I heard shouts, oaths, but there was no firing, and was far enough ahead to be invisible by the time I attained the bank.

An open barge lay there, a mere black smudge, and I stumbled blindly across this, dropping silently over its side into the water.

It was not thought, but breathless inability to attempt more, which kept me there, clinging to a slat on the side of the barge, so completely submerged in the river, as to be invisible from above.

Swearing fiercely, my pursuers stormed over the barge, swinging their swords along the edges to be sure I was not there.
One blade pricked me slightly, but I held on, sinking yet deeper into the stream.

I could see the dim outline of heads peering over, but was not discovered.