OVER THE BOUNDARY LINE

It was with the queerest possible feeling that Andy saw the land slipping away, and realized that they were at last launched upon the water part of the voyage.

It seemed as though they had cast loose from their safe moorings, and were adrift upon an uncharted sea. When comparing his feelings with other aviators in later times, he learned that every one of them had experienced exactly similar sensations the first time they passed out of touch of land, and found the heaving sea alone beneath them. It was a sort of air intoxication; Andy even called it sea-sickness, though doubtless most of it came from imagination alone.

"There they go, Frank!" he called out, not ten minutes later.

The land was far behind them now, and still in the other three directions they saw only the level surface of the great lake.

His exclamation was called out by a sudden change in the method of advance adopted by those in the leading aeroplane. Instead of keeping along in a direct line the biplane had uptilted and was now shooting downward in what seemed a terribly perilous way; just as though the pair of precious scoundrels had taken a notion to end the pursuit by seeking a plunge into the water.

But both boys knew differently, and that this was only a volplane, adopted by experienced and rash aviators as a means of reaching the lower air currents more rapidly than by slow spirals; or else undertaken when having engine trouble that threatens destruction.

Frank was ready to follow suit. It would not be the first time by long odds that the Bird boys had accomplished this speedy method of descending from high altitudes. There was always an exhilaration about the clever trick that appealed irresistibly to their natures; though Frank would never have attempted it unless reasonably sure that the conditions were favorable for success.

"Hold fast, Andy!" he remarked, quietly.

The hum of the motor suddenly ceased, and with its cessation the hydroplane was turned head-on toward the surface of the lake, four thousand feet below.

Down they went, plunging toward what seemed to be instant destruction; but a steady hand was at the wheel, and the pilot knew just what was necessary to do at the proper instant in order to bring this rapid descent to a stop, and right the airship on a level keel.

But there was no time just then to note what the rival aeroplane might be doing. Whether the experienced airman in charge managed to stop that downward plunge before reaching the surface of the lake; or failing went to his death, was a matter that did not concern them now, since they had their own affairs to look after.

To tell the truth, Andy's heart seemed to be in his throat as they made the drop. As yet they had never tried out the new hydroplane in a trick of this sort; and hence really did not know just how it might act; though Frank must have been pretty confident, else he would never have attempted it.

Given the choice the Bird boys would easily have decided to descend from their lofty height by means of the much safer if slower "spirals," each circle seeing the aeroplane lower than before. But since the reckless man in the other air craft led the way, Frank had chosen to follow. He believed that he could accomplish any feat that was possible to Casper Blue, especially now that the old air navigator had a handicap in the way of a crippled arm.

The water seemed rushing up to meet them; so it looked to Andy, whose anxious gaze was fastened upon the lower depths, as they dipped down in that terrific swoop. But then, he had seen the same thing when over the land, so that in itself this did not daunt him.

"Oh!"

That exclamation seemed to be forced from Andy's lips when he felt Frank give a quick turn to the lever that caused the deflecting rudder to again resume a normal position. The drop of the aeroplane was brought to a gradual stop, and when immediately afterwards the buzz of the motor announced that the propelling power was again at work, it was no wonder that the nervous boy expressed his relief by giving vent to that cry. There was a world of gratitude back of that word, it can be set down as certain; for no matter how confident Andy might have been concerning his cousin's ability to accomplish wonders, the new hydroplane was as yet untried in many things.

Now he even dared take his awed gaze from the heaving waters beneath the framework of the aeroplane, and give a thought to those whom they had chased overland and water for nearly three hours.

"Bully for Casper Blue! He made the riffle too! he's all to the good!" was the way the impulsive Andy announced his discovery to Frank, who just then could not spare even a second to take his attention off the working of the motor.

After all, it was not so very strange that the boy should express himself in this way. True, the man he was praising was now a criminal, and they sought to effect his arrest in some manner as yet vague and uncertain; but it was not in this light Andy viewed him just then. As a birdsman Casper Blue had proved that he still possessed the nerve and skill to direct a daring flight, and that all the tricks known to celebrated fliers were at his finger's ends.

Any one who has risked his life up among the clouds must always respect such a valiant spirit, even though aware that the object of his admiration has in other ways forfeited the esteem of all honorable men.

There was the biplane moving along on a level keel, and not more than two hundred feet above the water. And still the course held due north, showing that the desperate men who were thus fleeing from arrest had not the slightest intention of changing their plans.

"What do you think of her now, Andy?" asked the pilot, with a quiver of pride in his voice.

"You must mean our new craft, I take it, Frank; and I want to say that she's a real peach, if ever there was one. We never volplaned as easy as that in our lives, and that's a fact. Why, it was like sliding downhill on a sled, with never a single bump on the way. I could do that all day, and never get enough."

"Dangerous business, all the same," remarked Frank; "and doubly so when you don't happen to be well acquainted with your machine. A single hitch, and we would have struck the water at a terrible rate."

"But all the same we didn't, Frank," the other went on, jubilantly; for now that this peril was of the past Andy could be his old self again.

"And they did just as well," remarked Frank, always ready to give credit, even though it might be to a rival, for his nature was generous to a fault.

"Well, that biplane was easier to manage than our hydroplane, with the pontoons underneath," Andy went on to say, grudgingly; for no one could ever convince him that Frank had his superior as an air pilot; and he would sooner go up to a record height of fifteen thousand feet in company with his cousin, than accompany the most famous man living.

