Harry Potter GOF question?

Question:

Harry Potter GOF question?

Where in GOF is a patronus used for communication? JKR said this was the first book in which she presented this form of communication and I really don't know where it is.

Best Answer - Chosen by Asker: Sean - I think I remember one case in GOF when a patronus was used for communication. It was when Harry and Krum find Barty Crouch's dead body. Harry goes to the castle to tell Dumbledore and Krum stays behind to watch the body. When Harry and Dumbledore find Krum unconscious and Crouch's body missing, Dumbledore sends his patronus (to Harry it looked like a silver light) to fetch Hagrid.