"Friends, I have unexpected good news! It is well that we met this man or we would have gone many miles out of our way. My brother has been moved to another mine since the revolutionists located him for me. He is in a lonely district many miles from here. This man was in the same mine with him, until my brother was transferred, and then Mr. Borious escaped. We will have to change our plans."

"And where are we to head for now?" asked Tom.

"Near to the town of Haskaski, where my poor brother is working in a sulphur mine!"

"Then let's get a move on!" cried Tom with enthusiasm. "Do you think this man will come with us, Mr. Petrofsky, to help in the rescue, and show us the place?"

"He says he will," translated the exile, "though he is much afraid of our strange craft. Still he knows that to trust himself to it is better than being captured, and sent back to the mines to starve to death!"

"Good!" cried Tom. "And if he wants to, and all goes well, we'll take him out of Russia with us. Now get busy, Ned, and we'll have this machine in shape again soon."

While Ivan Petrofsky took his new friend inside, and explained to him about the workings of the Falcon, Tom and Ned labored over the gas machine with such good effect that by night it was capable of being used. Then they went aloft, and making a change in their route, as suggested by Mr. Borious, they headed for the desolate sulphur region.

For several days they sailed on, and gradually a plan of rescue was worked out. According to the information of the newcomer, the best way to save Mr. Petrofsky's brother was to make the attempt when the prisoners were marched back from the mines to the barracks where they were confined.

"It will be dark then," said Mr. Borious, "and if you can hover in your airship near at hand, and if Mr. Petrofsky can call out to his brother to run to him, we can take him up with us and get away before the guards know what we are doing."

"But aren't the prisoners chained?" asked Tom.

"No, they depend on guards to prevent escapes."

"Then we'll try that way," decided the young inventor.

On and on they sailed, the Falcon working admirably. Verst after verst was covered, and finally, one morning, Mr. Borious, who knew the country well, from having once been a prisoner there, said:

"We are now near the place. If we go any closer we may be observed. We had better remain hidden in some grove of trees so that at nightfall we can go forth to the rescue."

"But how can we find it after dark?" asked Ned.

"You can easily tell by the lights in the barracks," was the answer. "I can stand in the pilot house to direct you, for nearly all these exile prisons are alike. The prisoners will march in a long line from the mine. Then for the rescue."

It was tedious waiting that day, but it had to be done, and to Tom, who was anxious to effect the rescue, and proceed to the place of the winds to try his air glider, it seemed as if dusk would never come as they remained in concealment.

But night finally approached and then the great airship went silently aloft, ready to hover over the prison ground. Fortunately there was little wind; and she could be used as a balloon, thus avoiding the noise of the motor.

"The next thing I do, when I get home," remarked Tom, as they drifted along. "Will be to make a silent airship. I think they would be very useful."

With Mr. Borious in the pilot house, to point out the way, Tom steered through the fast-gathering darkness. The Russian had soon become used to the airship, and was not at all afraid.

"Can you go just where you want to, as a balloon?" asked the new guide.

"No, but almost," replied Tom. "At the last moment I've got to take a chance and start the motor to send us just where we want to go. That's why I think a silent airship would be a great thing. You could get up on the enemy before he knew it."

"There are the prison barracks," said the guide a little later, his talk being translated by Mr. Petrofsky. Below and a little ahead of them could been seen a cluster of lights.

"Yes, that looks like a line of prisoners," remarked Ned, who was peering through a pair of night glasses.

"Where?" asked Tom eagerly, and they were pointed out to him. He took an observation, and exclaimed:

"There they are, sure enough. Now if your brother is only among them, Mr. Petrofsky, we'll soon have him on board."

"Heaven grant that he may be there!" said the exile in a low voice.

A moment later, the Falcon, meanwhile having been allowed to drift as close as possible to the dimly-seen line of prisoners, Tom set in motion the great motor, the propeller blades heating the air fiercely.

At the sound there was a shout on the ground below, but before the excitement had time to spread, or before any of the guards could form a notion of what was about to take place, Tom had sent his craft to earth on a sharp slant, closer to the line of prisoners than he had dared to hope.

Mr. Petrofsky sprang out on deck, and in a loud voice called in Russian:

"Peter! Peter! If you are there, come here! Come quickly! It is I, your brother Ivan who speaks. I have come to save you—save you in the wonderful airship of Tom Swift! Come quickly and we will take you away! Peter Petrofsky!"

For a moment there was silence, and then the sound of some one running rapidly was borne to the ears of the waiting ones. It was followed, a moment later, by angry shouts from the guards.

"Quick! Quick, Peter!" cried the brother, "over this way!"

