'… this book is a fine introduction and exposition of many of the theory's features. … A beautiful approach is taken: the authors show that a consistent theory of electromagnetism can be derived from the simple supposition that there is a force … I strongly recommend this book for a very wide range of readers. Advanced undergraduates will obtain a good first understanding of GR; postgraduates will find it a useful reference book, and will no doubt learn a great deal that they have not fully covered at undergraduate level. Researchers and lecturers will also find it an invaluable book, not only for recommending to students, but also for obtaining significant new insights themselves.' The Observatory