grumbled Ned. “I don’t—say, Jack,” he broke off suddenly, “am I seeing things or is that beach narrower than it was?”

A worried look passed over Jack’s face.

“I’m afraid your eyesight is all right, Ned,” he said. “The water is closer than it was, beyond a doubt.”

“And that means?” gasped Captain Andrews. “That we are sinking,” calmly said Professor Chadwick. “There is no use deceiving ourselves. Jack, send out a call for aid. There may be a chance of some ship catching the message.”

Jack sent an appeal flashing forth from the wireless. Then he listened as usual for an answer.

It came, but not in the way he had expected. He flung the receivers from his ears with an angry expression.

“It’s that rascal Herrera,” he said. “He intercepted the call.”

“The villain! What did he say?” demanded Mr. Jesson.

“He said that we could stay here till the island sank, for all he cared, and added that Diaz had been driven out of Mexico, and that he was off to Europe with those gems.”

“Dat dere coffee-colored man is de worst no ’count trash I ebber done heard of,” announced Jupe solemnly, while the others stood thunderstruck at such pitiless behavior.

Before they could utter a word of comment, however, another shock struck the island. And this time it caused an amazing thing to happen. The centre of the isolated spot of land had been quite an elevation. During this spasm of the earth, however, an astonishing change took place in the form of the island. The “crown” of the sandy little place sank until it was depressed into a sort of cup. On the outer rim of this odd subsidence of the island, were the adventurers who looked with alarmed eyes on this freak of the earthquake. It mean only one thing, and that was that if another shock occurred and the land sank any further, that the sea must overwhelm it utterly.

While they were still looking over the altered scene. Captain Andrews gave a shout.

“Shiver my timbers,” he cried, “look yonder, will you?”

The subsidence of the centre of the island, of course, gave them a clear view of the distant shore and of the neck of water between it and the island.

An astounding thing had happened, as the adventurers could now see. Although they had not known it, the island had once formed part of the mainland, and a narrow neck still connected it at a depth of only a few feet at low water. It was now low tide, and the earthquake, while it depressed the central part of the island, had performed a still more astonishing freak.

It had raised this narrow neck linking it to the shore till it was quite a few inches above the level of the water, making a causeway of wet sand between the island and the mainland!

Jack was the first to grasp the significance of this. He gave a glad shout as he did so.

“Hurrah! We are saved!” he cried. “The earthquake has saved us!”

“What?” demanded his hearers, not quite so quick-thinking as Jack.

“Don’t you see?” exclaimed the boy. “We can drive the Flying Road Racer ashore over that neck of sand as easily as if we were taking a spin in the park.”

“But suppose another shock causes the neck of sand to subside again?” asked Mr. Jesson skeptically.

“We must take our chances of that,” Tom answered him. “In any case, it means death to remain where we are.”

As Jack spoke, the island gave another trembling shake. It was only a slight one, but it warned them that, in all probability, there were to be more violent shocks succeeding it.

It was plain enough that their escape, if it was to be made at all, must be made quickly. Jack and Tom at once set about dismantling the wireless station and packing the apparatus.

The hastily extemporized life jacket balloons were hauled down and the wires coiled. When this had been done. Jack told everybody to take their seats in the car, on the top of which the dismantled gas bag had been folded by the captain and the two sailors, while Abner Jennings helped Jupe to pack up.

Jack took his seat last of all and started the engine going. It worked without a hitch, and the auto,—a flying machine no longer,—moved off across the sand, heavily laden as it was, without difficulty.

The rim about the submerged centre of the island was soon circumnavigated, and the beginning of the narrow neck of land reached. Then Jack fairly “let the car out.”

The newly formed isthmus was hard, and the car flew over it under the full power of its engines.

“Mighty good t’ing dere ain’t no speed laws in dis part ob de world,” grunted Jupe as they flew along.

