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!