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 had 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