1 86 PRACTICAL TREE REPAIR 



It is absolutely essential that no growing bark 

 be permitted to remain inside of the cavity, for 

 it would be almost certain, ultimately, to press 

 against the lower surface of the tin and displace 

 it. And it is especially important that the edges 

 of the metal be laid and nailed in such a way that 

 no growth can get under them, and in such a way 

 that a callus will grow over them and the nail 

 heads as soon as possible. The way to make 

 sure that no living bark is left is either to chip off 

 the bark and wood just under it, or else, as in 

 the case of old inroUing calluses, to peel off the 

 bark and to scrape away all of the exposed cam- 

 bium. It is desirable, at the line at which the tin 

 meets the bark, that a little of the sapwood be 

 cut away, so that the tin may be a trifle below 

 the starting callus. 



As an interior dressing, a thorough coat of car- 

 bolineum will be enough. No heavier dressing is 

 required, for there is no weathering to be guarded 

 against and no bond to be produced between filling 

 and wood. 



Several different forms of sheet metal are used 

 in tinning trees, tin itself, odd as it may sound, 

 being the least valuable. But the word " tin " 

 is so very handy, both as a ;ioun and as a verb, 

 that it is the natural one to use in speaking in a 

 general way of sheet metal. 



Sheet zinc comes in several degrees of hardness, 