For an instant only the exile showed a single electric flash light, that his brother might see in which direction to run. The echo of the approaching footsteps came nearer, the shouts of the guards redoubled, and then came the sound of many men running in pursuit.

"Hurry, Peter, hurry!" cried Mr. Petrofsky, and, as he spoke in Russian the guards, of course, understood.

Suddenly a rifle shot rang out, but the weapon seemed to have been fired in the air. A moment later a dark figure clambered aboard the airship.

"Peter, is it you?" cried Ivan Petrofsky, hoarsely.

"Yes, brother! But get away quickly or the whole guard will be swarming about here!"

"Praise the dear Lord you are saved!"

"Is it all right?" cried Tom, who wanted to make sure they were saving the right man.

"Yes! Yes, Tom! Go quickly!" called Ivan Petrofsky, as he folded his brother in his arms. A moment later, with a roar, the Falcon shot away from the earth, while below sounded angry cries, confused shouts and many orders, for the guards and their officers had never known of such a daring rescue as this.



CHAPTER XXII

IN THE HURRICANE

There was a volley of shots from the prison guards, and the flashes of the rifles cut bright slivers of flame in the darkness, but, so rapidly did the airship go up, veering off on a wide slant, under the skillful guidance of Tom that the shots did no harm.

"Bless my bullet pouch!" cried Mr. Damon. "They must be quite excited."

"Shouldn't wonder," calmly observed Ned, as he went to help his chum in managing the airship. "But it won't do them any good. We've got our man."

"And right from under their noses, too," added Ivan Petrofsky exultingly. "This rescue of an exile will go down in the history of Russia."

The two exile brothers were gazing fondly at each other, for now that the Falcon was so high, Tom ventured to turn on the lights.

A moment later the three Russians were excitedly conversing, while Tom and Ned managed the craft, and Mr. Damon, after listening a moment to the rapid flow of the strange language, which quite fascinated him, hurried to the galley to prepare a meal for the rescued one, who had been taken away before he had had a chance to get his supper.

His wonder at his startling and unexpected rescue man well be imagined, but the joy at being reunited to his brother overshadowed everything for the time being. But when he had a chance to look about, and see what a strange craft he was in, his amazement knew no bounds, and he was like a child. He asked countless questions, and Ivan Petrofsky and Mr. Borious took turns in answering them. And from now on, I shall give the conversation of the two new Russians just as if they spoke English, though of course it had to be translated by Ivan Petrofsky, Peter's brother.

If Peter was amazed at being rescued in an airship, his wonder grew when he was served with a well-cooked meal, while high in the air, and while flying along at the rate of fifty miles an hour. He could not talk enough about it.

By degrees the story of how Tom and his friends had started for Russia was told, and there was added the detail of how Mr. Borious came to be picked up.

"But brother Ivan, you did not come all that distance to rescue me; did you?" asked Peter.

"Yes, partly, and partly to find the platinum mine."

"What? The lost mine that you and I stumbled upon in that terrible storm?"

"That is the one, Peter."

"Then, Tom Swift may as well return. I doubt if we can even locate the district where it was, and if we did find it, the winds blow so that even this magnificent ship could not weather the gales."

"I guess he doesn't understand about my air glider," said Tom with a smile, when this was translated to him. "I wish I had a chance to put it together, and show him how it works."

"Oh, it will work all right," replied Ned, who was very proud of his friend's inventive ability.

"Now, what is the next thing to be done?" asked Tom, a little later that evening, when, supper having been served, they were sitting in the main cabin, talking over the events of the past few days. "I'd like to get on the track of that platinum treasure."

"And we will do all in our power to aid you," said Ivan Petrofsky. "My brother and I owe much to you—in fact Peter owes you his life; do you not?" and he turned to him.

"I do," was the firm answer.

"Oh, nonsense!" exclaimed Tom, who did not like to be praised. "I didn't do much."

"Much! You do not call taking me away from that place—that sulphur mine—that horrible prison barrack with the cruel guards—you do not call that much? My friend," spoke the Russian solemnly, "no one on earth has done so much for me as you have, and if it is the power of man to show you where that lost mine is, my brother and I will do so!"

"Agreed," spoke Ivan quietly.

"Then what plans shall we make?" asked Tom, after a little more talk. "Are we to go about indiscriminately, or is there any possible way of getting on the trail?"

"My brother and I will try and decide on a definite route," spoke Ivan Petrofsky. "It is some time since I have seen him, and longer since we accidently found the mine together, but we will consult each other, and, if possible make some sort of a map."

This was done the next day, the present maps aboard the Falcon being consulted, and the brothers comparing notes. They began to lay out a stretch of country in which it was most likely the lost mine lay. It took several days to do this, for sometimes one brother would forget some point, and again the other would. But at last they agreed on certain facts.

