American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 651
gthe line. This tends to keep a uniformstrain on the poles. Insulators.—Some of the essentials of aninsulator, for aerial purposes, are thatit shall have high electrical resistance, shallpossess strength, permit a good hold uponthe Avire, shed rain freely, have no dark recesses for the… … FIG. 408. ^•iiiiiiiiiiiiifiiiiiiP FETTER DRIVE SCREW. but it is not an insulator, and glass possesses non-conducting qualities but is more orless brittle. A combination of both might possess strength and high insulation butwould be opaque. In Europe, porcelain and earthenware insulators are very…
Telegraph
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