Heroes of the Telegraph

'The phonograph,' said Edison of his favourite, 'is my baby, and I expect it to grow up a big fellow and support me in my old age.' Some people are still in doubt whether it will prove more than a curious plaything; but even now it seems to be coming into practical use in America, if not in Europe. After the publication of the phonograph, Edison, owing, it is stated, to an erroneous description of the instrument by a reporter, received letters from deaf people inquiring whether it would enable them to hear well. This, coupled with the fact that he is deaf himself, turned his thoughts to the invention of the 'megaphone,' a combination of one large speaking and two ear-trumpets, intended for carrying on a conversation beyond the ordinary range of the voice--in short, a mile or two. It is said to render a whisper audible at a distance of 1000 yards; but its very sensitiveness is a drawback, since it gathers up extraneous sounds. To the same category belongs the 'aerophone,' which may be described as a gigantic tympanum, vibrated by a piston working in a cylinder of compressed air, which is regulated by the vibrations of the sound to be magnified. It was designed to call out fog or other warnings in a loud and penetrating tone, but it has not been successful. The 'magnetic ore separator' is an application of magnetism to the extraction of iron particles from powdered ores and unmagnetic matter. The ground material is poured through a funnel or 'hopper,' and falls in a shower between the poles of a powerful electro-magnet, which draws the metal aside, thus removing it from the dress.