"This is the nearest we can come to it," said Ivan Petrofsky to Tom. "The lost platinum mine lies somewhere between the city of Iakutsk and the first range of the Iablonnoi mountains. Those are the northern and southern boundaries. As for the western one, it is most likely the Lena river, and the eastern one the Amaga river. So you see you have quite a large stretch of country to search, Tom Swift."

"Yes, I should say I had," agreed the young inventor. "But I have had harder tasks. Now that I know where to head for I'll get there as soon as possible."

"And what will you do when you arrive?" asked Ned.

"Fly about in the Falcon, in ever-widening circles, starting as near the centre of that area as possible," replied Tom. "And as soon as I run into a steady hurricane I'll know that I'm at the place of the big winds, and I'll get out my glider, for I'll be pretty sure to be near the place."

"Bless my gas meter!" cried Mr. Damon. "That's the talk!"

Tom put his plan into operation at once, by heading the nose of his craft for the desolate region mapped out by the Russian brothers.

The days that followed were filled with weary searching. It was like the time when they had sought for the plain of the great ruined Temple in Mexico, that they might locate the underground city of gold. Only in this case they had no such landmark as a great Aztec ruin to guide them.

What they were seeking for was something unseen, but which could be felt—a mysterious wind—a wind that might be encountered any time, and which might send the Falcon to the earth a wreck.

The Russian brothers, staggering about in the storm, had seen the mine under different conditions from what it would be viewed now. Then it was winter in Siberia. Now it was summer, though it was not very warm.

On and on sailed the Falcon. The weather could not have been better, but for once Tom wanted bad weather. He wanted a blow—the harder the better—and all eyes anxiously watched the anemometer, or wind gage. But ever it revolved lazily about in the gentle breeze.

"Oh, for a hurricane!" cried Tom.

He got his wish sooner than he anticipated. It was about two days after this, when they were going about in a great circle, about two hundred miles from the imaginary centre of the district in which the mine lay, that, as Mr. Damon was getting dinner a dish he was carrying to the table was suddenly whisked out of his hand.

"I say, what's the matter?" he cried. "Bless my—"

But he had no time to say more. The airship fairly stood on end, and then, turning completely about, was rapidly driven in the opposite direction, though her propellers were working rapidly.

"What's up?" yelled Ned.

"We are capsizing!" shouted Ivan Petrofsky, and indeed it seemed so, for the airship was being forced over.

"I guess we've struck what we want!" cried Tom. "We're in a hurricane all right! This is the place of the big wind! Now for my air glider, if I can get the airship to earth without being wrecked! Ned, lend a hand! We've got our work cut out for us now!"



CHAPTER XXIII

THE LOST MINE

For several moments it seemed as if disaster would overtake the little band of platinum-hunters. In spite of all that Tom and Ned could do, the Falcon was whipped about like a feather in the wind. Sometimes she was pointing her nose to the clouds, and again earthward. Again she would be whirling about in the grip of the hurricane, like some fantastic dancer, and again she would roll dangerously. Had she turned turtle it probably would have been the last of her and of all on board.

"Yank that deflecting lever as far down as it will go!" yelled Tom to his chum.

"I am. She won't go any farther."

"All right, hold her so. Mr. Damon, let all the gas out of the bag. I want to be as heavy as possible, and get to earth as soon as we can."

"Bless my comb and brush!" cried the odd man. "I don't know what's going to become of us."

"You will know, pretty soon, if the gas isn't let out!" retorted Tom grimly, and then Mr. Damon hastened to the generator compartment, and opened the emergency outlet.

Finally, by crowding on all the possible power, so that the propellers and deflecting rudders forced the craft down, Tom was able to get out of the grip of the hurricane, and landed just beyond the zone of it on the ground.

"Whew! That was a narrow squeak!" cried Ned, as he got out. "How'd you do it, Tom?"

"I hardly know myself. But it's evident that we're on the right spot now."

"But the wind has stopped blowing," said Mr. Damon. "It was only a gust."

"It was the worst kind of a gust I ever want to see," declared the young inventor. "My air glider ought to work to perfection in that. If you think the wind has died out, Mr. Damon, just walk in that direction," and Tom pointed off to the left.

"Bless my umbrella, I will," was the reply and the odd man started off. He had not gone far, before he was seen to put his hand to his cap. Still he kept on.

"He's getting into the blow-zone," said Tom in a low voice.

The next moment Mr. Damon was seen to stagger and fall, while his cap was whisked from his head, and sent high into the air, almost instantly disappearing from sight.

"Some wind that," murmured Ned, in rather awe-struck tones.

