back from the rim, Dad picked up a half breed whom the
boys named Chow, because he was always chewing. If not food, Chow was
forever munching on a leaf or a twig or a stick. His jaws were ever
at work until the boys were working their own jaws out of pure sympathy.

The march was taken up to Bass Trail, which they reached about noon of
the second day and started down. No unusual incident occurred during
this journey. They found the trail in good condition, and though steep
and precipitous in places, it gave the Pony Rider Boys no worry. After
having experienced the perils of the other trail, this one seemed tame.

From Bass Trail they worked their way down and across into Bright Angel
Gulch, where they made camp and awaited the arrival of Chow and the
mules with their tents and provisions.

Chow arrived late the same day. Tents were pitched and settled. It was
decided for the present to make this point their base of supplies. When
on short journeys they would travel light, carrying such equipment as
was absolutely necessary, and no more.

This gulch was far from the beaten track of the ordinary explorer, a
vast but attractive gash in the plateau. In spots there was verdure,
and, where the water courses reached in, stretches of grass with here
and there patches of gramma grass, grease wood and creosote plants with
a profusion of flowers, mostly red, in harmony with the prevailing
color of the rocks that towered high above them. At this point the
walls of the Canyon reached nearly seven thousand feet up into the air.

Down there on the levels the sun glared fiercely at midday, but along
toward night refreshing breezes drifted through the Canyon, making the
evenings cool and delightful. But there were drawbacks. There were
snakes and insects in this almost tropical lower land. The boys were
not greatly disturbed over these things. By this time they were pretty
familiar with insects and reptiles, for it will be remembered that they
had spent much time in the wilder places of their native country.

For the first twenty-four hours of their stay in "Camp Butler," as they
had named their base in honor of Tad himself, they did little more than
make short excursions out into the adjoining canyons. The Professor
embraced the opportunity to indulge in some scientific researches into
the geology of the Canyon, on which in the evening he was wont to dwell
at length in language that none of the boys understood. But