They rested in silence for five minutes by Rick's watch, then resumed, working as close to the top of the pile as they could get.

Scotty suddenly let out a yell, and Rick dodged to escape another rock, then leaped down as the whole pile crumbled. The rocks didn't fall far.

"Look," Scotty said breathlessly.

Rick turned on his own light to supplement the dim beam of Scotty's.

Blackness yawned at the top of the slide!

Scotty was first through the hole, but Rick was right behind him. They emerged in a continuation of the tunnel, but on a higher level. Their lights showed that the tunnel continued.

They followed it for perhaps fifty feet, and found themselves in a cross tunnel in which their tunnel ended.

Scotty looked at Rick in the beam of the flashlight.

"We're somewhere," he said. "But where?"

Rick grinned. There was a definite breeze blowing, and he knew the outside and safety were not far away. "We're in the mine, under the same old hill. Soon as we find the source of that breeze, I'll identify our position within two feet."

Scotty returned the grin. "What are we waiting for? Let's go!"

CHAPTER XVIII

The First Fact

Rick said, "Hold it a minute. Which way do we go? If we a.s.sume the tunnel we came out of was fairly constant in direction, we should turn right to come out on the side of the hill where we saw the Frostola man a while ago. If we turn left, we go deeper into the hill."

Both boys saw the implication the moment the words left Rick's lips.

"Right it is," Rick added quickly. "First thing we have to do is see if there really is a way out."

They turned right into the cross tunnel, and met the breeze head on. So long as they followed the direction of the breeze, they were approaching the outside air.

Within a hundred feet they saw a glimmer of daylight and broke into a run. The glimmer became an opening, irregular in shape, but obviously big enough for an entrance.

"We made it!" Rick exulted. "Let's get a good look at that sunshine!"

"Careful," Scotty cautioned. "We'll have to let our eyes adjust fully or the glare will hurt. Besides, it may not be a good idea to go barging out into the open. Might be some ghosts hanging around."

"You're right. Anyway, let's take a brief look. What's blocking the opening?"

As they approached he saw that it was the trunk of a fallen tree, festooned with blackberry bushes. When they looked through the entrance, blinking in the light, they saw that the tree wasn't really a block, because there was plenty of room to crawl out of the tunnel.

"That trunk makes a mighty good shield," Scotty said thoughtfully. "Bet this entrance is invisible ten feet away, except from the air!"

"And I'll add my own bet, that the entrance is very close to where we met the Frostola man this morning, and that he wonders if we spotted it from the plane."

Scotty shook his head. "No betting on sure things. This explains the interest in the plane, all right. Stand by, old son. I'm going to make a quick recon and be sure the coast is clear."

"Okay. Eyes adjusted?"

"Enough." Scotty went through the entrance on hands and knees. Rick saw his legs as he stood up and surveyed the scene.

"Come on out," Scotty called. "We're alone."

Rick joined him. The fallen tree trunk came above their knees. As Scotty had said, it made an effective shield for the mine entrance.

Rick studied the entrance itself. Probably it had once been a regular timbered entrance, like the one on the other side of the hill, but it had fallen in, the rocks wedging to form a low pa.s.sage into the tunnel inside. The whole hillside was overgrown with brambles, down to the two-rut road below them, almost at the place where they had met the peddler.

"We were within fifty feet of this entrance," Rick said, "and never suspected it."

"The Frostola man knew it. Do you think he thought we knew it?"

"Possible, I suppose. I'm not so interested in what he thinks as I am in what he was doing here. Where would we have ended if we had taken the left-hand turn, do you suppose?"

"Why suppose? Unless you've had enough of mines for one day, we can go back in and find out."

"I've had enough, but not enough to miss a chance like this. My flashlight is still strong and it shouldn't take more than a few minutes."

"Then let's go. No telling when a spook may visit the mine from this end. Of course there's no telling about Uncle Frostola, either. He may be inside."

That hadn't occurred to Rick. He thought it over, then shrugged. "We might as well take the chance. If he is inside, that proves something, and we're two to his one. Besides, it's late, and any sensible man is eating his supper. Come on."

He led the way back into the cave, but because of the peddler's possible presence, he wasn't as headlong in his traversing of the tunnel as he might otherwise have been.

They pa.s.sed the side tunnel from which they had emerged a short time before and entered entirely new territory. It wasn't unlike the rest of the mine, consisting of a main bore with some alcoves indicating either deviations of the ore vein or niches cut to allow ore carts to pa.s.s.

Walking rapidly, but alert for either sound or light, they traveled through the tunnel at a good speed.

"We've been walking quite a while," Rick said finally. "How long do you suppose this shaft is?"

Scotty thought it over. "It can't be any longer than the hill is wide, because we're traveling through the hill. It must be about the same length as the lower tunnel."

"Why two tunnels?" Rick asked. "I doubt that there were two veins of ore."

Scotty reminded him of the good ore they had seen in the ceiling of the lower tunnel. "There might have been just one vein, about two tunnels high. They were limited to pick and shovel for tools in those days, remember, maybe with a little powder for blasting. It would have been more convenient to work within range of tools like shovel and pick. So the ceiling is as high as a man with a pick can reach, and as wide as the ore vein was wide. That's a little confused, but I'm sure you follow me."

"Sounds reasonable," Rick agreed. "Only this tunnel can't go on much farther, or we'll be in the middle of the picnic--Hey! Scotty, take a look!"

Ahead in the tunnel was a box, and on the box was metal that reflected the flashlight's beam. In a second the boys stood over it.

Rick's heart pounded rapidly. Here was the proof. Here was Missing Fact Number One. Here was verification of at least part of their speculation.

An eight-millimeter motion-picture projector!

Rick motioned to the front of the machine with a trembling hand. "Look, there's a film in place, and it's a continuous loop. Once it's threaded it will repeat over and over unless cut off."