cliffs in order to be safe. Nobody seems to know what they were afraid
of, whether savage tribes, or great beasts that may have roamed this
part of the country a thousand and more years ago."

"And that's the bait that has drawn the old scientist here, to study it
all out, and write up the history of the people who looked on this very
picture so many hundreds of years back. Why, Frank, some of the cliffs
they say are about a mile high! That's hard to believe, for a fact."

"But it's been proved true," the other asserted. "The trouble is, that
everything here is on such an awful big scale that a fellow fools
himself. Actual measurement is the only way to prove things. The eye
goes back on you. Why, I've looked out on a clear day in Colorado, and
believed I could walk to a mountain in an hour. They told me it's base
was fifty miles away; and there you are."

"Well, we'll have to put off looking till morning," said Bob,
regretfully; "because the sun's dropped out of sight, and it's getting
pretty thick down there in the hole. And to think that to-morrow we'll
be pushing along through that place, with the walls shutting us in on
both sides."

"Not only to-morrow, but for many days, perhaps," Frank added; for more
than ever did he begin to realize the enormous task that confronted
them; it was almost like looking for a needle in a haystack; but if one
possesses a powerful magnet, even then the bit of steel may be recovered
in time.

Did they happen to know of any such magnet?

Almost unconsciously Frank's thoughts went out toward that old Moqui
brave, Havasupai, who had fled from his village because of some act
which he had committed; but who was now determined to return, and take
his punishment with the stoicism Indians have always shown.

The Moqui might be the connecting link! He alone knew where the hermit
had his lodging, possibly in one of those quaint series of cliff
dwellers' homes, which for some reason he called Echo Cave.

"We must ask if our friend Sheriff Stanwix has been here," Bob
suggested, as they went to their room to prepare for supper.

"Oh!" replied his chum, "I did that when I spoke with the clerk at the
desk. You were looking after the ponies at the time, so as to make sure
they'd be well taken care of for a week, or a month if necessary."

"And what did he tell you, Frank?"

"They got here, all right," came the reply. "If you'd looked sharp when
you were out there in the hotel stables, yo