In a moment he saw that it was a raft resuming its voyage down the river, and he determined to make an inquiry from its crew before landing.
Pulling his skiff alongside, the young man sprang aboard.

As he did so he noticed that the white object was a tent, and that there was a single "shanty" amidship.

It was the very raft that had been described to him as being the only one to pass down the river the day before.
These details so occupied his attention that he did not notice a skiff made fast to the side of the raft just forward of where he tied his own.

Not seeing it, he did not, of course, ask any questions concerning it.

If he had, he might have learned that the raftsmen had just picked it up, floating, empty and ownerless, down the river.
There had been no oars in it, but they had rowed it to the raft with an extra pair from their own skiff.