Modern practice of the electric telegraph : a handbook for electricians and operators (1874)
Pope, Frank L., 1840-1895 · New York : D. Van Nostrand · leaf 73
d with hot coaltar, to preserve it from decay.The line wire is tied to theoutside of the shield, in thesame manner as when the glassinsulator is used. This insulator is usuallymounted upon an oak bracket,as in Fig. 33, secured by spikesto the side of the pole or othersupport. When it is intendedto… … Fig. 33.
Telegraph
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