PRACTICAL TREE SURGERY 



727 



decayed and diseased wood should be 

 removed from the spHt and creosote 

 and tar apphed, after which it can be 

 bolted just beneath the crotch, so as to 

 close the crack or at least bring the 

 parts back to their normal position m 

 case decayed matter has been exca- 

 vated from the crack. If the split is a 

 recent one, a washing of creosote onlv 

 will usually be sufficient before draw- 

 ing the sides together with bolts. Un- 

 der certain conditions, particularly in 

 large trees, it may be necessary to use 

 a rope and tackle blocks to pull the 

 limbs together some distance above the 

 crotch, in order to properly close the 

 crack before bolting it. 



I f the cavity has a comi^aratively 

 large opening or has little or no under- 

 cutting, it is the custom to drive flat- 

 headed wire nails into the wood in the 

 interior in order to hold the cement 

 filling firmly in place. In medium- 

 sized cavities nails two and a half or 

 three inches long are usually driven 

 into the wood for about half their 

 length (Plate No. 4, figure 2). 



TREATING. 



After the decayed and diseased mat- 

 ter has been completely excavated and 

 the edges of the sap wood and bark 

 shellacked, the next step is to sterilize 

 the interior of the cavity in order that 

 all germs of disease or decay which 

 are i)resent may be killed and that any 

 which may come in contact with the 

 cut surfaces during subsequent opera- 

 tions may be destroyed. As already 

 stated, creosote appears to be one of 

 the best ])reparations to use. Every 

 cut part of the wood and l)ark must be 

 creosoted, and o\er this a heavy coating 

 of tar or hot asphalt should lie ajiplied 

 before the cavity is filled. 



MIX IXC TIIK CEMENT. 



A good grade of Portland cement 

 and clean, sharp sand free from loam 

 ( 1 pcM-t of cement to 3 or less of sand; 

 should be used. A quantity of drv 

 cement and sand sufficient to fill the 

 cavity should be thoroughly mixed be- 

 fore the requisite amount of water to 

 make a rather stifif mortar is added and 

 the whole mixture worked to an even 



consistency. In large cavities fine 

 gravel free from loam is sometimes 

 substituted for the sand. 



CEMENTING. 



For placing the mixture in the cavity 

 a mason's flat trowel and an ordinary 

 garden trowel with a curved blade will 

 be found con\enient. A tamping stick, 

 1 or 2 inches thick and 1 to o feet long, 

 according to the size of the cavity, will 

 be needed ; also some rocks and a pail 

 of water if the cavity is a large one. 

 A layer of cement 2 or 3 inches deep 

 can now be placed in the bottom of the 

 cavity with the garden trowel and 

 tamped firmly in place. This opera- 

 tion is repeated until the cement is S 

 to 12 inches thick. Wet rocks of vari- 

 ous sizes may be embedded in the ce- 

 ment ])rovided they do not reach with- 

 in an inch or two of its outer face. If 

 the mixture is too wet, it will tend to 

 run out of the cavity under the opera- 

 tion of tamping. If too little water has 

 l)een used, it will not pack down 

 Ijromptly. The top of the cS to 12-inch 

 block of cement is then smoothed with 

 the flat trowel so that it will slant slight- 

 ly downward from back to front, in 

 order to facilitate drainage. Over the 

 top of this cement block a double or 

 single sheet of tarred roofing (or thin- 

 ner) paper is placed after it has been 

 cut so as to fit the cavity. (Jn top of 

 this, another l)lock of cement is buili 

 as soon as the first block is sufficiently 

 hard to stand the weight and tamping 

 without forcing any of it out at the bot- 

 tom of the cavity. If the interior of 

 the cavity extends well above the level 

 of the external opening, it may occasion- 

 ally be necessary to bore or cut a down- 

 ward slanting hole from the outside to 

 the to]) of the interior cavity, through 

 which a watery mixture of cement may 

 be poured to fill the upper jiart of the 

 cavity and the hole. The main opening 

 of the cavity must be completely closed 

 with the stift'er cement before this wat- 

 ery mixture is introduced. When a 

 block of the cement has partially hard- 

 ened, it will be necessary to carefully 

 smooth the outer surface or cut it down 

 with the flat trowel to the level of the 

 cambium, taking great care that the lat- 



