Edison, Thomas A. (Thomas Alva), 1847-1931; Inventors -- United States -- Biography
price. Again I said: 'Make me an offer.' Again he named $100,000. I
accepted, providing he would pay it at the rate of $6000 a year for
seventeen years. This was done, and thus, with the telephone money, I
received $12,000 yearly for that period from the Western Union Telegraph
Company."
A year or two later the motograph cropped up again in Edison's work in a
curious manner. The telephone was being developed in England, and Edison
had made arrangements with Colonel Gouraud, his old associate in the
automatic telegraph, to represent his interests. A company was formed, a
large number of instruments were made and sent to Gouraud in London, and
prospects were bright. Then there came a threat of litigation from
the owners of the Bell patent, and Gouraud found he could not push
the enterprise unless he could avoid using what was asserted to be an
infringement of the Bell receiver. He cabled for help to Edison, who
sent back word telling him to hold the fort. "I had recourse again,"
says Edison, "to the phenomenon discovered by me years previous, that
the friction of a rubbing electrode passing over a moist chalk surface
was varied by electricity. I devised a telephone receiver which was
afterward known as the 'loud-speaking telephone,' or 'chalk receiver.'
There was no magnet, simply a diaphragm and a cylinder of compressed
chalk about the size of a thimble. A thin spring connected to the centre
of the diaphragm extended outwardly and rested on the chalk cylinder,
and was pressed against it with a pressure equal to that which would be
due to a weight of about six pounds. The chalk was rotated by hand.
The volume of sound was very great. A person talking into the carbon
transmitter in New York had his voice so amplified that he could be
heard one thousand feet away in an open field at Menlo Park. This great
excess of power was due to the fact that the latter came from the person
turning the handle. The voice, instead of furnishing all the power
as with the present receiver, merely controlled the power, just as an
engineer working a valve would control a powerful engine.
Public-domain text, read in full here on John Shaqi.
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