Chapter VII. The Air Glider
 

Mr. Damon continued to hammer away at the window sash with the piece of driftwood. There were splinters of the frame and jagged pieces of glass sticking out, making it dangerous for the exile to slip through.

"Come on! Come on!" the eccentric man continued to call. "Bless my safety valve! We'll save you! Come on!"

Mr. Petrofsky was leaping across the room, just ahead of the one guard. The other two were at the open door now, through which Tom could be seen. Then the spies, realizing in an instant that they had been deceived, made a dash after their comrade, who had his hand on the tails of the exile's coat.

"Break away! Break loose!" cried Mr. Damon, who, by this time had cleared the window so a person could get through. "Don't let them hold you!"

"I don't intend to!" retorted Mr. Petrofsky, and he swerved suddenly, tearing his coat, from the grasp of the guard.

In another instant the exile was at the casement, and was being helped through by Mr. Damon, and there was need of it, for the three guards were there now, doing their best to keep their prisoner.

"Pull away! Pull away!" cried Mr. Damon.

"We'll help you!" shouted Tom, who, now that his trick had worked, had sped around to the other side of the hut.

"Don't be afraid, we're with you!" exclaimed the detective, who was with the young inventor.

"Grab him! Keep him! Hold him!" fairly screamed the rearmost of the three guards. "It is a plot of the Nihilists to rescue him. Shoot him, comrades. He must not get away!"

"Don't you try any of your shooting games, or I'll take a hand in it!" shouted the detective, and, at the same moment he drew his revolver and fired harmlessly in the air.

"A bomb! A bomb!", yelled the guards in terror.

"Not yet, but there may be!" murmured Tom. The firing of the shot produced a good effect, for the three men who were trying to detain Ivan Petrofsky at once fell back from the window and gave him just the chance needed. He scrambled through, with the aid of Mr. Damon, and before the guards could again spring at him, which they did when the echoes of the shot had died away. They had realized, too late, that it was not a bomb, and that there was no immediate danger for them.

"Come on!" cried Tom. "Make for the airship! We've got to get the start of them!"

Leading the way, he sprinted toward the road that led to the place where the airship awaited them. He was followed by Mr. Damon and the detective, who had Mr. Petrofsky between them.

"Are you all right?" Tom called back to the exile. "Are you hurt? Can you run?"

"I'm all right," was the reassuring answer. "Go ahead; But they'll be right after us."

"Maybe they'll stop when they see this," remarked the detective significantly, and he held his revolver so that the rays of the newly-risen moon glinted on it.

"Here they come!" cried Tom a moment later, as three figures, one after the other, came around the corner of the house. They had not taken the shorter route through the window, as had Mr. Petrofsky, and this gained a little time for our friends.

"Stop! Hold on!" cried one of the guards in fairly good English. "That is our prisoner."

"Not any more!" the young inventor yelled back. "He's ours now."

"Look out! They're going to shoot!" cried Mr. Damon. "Bless my gunpowder! can't you stop them some way or other, Mr. Detective?"

"The only way is by firing first," answered Mr. Trivett, "and I don't want to hurt them. Guess I'll fire in the air again."

He did, and the guards halted. They seemed to be holding a consultation, as Tom learned by glancing hastily back, and he caught the glisten of some weapon. But if the three men had any notion of firing they gave it up, and once more came on running. Doubtless they had orders to get their prisoner back to Russia alive, and did not want to take any chances of hitting him.

"Leg it!" cried Tom. "Leg it!"

He was well ahead, and wanted the others to catch up to him, but none of the men was a good runner, and Mr. Petrofsky, by reason of being rather heavily built, was worse than the other two, so they had to accommodate their pace to his.

"I wonder if we can make it," mused Tom, as he realized that the airship was a good distance off yet. the guards, though quite a way in the rear now were coming on fast. "It's going to be a close race," thought the young inventor. "I wish we'd brought the airship a little nearer."

It was indeed a race now, for the guards, seeming to know that they would not be shot at, were coming on more confidently, and were rap-idly lessening the distance that separated them from their recent prisoner.

"We've got to go faster!" cried Tom.

"Bless my shoe leather!" yelled Mr. Damon. "I can't go any faster."

Still he did make the attempt, and so did the exile and the detective. Little was said now, for each of the parties was running a dogged race, and in silence. They had gone possibly half a mile, and the first advantage of Tom and his friends was rapidly being lost, when suddenly there sounded in the air above a curious throbbing noise.

"Bless my gasolene! What's that?" cried Mr. Damon.

