The Early History of Radio: from Faraday to Marconi
Radio was as much the culmination of the work of a series of scientists in the 19th Century, starting with Faraday, as it was an invention by Marconi. This book aims to illustrate the contributions made by these scientists and show how each was dependent upon the work and ideas of his predecessors; Faraday, Henry, Maxwell, Hughes, Fitzgerald, Hertz, Lodge and Marconi.
Inspec keywords: resonance; radio receivers; Maxwell equations; history; electromagnetic wave propagation; radio transmitters; electromagnetic field theory
Other keywords: resonance; Marconi; transmitter; electromagnetic wave propagation; electromagnetic field; Gerald Ganatt; Maxwell; Faraday's first prediction; radio; prehistory; receiver
Subjects: Electromagnetic wave propagation; Electromagnetic waves: theory; History of science; Other general electrical engineering topics; Radio links and equipment
In essence, the early history of wireless telegraphy, or perhaps it would be more correct to call it the 'pre-history', is the history of electromagnetic waves, the prediction of their existence by Faraday, the mathematical definition of the conditions for their propagation by Maxwell, and the eventual demonstration of their physical existence by Hertz with his experimental confirmation of the identity of their characteristics with those of visible light.
Tributes have often been paid to Michael Faraday as the outstanding pioneer of the electrical industry, a reputation which is perhaps largely founded upon his discovery of electromagnetic induction in 1831. It has been far less common, however, to regard Faraday as the scientist upon whose work the whole theory and practice of radio communication has developed. Yet such is the case, for without Faraday there would have been no Clerk Maxwell, no Hertz, no Marconi, and it is almost certain that the advent of wireless telegraphy would have been delayed by many years. Faraday's work was in fact fundamental to the development of electromagnetic theory and to the propagation of electromagnetic waves and it is therefore appropriate here to review briefly the stages by which, over a period of more than thirty years, his ideas and theoretical concepts developed to form the foundations for the work of Clerk Maxwell.
James Clerk Maxwell's interest in electromagnetic theory was almost certainly inspired initially by another young Cambridge wrangler, William Thomson (later Lord Kelvin), who in 1846-47 had made a mathematical investigation into the similarities between electromagnetic phenomena and elasticity. In the course of this investigation, he had examined the equations of equilibrium of an incompressible elastic solid in a state of strain and he had shown that elastic displacement was analogous to the distribution of electric forces in an electrostatic field. Thomson's memoir was concerned with equilibrium conditions but its results were such as to suggest to Maxwell a few years later that the analogies between elastic strain and electrostatic forces might be extended and applied to the propagation of electromagnetic forces through an appropriate medium. One of the first steps in following this line of thought was to investigate the possible characteristics of an appropriate medium and, having been greatly impressed with his reading of Faraday's Experimental Researches in Electricity, and with his whole concept of lines of force, Maxwell commenced by translating Faraday's ideas into mathematical terms.
To Heinrich Rudolf Hertz clearly belongs the honour of being the first actually to demonstrate the reality of electromagnetic waves in the air; to Lodge, whose interest in electromagnetic waves was aroused earlier than that of the rather younger Hertz, unquestionably belongs the credit of playing a vital role in the introduction and early development of practical radio communication.
The chapter is about the great contribution made by Sir Oliver Lodge to the early development of wireless telegraphy.
This chapter reverts to the mid-1890s but, before considering the events which followed upon young Marconi's arrival from Italy in the early spring of 1896, it is necessary to refer to the claims which have been so widely made in recent years on behalf of Aleksandr Popov, whose work during 1895 is alleged to constitute him the 'true inventor of radio'. The claims, which have a background of political propaganda, have been disseminated so widely that it is necessary to take serious notice, even if only to demolish them. The development of radio was, like that of so many other inventions, not the work of any single individual but the ultimate outcome of a whole succession of observations, theories and discoveries at the hands of a number of physicists and mathematicians extending over a very considerable period of time. Each stage in the progression was essential, none was redundant and each was completely dependent on what had gone before. Thus it is inappropriate, as it is with so many other inventions, to cite any particular individual as the sole 'inventor'; indeed to do so distorts the real history.
The story of Guglielmo Marconi's birth on 25 April 1874 and his upbringing in Italy has been told by others, notably by Professor W.P. Jolly in his biography of Marconi. Marconi commenced his experiments during the autumn of 1894 and, during the summer of 1895, he was able to send signals on his father's estate over a distance of about one mile.
