Place: United Kingdom, England
Subject: biography, physics
English physicist and electrical engineer who predicted the existence of the ionosphere, which was known for a time as the Kennelly-Heaviside Layer. Heaviside made significant discoveries concerning the passage of electrical waves through the atmosphere and along cables, and added the concepts of inductance, capacitance, and impedance to electrical science.
Heaviside was born in Camden Town, London, on 18 May 1850. His uncle was Charles Wheatstone, who was a pioneer of the telegraph and may have stimulated in him an interest in electricity. Heaviside received only an elementary education, and was mainly self-taught. He took up employment with the Great Northern Telegraph Company at Newcastle upon Tyne in 1870, when he was 20. This employment lasted only four years, when he was forced to retire because of his deafness. Shortly after he is believed to have visited Denmark to study telegraph apparatus. On his return he was supported first by his parents and later in life he lived with his brother. Heaviside never obtained an academic position but received several honours, including fellowship of the Royal Society in 1891 and the first award of the Faraday Medal by the Institution of Electrical Engineers shortly before he died in Paignton, Devon, on 3 February 1925.
During his early years, Heaviside was absorbed by mathematics. He was familiar with the attempt by Peter Tait (1831-1901) to popularize the quaternions of William Rowan Hamilton, but he rejected the scalar part of the quaternions in his notion of a vector. Heaviside's vectors were of the form:
v = ai + bj + ck
where i, j, and k are unit vectors along the Cartesian x-, y-, and z-axes respectively. When Heaviside became involved with work relating to James Clerk Maxwell's famous theory of electricity, he wrote Maxwell's equations in vector form incorporating some discoveries of his own. Heaviside also used operator techniques in his expression of calculus and made much use of divergent series (those with terms whose sum does not approach a fixed amount). He made great use of these in his electrical calculations when many mathematicians were afraid to venture away from convergent series.
In his twenties and thirties, Heaviside became very interested in electrical science, first carrying out experiments and then developing advanced theoretical discussions. These were, in fact, so advanced that they were eventually dismissed by some mathematicians and scientists, and were classed as too abstract to be published in the electrical journals. He expressed his ideas in the three-volume Electromagnetic Theory (1893-1912). Much of this work extended Maxwell's discoveries but he made many valuable discoveries of his own. Heaviside visualized electrical ideas often in mechanical terms and thought of the inertia of machines as being similar to electrical inductance.
When Heaviside became involved with the passage of electricity along conductors, he modified Ohm's law (see Georg Ohm) to include inductance and this, together with other electrical properties, resulted in his derivation of the equation of telegraphy. On considering the problem of signal distortion in a telegraph cable, he came to the conclusion that this could be substantially reduced by the addition of small inductance coils throughout its length, and this method has since been used to great effect.
In the third volume of his Electromagnetic Theory, Heaviside considered wireless telegraphy and, in drawing attention to the enormous power required to send useful signals long distances, he suggested that they may be guided by hugging the land and sea. He also suggested that part of the atmosphere may act as a good reflector of electrical waves. Arthur Kennelly (1861-1939) in the USA also made a similar suggestion and this layer, which was for some time known as the Kennelly-Heaviside layer, was subsequently shown to exist by Edward Appleton. This part of the atmosphere, about 100 km/62 mi above the ground, is now known as the ionosphere.
Although from time to time Heaviside had his detractors, perhaps because he was unorthodox in his approach, he was later known and highly valued by the leading physicists and electrical engineers of his day.
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