The shore appeared to rush toward them, but if they had hoped to see any signs of human habitation as they drew close to it they were mistaken. Nothing but a mass of trees, backed by rising ground, appeared along the coast as far as the eye could reach in either direction.

As they sped along they heard behind them a sudden mighty uproar. Gazing back they saw the ocean heaving and boiling all about the island they had left, as if it had been a witches’ caldron. Great jets of water shot up, and the surface of the sea was flecked with foam and spume.

The sight fascinated every one of them but Jack, who had to be intent on his driving.

“The whole island is going!” shouted the Professor.

He was right.

With a sudden booming roar and upheaval of the ocean, the entire mass of land sank under the waves, which for a long time boiled and simmered above it. Just as the last vestige of the island vanished, leaving only the newly created peninsula projecting from the land, they reached the solid earth.

Their dash to the mainland had taken place only just in time. A little more delay, they realized with shudders, would have meant their total annihilation.

“I said the island would go,” cried Abner Jennings triumphantly. “I’ve ’em vanish like that in the South Seas.”

No one had any comment to make. The horror of what they had just witnessed struck them all dumb. The gratitude they felt to Divine Providence for their lucky rescue filled their hearts to overflowing, and left no room for speech.

The Flying Road Racer was stopped, and they silently gazed for a long time at the bubbling, heaving waters.

The sight was impressive, even if it did cause a shiver and inspire a feeling that bordered on fear.

After a while the Professor spoke. His tone was as solemn as his words.

“Boys,” he said, addressing his young friends, “we have just witnessed something that many scientists would give a great deal to behold.”

“Well, candidly,” said Tom, “I’ve seen enough of it.”

So had they all, in fact, and the Flying Road Racer was soon turned north, following a rough road that ran parallel with the sea-coast.

It was now late afternoon, and the shadows were lengthening apace. Before long the swift tropic night would overtake them. Although they had arrived at a determination to continue traveling north till they arrived at a large city, where a telegraph wire could be found, they did not care to risk advancing over the rough, half-formed road in the darkness, so a halt was made where a small stream of fresh water ran down to the sea, and they prepared to spend the night there.

It was somewhat chilly and a roaring fire was built around which they seated themselves after the evening meal. All were rather silent and abstracted, and there was no inclination for conversation. The Professor had brought out the silver casket and was examining some queer marks like hieroglyphics on its cover.

“I’m sure they have some sort of meaning,” he remarked to Mr. Jesson, “but it’s beyond me to make out what it can be. See if you can do any better.”

He handed the box to his brother-in-law to examine. But in the transfer it was fumbled, and before Mr. Jesson could save it the silver casket rolled toward the fire, only stopping when it was embedded in a mass of embers.

It was raked out with a stick by Mr. Jesson before it was damaged. He set it aside to cool before examining it, and in the meantime the boys took occasion to observe it more narrowly than they had yet found opportunity to do.

“Say, I thought that those knobs on the top were dull-colored!” exclaimed Jack Chadwick suddenly.

“Why, so they are!” rejoined Mr. Jesson. “Some sort of inferior stone, I guess. They——”

“But they are not dull! Look!”

Risking burning his fingers. Jack seized the still warm casket and held it toward his elders.

On the cover, embedded in the silver, flashed and winked in the firelight, three magnificent gems, red, blue, green!

“Let me look at that a minute. Jack,” exclaimed Professor Chadwick in sharp, excited tones.

He took the box from his son, and an instant later his head and Mr. Jesson’s were close together over the rifled silver casket.

“Well, gentlemen?” said Ned after a while.

“Well,” echoed Professor Chadwick, “we have made a most astounding discovery. These gems which Jack discovered,—for they are genuine, there’s not a doubt of it,—must have been covered with wax of some sort. The heat of the fire, when the box fell into it, melted this substance, and—well, here are three gems worth, conservatively, two hundred and fifty thousand dollars; probably a great deal more.”

The listeners looked at him in amazement.

