. American telephone practice . higher, owing to the 778 AMERICAN TELEPHONE PRACTICE. cleaner condition of the surface. In good weather the double-petti-coat insulators gave much higher resistance than the single or cor-responding size, but during a rainstorm a double-petticoat form wasinferior to the single, although it was found to dry more rapidly aftera storm. The determination of the pole line route is a matter of no smallimportance. Right of way must be secured, and this usually callsforth all the ingenuity of the party unfortunate enough to be assignedto that duty. Before distributing t
. American telephone practice . higher, owing to the 778 AMERICAN TELEPHONE PRACTICE. cleaner condition of the surface. In good weather the double-petti-coat insulators gave much higher resistance than the single or cor-responding size, but during a rainstorm a double-petticoat form wasinferior to the single, although it was found to dry more rapidly aftera storm. The determination of the pole line route is a matter of no smallimportance. Right of way must be secured, and this usually callsforth all the ingenuity of the party unfortunate enough to be assignedto that duty. Before distributing the poles and other material theroute should be thoroughly studied in every detail. Stakes shouldbe driven marking the location of the poles. It should be borne inmind in locating these stakes that bends in the pole line should beavoided wherever possible, that the ground should be of such natureas to form as good a support as possible for the pole, that there shallbe no interference from trees, houses or other poles, and lastly. FIG. 545.—DOUBLE-GLASS TRANSPOSITION INSULATOR. that the route shall be as direct as possible. When a turn must bemade it should be so located, if possible, that the guy wire requiredto hold up the corner will have suitable anchoring ground. Lackof attention to these preliminary details too often brings an endlessamount of trouble in the way of rehandling of poles, redigging ofholes and similar useless labor. When the ground is level or gently undulating, no provision needbe made for grading the pole tops. Where, however, the countryis hilly it is well to make a survey of the route with a level, plac-ing the instrument between each successive pair of stakes and takinga front and back sight from each position to the adjacent record of the data thus obtained will enable one to plat the ver-tical section of the route. The profile of the pole tops may then be POLE LINE CONSTRUCTION. 779 platted, care being taken to smooth out all sharp bends in i
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