In his "Principle of Relativity" the author gave a comprehensive account of this subject, including detailed mathematical developments. The present volume is intended for the use of the experimental rather than of the mathematical physicist. It emphasizes the close relation between the principles of relativity and electron theory, and those aspects of the subject which are most closely related to experimental investigations. Mathematics is not altogether avoided, but is reduced to the minimum necessary to clear understanding. An account is given of the various experiments, the failure of which seemed to demand some revision of traditional notions regarding time and space. The topics treated in successive chapters are: The origin of the principle; the relativity of space and time; the relativity of the electromagnetic vectors; mechanics and the principle of relativity; Minkowski's four-dimension vectors; the new mechanics; relativity and an objective ether. In the latter chapter the author gives reasons for the belief that the existence of an ether is not necessarily inconsistent with the principles of relativity.

-The Physical Review [1916]