But whether I had drifted above or below the causeway I had not the slightest clew to tell.
I pushed steadily forward, with some increasing sense of lassitude, passing one marshy islet after another, all seeming strangely out of place, and sometimes just reaching with my foot a soft tremulous shoal which gave scarce the shadow of a support, though even that shadow rested my feet.

At one of these moments of stillness it suddenly occurred to my perception (what nothing but this slight contact could have assured me, in the darkness) that I was in a powerful current, and that this current set _the wrong way_.

Instantly a flood of new intelligence came.

Either I had unconsciously turned and was rapidly nearing the Rebel shore,--a suspicion which a glance at the stars corrected,--or else it was the tide itself which had turned, and which was sweeping me down the river with all its force, and was also sucking away at every moment the narrowing water from that treacherous expanse of mud out of whose horrible miry embrace I had lately helped to rescue a shipwrecked crew.
Either alternative was rather formidable.

I can distinctly remember that for about one half-minute the whole vast universe appeared to swim in the same watery uncertainty in which I floated.