American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 654
W. U. INSULATOR. wire may still be held by the pin upon the cross arm. FIG, 414, … RUBBER INSULATOR. A rubber insulator in which an iron hook is inserted, as snown in Ficr. 4x4, is usett 542 AMERICAN TELEGRAPHY. extensively on the underside of cross-arms, in cities, especially on house-top fixtures.TEEE INSULATOR.—When from any cause whatever it is found impracticable topass…
Telegraph
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