chapter  4
Pages 21

The radio is the clearest example in these histories of a machine already in existence-‘invented’—but not recognised as such. We have seen that the physicists of the world were intent on demonstrating the truth of theories promulgated by Maxwell and Helmholtz in the 1860s by using a variety of laboratory devices and how these had impacted on the development of the telephone, the phonograph and the gramophone (Figure 10). Their importance to radio is even more pronounced.