"That's so," agreed his chum. "But we'd better help Mr. Damon," for that gentleman was slowly crawling back, not caring to trust himself on his feet, for the wind had actually carried him down by its force.

"Bless my anemometer!" he gasped, when Tom and Ned had given him a hand up. "What happened?"

"It was the great wind," explained Tom. "It blows only in a certain zone, like a draft down a chimney. It is like a cyclone, only that goes in a circle. This is a straight wind, but the path of it seems to be as sharply marked as a trail through the forest. I guess we're here all right. Does this location look familiar to you?" he asked of the Russian brothers.

"I can't say that it does," answered Ivan. "But then it was winter when we were here."

"And, another thing," put in Peter. "That wind zone is quite wide. The mine may be in the middle, or near the other edge."

"That's so," agreed Tom. "We'll soon see what we can do. Come on, Ned, let's get the air glider out and put her together. She'll have a test as is a test, now."

I shall not describe the tedious work of re-assembling Tom Swift's latest invention in the air craft line—his glider. Sufficient to say that it was taken out from where it had been stored in separate pieces on board the Falcon, and put together on the plain that marked the beginning of the wind zone.

It was a curious fact that twenty feet away from the path of the wind scarcely a breeze could be felt, while to advance a little way into it meant that one would at once be almost carried off his feet.

Tom tested the speed of it one day with a special anemometer, and found that only a few hundred feet inside the zone the wind blew nearly one hundred miles an hour.

"What is it like inside, I wonder?" asked Ned.

"It must be terrific," was his chum's opinion.

"Dare you risk it, Tom?"

"Of course. The harder it blows the better the glider works. In fact I can't make much speed in a hundred-mile wind for with us all on board the craft will be heavy, and you must remember that I depend on the wind alone to give me motion."

"What do you think causes the wind to blow so peculiarly here Tom?" went on Ned.

"Oh, it must be caused by high mountain ranges on either side, or the effects of heat and cold, the air being evaporated over a certain area because of great heat, say a volcano, or something like that; though I don't know that they have volcanoes here. That creates a vacuum, and other air rushes in to fill the vacant space. That's all wind is, anyhow, air rushing in to fill a vacuum, or low pressure zone, for you remember that nature abhors a vacuum."

It took nearly a week to assemble the Vulture, as Tom had named his latest craft, from the fact that it could hover in the air motionless, like that great bird. At last it was completed and then, weights being taken aboard to steady it, all was ready for the test. Tom would have liked to have taken all his passengers in the glider, for it would work better then, but the three Russians were timid, though they promised to get aboard after the trial.

The test came off early one morning, Tom, Ned and Mr. Damon being the only ones aboard. Bags of sand represented the others. The glider was wheeled to the edge of the wind zone and they took their places in the car. It was hard work for the gale, that had never ceased blowing for an instant since they found its zone, was very strong. But the glider remained motionless in it, for the wing planes, the rudders, and equalizing weights had been adjusted to make the strain of the wind neutral.

"All ready?" asked Tom, when his chum and his friend were in the enclosed car of the glider.

"As ready as I ever shall be," answered Ned.

"Bless my suspenders! Let her go, Tom, and have it over with!" cried the odd man.

The young inventor pulled a lever, and almost instantly the glider darted forward. A moment later it soared aloft, and the three Russians cheered. But their voices were lost in the roar of the hurricane, as Tom sent his craft higher and higher.

It worked perfectly, and he could direct it almost anywhere. The wind acted as the motive power, the bending and warping wings, and the rudders and weights controlling its force.

"I'm going higher, and see if I can remain stationary!" yelled Tom in Ned's ear. His chum only nodded. Mr. Damon was seated on a bench, clinging to the sides of it as if he feared he would fall off.

Higher and higher went the Vulture, ever higher, until, all at once, Tom pulled on another lever and she was still. There she hung in the air, the wind rushing through her planes, but the glider herself as still and quiet as though she rested on the ground in a calm. She hardly moved a foot in either direction, and yet the wind, as evidenced by the anemometer was howling along at a hundred and twenty miles an hour!

"Success!" cried Tom. "Success! Now we can lie stationary in any spot, and spy out the land through our telescope. Now we will find the lost platinum mine!"

"Well, I'm not deaf," responded Ned with a smile, for Tom had fairly yelled as he had at the start, and there was no need of this now, for though the wind blew harder than ever it was not opposed to any of the weights or planes, and there was only a gentle humming sound as it rushed through the open spaces of the queer craft.

Tom gave his glider other and more severe tests, and she answered every one. Then he came to earth.

"Now we'll begin the search," he said, and preparations were made to that end. The Russians, now that they had seen how well the craft worked, were not afraid to trust themselves in her.

