Heaviside, Oliver (1850–1925)

views updated

HEAVISIDE, OLIVER (1850–1925)

Oliver Heaviside was born May 13, 1850, in London, England. He was a physicist and mathematician whose theoretical work played a large part in the understanding of radio transmission and long-distance telephony. Educated at Camden House School in London, Heaviside came fifth in the College of Preceptors examination out of five hundred pupils. He left school in 1866 and continued to study. He learned Morse code and studied electricity and languages. In 1868 he went to Denmark and became a telegraph operator, and in 1870 he was appointed Chief Telegraph Operator.

In 1871 Heaviside returned to England to take up a post with the Great Northern Telegraph Company dealing with overseas traffic. In 1875 he had to leave the job due to increasing deafness. Heaviside was encouraged to continue his electrical research by his uncle, Charles Wheatstone, who with W. F. Cooke patented the electric telegraph in 1837, and who later devised the Wheatstone bridge, an electrical network for measuring resistance.

In 1872 Heaviside's first paper, "Comparing of Electromotive Forces," was published. Heaviside's second paper was published in 1873 and attracted the attention of Scottish physicist James Clerk Maxwell. In 1873 Heaviside was inspired by Maxwell's treatise on electricity and magnetism. It took Heaviside several years to fully understand Maxwell's book, which he then set aside to follow his own course of thinking. Finding Maxwell's conventional mathematics difficult to apply to practical matters, Heaviside introduced a simpler treatment that, in his opinion, did not impair accuracy. It proved to be controversial. His proofs did not conform to the standards of the time and his methods on partial differential equations had varying success.

In 1874 Heaviside established the ordinary symbolic method of analyzing alternating current circuits in common use today. It was a technique developed about fifteen years before AC came into commercial use. He emphasized the role of metallic circuits as guides, rather than conductors of AC currents. He discussed in detail causes of line distortion and suggested ways of alleviating it.

Between 1880 and 1887 Heaviside developed his operational form of calculus, a branch of mathematics that permits the manipulation of varying quantities applicable to practical problems, including such matters as electrical circuits with varying voltages and currents. Heaviside received a great honor in 1891 when he was elected a Fellow of The Royal Society in recognition of his work on electromagnetic waves. He was later the first recipient of the Society's Faraday Medal. The first volume of his great work "Electromagnetic Theory" was published in 1893 and a second volume in 1899. A third volume was published in 1912, but he died before completing the fourth.

In 1902 Heaviside's famous prediction about an ionized layer in the atmosphere that would deflect radio waves was published in an article titled "Telegraphy," in the tenth edition of "Encyclopaedia Britannica." The idea came when he was considering the analogy between the movement of electric waves along a pair of conducting wires and over a conducting earth. Discussing the possibility of radio waves being guided around a curved path he suggested: "There may possibly be a sufficiently conducting layer in the upper air. If so, the waves will, so to speak, catch on to it more or less. Then guidance will be by the sea on one side and the upper layer on the other." The layer was first named the Heaviside Layer and later the Kennelly-Heaviside Layer, as a similar prediction had been made around the same time by Arthur Kennelly at Harvard University. The hypothesis was proved correct in 1924 when radio waves received from the upper atmosphere showed that deflection of upward waves took place at a height of approximately 100 kilometers.

Heaviside made a significant contribution to electrical communications when he advocated the introduction of additional inductance in long-distance telephony cables although there was then no practical means to add it. His idea was eventually patented in 1904 by Michael Campbell of AT&T after Heaviside and George Pupin of Columbia University had shown it was possible to apply inductance in the form of uniformly spaced loading coils. By 1920 engineers had installed such loading on thousands of miles of cable, particularly in the United States.

During his lifetime, Heaviside made extensive contributions to pure mathematics and its practical applications to alternating current, vector analysis and telegraphy. He introduced new concepts that later became commonplace thinking and expressions for every electrical engineer, and invented much of the language now basic to communication engineering, including such words as "capacitance," "inductance," "impedance," and "attenuation."

Heaviside's last years were spent as an embittered recluse at Torquay, Devon where he allowed only a few people to visit him. For much of his life he suffered from recurring jaundice that was to prove fatal. He died on February 3, 1925. Heaviside's work has been an inspiration to countless electrical engineers and mathematicians. Time has enhanced the esteem in which he is held; succeeding generations have spent many hours studying his writings. As a lasting honor, craters on Mars and the Earth's moon were named after him.

Alan S. Heather