But in a fog, they pass Cairo without knowing it.

By and by they begin to suspect the truth, and Huck Finn is persuaded to end the dismal suspense by swimming down to a huge raft which they have seen in the distance ahead of them, creeping aboard under cover of the darkness, and gathering the needed information by eavesdropping:-- But you know a young person can't wait very well when he is impatient to find a thing out.

We talked it over, and by and by Jim said it was such a black night, now, that it wouldn't be no risk to swim down to the big raft and crawl aboard and listen--they would talk about Cairo, because they would be calculating to go ashore there for a spree, maybe, or anyway they would send boats ashore to buy whiskey or fresh meat or something.

Jim had a wonderful level head, for a nigger: he could most always start a good plan when you wanted one.
I stood up and shook my rags off and jumped into the river, and struck out for the raft's light.

By and by, when I got down nearly to her, I eased up and went slow and cautious.