American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 653
tie wire is apt tocrunch the glass, thereby inii)aring the insulation; in fact, introducino- a source of 40 AMERICAN TELEGRAPHY. defective insulation, often very difficult to discover. The lower tlie groove on tlieinsulator the less is the strain on the supporting pin, but at that point the glass… … B. AND O. INSULATOR. PONY INSULATOR. petticoat, as seen in Fig. 412, in which a section of the lower part of the in-sulator is removed to show the double petticoat. This insulator is known as theW. IT. double petticoat insulator. In Fig. 413 is shown a form of insulator de-signed to still further…
Telegraph
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