SHADE TREES. 



169 



slightest strain, and only a bolt passing through the tree, provided with 

 a washer and nut, is suitable for such work. If stranded wire is employed 

 it may pass around an imbedded iron bolt 

 at the back side of the limbs. 



In any system of strengthening trees, 

 whether by wires or other methods, the 

 best mechanical principles should be em- 

 ployed and a careful estimate made of the 

 amount of load that must be carried; also 

 the proper angle of attacliment, etc. The 

 amount of strain to overcome in wiring 

 trees is invariably underestimated, even 

 with an ordinary amount of swaying. 

 During severe tempests hardly any treejs 

 safe, a twisting air movement of great 

 velocity acting as a severe strain. It^is 

 always wise to have the chain or wire used 

 far within the limit of safety. Since the 

 limbs or branches of a tree have a tendency 



Fig. 31. — Iron band around limbs 

 of tree. An objectionable method. 



to move inwards during cold 

 weather, causing chains and wires 

 to become slack, all wires should 

 be drawn tight at their installa- 

 tion. 



In many cases of chaining and 



bolting the washer and nut are 



placed on the outside of the bark, 



and often no attempt is made to 



cut off the ends of the bolts. The 



unsightliness of this method makes 



it objectionable. It is better to 



cover the nut and washer, which 



may be done by countersinking them into the wood of the tree by means 



of \ a gauge or extension bit, and the free ends of the bolts should be cut 



off close to the nuts. The washer and nut should be well imbedded in 



Fig. 32. — Improper method of chain- 

 ing tree. Dotted lines show more 

 effective method: (6) bolt, (c) 

 chain. All chains, however, too low. 



