med to see smoke everywhere. But, as he swept round
the horizon, suddenly his whole figure stiffened. He looked long, then,
with a sigh of relief, turned away, and completed his circuit of the
horizon. This done, he directed the glasses anew where he had looked
before. He looked long, unsatisfied, then lay down on the rock where he
could rest the glasses and scanned the scene for several minutes.

"Be sure," Merritt had once warned him, "better spend a half an hour at
the start than lose two hours later."

But Wilbur felt sure and rushed for his horse. Half-way he paused. Then,
going deliberately into the shade of a heavy spruce, he half-closed his
eyes for a minute or two to let the muscles relax. Then quietly he came
to the edge of the cliff, and directing his glasses point-blank at the
place he had been examining so closely, scanned it in every detail. He
slipped the glasses back into their case, snapped the clasp firmly,
walked deliberately back to his horse, who had been taking a few
mouthfuls of grass, tightened the cinches, looked to it that the saddle
was resting true and that the blanket had not rucked up, vaulted into
the saddle, and rode to the edge of the cliff. There was no doubt of it.
Hanging low in the heavy air over and through the dark foliage of pine
and spruce was a dull dark silver gleam, which changed enough as the
sunlight fell upon it to show that it was eddying vapor rather than the
heavier waves of fog.

"Smoke!" he said. "We've got to ride for it."

[Illustration: NO WATER, NO FORESTS. NO FORESTS, NO WATER.

Example of country which irrigation will cause to become wonderfully
fertile.

_Photograph by U. S. Forest Service._]

[Illustration: WITH WATER!

In the foreground, a field and orchard; in the background, the
sand-dunes of the arid desert. Transformation effected by a tiny stream
and a poplar wind-break.

_Photograph by U. S. Forest Service._]

CHAPTER XV

THE FOREST ABLAZE

As Wilbur broke into a steady, if fast pace, it seemed to him that all
his previous experiences in the forest had been directed to this one
end. True, once before, he had seen smoke in the distance and had ridden
to it, but then he had felt that it was a small fire which he would be
able to put out, as indeed it had proved. But now, while there was no
greater cloud of smoke visible than there had been before, the boy felt
that this was in some measure different.

As his horse's hoofs clatt