Much has been written about Faraday and Marconi, and about the history of the development of radio from the time of Marconi. However, Gerald Garratt's special interest was in what might be termed the 'prehistory' of radio. This book therefore outlines the sequence of development from Faraday's first prediction and concept of the electromagnetic field: Maxwell worked out the mathematics of electromagnetic wave propagation and Hertz demonstrated their physical existence. Lodge identified the need for resonance between transmitter and receiver, thus leading to Marconi's successful practical application.