The book Jack Chadwick had been reading,—a volume dealing with some rather dry experimental work,—slipped from his fingers and fell with a crash on the floor of the veranda. At the sudden interruption to the sleepy, breathless calm of Lone Island on a July noon, his cousin Tom Jesson, sixteen, and more than a year Jack’s junior, looked up from the steamer chair in which he, too, was extended, with one of his quiet smiles.

Suspending his task of wrapping some new condenser plates with glittering tin-foil, he gazed about him. In front of the bungalow was a strip of dazzling white sand,—the beach. Beyond shimmered the cobalt-blue waters of the Gulf of Mexico. At a small wharf lay a capable-looking motor cruiser, painted white and about forty-five feet in length. She had been moored thus for the past seven days—ever since Jack and his cousin and their colored attendant, Jupe, had landed on the island after an uneventful passage from Galveston.

“Dozed off,” chuckled Tom, regarding Jack as the latter’s eyelids closed drowsily; “well, I don’t know that I blame him. Waiting on Lone Island with nothing to do but read, eat and sleep, does get monotonous after a week of it.”

Suddenly a gong, affixed to the freshly painted wall above their heads, broke forth in a wild, insistent clamor.

“Clang! C-l-a-n-g! Clang! Clang!—Clang! Clang!”

The effect on Tom was electrical.

“L-I in the Continental Code!” he exclaimed springing to his feet. “Hurray, Jack, old boy! Wake up! It’s our call at last!”

Jack Chadwick galvanized from his nap into vibrant action with hardly less suddenness than had marked Tom’s arousing. Three times the gong, connected by an ingenious arrangement of Jack’s with his detector, beat out brazenly the call of Lone Island. Then came the signature:

“S-K.”

“Whoop! It really is the Sea King at last!” exclaimed Jack, his blue eyes dancing. The lees of sleep had cleared from them as if by magic.

“Race you to the wireless station, Tom!” he shot out, jumping from the veranda without bothering about the steps.

“You’re on!” was the instant response. Like a flash Tom was at his side.

The few dozen yards between the bungalow and the shed of raw, resinous-smelling pine lumber that housed the wireless was covered in less time than it takes to tell it. Panting from their dash through the heavy sand the two lads flung themselves, shoulder to shoulder, at the door.

“Dead heat!” laughingly proclaimed Jack, as he opened the portal and hastened to the array of shining instruments which occupied most of the space within.

All this time, behind them, the bell had kept up its insistent tocsin. With a quick movement Jack “threw” a “knife-blade” switch. Instantly the resonant drone of a dynamo filled the small sun-heated shack. Bending forward. Jack depressed the sending key.

Flash! C-r-a-s-h!

A wriggling snake of blue flame leaped, like a live thing, between the polished sparking points.

Alternately pressing and releasing his key. Jack sent an answer to the message. With nimble fingers he directed the powerful electric impulses, which were winging into space from the lofty aerials stretched between their masts above the shed.

While he did this with one hand, with the other he deftly adjusted the bright metal head band with its twin receivers that fitted over each ear. This accomplished, he drew toward him a pencil and a pad of paper.

“L-I! L-I! L-I!”

Crackling and squealing the powerful spark volleyed across the gap, and rushing into the aerials went flashing hundreds of miles through the ether.

Then came a pause. Tom, his hand on Jack’s shoulder, leaned eagerly forward and over him, watching for the first words of the message from space to be written on the pad.

All at once Jack began to write. His fingers flew fast in response to the flood of dots and dashes that came beating against his ear drums, transmitted by the sensitive diaphragms of the receivers.

To an untrained ear the soft tappings would have sounded as vague and undefined as the footsteps of a fly on a sheet of sensitive matter. But to Jack, the whisperings winging their way in three hundred meter waves through space were as clear as a story read aloud.

As he wrote, shoving his pencil over the sheets as fast as he could, Tom began to gasp.

“Great ginger-snaps!” he choked out, and then, “Well, we were sighing for action, and it looks as if we’ll get it in big, juicy chunks before we’re much older.”

While the message, destined to have such an important effect on their immediate future, is still pulsing through the air, we will take the opportunity to place the reader in closer touch, so to speak, with our two lads. Jack Chadwick, then, was the only son of Professor Chester Chadwick, an inventor, whose various discoveries in many mechanical fields had resulted in gaining him a handsome fortune. Jack’s mother had died when he was a tiny lad, and, as he was an only son, he had been brought up in constant association with his father. Almost as soon as he had mastered his earliest lessons Jack was familiar with his parent’s laboratory and workshop, and Mr. Chadwick, delighted at the interest the boy displayed in science, had made him a close companion.

When Jack was twelve years old a new interest entered his life. His cousin, Tom Jesson, came to live with them at Mr. Chadwick’s handsome home on the outskirts of Boston. Tom was the son of Jasper Jesson, the noted traveler, and, like Jack, he was motherless. Mr. Jesson had, some time before, accepted a commission from a scientific institute to travel and collect antiquities in the then little-known territory of Yucatan. From this expedition he did not return within the year allotted him to complete his researches.

