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

More than a week pa.s.sed. 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 pa.s.sed, 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 gla.s.s. Mr. Damon, with a pair of ordinary field gla.s.ses, 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 gla.s.ses, 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 pa.s.sed 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 gla.s.s 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 blew 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."