PRACTICAL TREE SURGERY 



729 



used to fill a cavity, some sort of cloth 

 or wire dam will have to he used to 

 hold the cement in place until it is 

 hard. For this purpose strips of hur- 

 lap wrapped tightly around the tree 

 so as to cover the lower part of the 

 opening may be sufficient if the mixture 

 is not very thin ; otherwise, a more 

 closely woven fabric, such as canvas 

 or carpet, may be used. 



After the cement filling has become 

 thoroughly dr)', the outer face may be 

 painted with coal tar or jjaint, espe- 

 cially around the edges where cracks 

 are likely to appear. This should not 

 be done for several weeks after the 

 cement has been put into the cavity. 



TlN.\i:o C.WITIKS. 



Sheet tin, zinc, and iron have been 

 (|uite extensively used to cover 

 cavities. When properly applied, 

 these- coverings often serve to 

 keep out disease and insects for 

 a long time. Oftentimes they are 

 improperly applied, or the cavity 

 is not properly treated. Under 

 such conditions these tin-covered 

 cavities are a greater menace to 

 the tree than open cavities. In 

 ])reparing a cavity for a sheet- 

 metal covering, all the decayed, 

 diseased and insect-eaten wood is 

 removed in the manner indicated 



No. 1. — Limbs of an Elm 

 tree guyed by severa', 

 independent chains 15 

 feet above the crotches. 

 Plate Xo. 7. 



Xo. 2. — A split 

 crotch guyed by 

 means of a long 

 bolt about eighteen 

 inches above the 

 crotch. 



Xo. 3. — A tupelo tree nearly strangled by tele- 

 graph wires wrapped around the trunk. 



under cement fillings, with two excep- 

 tions : There is no need of undercutting 

 the caxity and there should be a narrow 

 lalf-inch ledge of wood around the 

 edge of the cavity to which the margin 

 of the sheet metal can be tacked. The 

 excavated cavity must be thoroughly 



