PRACTICAL TREE SURGERY 403 



so strenuously advocate its adoption do not always consider that in 

 the end it is the patrons who have to pay for it. 



Another method of preventing injuries is the erection of high 

 poles to bring the wires over the trees. This is sometimes done, 

 especially where the trees are young or of a species that naturally 

 grows low, when a very high pole would be sufficient to clear them 

 for many years. The cable system may be used for telephone wires, 

 and much injury to trees prevented. Large cables are rather ex- 

 pensive to install, but what is termed the "ring construction" system 

 may be used to advantage in many instances, particularly in the 

 suburbs. In this way it is possible to run a line through avenues 

 of fine trees in the country districts without necessitating pruning 

 or disfiguration. 



Rights of way for poles on private property back of residences 

 are sometimes secured, and by this means the poles and wires may 

 be removed from the streets, much to the advantage of the trees. 

 But such rights are often difficult to secure, and are not always 

 satisfactory either to the public service corporations i.ir the owners 

 of the property. The former naturally do not care much fur these 

 rights of way unless they are legal and permanent, and the owners 

 in granting permanent rights run a risk of lowering the value of the 

 property. Most of the very high-tension transmission ser\ices, 

 however, are at present on private property, and seldom interfere 

 with trees. High-tension lines are affected seriously merely liy cli'se 

 proximity to trees; therefore, these rights of way ha\e hi include 

 broad strips of land — of course expensive. 



On general principles it is not wise to allow wires to be attached 

 to trees, although this is often done. Trolley and electric light wires 

 are frequently guyed to trees, but they are a source of danger, since 

 injury is likely to occur from the crossing of the wires, and light- 

 ning discharges occasionally pass from the wires t" the tree, caus- 

 ing damage. It is, however, often better to allow this than to endure 

 the erection of ugly poles; but proper insulation of the wires should 

 be insisted on, although ordinary insulators ha\'e little eft'ect on 

 lightning discharges. 



The lag-bolt system in common use for guying wires to trees is 

 not the best method, for sooner or later the wire and the bolt lie- 

 come embedded in the tree and cause injury. Moreover, a direct 

 metal connection with a tree is objectionable. Tlie block system is 

 better, although it may not in all cases be free from objections. 

 In no case should a wire be allowed to pass tightly around a tree, 

 as it will girdle it in time. When live wires come into contact with 

 limbs, some type of insulator should be employed. There are various 

 types, some being eft'ective in preventing injury from low-vi:dtage 

 lines. 



Wires often accidentally come into contact with trees by the dis- 

 placement of poles, particularly on curves, where the strain is very 

 great, but much of this injury may he prevented by embedding the 



