120 



Canadian Foresiry JaiiDuiI, July, 1915 



strengthened. The cement filling itself 

 aids very little in strengthening a tree. 

 A cavity less than two feet in length 

 rarely requires a bolt, but longer ones 

 where a large portion of the interior 

 has been removed, should be bolted 

 every eighteen inches. The liolts are 

 from % to 1 inch in diameter and 

 have heavy washers at each end. Oval 

 washers are better than round ones 

 since they should ])e countersunk on 

 the outside of the trunk and the 

 wound thus caused being elongated 

 will heal more readily. Wounds 

 caused by countersinking washers 

 should be treated in the same way as 

 all other wounds. 



FUUng Cavities. 



After the cavities have been bolted, 

 creosoted and tarred, the next step is 

 to fill in with cement. It might be 

 added here, that in the case of cavities 

 Avith such a shape that the cement 

 would work loose and fall out after it 

 hardens, it will be necessary to over- 

 come this tendency by driving many 

 three-incli nails luilf-way into the 

 wood throughout the interior. The 

 heads of these nails will become em- 

 bedded in the cement and hold it in 

 place. When a tree has been bolted 

 this nailing may not be necessary. An- 

 other method is to so under cut the 

 wood near the margin of the cavity 

 that the filling will be wider than the 

 opening. In under cutting, however, 

 care should be taken to have the wood 

 at the edge of the wound not less than 

 an inch in thickness. 



The filling mixture should consist 

 of a good grade of cement and clean 

 sand. One part of cement to three or 

 less of sand. The two to be thorough- 

 ly mixed before adding water. Only 

 enough of this added to make a rather 

 stiff mortar should be used. 



The mortar may be placed in the 

 cavity with a mason's trowel and 

 tamped well into place. In long ver- 

 tical cavities it will be necessary to 

 start at the bottom and fill in a sec- 

 tion at a time, holding the material in 



place with a piece of sheet metal until 

 it has set, and then proceed to fill in 

 the section on top. These sections or 

 blocks should not be more than a foot 

 in height and divided one from the 

 other by a sheet of tarred roofing 

 paper cut to fit the cavity cross-sec- 

 tion. Before the top of a section has 

 comi)letely hardened it should be 

 smoothed so that the paper can be 

 laid evenly on it. Dividing the cement 

 in l)locks in this manner will allow for 

 the twisting and bending a tree trunk 

 must necessarily endure in a high 

 Avind. Otherwise the cement will in 

 time break up and crumble out. 



Finishing Off tJic Face. 



Where the cavity extends up into 

 the trunk beyond the top of the open- 

 ing it may be necessary to cut a small 

 sloping opening into this cavity from 

 above and pour a more liquid cement 

 through it. 



In the case of very large cavities, 

 fine clean gravel is sometimes used 

 instead of sand. Stones 6 to S inches 

 in diameter are also frequently used. 

 These should be wet before being 

 placed in the mortar and be kept well 

 back from the sides and face of the 

 filling. 



Before each block or section has 

 become completely hardened its face 

 should be finished off. The face should 

 conform to the general shape of the 

 woody portion of the tree. It should 

 not be allowed to stand or bulge out 

 beyond the bark, otherwise the tree 

 would be hindered in its attempt to 

 cover the cement with a new growth. 

 It is usual in filling a cavity in the 

 first place to keep it well back and 

 later, before the cement has quite 

 hardened, ta bring up the surface to 

 the proper level. 



After the filling has thoroughly 

 dried the face may be painted over 

 with i)aint or tar. 



Trees that have been repaired 

 should be inspected from time to time 

 and careful watch kept to see if any 

 .further attention is required. 



