TREE-LINE CONSTRUCTION 73 



rapidly to wear thin at the staple. In these situations windfall is often not very 

 great, and good results can be secured by tying the insulator down to a nail or 

 staple set below it or by abandoning the use of the staple entirely - and wiring the 

 split insulator tight against the tree with a loop around the tree itself. Still another 

 method that has proved satisfactory is to employ the tie shown in Fig. 32E, but 

 instead 1 of making a plain loop of wire around the staple, to use galvanized-iron 

 wire-rope-thimbles around which to make this loop. Get the size used with iVin. 

 wire rope. 



A similar .method can often be used to advantage in constructing pole lines 

 through dense istands of small, dead spruce, so common in the northern forest. In 

 this region it is sometimes impracticable to cut &n adequate right of way at once, 

 for lack of funds, but a pole line is necessary for lack of suitable tree supports. 

 Under these circumstances poles should be set in straight lines as for a pole line but 

 split insulators tied down to a spike below the wire should be employed 1 . All large, 

 dead snags should be cut, and when later a full right-of-way clearing is made the 

 regular bracket and pony glass insulator may be substituted. 



9 CROSSING MEADOWS AND PARKS 



It muy sometimes be preferable to cross small meadows and parks instead of 

 making the detour necessary to the continued use of trees. Poles should ordinarily 

 be used to make crossings of this kind. 



When not more than six or eight poles are necessary, they should be considered 

 as trees, and the line wire attached to each by a split insulator, allowing as much 

 slack as elsewhere in the line. In this way no injury to the portion of the line in 

 the park or meadow will be caused by a tree falling on an adjoining span. If a 

 large number of poles is required, the first eight poles on each side of the meadow 

 should 1 be equipped with split insulators. For the remaining distance the standard 

 pole-line construction with the sag in the spans as indicated' in Table I) should be 

 used. Do not " stagger " any of the poles unless they are properly raked and guyed 

 to witbstand the strain. 



10 CROSSING KIVERS AND CANYONS 



Where it is necessary to cross a river or canyon less than 500 ft. in width, n 

 pole should be set (do not use a topped tree) on each side of the canyon or river 

 and securely anchored 1 . Each pole should be equipped with double brackets and the 

 wire tied to the insulators with the figure 8 tie. 



Where the span exceeds 500 ft., specific instructions should be obtained from 

 the district inspector before construction is begun. 



11 CROSSING DIVIDES AND BUILDING TO LOOKOUT POINTS 



Two methods may be followed in constructing lines across divides and watersheds 

 and to lookout points. 



The usual tree-line construction should be used when the timber is heavy and 

 such construction practicable. The line should follow a trail or road. Frequent 

 switch-backs may be necessary in order to get over the divide. 



The line should be hung in split tree insulators, using the regular attachment 

 C, Fig. 32, except on trees at very abrupt changes in line direction. At such points 

 a tie wire similar to B or E, Fig. 32, should be used, the tie being made of single 

 No. 12 B.W.G., B.B., galvanized wire. This tie is lighter than the main line and 

 a trifle stronger than the ordinary ties (C and D, Fig. 32), and will break as soon 

 as more than one tree falls across the line, thereby providing all of the slack between 

 the tree at the turn and the acftacent trees. 



