The dynamo and magneto were doing much more efficient work since Tom had put the new platinum in, and the Falcon was making better time than ever before. They were flying at a moderate height, and could see wondering men, women and children rush out from their houses, to gaze aloft at the strange sight. Paris was now far behind, and that night they were approaching the borders of Prussia, as Mr. Petrofsky informed them, for he knew every part of Europe. The route, as laid down by Tom and the Russian, would send the airship skirting the southern coast of the Baltic sea, then north-west, to pass to one side of St. Petersburg, and then, after getting far enough to the north, so as to avoid the big cities, they would head due east for Siberia. "In that way I think we'll avoid any danger from the Russian police," remarked the exile. For the next few days they flew steadily on at no remarkable speed, as the extra effort used more gasolene than Tom cared to expend in the motor. He realized that he would need all he had, and he did not want to have to buy any more until he was homeward bound, for the purchase of it would lead to questions, and might cause their detention. Mr. Damon gave his friends good meals and they enjoyed their trip very much, though naturally there was some anxiety about whether it would have a successful conclusion. "Well, if we don't find the platinum mine we'll rescue your brother, if there's a possible chance!" exclaimed Tom one day, as he sat in the pilot house with the exile. "Jove! it will be great to drop down, pick him up, and fly away with him before those Cossacks, or whoever has him, know what's up." "I'm afraid we can't make such a sensational rescue as that," replied Mr. Petrofsky. "We'll have to go at it diplomatically. That's the only way to get an exile out of Siberia. We must get word to him somehow, after we locate him, that we are waiting to help him, and then we can plan for his escape. Poor Peter! I do hope we can find him, for if he is in the salt or sulphur mines it is a living death!" and he shuddered at the memory of his own exile. "How do you expect to get definite information as to where he might be?" asked Tom. "I think the only thing to do is to get in touch with some of the revolutionists," answered the Russian. "They have ways and means of finding out even state secrets. I think our best plan will be to land near some small town, when we get to the edge of Siberia. If we can conceal the airship, so much the better. Then I can disguise myself and go to the village." "Will it be safe?" inquired the young inventor. "I'll have to take that chance. It's the only way, as I am the only one in our party who can speak Russian." "That's right," admitted Tom with a laugh. "I'm afraid I could never master that tongue. It's as hard as Chinese." "Not quite," replied his friend, "but it is not an easy language for an American."