I hope this book will be useful to at least two groups of individuals: the nonspecialist reader with a general knowledge of solid-state science and seeking an introduction to the theory and practice of the Hall effect in metals, and the specialist seeking a contemporary review of the relevant literature. The literature has been surveyed thoroughly up to the middle of 1970, while the more accessible journals have been followed to late 1970. I have been selective in cases where there is a great volume of literature, particu larly in the case of old or obscure measurements of low accuracy, but in all cases I have tried to present the reader with sufficient information to judge whether a particular reference matches his interest and is therefore worth tracing. I compiled the book from reading the original publications, but inevitably there will be errors arising in transcription or inadvertent omissions. I hope the reader finding these will be charitable enough to write to me. lt is a pleasure to acknowledge the numerous useful discussions I have had at various times with associates and colleagues, particularly Drs. Mme M. T. Beal-Monod, J. E. A. Alderson, R. D. Barnard, T. Farrell, and P. Monod. Their influence appears at various points in the text-although, of course, they must not be held responsible for anything I have written.