Wireless Telegraphy and Telephony
Forfatter: Alfred P. Morgan
År: 1917
Forlag: The Norman W. Henley Publishing Company
Sted: New York
Udgave: Third Edition, Fully Illustrated
Sider: 33
UDK: 621.396.1 Mor
A practical Treatise on Wireless Telegraphy and Telephony, giving Complete and Detailed Explanations of the Theory and Practice of Modern Radio Apparatus and its Present Day Applications, together with a chapter on the possibilities of its Future Development
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WIRELESS TELEGRAPHY
I38
The waves that Hertz produced are the electromagnetic
or Hertzian waves of radiotelegraphy.
Many thousand commercial wireless stations clot the face
of the earth. Daily time signals, weather reports and storm
warnings flash to ships far out in the ocean from govern-
ment observatories. Late at night, in the midnight hours,
Fig. 150.—An amateur wireless telegraph station.
when the world is asleep, powerful land stations commence
to whisper press dispatches, and the next morning the
ocean daily, containing the same news as our morning paper,
is laid on the breakfast table of the ocean greyhound. A
distress signal sends revenue cutters scurrying along the
coast, and brings rescue to hundreds of imperiled lives.
The Navy Department issues an order, and a few minutes
later it is in the hands of the commanding officer of a fleet,
a thousand miles away. Wireless links two continents
across a table, and yet this wonderful apparatus is so simple
that a sixteen-year-old boy can build instruments with a