in the action, and shut its eyes.  It was the rest time of the wild, and the same instinct appealed to the leader of the distant herd.  Down it went where it stood as the pony had done, disappeared absolutely from view.  A moment later another followed, and another, and another.  It was almost uncanny, there in the fantastic glimmer, that disappearance.  In the space of minutes, look where one would, the horizon was blank.  Where the herd had been there was nothing, not even a blot.  It was as the desert, and the vanished herd a mirage.  It was like the far northland tight in the grip of winter, like the ocean at night.  It was the Dakota frontier at midday.

Again time passed and, motionless as at first, wide eyed, the man lay looking out.  The pony was sound asleep now.  Its nostrils widened and narrowed rhythmically and it snored at intervals.  Save for this and the soft crackle of the grass and the aeolian song of the wind the earth was still; still as death; so still that, indescribably soft as it was immeasurably distant, the man detected of a sudden against it a new sound.  But he did not stir.  The black eyes looked out motionless as at first.  He merely waited a minute, two—­and it came again; a bit louder this time, more distinct, unmistakable.

This time the listener moved.  Deftly, swiftly, he unrolled the gaudy blanket, spread it thin upon the ground, covered it completely with his body.  In lieu of a pillow his arms crossed under his head, and, leaning back, the hat brim still shading his eyes, he lay gazing up into the sky, motionless as a prairie boulder.

Again the sound was repeated; not a single note, but a medley, a chorus.  It was still faint, still immeasurable as to distance; but nearer than before and approaching closer second by second.  Not from the earth did it come, but from the air.  Not by any stretch of the imagination was it an earthly sound, but aerial.  It was an alien note and still it was not alien.  There upon the silent earth with its sunshine and its illimitable distances, it seemed very much a part of the whole.  Its keynote was the keynote of the time and place, its message was their message, the thrill it bore to the listener the thrill of the whole.  It was not a musical call, that steadily approaching sound.  No human being has ever been able to locate it in pitch or metre; yet to such as the listening man upon the ground, to those who have heard it year by year, it is nevertheless the sweetest, most insistent of music.  Beside it there is no other note which will compare, none other which even approaches its appeal.  It is the spirit of the wild, of magnificent distances, of freedom impersonate.  It is to-day, it was then; for the sound that the man heard drawing nearer and nearer that October afternoon was the swelling, diminishing note of the migrant on its way south, of the grey Canada honker en route from the Arctic circle to the Gulf of Mexico.