Heroes of the Telegraph

John Munro · 1891 · 281 pages

Heroes of the Telegraph

John Munro181

'Lord of the speaking lyre, That with a touch of fire Strik'st music which delays the charmed spheres.' Professor Bell has accomplished the curious feat of speaking along a beam of sunshine 830 feet long. The apparatus consisted of a transmitter with a mouthpiece, conveying the sound of the voice to a silvered diaphragm or mirror, which reflected the vibratory beam through a lens towards the selenium receiver, which was simply a parabolic reflector, in the focus of which was placed the selenium cells connected in circuit with a battery and a pair of telephones, one for each ear. The transmitter was placed in the top of the Franklin schoolhouse, at Washington, and the receiver in the window of Professor Bell's laboratory in L Street. 'It was impossible,' says the inventor, 'to converse by word of mouth across that distance; and while I was observing Mr. Tainter, on the top of the schoolhouse, almost blinded by the light which was coming in at the window of my laboratory, and vainly trying to understand the gestures he was making to me at that great distance, the thought occurred to me to listen to the telephones connected with the selenium receiver. Mr. Tainter saw me disappear from the window, and at once spoke to the transmitter. I heard him distinctly say, "Mr. Bell, if you hear what I say, come to the window and wave your hat!" It is needless to say with what gusto I obeyed.' The spectroscope has demonstrated the truth of the poet, who said that 'light is the voice of the stars,' and we have it on the authority of Professor Bell and M. Janssen, the celebrated astronomer, that the changing brightness of the photosphere, as produced by solar hurricanes, has produced a feeble echo in the photophone.

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