Suddenly we shot out through the screen of concealing boughs into the broader stream beyond, and I struggled hastily to swerve the boat’s bow upward against the current.  The downward sweep of the water at this point was not particularly strong, the main channel being some distance further out, and we were soon making perceptible progress.  The light here in the open was better, although dim enough still, and revealing little of our surroundings.  All was wrapped in gloom along shore, and beyond the radius of a few yards no objects could be discerned.  The river itself swept past us, a hidden mystery.  Sam knelt on his knees, peering eagerly forward into the blackness, an occasional growl of his voice the only evidence of his presence.  I doubt if I had taken a dozen strokes, my whole attention centered on my task, when the sudden rocking of the boat told me he had scrambled to his feet.  Almost at the same instant my ears distinguished the sharp chugging of an engine straight ahead; then came his shout of alarm, “God, A’mighty!  Dar’s de keel-boat, sah.  Dey’s goin’ fer ter ram us!”

I twisted about in my seat, caught a vague glimpse of the advancing shadow, and leaped to my feet, an oar gripped in my hands.  Scarcely was I poised to strike, when the speeding prow ripped into us, and I was catapulted into the black water.

CHAPTER XVIII

THE LOSS OF RENE

There was the echo of an oath, a harsh, cruel laugh, the crash of planking, a strange, half-human cry of fright from the negro—­that was all.  The sudden violence of the blow must have hurled me high into the air, for I struck the water clear of both boats, and so far out in the stream, that when I came again struggling to the surface, I was in the full sweep of the current, against which I had to struggle desperately.  In the brief second that intervened between Sam’s shout of warning, and the crash of the two boats, I had seen almost nothing—­only that black, menacing hulk, looming up between us and the shore, more like a shadow than a reality.  Yet now, fighting to keep my head above water, and not to be swept away, I was able to realize instantly what had occurred.  I had been mistaken; Kirby had not fled down the river; instead he had craftily waited this chance to attack us at a disadvantage.  Convinced that we would decide to make use of the rowboat, which he had left uninjured for that very purpose, and that we would venture forth just so soon as the night became dark enough, he had hidden the stolen craft in some covert along shore, to await our coming.  Then he sprang on us, as the tiger leaps on his prey.  He had calculated well, for the blunt prow of the speeding keel-boat had struck us squarely, crushing in the sides of our frail craft, and flinging me headlong.