PREFACE
This introduction to the Theory of Relativity is based in part upon a course of lectures delivered in University College, London, 1912-13. The treatment, however, has been made much more systematical, and the subject matter has been extended very considerably; but, throughout, the attempt has been made to confine the reader's attention to matters of prime importance. With this aim in view, many particular problems even of great interest have not been touched upon. On the other hand, it seemed advantageous to trace the connexion of the modern theory with the theories and ideas that preceded it. And the first three chapters, therefore, are devoted to the fundamental ideas of space and time underlying classical physics, and to the electromagnetic theories of Maxwell, Hertz-Heaviside and Lorentz, from the last of which Einstein's theory of relativity was directly derived. In the exposition of the theory itself free use has been made not only of the matrix method of representation employed by Minkowski, but even more of the language of quaternions. Very little indeed of these mathematical methods is required to follow the exposition, and this little is given in Chapter V., in a form which will be at once accessible to those acquainted with the elements of the ordinary vector algebra.
It is hoped that the book will give the reader a good insight into the spirit of the theory and will enable him easily to follow the more subtle and extended developments to be found in a large number of special papers by various investigators.
