The boys' life of EdisonMeadowcroft, Wm. H. (William Henry)
General
The boys' life of Edison
Meadowcroft, Wm. H. (William Henry)
Edison, Thomas A. (Thomas Alva), 1847-1931 -- Juvenile literature
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 some 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 center 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.
"I made six of these receivers and sent them in charge of an expert on
the first steamer. They were welcomed and tested, and shortly afterward
I shipped a hundred more. At the same time I was ordered to send twenty
young men, after teaching them to become expert. I set up an exchange
of ten instruments around the laboratory. I would then go out and get
each one out of order in every conceivable way, cutting the wires of
one, short-circuiting another, destroying the adjustment of a third,
putting dirt between the electrodes of a fourth, and so on. A man would
be sent to each to find out the trouble. When he could find the trouble
ten consecutive times, using five minutes each, he was sent to London.
About sixty men were sifted to get twenty. Before all had arrived,
the Bell Company there, seeing we could not be stopped, entered into
negotiations for consolidation. One day I received a cable from Gouraud
offering 'thirty thousand' for my interest. I cabled back I would
accept. When the draft came I was astonished to find it was for thirty
thousand pounds. I had thought it was dollars."
After the consolidation of the Bell and Edison interests in England the
chalk receiver was finally abandoned in favor of the Bell receiver--the
latter being more simple and cheaper. Extensive litigation with
newcomers into the telephone field followed, and Edison's carbon
transmitter patent was sustained by the English courts, while Bell's
was declared invalid.
Public-domain text, read in full here on John Shaqi.
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