Mark didn’t say anything, but I could see, by the way he tipped his head to one side, he was listening careful. We paddled on for ten minutes, and the noise came again. It was a sort of mix-up of rattle and rumble and roar. It sounded to me like a team crossing a bridge, but, after all, it didn’t sound quite like it.
“’Tain’t a b-b-bridge,” says Mark.
“What is it, then?”
“Dun’no’,” says he.
Pretty soon it went off again. Rattle, rattle, rumble, rumble, clatter, clatter, with a sort of squeal twisted in for good measure.
“S-some kind of a machine,” says Mark.
It kept coming every little while, sometimes as much as twenty minutes apart, and growing louder every time it came.
“S-sounds like a machine,” says Mark.
That’s what it was, but, when you come to think of it, it was a funny sort of a machine, and funny things were being done with it. About half past four we came slap onto it. It was a big scow more than fifty feet long and twenty or so wide. A flat, square house covered about two-thirds of it, and a whopping big derrick stuck up near the front end. There was a smoke-stack, so we knew there must be an engine. We’d have found that out pretty quick, anyhow, because it was hissing and fussing and spluttering away, and steam was spurting out of the side every little while.
A big cable stretched from the boom of the derrick up-stream, and the end of it was hitched to two of the biggest timbers I ever saw. They were hewn square, and each of them must have been sixty feet long. They were fastened side by side into a raft that would have floated an elephant. There were two men on it. I didn’t pay special attention to them, because I was so interested in the raft, but Mark did. I heard him let his breath go in the whoppingest sigh of relief a man ever heaved.