This book presents a thorough survey of electric railway development from the earliest days of the London Underground to modern electrified main line trains. Coverage includes chapters on signaling and communications, power supplies, and a detailed survey about traction systems, both AC and DC. The introduction, first of mercury arc rectifiers, and later of power semiconductor controls, is also discussed in detail. The author has a long standing interest in engineering history and has written many papers on aspects of railway technology. This book will be of particular interest to scientists and historians interested in the development of electric railways.