Modern practice of the electric telegraph : a handbook for electricians and operators (1874)
Pope, Frank L., 1840-1895 · New York : D. Van Nostrand · leaf 72
sthe principal objection tothe use of these substancesin the construction of an in-sulator. Hard rubber is in itself abetter insulator than glass ;but its surface, from exposureto atmospheric influences, soonloses its property of repellingmoisture, and becomes roughand porous. A surface which… … Fig-. 32. 92. The Glass Insulator.—The insulator most com-monly employed in this country is the glass. This isgenerally made in the form represented by Fig. 32,which is a sectional view of the insulator fixed upon awooden bracket, the latter being securely spiked to theside of the pole. The line…
Telegraph
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![An illustration from Catalogue des monuments et inscriptions de l'Égypte antique / publié sous les auspices de S.A. Abbas II Helmi par la direction générale du Service des antiquités [de l'Égypte] ; par J. de Morgan, U. Bouriant, G. Legrain, G. Jéquier, A. Barsanti (1894)](https://img.insideoutlibrary.com/img/200/ia-cataloguedesmonu21egyp-130-207.webp)