As I have explained, there was an enclosed car, capable of holding six. In this were stores, supplies and food sufficient for several days. Tom's plan was to leave the airship anchored on the edge of the wind zone, as a sort of base of supplies or headquarters. From there he intended to go off from time to time in the wind-swept area to look for the lost mine.

There were weary days that followed. Hour after hour was spent in the air in the glider, the whole party being aboard. Observation after observation was taken, sometimes a certain strata of wind enabling them to get close enough to the earth to use their eyes, while again they had to use the telescopes. They covered a wide section but as day after day passed, and they were no nearer their goal, even Tom optimistic as he usually was, began to have a tired and discouraged look.

"Don't you see anything like the place where you found the mine?" he asked of the exile brothers.

They could only shake their heads. Indeed their task was not easy, for to recognize the place again was difficult.

More than a week passed. They had been back and forth to their base of supplies at the airship, often staying away over night, once remaining aloft all through the dark hours in the glider, in a fierce gale which prevented a landing. They ate and slept on board, and seldom descended unless at or near the place where they had left the Falcon. Once they completely crossed the zone of wind, and came to a calm place on the other side. It was as wild and desolate as the other edge.

Nearly two weeks had passed, and Tom was almost ready to give up and go back home. He had at least accomplished part of his desire, to rescue the exile, and he had even done better than originally intended, for there was Mr. Borious who bad also been saved, and it was the intention of the young inventor to take him to the United States.

"But the platinum treasure has me beat, I guess," said Tom grimly. "We can't seem to get a trace of it."

Night was coming on, and he had half determined to head back for the airship. Ivan Petrofsky was peering anxiously down at the desolate land, over which they were gliding. He and his brother took turns at this.

They were not far above the earth, but landmarks, such as had to be depended on to locate the mine, could not readily be observed without the glass. Mr. Damon, with a pair of ordinary field glasses, was doing all he could to pick out likely spots, though it was doubtful if he would know the place if he saw it.

However, as chance willed it, he was instrumental in bringing the quest to a close, and most unexpectedly. Peter Petrofsky was relieving his brother at the telescope, when the odd man, who had not taken his eyes from the field glasses, suddenly uttered an exclamation.

"Bless my tooth-brush!" he cried. "That's a most desolate place down there. A lot of trees blown down around a lake that looks as black as ink."

"What's that!" cried Ivan Petrofsky. "A lake as black as ink? Where?"

"We just passed it!" replied Mr. Damon.

"Then put back there, as soon as you can, Tom!" called the Russian. "I want to look at that place."

With a long, graceful sweep the young inventor sent the glider back over the course. Ivan Petrofsky glued his eyes to the telescope. He picked out the spot Mr. Damon had referred to, and a moment later cried:

"That's it! That's near the lost platinum mine! We've found it again, Tom—everybody! Don't you remember, Peter," he said turning to his brother, "when we were lost in the snow we crawled in among a tangle of trees to get out of the blast. There was a sheet of white snow near them, and you broke through into water. I pulled you out. That must have been a lake, though it was lightly frozen over then. I believe this is the lost mine. Go down, Tom! Go down!"

"I certainly will!" cried the youth, and pulling on the descending lever he shunted the glider to earth.



CHAPTER XXIV

THE LEAKING TANKS

Like a bird descending from some dizzy height, the Vulture landed close to the pool of black water. It was a small lake and the darkness must have been caused by its depth, for later when they took some out in a glass it was as clear as a crystal. Then, too, there might have been black rocks on the bottom.

"Can it be possible that we are here at last?" cried Tom, above the noise of the gale, for the wind was blowing at a terrific rate. But our friends knew better now how to adjust themselves to it, and the lake was down in a valley, the sides of which cut off the power of the gale. As for the glider it was only necessary to equalize the balance and it would remain stationary in any wind.

"This is the place! This is the place!" cried Ivan Petrofsky. "Don't you remember, Peter?"

"Indeed I do! I have good cause to! This is where we found the platinum!"

"Bless my soul!" cried Mr. Damon. "Where is it, in the lake?"

"The mine itself is just beyond that barrier of broken and twisted trees," replied the elder Russian brother. "It is an irregular opening in the ground, as though once, centuries ago, an ancient people tried to get out the precious metal. We will go to it at once."

"But it is getting late," objected Ned.

"No matter," said Tom. "If we find any platinum we'll stay here all night, and longer if necessary to get a good supply. This is better than the city of gold, for we're in the open."

"I should say we were," observed Mr. Damon, as he bent to the blast, which was strong, sheltered even as they were.

