In "Robinson Crusoe", how did Friday get on the island? in robinson crusoe

In
Chapter 22 of the book, Friday and another person are captives of
the cannibals who evidently come to the island to have their festivities and then leave by
canoe. One victim is killed, and the other, Friday, runs in the direction of Crusoe's
fortress.

Crusoe had previously had a dream of this very eventuality some
time earlier and is surprised that it is playing out in front of him.  He convinces the victim
that he is friendly, kills two cannibals who are pursuing the victim, and helps Friday hide in
his cave.

Friday then claims loyalty forever to Crusoe.

This savage seeing a little chance for life darted away from his
captors He ran very fast right toward my home I was dreadfully frightened when I saw this for I
thought all the savages were after him...By a great deal of coaxing I got him to come to me at
last He threw himself at my feet and placed my foot on his head to show me that he would be my
servant forever I raised him up and treated him kindly  href="http://books.google.com/books?id=amwAAAAAYAAJ&dq=robinson%20crusoe%3A%20how%20did%20Friday%20get%20on%20the%20island&pg=PA96&ci=204,771,722,282&source=bookclip"> 
By ,  Robert Trumbull,  Samuel Taylor Coleridge