And the doctor stuck in the saddle.  He had set his teeth, and he was a sea-sick greenish-white.  His hat was a-jog over one ear—­his shirt tails flew out behind.  And still he remained to battle.  Aye, for he ceased the passive clinging to the saddle.  He gathered up the long quirt which had hitherto dangled idly from his wrist, and at the very moment when the piebald had let out another notch in his feats, the doctor, holding on desperately with one hand, with the other brandished the quirt around his head and brought it down with a crack along the flanks of the piebald.

The effect was a little short of a miracle.  The mustang snorted and leaped once into the air, but he forgot to come down stiff-legged, and then, instantly, he broke into a little, soft dog trot, and followed humbly in the trail of the black stallion.  The laughter and cheers from the house were the sweetest of music in the ears of Doctor Randall Byrne; the most sounding sentences of praise from the lips of the most learned of professors, after this, would be the most shabby of anticlimaxes.  He waved his arm back to a group standing in front of the house—­Buck Daniels, Kate, the lantern-jawed cowboy, and Wung Lu waving his kitchen apron.  In another moment he was beside the rider of the stallion, and the man was whistling one of those melodies which defied repetition.  It simply ran on and on, smoothly, sweeping through transition after transition, soaring and falling in the most effortless manner.  Now it paused, now it began again.  It was never loud, but it carried like the music of a bird on wing, blown by the wind.  There was about it, also, something which escaped from the personal.  He began to forget that it was a man who whistled, and such a man!  He began to look about to the hills and the sky and the rocks—­for these, it might be said, were set to music—­they, too, had the sweep of line, and the broken rhythms, the sense of spaciousness, the far horizons.

That day was a climax of the unusual weather.  For a long time the sky had been periodically blanketed with thick mists, but to-day the wind had freshened and it tore the mists into a thousand mighty fragments.  There was never blue sky in sight—­only, far up, a diminishing and lighter grey to testify that above it the yellow sun might be shining; but all the lower heavens were a-sweep with vast cloud masses, irregular, huge, hurling across the sky.  They hung so low that one could follow the speed of their motion and almost gauge it by miles per hour.  And in the distance they seemed to brush the tops of the hills.  Seeing this, the doctor remembered what he had heard of rain in this region.  It would come, they said, in sheets and masses—­literal water-falls.  Dry arroyos suddenly filled and became swift torrent, rolling big boulders down their courses.  There were tales of men fording rivers who were suddenly overwhelmed by terrific walls of water which rushed down from the higher mountains in masses four and eight feet high.  In coming they made a thundering among the hills and they plucked up full grown trees like twigs thrust into wet mud.  Indeed, that was the sort of rain one would expect in such a country, so whipped and naked of life.  Even the reviving rainfall was sent in the form of a scourge; and that which should make the grass grow might tear it up by the roots.