"Will it be safe to remain all night?" asked Mr. Borious, with a glance about the desolate country.

"We have plenty of food," replied Tom, "and a good place to stay, in the car of the glider. I don't believe we'll be attacked."

"No, not here," said the elder Petrofsky. "But we still have to go back across Siberia to escape."

"We'll do it!" cried Tom. "Now for the platinum treasure!"

They went forward, and it was no easy work. For the wind still New with tremendous force though nothing like what it did higher up. And the ground was uneven. They had to cling to each other and it was very evident that no airship, not even the powerful Falcon, could have reached the place. Only an air glider would answer.

It took them half an hour to get to the opening of the ancient mine, and by that time it was nearly dark. But Tom had thought to bring electric torches, such as he had used in the underground city of gold, and they dispelled the gloom of the small cavern.

"Will you go in?" asked Ivan Petrofsky, when they had come to the place. He looked at Tom.

"Go in? Of course I'll go in!" cried our hero, stepping forward. The others followed. For some time they went on, and saw no traces of the precious metal. Then Ned uttered a cry, as he saw some dull, grayish particles imbedded in the earth walls of the shaft.

"Look!" he cried.

Tom was at his chum's side in a moment

"That's platinum!" cried the young inventor. "And of the very highest grade! But the lumps are very small."

"There are larger ones beyond," said the younger Russian brother.

Forward they pressed, and a moment later coming around a turn in the cavern where some earth had fallen away, evidently recently, Tom could not repress a cry of joy. For there, in plain sight, were many large lumps of the valuable metal, in as pure a state as it is ever found. For it is always mixed with other metals or chemicals.

"Look at that!" cried Tom. "Look at that! Lumps as large as an egg!" and he dug some out with a small pick he had brought along, and stuffed them into his pocket.

"Bless my check book!" cried Mr. Damon, "and that stuff is as valuable as gold!"

"More so!" cried Tom enthusiastically.

"Oh, here's a whopping big one!" cried Ned. "I'll bet it weighs ten pounds."

"More than that!" cried Tom, as he ran over and began digging it out, and they found later that it did. Platinum is usually found in small granules, but there are records of chunks being found weighing twenty pounds while others, the size of pigeons' eggs, are not uncommon.

"Say, this is great!" yelled Ned, discovering another large piece, and digging it out.

"I am glad we could lead you to it," said the elder Russian brother. "It is a small return for what you did for us!"

"Nonsense!" cried Tom. "These must be a king's ransom here. Everybody dig it out! Get all you can."

They were all busy, but the light of the two torches Tom had brought was not sufficient for good and efficient work, so after getting several thousand dollars worth of the precious metal, they decided to postpone operations until morning, and come with more lights.

They were at the work soon after breakfast, the night in the air glider having passed without incident. The treasure of platinum proved even richer than the Russians had thought, and it was no wonder the Imperial government had tried so hard to locate it, or get on the trail of those who sought it.

"And it's all good stuff!" cried Tom eagerly. "Not like that low-grade gold of the underground city. I can make my own terms when I sell this."

For three days our friends dug and dug in that platinum mine, so many years lost to man, and when they got ready to leave they had indeed a king's ransom with them. But it was to be equally divided. Tom insisted on this, as his Russian friends had been instrumental in finding it. Toward the end of the excavation large pieces were scarce, and it was evident that the mine was what is called a "lode."

"Well, shall we go back now?" asked Tom one day, after the finish of their mining operations. The work was comparatively simple, as the platinum lumps had merely to be dug out of the sides of the cave. But the loneliness and dreariness of the place was telling on them all.

"Can't we carry any more?" asked Ned.

"We could, but it might not be safe. I don't want to take on too much weight, as my glider isn't as stable as the airship. But we have plenty of the metal.

"Indeed we have," agreed Ivan Petrofsky. "Much of mine and my brother's will go toward helping relieve the sufferings of the Siberian exiles," he added.

"And mine, too," said Alexis Borious.

They started back early the next morning in a more terrific gale than in any the glider had yet flown. But she proved herself a stanch craft, and soon they were at the place where they had left the airship. It was undisturbed.

Four days were spent in taking apart the glider and packing it on board the Falcon. Then, with the platinum safely stored away Tom, with a last look at the desolate land that had been so kind to them, sent his craft on her homeward way.

It was when they were near the city of Pirtchina, on the Obi river, that what might have proved a disastrous accident occurred. They were flying along high, and at great speed, for Tom wanted to make all the distance he could, to get out of Siberia the more quickly. They had had a fair passage so far, and were congratulating themselves that they would soon be in civilization again.

Suddenly, Mr. Damon, who had been on the after deck, taking observations through a telescope, came running forward, crying out:

"Tom! Tom! What is that water dripping from the back part of the airship?"

