132 PRACTICAL TREE REPAIR 



common tools and appliances, and is easily and 

 quickly put into the tree. On the other hand, it is 

 absolutely u,nlike wood in all its properties, being 

 heavy, cold and rigid, while wood is light, warm 

 and elastic. It is very difficult to get a good junc- 

 tion between wood and cement. Cement is always 

 somewhat porous, and usually damp, and attracts 

 and condenses moisture, the greatest enemy of the 

 life of wood. It is very weak when it is new, 

 and is then and later frequently crushed by the 

 immense strength of a bending and twisting tree. 

 Almost the only thing in its favor is its conveni- 

 ence. Many situations and co;iditions, however, 

 can be found in which the drawbacks of concrete 

 are minimized in Importance, and in which it is 

 as good a material as any. 



Perhaps an attempt to lay down certain rules 

 covering these points would be worth while: In 

 basal cavities which are well grounded and which 

 do not extend up into the trunk a distance greater 

 than two or three times its diameter, use concrete. 

 In small cavities, at least so small in relation to 

 the size of the trunk in which they occur that when 

 the tree sways they move as a unit and do not vary 

 much in shape, use concrete if the wood is dry. 

 When the conditions are slightly more severe than 

 these, concrete can often be used with safety, pro- 

 vided extreme care is taken with the braces, the 

 dressing of the cavity, and the covering of the sur- 



