“yes, boys,” went on uncle tod, “it looks as though we had played the game out. there’s the end of the tunnel—it’s much shorter than i ever thought, for sam and i never came this far before—and we haven’t seen a drop of water the whole length.”

they had walked to where daylight gleamed and found that they could pass out of the tunnel into the open. they emerged at the side of a hill, very much the same sort of hill that was behind the cabin at the mine camp. below them lay the valley, winding off to the east and west—a deserted desolate valley, dotted here and there, perhaps, with the camps of hopeful miners, but which camps were too small to be seen amid the trees and bushes.

“the river was here once,” said uncle tod, “but it’s gone now.”

“how can you tell it was here?” asked chot.

“by the way the stones are worn,” was the answer. “see how smooth and rounded they are, where water has been flowing over them for years and years. but there is no water now, worse luck!”

the boys easily recognized the dry bed of some former stream—lost river beyond all doubt. but where was lost river now? that is what they wanted to know.

as uncle tod had said, the tunnel was much shorter than he had supposed. they had come not more than three miles under the mountain—a long enough passage if it had been dug by the hand of man for a railroad, as it was all through solid rock—but the rushing water which had, seemingly, bored the passage, took no note of time. it had centuries at its disposal, and had worn its way slowly.

entering the tunnel at the camp, the explorers had wound their way through it, with the comparatively unimportant accidents i have described, and had emerged through a hole in the side of the mountain. all about them were water-worn stones, and they could trace where the stream had flowed downward from where they stood, but in the opposite direction from that in which they had been traveling. in other words they had walked against the direction of the stream.

“and that’s the queer part of it,” said uncle tod. “all along, boys, we’ve been going up grade through the tunnel, and that means the water of lost river flowed down, just as it did before my mine went dry. now we get here and at this point the course of the stream shows that the water must have flowed the other way, in the same direction we have been going.”

“you mean this hole here, where we just came out, is a sort of diving place,” suggested rick.

“that’s it—a miniature watershed. back of us, in the tunnel where we just came from, the water flowed east. here it began and flowed west—that is when there was any water.

“so i can’t see,” went on uncle tod, “any use in keeping on. lost river was here, but it’s gone. when it will come back—no one knows. not much use waiting for it, i reckon. i don’t see why sam and i didn’t find this out before, but he got frightened by a lot of queer noises in the tunnel, and wouldn’t keep on. i didn’t dare risk going alone, and we never got as far as here.

“but this is the end—i’m going to give up now!”

“it’s too bad,” said rick, nursing his bruised arm tenderly. “i thought we’d find something. what are you going to do now, uncle tod?”

“oh, give up and go back east, i reckon. i’ve got other mines in different parts of the country, but i wanted this to pan out well for sam’s sake. it’s the only one he has an interest in. but it wasn’t to be, i guess. i’m sorry i brought you boys out on such a wild-goose chase!”

“oh, we don’t mind,” rick hastened to say.

“i guess not!” cried chot. “we’ve had packs of fun!”

“and we’ll have more,” suggested rick. “we don’t have to go back right away; do we?”

“no, i reckon not,” his uncle said. “might as well stay and have a little vacation while you’re here. and maybe sam and i will prospect around a bit. might happen to hit on some nuggets or pockets that would pay us for our grub, anyhow. we’ll stay a while. but now i’m going to head back for camp.”

“through the tunnel?” asked rick.

“no, we can go back along this side valley trail. looks like a fairly good one though i haven’t traveled it myself. well, it’s too bad, but i’ve got to give up!”

with a sigh, uncle tod led the way from this second opening of the mysterious tunnel, back toward his camp. and as rick followed him there came into the lad’s mind an idea that, eventually, was responsible for the solution of the mystery of lost river; all of which will be related in due time.

it was nearly night when the travelers, foot-sore and weary, with aching bones, reached the mine camp. ruddy, panting and tired, stretched out in his accustomed place and promptly went to sleep.

“well?” asked sam rockford inquiringly. “what did you find?”

“nothing,” answered uncle tod.

“i thought you would,” was the gloomy one’s comment. “well, what you goin’ to do now, tod?”

“nothing, i reckon. i’ll let the boys have a good time, and then i’ll go back east with ’em. this mine isn’t worth the powder to blow it up—without water to wash out the pay stuff.”

“i reckon not,” assented sam. “but what did you hear in the tunnel, tod; any strange ghost voices?”

“nonsense! of course not! but we came to the farther end which you and i never reached. the tunnel just peters out at a place where lost river, apparently, ran both ways. but just now it isn’t running either way. it’s gone!”

“doesn’t take a weather prophet to see that,” grunted sam. “well, you’ve got a few other claims around here. might as well work them while the boys are having a vacation.”

“i reckon so,” agreed uncle tod, and his voice was almost as gloomy as that which sam so often used.

as for rick and chot they were too tired then to think much about it—all they wanted was “grub,” and sam prepared an unusually good supper. as least so it tasted to rick, chot and ruddy.

it was two or three days after the disappointing exploration of the tunnel, during which time the boys, their sore spots healed, romped with ruddy about the surrounding country, meeting miners and other characters who told strange tales of lost river. some of the more ignorant held that the stream, and the tunnel through which it formerly flowed, were enchanted, or under the spell of some evil spirit. but of course rick and chot laughed at this.

the two boys and their dog (for chot claimed a loving interest in ruddy) paid several more visits to the second opening of the tunnel—the place where uncle tod had been so disappointed—and it was after one of these visits, sitting by themselves in the mine cabin as they were (for uncle tod and sam had gone out) it was at this time that rick started drawing something with pencil and paper.

“what you doing?” asked chot. “going to write a story of lost river?”

“not much, though after we find it maybe i will,” rick answered with a laugh.

“what do you mean—do you think you’re going to find it?”

“i might,” was the cool answer. “look here, chot, what do you think of that?” and rick passed to his chum a sketch, or drawing, on which certain words were written. chot studied for a few moments, and then his eyes brightened as he cried:

“golly! maybe that’s the way it really happened, rick!”

“it’s worth trying, anyhow; don’t you think?”

“i sure do! cracky! i didn’t know you were such a sketch artist. this is a regular pirate’s treasure map.”

“it may turn out that way,” chuckled rick. “i’ve been thinking about this ever since uncle tod gave up, and it came into my head that this may solve the mystery.”