after lunch, the ramblers accompanied fenton to "mystery falls," as they termed the cataract. to reach it, they had to pass around a ledge of rock into a third valley.

"my!" observed sam, striving to make his voice heard above the roar and his face paling a little, "isn't it awful to think of what——"

"don't think of it, sam," interrupted dave, with a laugh, "but enjoy the scene."

and all agreed that it was a spectacle well worth seeing. the water of canyon river, in the shadow of the great walls, roared and thundered, as it dashed with mighty force over the brink, to madly froth and seethe and bubble and swirl away two hundred feet below.

all felt a tremor when they thought of the fate of the "dauntless" and "speedy" and the awful plunge which each boat must have taken.

it was a long time before the boys could tear themselves away from the fascinating spectacle. naturally, they were anxious to return to the village. now that their own dangers were past, they felt so terribly worried about dick travers and tommy clifton that any real enjoyment was out of the question.

howard fenton agreed to accompany them to mountain village on the following day.

that night, he again exchanged signals with neil prescott, the boys being deeply interested spectators of the proceeding.

the eventful morning arrived, and the four set out early, leaving stuart wells at the camp.

fenton led the way toward a gully and began scrambling up the side.

"jiminy crickets!" exclaimed bob. "work ahead, chubby."

and dave's only reply was a long drawn-out groan.

a bit further up, a patch of scrubby firs and bushes stood out sharply against their gray surroundings, and above that there was nothing but barren rock.

from ledge to ledge, the four made their way. fortunately, footholds on the steep, sloping sides were numerous, otherwise their task would have been almost impossible.

"whew—hot work," panted dave.

"but we're getting up, chubby," said bob. "the river begins to look like a creek."

they stood on a shelving rock, with somewhat the feeling that an explorer experiences when gazing upon a newly-discovered land for the first time.

"mighty few people have seen this," quoth dave. "pretty little valley, fenton."

"yes it is, dave."

"and there's wells—looks just like an ant. can't you hear his voice plainly? wonderful how sounds carry in a place like this."

stuart had seen them, and was giving a parting salutation.

up, up, slipping, sliding and scrambling; now on hands and knees, then drawing themselves almost by main force over rugged rocks, they progressed slowly toward the top.

each was, of course, provided with a heavy stick, or "alpen-stock," as dave called it, and these proved very useful.

at length, the toilsome climb was nearly over. they had reached the rounded projection of which howard had spoken. it rose from a wide ledge, and looked so dangerous that the ramblers' respect for the city boy's prowess was greatly increased.

"nice job ahead of us," grumbled sam. "my stars!"

"you fellows get up and throw me a rope," said dave. "i shall recommend this for an air-ship station. my! a fellow needs wings to get around anything like that."

"guess you understand why i felt stumped," laughed fenton. "but wait till you see it from the top."

"don't wonder silver valley hasn't many visitors," sighed bob. "i feel like calling for help."

after a long rest, howard fenton started ahead, while the others watched. it was hard, toilsome work, but, at length, they saw him drag himself laboriously over the top, and disappear from view. then a shout of approval went up.

"here comes a rope, fellows," announced fenton, a few minutes later.

it dangled downward over the smooth rock.

"i've fastened it up here, all right."

howard poked his face over the barrier, and peered down. "come ahead, chubby," he called. "don't depend too much on the rope."

the stout boy, with an alarming series of sighs and groans, obeyed.

at last all stood safely on the top, and agreed with howard that no one who did not know the lay of the land would care to venture down.

"howard, you have a pile of courage," said bob, and fenton smiled at the compliment.

after another short stop, he piloted them into the forest, following his blazed trail without difficulty.

the logger's hut was soon reached. jake lawson proved to be a rough, raw-boned mountaineer with an original manner of speech. he was profoundly astonished at the arrival of the boys, and still more astonished when he learned of their adventure in the canyon.

"wal, wal," he exclaimed, elevating his shaggy eyebrows; "if this hyar keeps up, they'll be a-sendin' pleasure parties through the gorge, an' takin' up tickets at t'other end."

the four partook of a good, square meal of bacon and beans at the cabin, and then resumed their march.

late in the afternoon, weary, dusty and footsore, they arrived at the resort house.