They stood or sat upon it, baited their hooks, and threw them over into the water.

They followed the bait with their eyes as it sunk slowly down into the dark depths, among the logs, and roots, and trunks of trees, which were lying submerged in the water.
The boys remained here an hour, but they caught no eels.

Either there were none there, or for some reason or other they chose not to bite.
They had some talk about going to another place, but before they decided upon that plan, Marco's attention was arrested by the sight of what appeared to be a large log floating down the river.

He pointed it out to the other boys, and, on closer examination, they saw that it was an old canoe, of the kind that are formed by hollowing out a log.
It was not of very large size and it appeared to be rather old and decayed.

Still, the boys wanted to get it very much.