What is a summary of Chapters 16,17,18 and 19 of The Cay?

In Chapter 16, Phillip buries Timothy.  At first he is angry that the old man has left him, but then he realizes that Timothy died so he could live.  Phillip takes stock of the things he must do now that he is alone - he must feed himself and Stew Cat, rebuild the hut and signal fire, and listen each day for the sound of a plane.  As he sets about his work, Phillip begins to understand just how well Timothy had prepared him to survive on his own.

Hungry for something other than fish, Phillip dives into the swimming hole in search of langosta in Chapter 17.  He catches one, but then is bitten by a large moray eel.  His wound is painful but not life-threatening. 

In Chapter 18, Phillip finally hears a plane, and lights the signal fire.  The plane does not come closer, however, and Phillip then realizes the smoke from the fire might not be noticeable enough.  He devises a way to make the smoke blacker, and a few days later, in late August, he hears explosions and a plane in the distance.  Even though his fire sends a clear signal into the sky, the plane does not come nearer, and Phillip is in despair.

In Chapter 19, Phillip's finds that his signal was, in fact, noticed, and he is finally saved.  He takes only Stew Cat and Timothy's knife with him when he leaves the island, and his rescuers do not at first believe he has survived on the cay since April when the Hato went down.  Phillip is reunited with his parents, and after three operations, regains his sight.  He is much changed by his experience, and hopes one day to return to the island where Timothy is buried.