. Electric railway journal . iary messenger wire, and above this is the main mes-senger wire that supports both of the other wires. Inthis section of the country the temperature ranges fromabout 110 deg. to minus 10 deg. Fahr., and this changesthe stresses in the wires from almost zero to approxi-mately the elastic limit. Over tangent tracks the construction is simple. Fromeach supporting structure a steel casting attached tothe horizontal beam acts as a support for three sus-pension-type, Locke insulators. Each of these insula-tors is of itself good for a working voltage of 11,000,and the thr
. Electric railway journal . iary messenger wire, and above this is the main mes-senger wire that supports both of the other wires. Inthis section of the country the temperature ranges fromabout 110 deg. to minus 10 deg. Fahr., and this changesthe stresses in the wires from almost zero to approxi-mately the elastic limit. Over tangent tracks the construction is simple. Fromeach supporting structure a steel casting attached tothe horizontal beam acts as a support for three sus-pension-type, Locke insulators. Each of these insula-tors is of itself good for a working voltage of 11,000,and the three are used as a special insurance againstline troubles. The insulators are of porcelain and are8 in. in diameter, somewhat over 5 in. long, having anultimate strength of 12,000 lb. Since the initial ener-gizing of the line about the middle of December therehas not been a single failure of any of these stringsof insulators. There is attached to the bottom insulator a malleable- 1066 ELECTRIC RAILWAY JOURNAL [Vol. XLV, No. 23. NORFOLK & WESTERN ELECTRIFICATION—TYPICAL MAIN-LINE CATENARY CONSTRUCTION AND TUBULAR BRIDGE iron casting which supports the messenger wire bybeing clamped to it. This casting has ample bearingfor the wire and also has arcing horns so that in caseof an insulator failing the arc would probably be fromthe casting instead of from the wire. The messengerwire is y2-in. extra-high-tension, galvanized, steelcable having a breaking strength of over 30,000 lb. Itis jointed by forged sockets which were especially de-signed to develop the full strength of the cable. Thenominal sag in the messenger wire is 5 ft. in a , the actual sag, of course, depending upon the par-ticular span. Spaced at 30-ft. intervals along the messenger wireare bent-strap clips which hold the hanger straps. Theselatter are of galvanized steel and they are all of differentlengths, depending upon the distance from the low pointof the messenger wire, the length of each hanger be-ing
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