With the passing of the years, developments and inventions in the electrical field succeeded each other in increasing tempo. In 1876, Alexander Graham Bell (1847–1922) developed the telephone. The sound to be transmitted via the telephone line was picked up by a funnel-shaped horn. The horn was terminated by a thin metal diaphragm immediately behind which was a small coil wound on a bar magnet. When sound entered the horn, the diaphragm vibrated and thereby varied the distance between the diaphragm and the coil. This caused a voltage to be generated in the coil that alternated in rhythm with the sound signal. When two such devices were linked by a long wire, the speaker at one end could bring the diaphragm at the other end into vibration. The same device was thus used for speaking and listening by alternately bringing it in front of the mouth and against the ear. This setup was improved fairly quickly and provided, among others, with a different kind of earpiece. Within a few years – in 1878 – the first public telephone network was opened in the United States.
Within a year after the introduction of the telephone, Thomas Alva Edison (1847-1931) had devised a contraption that consisted of a wooden cylinder around which was wound a sheet of tinfoil, an arm that enabled a needle to be brought into contact with the tinfoil, and a crank to rotate the cylinder. Edison set the needle in contacts with the tinfoil, rotated the cylinder with the aid of the crank, and into a horn-shaped mouthpiece attached to the needle he sang (or shouted): “Mary had a little lamb …”. When he turned the cylinder again, the horn of the instrument produced a recognizable reproduction of his voice. Thus was born the phonograph or, as it is better
known in Europe, the gramophone.
Although the reproduction was not of very good quality, the principle had been established. Ten years later, Emile Berliner (1851–1929), another American inventor, produced an improved version of the phonograph, which he called ‘gramophone’. In contrast to Edison’s instrument, which used a variable-resistance transmitter, that of Berliner used a flat disk instead of a rotating cylinder. The flat disk is, of course, the forerunner of the modern gramophone record. In the Berliner system, the grooves on the disk are modulated laterally, whereas those on the Edison cylinder are amplitude-modulated.
In 1879, in America, Edison, and in England, the British physicist and chemist Sir Joseph Wilson Swan (1828–1914) simultaneously introduced the first practical incandescent lamp. It was, perhaps,not so much the improvement of the filament that made the incandescent lamp a success as the evacuation of the bulb (in which Swan was aided by Charles Stearn, an expert in the production of high vacua). Edison and his team perfected the filament: after examination of thousands of alternatives, they devised the cotton-thread filament which, when joined with the bulb patents of Swan and Stearn, made the Edison lamp a commercial success.
In 1890, a young Dutch mechanical engineer, Gerard Philips (1858–1942), decided to set up his own company to produce incandescent lamps. This resulted in 1891 in the Philips Gloeilampenfabriek in Eindhoven, which soon became famous all over the world and is still an important multinational company today.
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