We've got to guess at that and take the risk of it.

We can roll a lot of the logs and timber into the river, tie 'em together, and float with the stream until we come to Wareville." "But if we never come to it ?" asked Paul.
"Then all we have to do is to get off the raft and follow the river back up the bank.

Then we are sure to reach home." This was so plausible that Paul was full of enthusiasm and they decided that they would set to work on the raft early in the morning..