File:Radio, miracle of the 20th century a story of human achievement that stands unrivalled in the history of humanity, together with a colorful portrayal, giving a broad, general view of the whole subject (14733758196).jpg

Identifier: radiomiracleof2000drin (find matches)
Title: Radio, miracle of the 20th century ... a story of human achievement that stands unrivalled in the history of humanity, together with a colorful portrayal, giving a broad, general view of the whole subject of wireless telegraph and telephone and its marvelous development
Year: 1922 (1920s)
Authors: Drinker, Frederick E. (from old catalog) Lewis, James G., (from old catalog) joint author
Subjects: Radio
Publisher: (Philadelphia, Printed by National publishing co.)
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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times from A to the opposite end, always in the same direction. Thentake the south pole of your magnet and place it on the Bend of your needle (opposite from A). Be sure that youcarry the magnet from one extreme end of the needle to the other at each stroke and always see to it that northpole of the magnet is contacted with the north pole of theneedle and vice versa. NORTH AND SOUTH POLES. Another way to make a magnet is to place the needleon the magnet, the desired north pole of the needle co-inciding with the north pole of the magnet and vice versa.Then hammer on the needle or bar repeatedly with awooden mallet. The same result may be obtained byselecting a bar just long enough to bridge across to bothpoles of an electromagnet. The bar is tapped as was thecase before. If a magnetized knitting needle be broken at its middlepoint each half of the needle is found to be a magnet.The ends which were north and south poles before break-ing remain north and south, while the broken ends become
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