1 68 PRACTICAL TREE REPAIR 



opening and the auxiliary ones is left for its 

 strengthening value, and if the shell is thin no 

 such value is present. Then, too, a thin patch of 

 wood between two holes, one of which is above 

 the other, is likely to die, dry out, check, and ad- 

 mit new decay. Once the size and place of the 

 openings are decided on, they should be made, 

 for to delay each inch of enlargement of a cavity 

 until it becomes absolutely necessary to make pos- 

 sible the use of the gouge, means that the work 

 is constantly being done at a disadvantage. It 

 is all hard where part of it might be easy. 



The great point about handling the excavation 

 of this type of cavity is to make sure, if concrete 

 is used as a filling material, that good drainage 

 is provided. This means that there must be a 

 downward slope from the lowest part of the cav- 

 ity, inside, to the lowest part of the opening. If 

 such is the case, any water which may enter the 

 cavity before the crack between the concrete and 

 the wood is covered by the growth of callus, 

 will be drained out at the bottom. To be sure, 

 it is not very reassuring to have to provide for 

 such a possibility, but experience has shown that 

 it is wise to provide for the disposal of water in 

 cavities, when filled with concrete, even though 

 the correct dressing or the cavity and of the outer 

 surface of the filling may reduce the possibility 

 of the entrance of water or of damage resulting 



