Identifier: belltelephonemag19amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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e set up a tube in which therewas an electrical discharge currentcarried by a stream of electrified—that is, ionized—molecules of mercuryvapor. Then he arranged to wobblethat stream sidewise through the mag-netic action of a telephone current ina coil essentially similar to that of atelephone receiver. In the tube heplaced two metal plates or electrodes.To these he connected a battery anda transformer in such a way as toform a transmitter the movable con-stituents of which were ionized mole-cules of gas instead of carbon grains.If there was no current in the receivercoil, then the arc stream flowed stead-ily and was undeflected, and there wasno current from the transmitter.When the arc stream was vibrated byan incoming telephone current, therewas produced an outgoing current ofsimilar vibrations, but of a magnitudegreatly increased because of the poweravailable in the battery. That ingenious mercury-arc re-peater was capable of good amplifica-tion, but it had a serious tendency to
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Mercury Arc Repeater Tube, 1912 The development of the lateH. D. Arnold be noisy in a way somewhat similarto that of an old-style carbon trans-mitter when it burned and siz-zled. It was tried out experimen-tally on telephone lines, but it wasused only under special engineeringsupervision, and never for any lengthof time. Development work on it wasdropped early because of the muchgreater promise of another device. This was the audion of Dr. Lee De-Forest, one of the most interestingand important inventions in modernelectrical arts. Although at that timea very crude instrument, incapable ofbeing used immediately as a repeaterin the telephone plant, its possibilities 12 Bell Telephone Quarterly JANUARY

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