This book would not have been possible without the encouragement, support, and assistance of my wife Joan. I want to thank Pete Meyers, who responded so positively to my proposal for the book; Nan Barber, my editor, whose help and patience made the writing process much easier and the words in this book so much better; and the technical reviewers, Daniel Mocsny and Godmund Schick, whose comments on the first draft I found invaluable.

John Broughton