e had to. In the past, though, it made a mighty good
watering-place for the cattlemen driving from one section of this
country to another. Sence they cut up that land over to the westward
inter farms, though, the big cattle drives have stopped, and I don't
suppose any one's bin around here for a long time, 'cepting those
varmints whose feet-marks we seen."

"How do you know they are varmints?" laughed Walt Phelps.

"Don't see what business they'd hev here otherwise, and----" began
Pete, but a perfect tempest of laughter at his expense drowned the rest
of his speech.

"Well, now that we seem to have pretty well explored the habitation
part of the mesa, let us make our way to the summit," suggested the
professor.

With a whoop and yell, the excited boys followed the suggestion at
once, and a dash up the narrow causeway followed at imminent risk of
one of another losing his footing.

"Hey, hold on thar!" yelled Pete, as they dashed upward, "we don't want
no funerals here, an' it's er drop of more'n a hundred feet to ther
ground."

This rather checked the boys' enthusiasm, and they went more slowly
thereafter.

The summit of the mesa was found to consist of a small plateau, about a
quarter of an acre in extent, perfectly bare, and shaped like a saucer.
Near the center was the hole which gave illumination to the council
hall below them, while in a spot almost exactly in the middle of the
queer elevation, was a rough, square erection of sun-baked brick. This
was about twelve feet in length, five feet in height, and six feet or
so through. Apparently it had once been a kind of an altar. The
professor thought this assumption tenable, as it was known that the
aborigines who had once inhabited the mesa had been sun-worshipers.

"Ugh!" shuddered Jack, as he gazed at the altar. "And they used to
offer human sacrifices here."

"I think it altogether likely," said the professor calmly; "probably
that altar has witnessed the immolation of more than a hundred victims
at a single tribal ceremony."

Ralph Stetson was clambering up on the altar as the professor spoke,
but at hearing these words he hastily descended again.

"I guess I'll defer examining it till some other time," he said
decidedly.

From the summit of the mesa a wonderful view could be obtained. At
that altitude the rocky, desolate range of sierras to the south could
be seen clearly, although a mile or so distant.

"Thar's the border yonder," said P