Inventors of Radio - David Edward Hughes
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Prior to reading the April 1961 issue of Radio-Electronics magazine's "Inventors of Radio" article, I don't recall ever having heard of David Edward Hughes. Of course most people have never heard of me, but then I haven't accomplished near as much as Mr. Hughes. Per the article, Dave (if you'll permit the familiar reference) not only developed a precursor to the teletype machine, but he also invented the first practical carbon microphone. Author Bartlett claims, too, that Hughes described, based on an investigation into induced currents due to the making and breaking of electrical contacts, the principle of the coherer (the first widely used form of wireless signal detector). Bartlett sums up by saying, "It has been said of Hughes' experiments in radio that they 'were virtually a discovery of Hertzian waves before Hertz, of the coherer before Branley and of wireless telegraphy before Marconi and others.'" Son of a gun. Inventors of Radio - David Edward Hughes
David Edward Hughes By Dexter S. Bartlett David Edward Hughes was born May 16, 1831, in London, England, but the family emigrated to America when he was about 7 years old. In 1850, he became professor of music at the College of Bardstown, Kentucky, and soon after of natural philosophy. Hughes' first research was with wire telegraph apparatus, for which he invented the polarized relay for more reliable action. Also, as early as 1855 he patented a type-printing telegraph, which could handle 30 words per minute. The forerunner of the modern teletype, it had means for synchronizing the transmitter and printer, with provision for correcting sync with each word sent, plus many other features used in today's equipment. By 1856, it was in use between New York and Boston and, by 1862, in a limited way, throughout Europe. However, in those days labor was cheaper than automation, so the Morse operators stayed at their keys. Next, in 1878, he turned his research to the telephone and made a major breakthrough with the first carbon microphone. Previously, Wheatstone, as far back as 1827, and Reis, in 1861, had tried, producing instruments that would transmit only tones or scratches. The Hughes microphone consisted of a bar of carbon on two supports of the same material. The imperfect contacts were affected by sound waves and would therefore transmit sound signals. He did not patent his microphone, believing it to be a discovery rather than an invention. Among those who improved Hughes' invention was Edison, who used carbon granules for his imperfect contacts, thus producing our modern telephone transmitter. In 1879, while working on his microphone, Hughes noticed a noise in his phones when a current was interrupted in another coil a few feet away. In a letter to Sir William Crookes, he wrote, "Further researches proved that an interrupted current in any coil gave out such intense extra currents that the whole atmosphere, even several rooms distant, would have a momentary charge which was received by my telephones, even through obstacles such as walls." Hughes used his imperfect-contact microphone as a detector. He discovered also that a loose contact between metals was equally sensitive, but that the metals would cohere after the passage of a wave, making the device useless. Thus Hughes discovered - and discarded - the coherer 10 years before its invention by Brimley. He staged a demonstration before members of the Royal Society, in which he transmitted and received signals over a distance of 500 feet. One of the secretaries of the society, Professor Stokes insisted that all the effects could be explained by induction, and argued his point with such vigor as to convince the delegation. Discouraged by the attitude of Professor Stokes, Hughes refrained from publishing the results of his experiments. However, he continued them for some years, ceasing apparently on the publication of the work of Hertz, which explained to him and the world the true nature of the waves whose existence Professor Stokes had denied. After his discouragement and the subsequent triumph of Hertz, Hughes maintained a complete silence on his early experiments, relating them only after considerable persuasion to the historian of telegraphy, J. J. Fahie, in a letter dated April 29, 1899. In his later life, he invented the induction balance (commonly called the Hughes balance), now used in metal locators and mine detectors. He also revised and organized his many papers on electricity and magnetism. Dying in 1900 in England, where he had spent the latter part of his life, he left a considerable fortune, which, according to his will, was divided among such projects as the establishment of scholarships and prizes in physical science, as well as donations to four London hospitals. It has been said of Hughes' experiments in radio that they "were virtually a discovery of Hertzian waves before Hertz, of the coherer before Branley and of wireless telegraphy before Marconi and others." References Encyclopaedia Britannica, 11th Edition. George Prescott, Electricity and the Electric Telegraph, 1882. Orrin Dunlap, Radio's 100 Men of Science, 1944. J. J. Fahie, History of Wireless Telegraphy, 1902. Cyclopedia of Applied Electricity, 1911.
Posted May 17, 2023 |
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