"Water?" exclaimed Tom. "No water is dripping from there."

"Come and look," advised Mr. Damon.

The young inventor raced back with him. He saw a thin, white stream trickling down from the lower part of the craft. Tom sniffed the air suspiciously.

"Gasolene! It's gasolene!" he cried. "We must have a leak in the supply tanks!"

He dashed toward the reserve storeroom, and at that moment, with a suddenness that was startling, the motor stopped and the Falcon lurched toward the earth.



CHAPTER XXV

HOMEWARD BOUND—CONCLUSION

"All right!" yelled Ned, as soon as he heard Tom's cry. "I've got her under control. We'll volplane down."

"Is it dangerous? Are we in danger?" asked Peter Petrofsky of his brother, in Russian.

"I guess there's no danger, where Tom Swift's concerned," was the answer. "I have not volplaned much, but it will be all right I think."

And it was, for with Ned Newton to guide the craft, while Tom did his best to stop the leak, the craft came gently to earth on the outskirts of a fairly large Siberian city. Almost instantly the Falcon was surrounded by a curious throng.

"You had better keep inside," said Ivan Petrofsky to his brother and Mr. Borious. "Descriptions of you are probably out broadcast by now, but I am still sufficiently disguised, I think."

"But what is to be done?" demanded the younger Russian brother. "If the gasolene is gone, how can we leave here?"

"Trust Tom Swift for that," was the reply. "Keep out of sight now, there is a large crowd outside."

Tom came from the tank room. There was a despondent look on his face.

"It's all gone—every drop," he said. "That's what made the motor stop."

"What's gone?" asked Mr. Damon.

"The gasolene. We sprung a leak in the main tank, somehow, and it all flowed out while we were flying along."

"Haven't you any more?"

"Not a bit. I was drawing on the reserve tank, hoping to get to civilization before I needed more. But its too late now. We will have to—"

"Bless my snow shoes!" cried Mr. Damon. "Don't say we'll have to stay here—in Siberia! Don't say that. My wife—"

"No, we won't have to stay here if we can get a supply of kerosene," interrupted Tom. "The motor will burn that. The only trouble is that we may be detained. The authorities probably know us by this time, and are on the watch."

"Then get it before they know we are here," advised Ned.

"I'll try," said Tom, and he at once conferred with the elder Petrofsky. The latter said he was sure kerosene could be had in town, and, rather than risk going in themselves, they hired a wagoner who agreed, for liberal pay, to go and return with a quantity. Until then there was nothing to do but wait.

Meanwhile the crowd of curiosity seekers grew. They thronged around the airship, some of them meddling with various devices, until Tom had to order them away with gestures.

One particularly inquisitive man insisted on pulling or twisting everything, until he happened to touch a couple of live wires, giving himself quite a shock, and then he ran away howling. But still the crowd increased, and at last Mr. Petrofsky said:

"I don't like this, Tom?"

"Why not?" They were all inside the craft, looking out and waiting for the return of the man with the kerosene. The leak in the tank had proved to be a small one, and had quickly been soldered. It had been open a long time, which accounted for the large amount of gasolene escaping. "What don't you like, Mr. Petrofsky?"

"So many men surrounding us. I believe some of them are officers dressed in civilians' clothes, and a Russian officer never does that unless he has some object."

"And you think the object is—?"

"To capture us."

"If it was that, wouldn't they have done it long ago—when we first came down?"

"No, they are evidently waiting for something perhaps for some high official, without whose orders they dare do nothing. Russia is overrun with officialdom."

And a little later Ivan Petrofsky's suspicion proved true. There arrived a man in uniform, who spoke fairly good English, and who politely asked Tom if he would not delay the start of the airship, again, until the governor could arrive from his country place to see it.

"We know you are going to leave us," said the Russian with a smile, "for you have sent for kerosene. But please wait."

"If your governor comes soon we'll wait," replied Tom. "But we are in a hurry. I wish that kerosene fellow would get a move on," he murmured.

"Oh, he will doubtless be here soon," said the officer. "Might I be permitted to come aboard and wait for my chief?"

"Sorry, but it's not allowed," replied our hero, straining his eyes down the road for a sight of the wagoner. At last he came, and Tom breathed easier.

But the crowd was bigger, and some of the men, though poorly dressed, seemed to be persons in authority. Tom had no doubt but what there was a plot afoot to detain him, and arrest the exiles, and that there were disguised soldiers in the throng. But they could not act without the governor's orders, and he was probably on his way with all haste.

"Lively now, get that kerosene in the tanks!" cried Tom to the man, motioning in lieu of using Russian. The youth was not going to meet the governor if he could help it.

