“I guess you’re right,” Pete said dubiously. “Only maybe we’d better go and get Mr. Dalton and the other men first.”
“If we leave the cave we’ll be seen,” Jupiter pointed out. “Besides, there isn’t time. We’ve got to move fast now with the advantages we have.”
“Some advantage,” Pete said, “but I guess you’re right, Jupe. Where do we start? I mean, we’ve been here before, and we didn’t know which way to go.”
“But this time we have more information,” Jupiter said confidently. “This time we know that the digging has something to do with the moaning.”
“How do you figure that?” Pete asked, mystified.
“Because neither the sheriff nor the Daltons nor the newspaper mentioned a word about any digging. So whoever is digging is doing it in secret. By deduction, it has to be connected with the moaning sound because it is the only activity that goes on secretly in the cave when no one is here!”
“Well… ” Pete remained unconvinced.
“Two unexplained facts in the same place almost certainly must be connected,” Jupiter persisted.
Pete’s eyes widened. “Sure, okay. What do we do then?”
“First, you can use your keen sense of direction to find that side passage where we heard the digging.”
Pete nodded. Mentally he retraced their steps since they had been captured by El Diablo. At last he said, “Jupe, I figure we have to find a passage that will take us north-west.”
“That way,” said Jupiter, looking at his compass and pointing to the left.
“Right,” Pete confirmed. “Let’s go!”
The two boys lit their candles, forgetting their earlier caution in the excitement of being so near to a solution of the mystery. As they approached the opening in the north-west wall, a sound came out as if to greet them.
“Aaaaaahhhhhhhh — ooooooo — oooooo — ooo!”
“The moaning!” Pete whispered.
“It never stopped, Pete. We’ve just become accustomed to it.”
“It seems closer now.”
“Because it’s coming from that tunnel!” Jupiter held his candle in the tunnel entrance. A strong draught of air blew the flame, and with it the moan came again.
“Aaaaaahhhhhhhh — ooooooo — oooooo — ooo!”
The two boys plunged into the passage, which soon led into a small cavern.
“I know where we are now, Jupe,” Pete said in a low tone.
“Blow out your candle, then,” whispered Jupiter. “We’ll use our flashlights.”
The boys covered their flashlights with their hands so that only a faint glow could be seen, and Pete led the way into the same tunnel through which the fake El Diablo had taken them earlier. The moan grew louder as they walked.
“Aaaaaahhhhhhhh — ooooooo — oooooo — ooo!”
As they approached the cross passage, they heard the sound of digging.
“Golly,” Pete gulped. “We really did hear digging.”
“Of course we did. Come on!” whispered Jupiter.
They plunged ahead into the man-made tunnel, moving as silently as possible. It was long and straight. At the end of it they saw a glow of light. Jupiter motioned for Pete to slow down.
The glow of light came from a hole in the side wall of the mine shaft. Rocks and boulders lay in piles all around it. The sound of digging was coming from the hole.
Cautiously the boys crept forward and peered into the hole, blinking at the bright light.
At that moment the moaning came again — so loud that the sound was painful to their ears. It echoed all around them, then gradually died away.
“Gosh!” Pete whispered. “It hurts my ears.”
Jupiter caught Pete’s arm. “Look!”
Their eyes had adjusted to the bright light inside the cavern, and they could see a figure bending over with a shovel in his hand.
Pete gulped.
The figure suddenly straightened, put down his shovel, and picked up a pickaxe. For a moment he was clearly visible in the light of his electric lantern — a man with white hair and a flowing white beard.
Old Ben Jackson.
15
Part of the Mystery Solved
Through the opening in the side wall, Pete and Jupiter watched Old Ben working inside the secret cavern. Every few minutes, at irregular intervals, the moaning shattered their ears. The noise did not seem to bother the old man at all. He kept digging at the base of the cavern wall with his pickaxe.
“Look,” Jupiter whispered. “It looks like another rock fall.”
“It’s a big one,” Pete whispered back.
“You see how those breaks in the rocks are sharp and clean?” Jupiter pointed out. “That fall happened very recently.”
Old Ben continued his work at the fall, unaware of the eyes watching him. The old prospector swung his axe with vigour and surprising strength for a man of his age. Then he put it down again, and picked up the shovel.
“Jupe!” hissed Pete. “Look at his eyes.”
The eyes of the old prospector gleamed wildly in the light of his electric lantern, just as they had the previous night when the old man had warned them against The Old One.
“Gold fever,” Jupiter said softly, “or, in this case, diamond fever. I’ve read that prospectors often get like that when they think they have a strike. Nothing can get in their way or stop them.”
“Gosh,” Pete whispered.
Old Ben turned again to the wall and dug steadily at the fallen rock loosened by his pickaxe. He shovelled it into a kind of tilted sieve. Every few minutes, while the boys watched, he bent down and picked something out of the dirt. Each time, he examined the object, laughed wildly, and put it into a small leather bag near the electric lantern.
“Are they diamonds?” Pete whispered.
“I expect so,” Jupiter responded in the same low voice. Old Ben was so involved in his work that he probably wouldn’t have heard the boys if they had spoken normally, but they were taking no chances.
“Then he has found a diamond mine,” Pete said.
Jupiter was staring at the rock fall, his round face furrowed with thought.
“It looks that way, Pete, only — ”
“What else could it be? He’s struck a diamond mine, and he knows it’s on Crooked-Y property. If anyone found out about it he’d at least have to share the diamonds with the Daltons, wouldn’t he? Maybe legally they all belong to Mr. and Mrs. Dalton. So he only digs at night, and he scares everyone away from the cave!”
Jupe nodded slowly. “I guess you’re right, Pete. That explains everything except — ”
“Except why the cave moans,” Pete interrupted. “And what makes it stop when anyone comes inside.”
“I wasn’t thinking of that,” Jupiter said, “but I think I can explain why the moaning stops. You see, the sheriff and Mr. Dalton must have found this mine shaft all right. Only they didn’t find the place where Old Ben is working.”
As Pete opened his mouth to ask a question, a bell began to ring insistently in the hollow cave.
Old Ben dropped his shovel and moved with amazing speed to a small box near his lantern. He touched something on the box and the clanging bell stopped. Then he picked up his lantern and the small leather bag and headed straight for the hole in the wall where Pete and Jupiter were crouching.
“Quick, Pete!” Jupiter whispered urgently.
The two boys scrambled back to hiding places behind the loose mounds of rock in the shaft. They were none too fast. They had barely got out of sight when Old Ben came through the hole in the wall. The old man laid down his lantern and leather bag, and picked up a long steel bar the boys had not noticed in the floor of the shaft.
At that moment the moan began once more.