Druse withdrew his eyes from the valley and fixed them again upon the group of man and horse in the sky, and again it was through the sights of his rifle.  But this time his aim was at the horse.  In his memory, as if they were a divine mandate, rang the words of his father at their parting:  “Whatever may occur, do what you conceive to be your duty.”  He was calm now.  His teeth were firmly but not rigidly closed; his nerves were as tranquil as a sleeping babe’s—­not a tremor affected any muscle of his body; his breathing, until suspended in the act of taking aim, was regular and slow.  Duty had conquered; the spirit had said to the body:  “Peace, be still.”  He fired.

III

An officer of the Federal force, who in a spirit of adventure or in quest of knowledge had left the hidden bivouac in the valley, and with aimless feet had made his way to the lower edge of a small open space near the foot of the cliff, was considering what he had to gain by pushing his exploration further.  At a distance of a quarter-mile before him, but apparently at a stone’s throw, rose from its fringe of pines the gigantic face of rock, towering to so great a height above him that it made him giddy to look up to where its edge cut a sharp, rugged line against the sky.  It presented a clean, vertical profile against a background of blue sky to a point half the way down, and of distant hills, hardly less blue, thence to the tops of the trees at its base.  Lifting his eyes to the dizzy altitude of its summit the officer saw an astonishing sight—­a man on horseback riding down into the valley through the air!

Straight upright sat the rider, in military fashion, with a firm seat in the saddle, a strong clutch upon the rein to hold his charger from too impetuous a plunge.  From his bare head his long hair streamed upward, waving like a plume.  His hands were concealed in the cloud of the horse’s lifted mane.  The animal’s body was as level as if every hoof-stroke encountered the resistant earth.  Its motions were those of a wild gallop, but even as the officer looked they ceased, with all the legs thrown sharply forward as in the act of alighting from a leap.  But this was a flight!

Filled with amazement and terror by this apparition of a horseman in the sky—­half believing himself the chosen scribe of some new Apocalypse, the officer was overcome by the intensity of his emotions; his legs failed him and he fell.  Almost at the same instant he heard a crashing sound in the trees—­a sound that died without an echo—­and all was still.

The officer rose to his feet, trembling.  The familiar sensation of an abraded shin recalled his dazed faculties.  Pulling himself together he ran rapidly obliquely away from the cliff to a point distant from its foot; thereabout he expected to find his man; and thereabout he naturally failed.  In the fleeting instant of his vision his imagination had been so wrought upon by the apparent grace and ease and intention of the marvelous performance that it did not occur to him that the line of march of aerial cavalry is directly downward, and that he could find the objects of his search at the very foot of the cliff.  A half-hour later he returned to camp.