46 



Fig. 26. Showing ridge 

 on tree, caused by feeble 

 lightning discharge. 



obviated in this way. 



since by the crossing of the wires injury is 

 likely to occur, and lightning discharges occa- 

 sionally pass from the wires to the tree, caus- 

 ing damage. It is, however, often better to 

 allow the wires to be attached to trees than to 

 endure the addition of ugly poles, but if wires 

 are to be attached to trees they should be 

 properly insulated, although ordinary insula- 

 tors have little effect on lightning discharges. 

 The lagbolt system in common use (see Fig. 

 22, A and Z) for guying wires to trees is not 

 the best method of attachment, since sooner 

 or later the wire and bolt become imbedded 

 in the tree and cause injury. The block sys- 

 tem ( J and E) is better, although it may not 

 be in all cases free from objections. In no 

 case should a wire be allowed to pass tightly 

 around a tree (B), as it will girdle it in 

 time. When live wires come into contact 

 with limbs some type of insulator should be 

 employed similar to that shown in P. 

 The porcelain and dowel insulator gives good 

 satisfaction. 



Wires often accidentally come in contact 

 with trees by the displacement of poles, par- 

 ticularly on curves, where the strain is very 

 great, but much of this injury may be pre- 

 vented by imbedding the poles in Portland 

 cement, and it should be pointed out that the 

 necessity for guying poles to trees may be 



ELECTRICAL INJURIES. 

 Alternating Currents. 



Electrical injuries, such as are caused by burning, are common to 

 trees, and occasion tree wardens a great deal of vexation. There 

 are many instances of large limbs being burned off, and in some 

 cases the burning is so extensive that the whole top of the tree is 



