"You're all right, Captain Joe," Case exclaimed. "You can't forget that lost channel any more than we can."

"I don't know whether there's a lost channel or not," the captain replied, "but I do know that there's a fresh supply of water coming into this stream right about here."

Case took a field gla.s.s and looked up the stream.

"There surely is a current starting in close to that bank," he finally said. "I can see sticks and bubbles popping up from the bottom.

There's a spring there, all right."

Alex took the gla.s.s and studied the river for a long time. Then he seized Captain Joe by the shoulder and pointed.

"Say," he said, "there's a nude body coming up out of that eddy Case saw. You can see it under the water, drifting down this way."

The boy dropped the gla.s.s clattering on the deck and sprang into the water.

"Here, here, boy! Come back!" cried Captain Joe.

"It's Clay!" shouted Jule. "Can't you see it's Clay!"

In a moment, Jule was in the water, too, and both boys were diving after the figure they had seen in the eddy.

They caught it in a moment, and managed to get it to the boat. Captain Joe and Case supplied ropes, and in an incredibly short s.p.a.ce of time, Clay lay stretched out on the deck.

"He's dead!" cried Alex "I just know he's dead!"

"They stripped him of his clothes and threw him in!" wailed Jule.

CHAPTER XXIII

THE LOST CHARTER IS FOUND

An instant after being laid on the deck, however, Clay opened his eyes and smiled up into the faces of his friends.

"He'll be saying, 'Where am I?' in a minute!" Alex cried, dancing joyfully about the prostrate figure. "That is the usual thing in stories, you know. He'll have to say, 'Where am I?' and I'll have to tell him that he mustn't talk. Look at him grin."

"What gets me," Captain Joe said, lifting the boy into a sitting position, "is how you came up from the bottom of the river without ever diving down to it. It looks uncanny."

"The lost channel!" answered Clay weakly.

"You found it, did you?" asked Alex.

"Boys, boys," said Captain Joe, "never mind the lost channel until we get this boy dressed and fed up."

The processes suggested by the captain were quickly accomplished, and in a short time, Clay sat in the cabin telling of the adventures of the morning. The boys listened wide-eyed.

"Now let me get this thing right," Captain Joe said. "You went into a whirlpool above the falls and came out into a cavern?"

"That's just it, exactly," Clay replied, still weak from his exertions. "I landed on a ledge, where I lay unconscious for a few moments and then followed down the channel of the underground river.

There is plenty of room in the cavern," he continued, "and plenty of fresh air, but the place is shy on light. I fell many times in the darkness."

"I thought it wasn't safe for me to be in there!" grinned Alex.

"I thought it wasn't safe for me be in there!" Clay replied with a wink, "and so I made my way out as swiftly as I could. At this end of the channel, the water runs out just below the surface of the west river, and I thought I'd better reduce my weight as much as possible before going through the opening, so I took off my clothes and was pushed out by the current."

"Looked mighty funny to see you come floating out of the river without ever having gone in!" laughed Jule.

"Now, boys," said Captain Joe, after the boys had discussed all phases of the situation, "let's size this thing up together. In the first place, Clay has undoubtedly discovered the lost channel."

"It might have been found years ago," Clay said, "if the men who tried to describe it had only said that it was a subterranean stream."

"And now, the question is," went on the captain, "whether the charter and the family jewels are anywhere in the cavern through which the lost stream runs."

"It seemed to me," Clay broke in, "that the cavern was big enough to hold a small sized city. It is just the kind of a place where one would naturally hide valuables."

"It seems to me," Alex complained, "that the hardest part of our job is still to come, even if we have discovered the lost channel. We can't go up there and dive through the whirlpool, as Clay did, because the outlaws would perforate us before we got anywhere near the falls."

"I've been thinking of that," Clay said, "and I believe there is a way to get into the cavern without getting wet. When I lay in the cavern, high up on the ridge, before being taken to the sh.o.r.e, the men with me emptied several tin cans of food and pitched them into a corner of the cavern. One of the cans was sent along with a kick, and I heard a splash of water when it fell."

"Je-rusalem!" cried Alex. "Show me where that cavern is, and I'll take a rope and go through the opening where the can fell!"

"What would these fellows on sh.o.r.e be doing all the time you were reaching the cavern?" asked Case.

"I am certain," Clay went on, "that there is an opening from the floor of the cavern to the chamber in which the lost river runs, for when I came down, I saw a blur of light about halfway through the journey."

"That settles that part of it, then," Captain Joe said. "We'll have to wait for a suitable opportunity and get into the chamber by way of the cave. And now," he continued, "I propose that we move out to the bay or the St. Lawrence, where we won't be under the guns of the enemy, and cook several square meals. Honest, boys," he went on, "I've been so worried lately, that I've almost lost my appet.i.te."

"Yes," Case laughed, "I notice you consumed only half a dozen of those Bismark pancakes for breakfast."

The _Rambler_ was dropped down to the bay with the launch still by her side, and, once out of rifle shot, the boys enjoyed the freedom of the deck.

"Now, we'll stay here until night," Captain Joe said, "and then we'll see what we can do towards finding that cavern and dropping down into the lost channel. We ought to explore it in one night with the help of our searchlights."

The plan mapped out by the captain was successfully carried out.

Leaving Jule on board the _Rambler_, the other members of the party crept cautiously ash.o.r.e that night, and were led directly to the cavern by Clay. They were not disturbed during the journey. Off to the east, they saw the reflection of a campfire and the sound of many voices showed the boys that the outlaws were not at all anxious to conceal their presence.

The opening leading from the cavern to the channel of the stream was large enough for even Captain Joe to pa.s.s through with comfort.

Directly under the opening was a ledge of rock and here the boys landed. Almost at the point of entry they saw marks on the wall which indicated that at some distant time an inscription had been carved there.

"We can't read the words," Clay said, flashing his searchlight over the wall, "but at least it tells us that this is somewhere near the scene of the old-time operations."

Alex, who had been poking about around an angle of rock, now gave a great shout of delight which called the boys to his side.

"There's your old safe!" he cried, pointing up to a niche in the wall, "and it's dollars to doughnuts that the lost charter and the jewels are inside of it!"

It was the work of only a few moments to bring the safe down from the ledge of rock to where the boys stood. It was merely a box of steel, not more than a foot in diameter each way, and was evidently constructed with thin walls for its weight was not great. However, it was tightly closed and the boys could see no means by which it might be opened. There was not even a keyhole or a b.u.t.ton.