30 METHODS OF COMMUNICATION FOR FOREST PROTECTION 



A less rigid type of construction being evidently required, the line wire was hung in 

 loops from the insulators instead of being rigidly wired to them. This was quickly 

 superseded by a porcelain knob which took the place of the wire loop, and these in 

 turn were displaced by the split porcelain insulator. The latter has undergone several 

 important modifications from the original style in order to meet field conditions more 

 perfectly. 



Meanwhile, there has been a steady improvement in the method of attaching the 

 insulators to trees. Plain wire hangers fastened with fence-staples were first employed. 

 These have given place to various other forms of hangers and fasteners until there are 

 now a variety of improved methods of attachment suited to special conditions. The 

 importance of abundant slack and of equalized spans was not at first fully perceived. 

 Experience soon demonstrated that these features of tree-line construction were vital, 

 and, however much the appearance of the resulting line might depart from previously 

 accepted standards, the conditions had to be met. 



Simultaneously there were developed several improved forms of instruments for 

 field use. At first the only portable instruments available belonged to two very 

 specialized classes linemen's test sets and military field sets. The latter were not 

 readily procurable, were expensive, and were not well adapted for use with the types of 

 station equipment generally employed on forest lines. The former, although cheap 

 and adapted to the station equipment, were heavy if sufficiently powerful, awkward to 

 carry, and poorly designed for rough usage. By combining the good points of each 

 class a portable telephone of less than 10 pounds weight was first designed. Sub- 

 sequently, by adopting from military telephones the vibratory system of signalling, a 

 field set of only 2 pounds weight was obtained. 



While both the methods and equipment have been thoroughly tested in the field 

 and are known to be reliable, nevertheless, the Forest 'Service engineers would be the 

 last to claim that their methods are susceptible of no further improvement. In fact, 

 new methods are constantly being devised and this is especially true where forest-pro- 

 tection lines are built in new regions. Several novel conditions have already been 

 encountered in 'Canada that have called for special methods, but changes in methods 

 by inexperienced builders where field conditions present no striking novelties are to 

 be avoided. The .author has seen this attempted with distinct lack of success on 

 several occasions and wishes to strongly deprecate any attempts by inexperienced 

 tree-line builders to improve on the methods of the Forest Service as reprinted in this 

 manual. 



Section 37 Influence of Timber Conditions on Choice of Construction Type 



A word about the types of Canadian timber to which one or the other of these 

 methods is likely to be better adapted may be in order. In many Canadian forest 

 regions untimbered areas of greater or less extent occur. These are more common in 

 western than in eastern forests and are particularly abundant in the Rocky Mountain 

 forests and in the drier portions of the British Columbia interior. Wherever it is 

 possible to build forest lines in these open meadow lands it should be done. If 

 durable poles are reasonably accessible the first cost will be only slightly increased, and 

 the greatly reduced maintenance charges and superior transmission secured will 

 amply justify any small extra expenditure for construction. 



1 MERCHANTABLE TIMBER 



The types -of timber most favourable for tree-line construction are those with 

 little or no underbrush and only moderately dense stands of trees of small size (10 to 

 15 inches in diameter at breast-height), with trunks clear of branches to a height of 

 20 to 25 feet or with only small pin branches, and with thin, tough bark. To these- 

 belong; the lodgepole pine stands of the West, which are the most favourable of all 



