Lodge, a physicist and writer, was involved in the development of the wireless telegraph. He coined the term coherer and gained the syntonic (or tuning) patent from the United States Patent Office. More controversially, he was a long time researcher into psychic phenomena and a dedicated believer in Spiritualism. After 1900, he became prominent in psychical research, believing strongly in the possibility of communicating with the dead. After he lost his son Raymond during WW1 he was convinced to have established contact with him through a medium. The investigation of the nature and properties of the Ether of Space was the most fascinating branch of Physics for Lodge. He presents his findings in this volume. Its contents include: The Luminiferous Ether and the Modern Theory of Light. The Interstellar Ether as a Connecting Medium; Influence of Motion on Various Phenomena; Experiments on the Ether; Special Experiment on Ethereal Viscosity; Ethereal Density; Further Explanations Concerning the Density and Energy of the Ether; Ether and Matter; Strength of the Ether; and General Theory of Aberration. Also see other titles by this author available from Kessinger Publishing.