"It looks like we might be booked for Canada, Frank," he went on to say, a minute later, after they had fallen into the new "stride" comfortably, and were rushing forward on a level stretch, with the surface of the lake close at hand.

"I shouldn't wonder," came the noncommital reply.

Now, Andy knew his cousin like a book. Perhaps it was something in the words; or on the other hand there may have been an undercurrent of doubt in the way Frank spoke, that aroused the other's suspicion.

"What is it, Frank?" he demanded, "for I reckon you see something that is all a blank to me? Take me in, won't you?"

"Oh! I was wondering what would happen if they had an accident away out on the lake, that's all," admitted the other.

"Well, in that event I guess it'd be up to the Bird boys to play the rescuer act for all it was worth. But Frank, do you think this new machine of ours could climb up off the water with four aboard? Wouldn't that be the limit?"

"To tell you the truth, Andy, I don't know, because we've never had the chance to try it out. With only two of us aboard you know how easy she climbed; three passengers she could hoist, but four might faze her. We can only wait and see, if ever the chance comes to make the test."

"But you wouldn't hesitate about trying the same, I know, Frank?"

"Of course not," the other remarked, confidently, "and especially when it might mean life or death to a poor fellow away out here on the lake miles from land. If we couldn't rise, we might still be able to float like a duck, and hope that some boat would come to the rescue. In the end that would be just the same."

"Do you know," said Andy, "I saw a tug pulling out at full speed from the little city on the shore of the lake, close to where we left land; and somehow I seem to have an idea they know all about us, and mean to keep in touch with us as long as they can, to be handy in case of accident. Perhaps, now, my message was phoned to Bloomsbury; and seeing about where we must be heading if we kept on a northerly course, they have wired up here to watch out for us. How about that, Frank; am I silly to figure that way?"

"I don't see why you should be, Andy. In fact, just as soon as you mentioned about the tug I began wondering if somehow these good people didn't know who we were, and what we were chasing after the biplane for."

They had to speak unusually loud in order to hear, even though their heads were close together at the time; for the propellers were whirling with a hiss, and the hum of the motor added to the noise. But then, it was all a merry racket that chimed in well with the spirit of the young aviators; and which gave them much the same pleasure that the splash through the foaming water of a ninety-foot racing yacht must awaken in the heart of an enthusiastic skipper, when he knows that every sail is drawing to the limit, and all things are working well.

"Have you figured out what we ought to do if by good luck we all get over to the other side, safe and sound?" went on Andy.

"We'll have to leave that," was the reply Frank made. "No use crossing a bridge till you come to it, you know, Andy."

"But they'll be safe then, Frank?" "I'm afraid so, even if I don't pretend to be up in all the international law connected with the passing of a thief from United States territory to Canada."

"But ain't that a measly shame?" ejaculated the indignant Andy, "to think of a robber being able to turn, and put his fingers to his nose and wiggle 'em at us, just because he happens to cross the boundary line. It oughtn't to be that way, Frank!"

"Of course not; and I guess lots of abler chaps than you and me have thought the same; but there it stands, and the two countries won't get together to change the law even a little bit. Every year dozens of embezzlers light out across the border for Canada, where they can spend their money, and start for Europe if they feel like it."

"Then perhaps it's the money they take with 'em that the Canadians like; though I wouldn't like to believe such a thing," ventured Andy.

"Hardly that; but both countries are jealous about bringing back political offenders, I've heard Judge Lawson say more than once. But don't let's talk any more'n we can help, Andy. We've got our hands full as it is watching those fellows, and keeping ready to match any trick they try."

This served to give Andy a new cause for concentrating his attention on the fleeing biplane once more. As yet the pilot of the leading airship had not diverted from his set course; but if he was as tricky as they had reason to believe, there was always a chance that he might engineer some scheme, sooner or later, looking to shaking off his pursuers here in the middle of the great lake, where possibly no mortal eye could witness the deed, so as to appear against him later on.

With the wind aft, of course the further they advanced the larger grew the waves; and Andy noticed that they were now of quite respectable size; though being directly above, he could not tell much about it, only that in many spots he saw the white caps breaking, and this served as a pointer.

Would the hydroplane be able to ride such a sea in safety, in case necessity compelled them to alight upon its swelling bosom?

Frank did not seem to doubt it, for he had the utmost confidence in the ability of those aluminum pontoons to sustain a great weight without sinking. What they would possibly have to fear more than anything else, was the chance of a capsize; and of course this would spell disaster as much as anything else.

Once they overtook a sailing schooner that was speeding along with a fair breeze. Possibly those aboard thought they were making most excellent time, with everything in their favor, but the aeroplanes sped past the vessel almost as though it were a toy craft.

A faint cheer was heard from those aboard who could be seen wildly waving head-gear, or red handkerchiefs; just as though what they considered a novel air race had been engineered especially for their amusement.

When Andy took occasion to look backward again in a short time he was amazed to discover how far distant the sails of the schooner seemed. And it was this incident more than anything else that gave him to understand just what amazing speed the aeroplanes were putting in their mad race across the inland sea.

But while up to now the voyage had been without incident worthy of mention, or accident of any kind, it could hardly be expected that this immunity would continue to the very end. The splendid good fortune that had hovered over both airships was apt to be brought to a sudden termination at any moment, as Frank well knew.