Elementary telegraphy : a manual for students; written specially to meet the requirements of the ordinary grade of the subject as published in the syllabus of the city and guilds of London Institute (1910)
Pendry, H. W. (Henry Walter) · London ; New York : Whittaker & Co. · leaf 91
used, Mr. Yarley designed an arrange-ment of bar magnets and a soft iron needle which OAved itspolarity to their influence. This form of induced needleis illustrated in Fig. CO. N S and N-^ S-^ are two barmagnets Avith like poles adjacent to AAhich soft iron stripsare fixed ; these, j)assing… … TELEGRA PH INi^TM UMENTS 81 paddle-sliaped needle of soft iron mu^neticully dividedby a layer of sj^elter (zinc). Tlie similar poles of themagnets are adjacent, and tliey are placed above andbelow the soft iron axle as shown in Fig. 01. l?y induc-tion the lower end of theneedle becomes north…
Telegraph
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