“But what were the gems that Herrera took out of the casket, then?” demanded Jack, when he found his voice.

“Imitations, undoubtedly,” was the reply of Mr. Jesson. “The tribe that owned the genuine stones adopted this cunning means of concealing the real ones by coating them with wax of some sort. Then they placed inferior gems, or cunning imitations, within the box, trusting to the cupidity of any one who stole them not to investigate further.”

And so it proved afterward. The stones, which the strange and seemingly trivial accident had revealed, turned out to be as fine specimens of their respective kinds as there are in existence. They were appraised at six hundred and eighty thousand dollars, but cryptic carvings on the back of them made them of infinitely more value to science as specimens of the treasures of a vanished race.

Despite their keen excitement over the discovery that, after all, Herrera had not decamped with the precious stones, the adventurers slept soundly and peacefully that night.

When they awakened the daylight was sparkling on land and sea, and Jupe was filling the air with appetizing aromas proceeding from his cooking fire.

It was while they were in the midst of the morning meal that Jack sprang to his feet with a shout.

“The Sea King! the Sea King!” he cried, pointing seaward.

About half a mile off shore, steaming leisurely along, was a fine-looking white yacht that the Professor speedily pronounced to be, indeed, the Sea King.

“The wireless, Tom, as quick as you can,” called Jack, and the two lads at once set about sending their life-jacket balloons aloft.

This time the message that Jack sent out reached the persons it was intended for, and an hour later a boat came ashore and the castaways found themselves among their friends.

Repairs had been effected in record time on the yacht, and those in charge of her had determined not to wait longer at Lone Island, but proceed south at once. They were urged to this course, also, by news from Mexico that the revolutionists had triumphed, and that Diaz had abdicated.

We should like to chronicle more of the adventures of the Boy Inventors on this trip, but the exigencies of space forbid it. Suffice it to say then, that while the Professor, the rescued explorer and the rest, including Captain Andrews, voyaged to Lone Island and thence home on the Sea King, the boys drove the Flying Road Racer through Mexico, and reached home in that way by the overland route. They had many exciting times, but none so filled with peril and incident as their career on the gulf had been.

In due time the Vagrant was also recovered and sent home by the newly formed Madero government. Of Herrera, all trace was lost for a time. But ultimately he was heard from in Paris, whither, as had been prophesied, he had fled when the Diaz government fell. But he is not leading the life of a luxurious refugee there. Far from it. The gems he had stolen with the exercise of so much villainy and planning, proved to be, as Professor Chadwick had conjectured, mere cheap imitations worth very little except as specimens of Maya workmanship. Herrera, when last heard from, was acting as a head waiter in an humble Mexican restaurant in the Latin quarter of the French capital.

The genuine gems were sold to a New York millionaire, and when he dies will be seen in his private museum, which will then be opened to the public. The proceeds were shared, by the wishes of Professor Chadwick and Mr. Jesson, with the faithful crew of the Sea King, each, from Captain Andrews down, receiving a due portion. A handsome monument was also erected above the grave of poor Kettle, who fell in the battle with the Mayas.

Professor Chadwick did not fulfill the object of his cruise in finding a new form of biologic life; but he often says that he established something far more precious,—namely, the safety of his long-lost brother-in-law, Tom Jesson’s father.

One morning, not long after the household at High Towers had settled down to its ordinary routine, a telegram came for Jack. It contained astonishing things, things which were—though he didn’t guess it at the time,—to open up an entirely new field of invention for him and his chums, Tom Jesson and Ned Bangs.

The message stated,—but positively, we must keep all that for another telling. In our next volume we will relate further astonishing and stirring occurrences in the lives of our ingenious, progressive young friends. The title of the forthcoming book will be The Boy Inventors and the Vanishing Gun,—a tale which promises to be of extraordinary interest to every American boy, brimful and running over, as it will be, with experiment and achievement along new and significant lines.