AMERICAN FORESTRY 



No.l. Large cavity in an 

 Elm filled with cement 

 blocks with layers of tarred 

 paper between. 



No. 3. Cavity shown in No. 

 2 which has been nailed and 

 partly filled with cement 

 and showing placing of rods 

 and use of wire dam. 



No. 2. Excavated cavity 

 for treating and filling. 



ready 



No. 4. A later stage of the work 

 showing in No. 2. 



No. 5. The same cavity after fill- 

 ing is completed. 



PLATE No. 5. CEMENT CAVITY FILLINGS, SHOWING DIFFERENT TYPES AND SUCCESSIVE STAGES. 



18 to 24 inches. Oftentimes a single 

 bolt can be placed so as to support bodi 

 sides (Plate No. 4, figure 2). In cer- 

 tain cavities it may be necessary to 

 place bolts at different angles (Plate 

 No. 4, figure 3). In any case a strip 

 <of uninjured cambium at least an inch 

 wide should be left between the edge 

 of the cavity and the bolt. On medium- 

 sized trunks, after deciding where the 

 bolts can most efficiently be placed, a 

 very sharp half-inch bit, sufficiently 

 long to reach through the trunk and 



cavity, can be used to bore the hole for 

 the bolt. On large, heavy trunks a 

 larger bit should be used. Heavy oval 

 or round iron or steel washers, about 

 three times the diameter of the bolt, 

 should be countersunk into the wood 

 by carefully cutting away the bark at 

 both ends of the -hole with a sharp 

 gouge or chisel (Plate No. 4, figures 2, 

 o and 4). 



All split cavities must be securely 

 bolted, particularly near the upper part. 

 If the split comes from a crotch, all 



