. The path, which zig-zagged up the face of the mesa was
about eight inches in width, not more, at its base, and varied--so far
as they could see from below--from that breadth to a foot, as it grew
higher.

From the base to the summit the mesa was probably about one hundred and
fifty feet in height, the windows not commencing till within twenty
feet of the top. Its length at the base was, roughly, three hundred
feet, and its thickness varied from three hundred feet or more at the
center, to a few feet at each end. Roughly, then, its basic outline
was that of an irregular parallelogram, while its profile was that of a
flat-topped cone. For some moments the little group stood in silence
as they gazed up at the yellowish-gray walls of the once-active mound.

Finally, recovering from their reverie, they set out after Coyote Pete
to scale the narrow pathway leading to the summit. But, as the
cow-puncher set his feet on the lowermost part of the path, he gave an
exclamation of astonishment and pointed downward.

There in the dust was a footprint,--several of them, in fact.

It was a startling discovery in that isolated part of the desert to
come upon the traces of human occupancy. Robinson Crusoe on his desert
island could not have looked any more astonished at the imprint of the
savage's sole, than did Coyote Pete. He stood looking down
speechlessly at his discovery, while the others crowded about him,
asking a dozen questions at once.

"If the sand-storm had hit this section, we'd been able to form some
idee of how long ago them hoofs was planted there," said Pete; "but as
it is, ther feller who wondered how ther apple got in ther dumpling
didn't hev a harder problem than the nut we've got to crack."

"There must have been several of them," said Jack, who had been gazing
in the dust, which lay thick on the pathway to the summit of the mesa.

"A dozen at least," nodded Pete. He tipped back his sombrero and
scratched his ruffled hair, fairly at a standstill to account for what
they had encountered.

"Mightn't it have been prospectors?" asked Ralph.

"Might hev bin, yes," agreed Pete; "but, fer one thing, my son,
prospectors don't usually travel in dozens."

"Hum--that's so," assented Jack, who at first had greeted Ralph's
suggestion eagerly.

"Look here!" cried Ralph suddenly, holding up a glittering object which
he had just discerned in the bunch-grass at the base of the mesa.

"What is it, my boy?" inq