Time went on and no word came from him, and at length he was given up for lost even by the most hopeful of his friends. And thus it was that his son Tom, then ten years old, came to High Towers, Mr. Chadwick’s estate, even then known as the home of a famous inventor.

And so Jack and Tom had practically grown up together in close association and with kindred interests.

To two lads of inventive mind, no more delightful field for their experiments could have been imagined than High Towers. A park of some fifty or sixty acres surrounded the house, which, among other features of a country estate, possessed a small lake. On this sheet of water Jack and Tom tried out models of a dozen different kinds of craft before they were fourteen. Professor Chadwick gave them practically “the run” of his workshops and experimental sheds, besides instructing them in scientific investigations.

Among other things, the lads had constructed a complete miniature railroad on the grounds, and had also built gliders of various types. But their most recent “craze” had been wireless telegraphy. With a dozen lads of their own age they had formed a “Wireless Club,” which met at High Towers every month. But, with the summer vacation, the members of the body had scattered, leaving only Jack and Tom to carry on the work. As Professor Chadwick stinted his son in nothing pertaining to his chosen pursuits, the two lads had assembled as complete an amateur station as could be found in the country.

In addition to the latest instruments and appliances, their natural ingenuity had enabled them to invent several additional features, some of them patentable,—as, for instance, the call-bell which tapped out the mysterious summons to the island station.

Which brings us back to Lone Island and to an explanation of how the two lads and Jupe, their faithful colored attendant, happened to be quartered on this low-lying, sandy, rather desolate patch of land off the coast of Texas, not far from the mouth of the Rio Grande. The islet belonged to Professor Chadwick, being part of an estate which had been owned by his wife, the daughter of a Texas cattle man. The lads had already camped there a winter, and knew the vicinity well.

About two months before this story opens, Professor Chadwick had left home, bound, so he informed the lads, on a biological investigation cruise among the Florida Keys and the West Indies. The lads had heard nothing more of him, or of his steam yacht, the Sea King, with the exception of a letter from Key West, and another from the island of Jamaica, stating that all was going well.

Imagine their bewildered astonishment and excitement therefore, when, two weeks before, a brief letter came to High Towers telling them to proceed, with Jupe, to Galveston, where the motor cruiser Vagrant would be awaiting them. Their instructions continued to inform them that they were to equip the Vagrant with wireless, and also purchase a portable bungalow and shed, with which to establish a wireless station on Lone Island. The letter, signed by Professor Chadwick, closed in his customary abrupt manner, without vouchsafing any explanation of his orders.

But Jack and Tom hardly needed any. The letter opened up before them a delightful vista of fun and adventure.

“Just fancy, a wireless island all to ourselves!” Jack had exclaimed as the boys joined hands in a wild war dance of delight. They had pleasant recollections of former jolly days in camp on the Gulf.

The letter enclosed a liberal draft on Professor Chadwick’s bank, and within forty-eight hours after receiving the missive which was to mean so much to them, the two cousins and chums, with the faithful Jupe attending them like a black shadow, were off for Galveston. On arrival there they went to the boatyard mentioned in the Professor’s letter, where they found the Vagrant,—the smart craft already mentioned as lying at the Lone Island wharf,—already equipped for sea, awaiting them.

To install a wireless plant on board did not take long. The most difficult part of their task lay in finding a suitable mast for the support of the aerials. Jack solved this problem by constructing a telescopic staff of steel tubing which, when not in use, could be lowered to a height of twelve feet. In use it could be raised to an altitude of sixty feet, giving a very fair radius of scope.

The materials for the wireless on the island, like those for the floating plant, had been brought from Boston. But the portable shack and bungalow were purchased in Galveston.

The Professor’s letter had instructed the lads to wait on the island for a message by wireless. Now it had come; come, too, with a startling suddenness that might be likened to a jolt. Tom, watching Jack’s fingers with burning eyes, finally saw this message inscribed on the receiving pad:

“Lone Island Station.—Proceed with all speed to Long. 96° W. by Lat. 27° N. Urgent. We are in dire peril.—Bangs, operator Sea King.”

The patter of the electric waves against the receivers ceased. No further word came, and Jack, after a brief interval, took off the headpiece and laid it down beside him on the table. For an instant the message, so utterly, wildly different from any they had expected, almost deprived him of speech.

Now his faculties rushed back, but he did not speak. Instead, he grounded the aerials by throwing the switch, and leaped to his feet with such impulsiveness that the stool on which he had been sitting went careering to the floor.

“Come on, Tom,” he cried, darting for the door.

As he ran he stuffed the message into the pocket of his linen jacket. Tom shot out of the shack after him.

“You’d better lock——” he began.

“Send Jupe to do it,” was the backward flung rejoinder, as Jack sprinted for the bungalow, “we’ve got to get grub on board and fill the water tanks within fifteen minutes.”

“And then what?”

“To sea—at top speed! The best the Vagrant can do will be none too quick! They need us out there,” he flung his arm seaward in an embracing gesture, “need us mighty bad, and it’s up to us to make a record run to the rescue.”