170 PRACTICAL TREE REPAIR 



this type of cavity. General rules for the choice 

 of filling materials have already been laid down, 

 and there is little that need here be added to them. 

 Asphalt is distinctly the best material, but if the 



opening is reasonably 

 small, the cavity well 

 drained, and the prob- 

 able strain on the filling 

 not great, a concrete 

 filling, well put in, may 

 be fairly satisfactory. 

 The surface of the 

 concrete, if used, must 

 be given a waterproof 

 application, after it has 

 thoroughly hardened. 



When injuries to the 

 trunk occur near crot- 

 ches, very bad cavities 

 often develop. They 

 are due, usually, to the 

 death of a large limb or the death or breaking off 

 of the upper part of the trunk. The resultant 

 cavity is called a " saddle." It is hard to make 

 a good job out of a saddle filling, for the reason 

 that parts of the filling are likely to be horizontal 

 or nearly so, making waterproofing difficult, while 

 the large amount of sway and movement in the 

 branches up which the saddle extends makes it 



Typical saddle-cavity show- 

 ing distribution of braces 