"The airship! It's the airship!" yelled Tom, as he saw a great dark shape slowly approaching. "Ned is bringing her to met us."

"Good!" cried the detective. "We need it I'm about winded!"

"This way, Ned! This way!" cried Tom, and, an instant later, they were in the midst of a brilliant glow, for Ned had turned the current into the great searchlight on the bow of the air craft, and the beams were focused on our friends. Ned could now see the refugees, and in a moment he sent the graceful craft down, bringing it to a halt on the ground near Tom.

"In with you!" cried the lad. "She's all ready to start up again!"

"Come on!" yelled Tom to the others. "We're all right now, if you hustle!"

"Bless my pin cushion!" gasped Mr. Damon, making a final spurt.

The three guards had halted in confusion on seeing the big, black bulk of the airship, and when they noted the gleaming of the searchlight they must have realized that their chances were gone. They made a rush, however, but it was too late. Over the side of the craft scrambled Tom, Mr. Damon, the detective and Ivan Petrofsky, and an instant later Ned had sent it aloft. The race was over, and the young inventor and his friends had won.

"You're the stuff!" cried Tom to Ned, as he went with his chum to the pilot house to direct the progress of the airship. "It's lucky you came for us. We never could have made the distance. We left the ship too far off."

"That's what I thought after you'd gone," replied his chum. "So I decided to come and meet you. I had to go slowly so as not to pass you in the darkness."

They were speeding off now, and Ned, turning the beams of the great searchlight below them, picked up the three guards who were gazing helplessly aloft after their fast disappearing prisoner.

"You're having your first ride in an airship, Mr. Petrofsky," remarked Tom, when they had gone on for some little distance. "How do you like it?"

"I'm so excited I hardly know, but it's quite a sensation. But how in the world did you ever find me to rescue me?"

Then they told the story of their search, and the unexpected clew from Russia. In turn the exile told how he had been attacked at the breakfast table one morning by the three spies--the very men who had been shadowing him--and taken away secretly, being drugged to prevent his calling for help. He had been kept a close prisoner in the lonely hut, and each day he had expected to be taken back to serve out his sentence in Siberia.

"Another day would have been too late," he told Tom, when he had thanked the young inventor over and over again, "for the papers would have arrived, and the last obstacle to taking me back to Russia would have been removed. They dared not take me out of the United States without official documents, and they would have been forged ones, for they intended trumping up a criminal charge against me, the political one not being strong enough to allow them to extradite me."

"Well I'm glad we got you," said Tom heartily. "We will soon be ready to start for Siberia."

"In this kind of a craft?"

"Yes, only much larger. You'll like it. I only hope my air glider works."

By putting on speed, Tom was able to reach Shopton before midnight, and there was quite an informal celebration in the Swift homestead over the rescue of the exile. The detective, for whom there was no further need, was paid off, and Mr. Petrofsky was made a member of the household.

"You'd better stay here until we are ready to start," Tom said, "and then we can keep an eye on you. We need you to show us as nearly as possible where the platinum field is."

"All right," agreed the Russian with a laugh. "I'm sure I'll do all I can for you, and you are certainly treating me very nicely after what I suffered from my captors."

Tom resumed work on his air glider the next day, and he had an additional helper, for Mr. Petrofsky proved to be a good mechanic.

In brief, the air glider was like an aeroplane save that it had no motor. It was raised by a strong wind blowing against transverse planes, and once aloft was held there by the force of the air currents, just like a box kite is kept up. To make it progress either with or against the wind, there were horizontal and vertical rudders, and sliding weights, by which the equilibrium could be shifted so as to raise or lower it. While it could not exactly move directly against the wind it could progress in a direction contrary to which the gale was blowing, somewhat as a sailing ship "tacks."

And, as has been explained, the harder the wind blew the better the air glider worked. In fact unless there was a strong gale it would not go up.

"But it will be just what is needed out there in that part of Siberia," declared the exile, "for there the wind is never quiet. Often it blows a regular hurricane."

"That's what we want!" cried Tom. He had made several models of the air glider, changing them as he found out his errors, and at last he had hit on the right shape and size.

Midway of the big glider, on which work was now well started, there was to be an enclosed car for the carrying of passengers, their food and supplies. Tom figured on carrying five or six.

For several weeks the work on the air glider progressed rapidly, and it was nearing completion. Meanwhile nothing more had been heard or seen of the Russian spies.

"Well," announced Tom one night, after a day's hard work, "we'll be ready for a trial now, just as soon as there comes a good wind."

"Is it all finished?" asked Ned.

"No, but enough for a trial spin. What I want is a big wind now."