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 133
of the outer cup assists the cleansingaction of the rain. The s(!rew thread allows the insulatorto be removed from the bolt. When wires have to beterminated sometimes a Langdon insulator is used. Thedouble-shed form with three groov(>s is shoAvu in Fig. 100.^rhe P.O. icrmnud insidator is a… … CD S TELEGRAPH LINES 123 for the attachment of wires carried away in a veiticaldirection.
Telegraph
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