hat do you see, Bob?"

"Honest now, I believe you've hit the bulls-eye this time, Frank."

"Then you think they're windows, about after the same style as those
holes in the rock where we climbed up the ladders to the deserted homes
of the old time cliff dwellers?" asked the other.

"Sure they are; no mistake about it, either," replied Bob, and then he
gave a low exclamation.

"What did you see?" demanded Frank, as if suspecting the truth.

"I don't know," came the reply; "but something seemed to move just
inside one of those openings. It may have been a garment fluttering in
the breeze that must be blowing so far up the heights; and then, again,
perhaps some hawk, or other bird, has its nest there, and just flew
past. I couldn't say, Frank; but I saw _something_, and it moved!"

Frank took the glass, and looked long and earnestly.

"Whatever it was," he remarked, "it doesn't mean to repeat the act. But
all the same, Bob, I've got a hunch we've found the place, and that Echo
Cave lies far up yonder in that beetling cliff."

"It's a fierce reach up there," remarked Bob, as he scanned the height.
"How under the sun d'ye suppose that old professor could ever get up and
down? Too far for him to have a rope ladder; and even if he had, how
could he reach the place at first? Frank, all the way up, I can't see
the first sign of any rock shelves, where ladders might have rested long
ago."

"That's so," replied the other, reflectively. "The face of the cliff is
as even and smooth as a floor. Nobody would ever look to find a cluster
of cliff dwellers' homes up there; that is, nobody but a man like
Professor Oswald, who has made a life study of such things, and knows
all the indications. But something tells me we're pretty near the end of
our long trail. The only question now is, how can we get in touch with
the hermit of Echo Cave?"

As night settled down the two boys returned to the fire, still
perplexed.

CHAPTER XVIII

FINDING A WAY UP

That night they kept no fire going. Frank seemed to think it best that
they remain quiet, so as not to announce their presence in the
neighborhood. Though for that matter, it would seem that if any one were
perched aloft in one of those slits in the face of the cliff, that
represented the windows of the cave dwellings, the entire canyon below
must be spread out like a book.

Nothing happened to disturb them. Once Frank thought he heard a distant
shout, and this excited h