Now it was a curious thing, but the more that wagoner and his helpers seemed to try to hurry, and pour the oil from the cans into the tank-opening of the airship, the slower they worked. They got in each others' way, dropped some cans, spilled others, and in general made such poor work at it that Tom saw there was something in the wind.

"Ned!" he exclaimed, "they're doing all they can to detain us. We've got to put that oil in ourselves. Just as we did the gasolene in France. It's the same sort of a delay game."

"Right, Tom! I'm with you."

"And I'll warn the crowd back, by telling them we are likely to blow up any minute!" added Ivan Petrofsky, which warning he shouted in Russian a moment later.

Backward leaped the throng, as though a bomb bad been thrown into their midst, even the supposed officers joining in the retreat. The oil wagon was now easy of access, and Tom and Ned, with Mr. Damon to aid them, hastened toward it. Then the work of filling the tanks went on in something like good old, United States fashion.

The last gallon of kerosene had been put aboard, and Tom and Ned with Mr. Damon, had climbed on deck, when the gaily uniformed officer, who had requested the delay, came riding up furiously.

"Hold! Hold! If you please!" he cried. "The governor has come. He wants to see you."

"Too late!" answered Tom. "Give him our best regards and ask him to some to the United States if he wants to see us. Sorry we haven't cards handy. Ned, take the pilot house, and shoot her up sharp when you get the signal. I'm going to run the motor. I don't know just how she'll behave on the kerosene."

"You must remain!" angrily cried the officer.

"The United States doesn't take 'must' from anybody, from the Czar down!" cried Tom as he disappeared into the motor room. The window was open, and the youth turned on the power the official cried again to him:

"Halt! Here comes the governor! I declared you arrested by his orders, and in the name of the Czar!"

"Nothing doing!" yelled Tom, and then, looking from the window, he saw approaching a troop of Cossacks, in the midst of whom rode a man in a brilliant uniform—evidently the governor.

"Stop! Stop!" cried the official.

"Here we go, Ned!" yelled Tom, and turning on more power the Falcon arose swiftly, before the very eyes of the angry governor, and his staff of Cossack soldiers.

Up and up she went, faster and faster, the motors working well on the kerosene. Higher and higher. The governor and his soldiers were directly below her now.

"Stop! Stop! You must stop. The Imperial governor orders it!" yelled the officer, evidently his Excellency's aide-de-camp.

"We can't hear you!" shouted Tom, waving his hand from the motor room window, and then, turning on still more power he flew over the city, taking his friends and the valuable supply of platinum with him. So surprised were the soldiers that they did not fire a shot, but had they done so it is doubtful if much damage could have been done.

"And now for home!" cried Tom, and homeward hound the Falcon was after a perilous trip through two storms. But she weathered them well.

In due season they reached Paris again, and now, having no reason for concealment, they flew boldly down, to change what remained of the kerosene for gasolene, as the motor worked better on that. The secret police learned that the exiles were aboard, but they could do nothing, as the offenses were political ones, and so Tom kept his friends safe.

Then they started on the long voyage across the Atlantic, and though they had one bad experience in a storm over that mighty ocean, they got safely home to Shopton in due season.

There is little more to tell. The platinum proved to be even more valuable than Tom had expected. He could have sold it all for a large sum, but he preferred to keep most of what he had for his inventive work, and he used considerable of it in his machinery. Ned disposed of his, selling Tom some at a lower price than market quotations, and the Russians got a good price for theirs, turning the money into the fund to help their fellow exiles. Mr. Damon also made a good donation to the cause, as did Tom and Ned.

Mr. Petrofsky and his brother, with the other exile, joined friends in New York, and promised to come and see Tom when they could.

"Well, I suppose you'll take a long vacation now," said Mary Nestor, to Tom, when he called on her one evening to present her a unique ring, with the stones set in some of the platinum he had dug in the Siberian mine.

"Vacation? I have no time for vacations!" said the young inventor. "I'm soon going to work on my silent airship, and on some other things I have in mind. I want more adventures."

"Oh, you greedy boy!" exclaimed Mary with a laugh.

And what adventures Tom had next will be found in the next book of this series, which will be entitled, "Tom Swift in Captivity; Or, a Daring Escape by Airship."

Tom had several offers to give exhibitions in his air glider, from aviation committees at various meets, but he declined.

"I haven't time," he declared. "I'm too busy."

"You ought to rest," his chum Ned advised him.

"'Bless my alarm clock!' as Mr. Damon would say," exclaimed Tom. "The best rest is new work," and then he began sketching his ideas for a silent motor craft, during which we will take leave of him for a while.

THE END