. The practical telephone handbook and guide to the telephonic exchange . from astraight line, or the less the angle the wires on the two sidesof the pole make with each other. Let p in Fig. 372 represent a pole, and p a and p b thedirections of the wires. Then if the pulls on the two sides areunequal, take p s on some scale, equal to the total stress on theright, and p s equal to the stress on the left, of the pole. Formthe parallelogram psrs, and draw its diagonal p r, which willrepresent in force and direction the resultant force of the pullof the wires. This resultant can be counteracted b
. The practical telephone handbook and guide to the telephonic exchange . from astraight line, or the less the angle the wires on the two sidesof the pole make with each other. Let p in Fig. 372 represent a pole, and p a and p b thedirections of the wires. Then if the pulls on the two sides areunequal, take p s on some scale, equal to the total stress on theright, and p s equal to the stress on the left, of the pole. Formthe parallelogram psrs, and draw its diagonal p r, which willrepresent in force and direction the resultant force of the pullof the wires. This resultant can be counteracted by a singlestay wire in the opposite direction, p r, which may be calculatedas for a terminal pole on which the wires pull with a stress equalto, and in the direction of, p r. An even better method ofcounteracting the pull on the pole when the angle is nearly a 376 PRACTICAL TELEPHONE HANDBOOK right angle is to use two stays in line with the directions of thetwo wires, as shown by the dotted lines in Fig. the stresses on both sides of the pole are equal, the re-. Fig. 372.—Diagram of Stresses on Angle Pole sultant, p r, will divide the angle, b p a, into two halves, andcalculation will be easy, as all the sides will be equal, and right-angled triangles can be formed by drawing the other diagonalfrom s to s CHAPTER XXV UNDERGROUND WORK The invention and improvement of dry-core cables and thegeneral adoption of metallic circuit lines has rendered the useof underground lines perfectly feasible and cheap, and has ledto a great extension in their use. It seems only a matter ofa short time before all telephone lines in towns will be rununderground, with the exception of the short lengths needed fordistribution, and even these will be dispensed with in sometowns. In most cases the cost of installing such underground lines ishigher than that of overhead lines when the number runningin any one direction does not exceed about 100 ; but for morethan this number the cost is less, a
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelephone, bookyear19
