GENERAL METHODS 125 



this connection it may be noticed that there is 

 always danger, especially when the bark is thin, 

 that the cambium will be killed by drying back 

 an inch or so from the edge of the opening. 

 This amounts to an enlargement, by so much, of 

 the wound, and measures should be taken to pre- 

 vent it. If the job lasts several days, the tempo- 

 rary edge of the opening should be shellacked if 

 the danger is considered sufficient to warrant the 

 trouble. When the edges have finally been 

 shaped and pared smooth, the bast and cambium 

 and the wood an inch below it should be painted 

 with shellac or liquid wax. Such treatment will 

 not only prevent drying but also the killing of 

 the cambium by the antiseptic dressing. 



BRACING 



Bracing is next. Braces are put in to 

 strengthen the tree, to make it more nearly rigid, 

 in order that it may not crush the filling, to assist 

 in the retention of the filling, and to prevent the 

 opening up of cracks around its edges. For all 

 these purposes it is almost futile to try to use 

 braces which are entirely within the cavity. Such 

 braces cannot be made stiff enough, and cannot be 

 anchored strongly enough to the wood. The only 

 way to do is to run the braces clean through from 

 one side of the trunk to the other, which of course 

 means that ordinary machine bolts are exactly 



