Through the black opening that confronted the boys came no sound. It was dark and mysterious. Even Ruddy, brave as he was, seemed to feel some mystic spell as he left, for a time, the hole beneath the gnarled tree and came to stand beside the lads. They saw him slink back and his tail droop¹ between his legs.  
“Shall we go in?” asked Chot again, rather puzzled by the silence of his chum. “Ruddy doesn’t seem to like it, but maybe he’ll follow when we go in.”
 
Rick shook his head.
 
“Not yet,” he answered. “Let’s wait until morning, and then we’ll take lanterns, ropes and things.”
 
“And something to eat,” added Chot. “We may be gone all day. And are you going to tell Uncle Tod?”
 
“Not until we find something that’s worth while telling,” was Rick’s answer. “He and Sam Rockford would only laugh at us if they came here and found out we’d chucked aside these stones just to uncover a hole in the side of the hill.”
 
“I think it’s more than just a hole,” declared Chot. “Don’t you think it’s part of the tunnel?”
 
“I’m sure it is!” asserted Rick. “You wouldn’t get that much air coming from just a hole or cave. There wouldn’t be any current. But you can feel how hard this wind pours out.”
 
“It sure does,” agreed Chot, and, indeed, there was a very decided² current of air coming from the opening they had uncovered by moving the stones.
 
“That shows there’s a shaft³, or tunnel, with air coming in the other end,” declared Rick. “Now the thing for us to do is to go in and—”
 
“Find Lost River,” interrupted Chot with a laugh.
 
“That’s it,” agreed his chum. “But we’ll go back to camp and start out again in the morning.”
 
“And aren’t you going to tell Uncle Tod?” Chot asked.
 
“Nope!” decided Rick. “Let’s have something worth while to tell him.”
 
“All right!” agreed Chot.
 
And so it was decided. Perhaps the boys were foolish in this, but they did not stop to consider the risks they took. Few boys do. It is not the quality of youth to think. Rush into danger, and, if possible, rush out again. That is why youth does so much—it seldom stops to count the cost.
 
“Come on, Ruddy!” called Rick, for the dog, after a brief inspection⁴ of the “tunnel,” as the boys called it, an inspection which did not seem to indicate that he liked it—had gone back to the hole beneath the tree.
 
Through the gathering⁵ darkness, but along a trail they now well knew, the boys and their dog tramped back to Uncle Tod’s camp. They went by the “outside route,” as they called it, as distinguished⁶ from the way leading through the tunnel in which Lost River once flowed to wash out the pay dirt at the mine.
 
“Where in the world have you lads been?” demanded Uncle Tod, as Rick, Ruddy and Chot appeared some time after supper had been served.
 
“Oh, prospecting⁷,” answered Rick, vaguely⁹ enough.
 
Uncle Tod laughed.
 
“Guess he’s a chip from the old block—meaning myself,” he said to Sam. “Did you find any nuggets?” he asked.
 
“Not yet,” answered Rick with a look at Chot to make sure his chum would say nothing of their discovery, which, after all, might amount to nothing.
 
“Well, sit up and have some grub,” invited Sam. “I kept the beans warm for you.”
 
“Thanks,” murmured Rick.
 
Fortunately Uncle Tod and Sam were too much occupied, in talking about a promising¹¹ prospect⁸ they had discovered that day, to pay great attention to the boys, and so the men did not closely question Rick and Chot.
 
The two boys did not sleep as soundly nor as easily that night as they had on other nights since coming to Lost River camp. The reason was they were thinking too much about what might lie in that dark and mysterious hole they had uncovered.
 
However, youth does not need very much sleep to refresh it, and what Rick and Chot obtained was enough to make them as fresh as daisies next morning. They were up, if not exactly with the lark¹², very shortly following that bird famed for early rising, and after breakfast Uncle Tod said:
 
“Boys, Sam and I are going off prospecting. It’s in a hard place, or we’d ask you to come along. I don’t like to leave you here at the camp, but—”
 
“Oh, we don’t mind,” Rick was quick to say. “We’ll go off by ourselves and have some fun.”
 
“All right,” agreed Uncle Tod, “but be careful, and take Ruddy with you. That dog knows a lot.”
 
“He sure does,” assented¹³ Rick.
 
Matters were turning out just as he and Chot hoped they would. The boys and dog could take what supplies and food they needed and spend all day exploring the mysterious tunnel.
 
“It couldn’t be better,” said Rick exultantly¹⁴ as Uncle Tod and his partner shuffled¹⁵ off down the trail.
 
“That’s right,” agreed Chot. “And if we come back and tell ’em we’ve found Lost River—”
 
“Oh, boy!” chanted Rick............