"It's the last word in aeroplanes. You don't need a motor to make it go." "Don't need a motor?" "No, the wind does it all. It's a sort of aeroplane, but the motion comes from the wind, acting on different planes, and this is accomplished by shifting weights. In it you can stand still in a fierce gale, if you like." "How, by tying her fast on the ground?" "No, hovering in the air. It's all done by getting the proper balance. The harder the wind blows the better the air glider works, and that's why I think it will be just the thing for Siberia. I'm going to get right at work on it, and you'll help me; won't you?" "I sure will. Say, is platinum worth much?" "Worth much? I should say it was! It's got gold beat now, and the available supply is very small, and it's getting more scarce. Russia has several mines, and the metal is of good quality. I've used some Russian platinum, but the kind Mr. Petrofsky gave me to-day was better than the best I ever had. If we can only find that lost mine we'll be millionaires all right." "That's what we thought when we found the city of gold, but the gold wasn't of as fine a grade as we hoped." "Well, nothing like that can happen in this platinum deal. It sure is rich ore that Mr. Petrofsky and his brother found. Poor fellow! To think of being an exile in that awful country, not knowing where you may be sent next. No wonder Mr. Petrofsky wants to rescue him." "That's right. Well, here we are. I wonder what your father will say when he hears you're thinking of another expedition, Tom?" "Oh, he'll want me to go when he hears about the exile." "And I'm sure my folks will let me go. How about Mr. Damon?" "I don't believe we can hold him back. It will make a nice party, just you and I, and Mr. Damon and Mr. Petrofsky. That will leave room for the other Russian--if we can rescue him," and with that Tom shut off the engine and glided to earth. It may well be imagined that Mr. Swift was surprised when his son told him the latest news, but he did not offer any serious objection to the young inventor going to Siberia. "Only you must be careful," he said. "Those Russian officers are ugly when it comes to trying to take away any of their prisoners. And this air glider--I don't exactly know about that. It's a new machine, and you want to be sure it works before you trust yourself to it." "I will," promised Tom. "Say, I've got plenty of work ahead of me,--to get my big airship in shape, and build the glider. You'll have to help me, dad." "I will, son. Now tell me more about this Mr. Petrofsky." Which Tom did. The days that followed were indeed busy ones for Tom. The young inventor made a model air glider that sailed fairly well, but he knew it would have to work better to be successful, and he bent all his energies in that direction. Meanwhile Mr. Damon had been told of the prospective trip.