At the aviation field the crowd had watched the departure of the two girls, flying the famous Kane Hydro-Aircraft, with eager interest but assured confidence in their making a successful trip. The Flying Girl never indulged in accidents, and her skill was universally admitted. To be sure, there was an added risk in flying over the water, but with a motor boat to sustain them when they alighted, the danger was reduced to a minimum and, in the minds of nearly all the spectators, a triumphant return was unquestioned. Hundreds of glasses followed the flight and although the management sent several bird-men into the air to amuse the throng the real interest remained centered on the dim speck that marked the course of the Flying Girl.

No sooner had Orissa and Sybil started on their voyage than Stephen Kane and Mr. Cumberford ran to the bluff overlooking the sea, where with powerful binoculars they could obtain an unobstructed view of the entire trip to the island and back again. Presently Madeline Dentry joined them, in company with Mr. and Mrs. Tupper, all standing silently with leveled glasses.

"She's working beautifully," muttered Steve, referring to his invention with boyish delight. "I'm sorry Ris didn't make a straight line of it, but she always likes to give the dear public the worth of their money.... Ah-h!"

"By Jove! that was an awkward turn," cried Mr. Cumberford, as they saw the Aircraft keel at a dangerous angle and then slowly right itself. "I'm surprised at Orissa. She usually makes her turns so neatly."

"I've an idea that blamed steering gear stuck," said Steve, ruefully. "I've been a little afraid of it, all along. But the girls are all right now. They're headed dead for the island and if Orissa makes a neat drop to the water the rest is easy."

No one spoke again for a time, all being intent upon the flying-machine. When it had seemed to reach the island, and even to pass over it, without a halt, there was an excited hum of amazement from the grand stand.

Madeline glanced at Stephen Kane's face and found it as white as a sheet. He was staring with dilated eyes toward the Aircraft.

"What in the mischief is Orissa up to now?" questioned Mr. Cumberford, uneasily. "Wasn't she to alight this side of the island?"

"Yes," answered Steve hoarsely.

"Then——She can't be joking, or playing pranks. It isn't like her. Why, they haven't swerved a hair's breadth from the course, or even slackened speed. They—they——"

"They're in trouble, I'm afraid," said Steve in trembling tones. "The control has failed them and they can't stop."

"Can't stop!" The little line of observers on the bluff echoed the thrilling words. From the grand stand came a roar of voices filled with tense excitement. Some thought the Flying Girl was attempting a reckless performance, with the idea of shocking the crowd; but Stephen Kane knew better, and so did Mr. Cumberford. As the two men held their glasses to their eyes with shaking hands, straining to discover a sign that Orissa had altered her course and was coming back, Madeline Dentry turned to look earnestly at the brother and father of the girls, knowing she could read the facts more truly from their faces than by focusing her own glasses on that tiny speck in the sky.

The moments dragged slowly, yet laden with tragic import. The powerful lenses lost the speck, now found it again—lost it for good—yet the men most affected by this strange occurrence still glared at the sky, hoping against hope that their fears were unfounded and that the Aircraft would come back.

Some one plucked Steve's sleeve. It was Chesty Todd, his big body shaken like an aspen.

"It—it has run away with 'em, Steve. It's gone wrong, man; there's danger ahead!"

"Eh?" said Steve, dully.

"Wake up and do something!"

Steve lowered his glasses and looked helplessly at Mr. Cumberford. Cumberford returned the stare, glowering upon the inventor.

"That's right; it's up to you, Kane. What are you going to do?" he asked coldly.

"There's no other hydro-aËroplane on the grounds," said the boy brokenly.

"Then get an aËroplane," commanded Cumberford, sharply.

"It would mean death to anyone who ventured to follow our girls in an aËroplane—not rescue for them."

Cumberford moaned, as if in pain; then stamped his foot impatiently, as if ashamed of his weakness.

"Well—well! What then, Stephen Kane?" he demanded.

Steve wrung his hands, realizing his helplessness.

"Gentlemen," said Madeline Dentry, laying a gentle hand on Mr. Cumberford's arm, "let me help you. There is no reason for despair just yet; the condition of those girls is far from desperate, it seems to me. Did I understand you to say, Mr. Kane, that your sister is unable to stop the engine, or to turn the machine?"

Steve nodded.

