On open ground like this, Nagger, carrying two hundred and fifty pounds, showed his wonderful quality.  He did not mind the heat nor the sand nor the glare nor the distance nor his burden.  He did not tire.  He was an engine of tremendous power.

Slone gained upon Wildfire, and toward evening of that day he reached to within half a mile of the stallion.  And he chose to keep that far behind.  That night he camped where there was dry grass, but no water.

Next day he followed Wildfire down and down, over the endless swell of rolling red ridges, bare of all but bleached white grass and meager greasewood, always descending in the face of that painted desert of bold and ragged steps.  Slone made fifty miles that day, and gained the valley bed, where a slender stream ran thin and spread over a wide sandy bottom.  It was salty water, but it was welcome to both man and beast.

The following day he crossed, and the tracks of Wildfire were still wet on the sand-bars.  The stallion was slowing down.  Slone saw him, limping along, not far in advance.  There was a ten-mile stretch of level ground, blown hard as rock, from which the sustenance had been bleached, for not a spear of grass grew there.  And following that was a tortuous passage through a weird region of clay dunes, blue and violet and heliotrope and lavender, all worn smooth by rain and wind.  Wildfire favored the soft ground now.  He had deviated from his straight course.  And he was partial to washes and dips in the earth where water might have lodged.  And he was not now scornful of a green-scummed water-hole with its white margin of alkali.  That night Slone made camp with Wildfire in plain sight.  The stallion stopped when his pursuers stopped.  And he began to graze on the same stretch with Nagger.  How strange this seemed to Slone!

Here at this camp was evidence of Indians.  Wildfire had swung round to the north in his course.  Like any pursued wild animal, he had began to circle.  And he had pointed his nose toward the Utah he had left.

Next morning Wildfire was not in sight, but he had left his tracks in the sand.  Slone trailed him with Nagger at a trot.  Toward the head of this sandy flat Slone came upon old corn-fields, and a broken dam where the water had been stored, and well-defined trails leading away to the right.  Somewhere over there in the desert lived Indians.  At this point Wildfire abandoned the trail he had followed for many days and cut out more to the north.  It took all the morning hours to climb three great steps and benches that led up to the summit of a mesa, vast in extent.  It turned out to be a sandy waste.  The wind rose and everywhere were moving sheets of sand, and in the distance circular yellow dust-devils, rising high like waterspouts, and back down in the sun-scorched valley a sandstorm moved along majestically, burying the desert in its yellow pall.

Then two more days of sand and another day of a slowly rising ground growing from bare to gray and gray to green, and then to the purple of sage and cedar—­these three grinding days were toiled out with only one water-hole.