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 he 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!"