A second edition of this text, initially published in 1957, is welcome. The book is by two wellknown English epidemiologists; the senior author is Principal Medical Officer, London County Council, and the junior author is Professor of Preventive Medicine and Public Health, University of Sheffield.
The authors stated their aims in the preface to first edition: "Our purpose in writing this book has been to present the main principles of epidemiology in a simple but comprehensive form that it is hoped will be useful both to students and practitioners." Now, seven years later, they add: "Since the appearance of the First Edition, epidemiological thought has pervaded many branches of medicine widely, and the literature abounds with example of its application. Although this book is concerned with principles, which in the main have changed little, this development must be recognized. Accordingly the opportunity has been taken to revise the whole text."