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1894 __ Telegraphy without wires
Oliver Lodge (1851-1940)
Comment : The great contribution made by Sir Oliver Lodge to the development of wireless telegraphy has been largely forgotten. His work held little of interest to the lay press, compared with that of Marconi in later years, yet it was Lodge who provided a number of the essential elements which made it possible for Marconi to develop a practical system of wireless communication. In preparation for two important lectures to the Society of Arts in 1887, he carried out some important experiments on the discharge of Leyden jars which showed beyond doubt that lightning discharges are oscillatory in nature. During the course of these experiments, Lodge showed the need for resonance between oscillatory circuits if an adequate transfer of energy was to take place between them; one of his experiments illustrated the "recoil kick" that occurs when an oscillatory discharge takes place in a resonant circuit. However, although Lodge could by now demonstrate the physical existence of electric waves along wires and could measure their wavelength, he still had no means of detecting their presence in space. The honour of being first to do this goes to Hertz who, at the end of 1886, had discovered that his "dipole" spark transmitter could also be used to detect the transmitted vibrations across the rooms. Lodge was invited to deliver a memorial lecture on "The Work of Hertz" at the Royal Institution, a few months after Hertz·s death on 1 January 1894. This lecture disseminated an understanding of the properties of Hertzian waves well beyond the small circle of mathematical physicists to whom the subject had previously appealed; the lecture was reprinted in serial form in the weekly journal “The Electrician”. The title of the lecture was actually a misnomer as Lodge dealt more with his own work (in particular, how he had developed the coherer) and that of others who had followed Hertz, than with the work of Hertz himself. The lecture provided great stimulation for Dr. Alexander Muirhead, an eminent telegraph engineer, and led to close collaboration between Lodge and Muirhead which was to last for almost twenty years. A few months later, in August 1894, Lodge was asked to repeat his lecture at a meeting in Oxford of the British Association for the Advancement of Science. By now, Muirhead had supplied him with a range of telegraphic equipment including a Kelvin marine galvanometer and a Morse inker. At the lecture, Lodge arguably became the first person in the world to demonstrate wireless telegraphy when he transmitted Morse coded letters over a distance of about 60 m, and through several brick walls, to a simple Morse receiver based on his improved coherer. This achievement was widely reported but, at the time, nobody foresaw any commercial applications for a system of "telegraphy without wires". This had to await the subsequent arrival of Marconi in England, during February 1896. (Marconi and Lodge virtually ignored the existence of one another and it is interesting to speculate on how the development of wireless communication might have proceeded, had they agreed to collaborate.) By his failure initially to follow up the practical possibilities of his own researches, Lodge lost the opportunity to acquire popular acclaim as the ´"nventor" of wireless telegraphy but his influence on its early development was profound. With his deep understanding of the phenomenon of electrical resonance, he was the first to emphasize the importance of tuning. In May 1897 some two months before the publication of Marconi's original patent Lodge applied for a patent which gave him priority in the exploitation of selective tuning by means of added inductance. This patent was to become one of the most famous and fundamental in the whole history of radio communications. As the century drew to a close, Lodge was still pre occupied with his academic studies at Liverpool and, from 1900 onwards, at the new University of Birmingham where he was appointed the Principal. Nevertheless, in association with Muirhead, he found time to develop a well engineered and practical system of wireless telegraphy in 1903 which, for a time, rivalled that of the Marconi Company. However, a widespread adoption of the system was thwarted, partly by the virtual monopoply which had been created between the Marconi Company and Lloyds (the company which ran the signalling system around the British coastline in those days) and partly because the Postmaster General had refused to issue licences to competing stations. ("Six Great Pioneers of Wireless", EBU Technical Review Spring 1995, pp. 82-96)
Urls : https://www.ebu.biz/fr/technical/trev/trev_263-pioneers.pdf (last visited )

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