But that accomplishment I had reserved for a retreat, for I knew that the longer I stayed down the more surely I should have to snort like a walrus when I came up again, and to approach an enemy with such a demonstration was not to be thought of.
Suddenly a dog barked.

We had certain information that a pack of hounds was kept at a Rebel station a few miles off, on purpose to hunt runaways, and I had heard from the negroes almost fabulous accounts of the instinct of these animals.

I knew that, although water baffled their scent, they yet could recognize in some manner the approach of any person across water as readily as by land; and of the vigilance of all dogs by night every traveller among Southern plantations has ample demonstration.

I was now so near that I could dimly see the figures of men moving to and fro upon the end of the causeway, and could hear the dull knock, when one struck his foot against a piece of limber.
As my first object was to ascertain whether there were sentinels at that time at that precise point, I saw that I was approaching the end of my experiment Could I have once reached the causeway unnoticed, I could have lurked in the water beneath its projecting timbers, and perhaps made my way along the main shore, as I had known fugitive slaves to do, while coming from that side.

Or had there been any ripple on the water, to confuse the aroused and watchful eyes, I could have made a circuit and approached the causeway at another point, though I had already satisfied myself that there was only a narrow channel on each side of it, even at high tide, and not, as on our side, a broad expanse of water.