"That's it," he said. "Something has broken. I can't imagine what it is, but there's no other way to explain the thing."

"Very well," rejoined Madeline, coolly, "let us, then, try to consider intelligently what will happen to them. Will they presently descend and alight upon the surface of the water?"

"I'm—I'm afraid not," Steve answered. "If that were possible, Orissa would have done it long ago. I think something has happened to affect the control, and therefore my sister is helpless."

"In that case, how long will they continue flying?" persisted Madeline.

"As long as the gasoline lasts—three or four hours."

"And how fast are they traveling, Mr. Kane?"

"I think at the rate of about forty-five miles an hour."

Miss Dentry made a mental calculation.

"Then they will descend about a hundred and fifty miles from here, in a straight line over that island," said she. "Having a boat under them, I suppose they will float indefinitely?"

Again Steve nodded, looking at the girl curiously and wondering at her logic.

"If—if they manage to alight upon the water in good shape," he replied more hopefully, "they'll be safe enough—for a time. And they have food and water with them. The only danger I fear for them, at present, is that when the gasoline is exhausted the machine will be wrecked."

"Don't you aviators often shut off your engine and volplane to the ground?" asked Madeline.

"Yes, with the elevator and rudder in full control. But that isn't the case with Orissa. I'm certain her elevator control has bound in some way. Were it broken, and free, the Aircraft would have wobbled, and perhaps tumbled while we were looking at it. The elevator is wedged, you see, and my sister can't move it at all. So, when the gasoline gives out, I—I'm not sure how the machine will act."

"Anyway," exclaimed Madeline, with sudden determination, "we are wasting valuable time in useless talk. Follow me at once."

"Where to?" asked Steve, in surprise.

"To my yacht. I'm going after the girls. Please come with us, Mr. Cumberford—and you, too, Mr. Todd. Aunty," turning to Mrs. Tupper, "if you require anything from the hotel for the journey I will send you there in the car; but you must hurry, for every moment is precious."

Mr. Cumberford straightened up, animated and alert, while his face brightened with a ray of hope.

"We will take my car to the bay," said he, eagerly, "and Mr. and Mrs. Tupper can use your own car to visit the hotel. Will you accompany us, or ride with your aunt?"

"With you," decided Madeline. "I must have the captain get up steam and prepare to sail. It won't take long; I've ordered them to keep a little steam all the time, in case I wish to take a party out for a ride."

Even as they were speaking all walked rapidly toward the long line of motor cars. Mrs. Tupper, who had not ventured a remark or made any protest—quite contrary to her usual custom—now astonished her niece by saying:

"Never mind the hotel; let us all go directly to the yacht. With those two poor girls in danger I couldn't bear to think I had caused a moment's delay. It is very comfortable on the yacht and—we'll get along all right for a day."

"To be sure; to be sure," agreed Mr. Tupper, nervously. "I shall be seasick; I'm bound to be seasick; I always am; but in this emergency my place is by Madeline's side."

Of course no protest would have affected Madeline's determination, and the worthy couple recognized that fact perfectly; hence they diplomatically abetted her plan.

Captain Krell had attended the exhibitions at the aviation field, but while there he kept one eye on Miss Dentry. During the panic caused by the runaway aËroplane he saw Miss Dentry in earnest conversation with Cumberford and Kane and marked their hurried departure from the field. So the gallant captain scuttled back to the yacht at his best speed, to find Miss Dentry already aboard and the engineer shoveling in coal.

Both Mr. Cumberford and Steve knew that the Salvador was by odds the fastest ship in the bay, and Madeline's prompt offer to go to the rescue of their imperilled daughter and sister awakened hope in their breasts and aroused their lively gratitude.

After all it did not take the yacht long to get under way. It was so perfectly manned and in such complete readiness that steam was the only requisite to begin a trip instantly. Madeline could scarcely wait while with aggravating deliberation they hoisted anchor, but she became more composed as the yacht slowly headed out of the bay, the crew alert and the big captain as eager as any of them to rescue the daring bird-maids.

By the time the Salvador reached the open sea the shore was lined with thousands of spectators, and the sight of the graceful yacht headed in chase of the two girls raised a cheer so lusty and heartfelt that it reached Madeline's ears and caused her to flush with pleasure and renewed determination.