I severed the line and we began to recede from the shore, cutting diagonally across the decidedly swift current.  Once beyond the protection of the point the star-gleam revealed the sturdy rush of the waters, occasionally flecked with bubbles of foam.  Sam handled the unwieldy craft with the skill of a practiced boatman and the laboring engine made far less racket than I had anticipated.  Ahead, nothing was visible but the turbulent expanse of desolate water, the Illinois shore being still too far away for the eye to perceive through the darkness.  Behind us the Missouri bluffs rose black, and fairly distinct against the sky, but dimming constantly as the expanse of water widened to our progress.  Pistol in hand, and vigilant to every motion of the negro, my eyes swept along that vague shore line, catching nowhere a spark of light, nor any evidence that the steady chug of our engine had created alarm.  The churning wheel flung white spray into the air, which glittered in the silver of the star-rays, and occasionally showered me with moisture.  At last the western shore imperceptibly merged into the night shadows, and we were alone upon the mysterious bosom of the vast stream, tossed about in the full sweep of the current, yet moving steadily forward, and already safely beyond both sight and sound.

CHAPTER XIII

SEEKING THE UNDERGROUND

Every moment of progress tended to increase my confidence in Sam’s loyalty.  His every attention seemed riveted upon his work, and not once did I observe his eyes turned backward for a glimpse of the Missouri shore.  The fellow plainly enough realized the situation—­that safety for himself depended on keeping beyond the reach of his master.  To this end he devoted every instant diligently to coaxing his engine and a skillful guidance of the boat, never once permitting his head to turn far enough to glance at me, although I could occasionally detect his eyes wandering in the direction of the girl.

She had not uttered a word, nor changed her posture since first entering the boat, but remained just as I had seated her, one hand grasping the edge of the cockpit, her gaze on the rushing waters ahead.  I could realize something of what must be passing through her mind—­the mingling of doubt and fear which assailed her in this strange environment.  Up until now she had been accorded no opportunity to think, to consider the nature of her position; she had been compelled to act wholly upon impulse and driven blindly to accept my suggestions.  And now, in this silence, the reaction had come, and she was already questioning if she had done right.

It was in my heart to speak to her, in effort to strengthen her faith, but I hesitated, scarcely knowing what to say, deeply touched by the pathetic droop of her figure, and, in truth, uncertain in my own mind as to whether or not we had chosen the wiser course.  All I dared do was to silently reach out one hand, and rest it gently on those fingers clasping the rail.  She did not remove her hand from beneath mine, nor, indeed, give the slightest evidence that she was even aware of my action.  By this time the eastern shore became dimly defined through the black mist, and the downward sweep of the current no longer struck in force against our bow.