THE USE OF EXPLOSIVES IN FORESTRY. 211 



The explosive in both cases is supposed to be gehgnite. In 

 the case of large stumps the main spreader roots must first be 

 located and cut by exploding suitable charges underneath them. 

 The method of blasting is to bore a hole either vertically or 

 obliquely into the stump. The explosive is placed in the hole 

 and carefully stemmed and fired by an ordinary or an electric 

 fuse in the usual way. 



For the purpose of clearing land of scrub or heavy under- 

 growth, it is recommended that holes 3 feet deep should be 

 made in rows in the ground, the distance between the holes 

 in each row being about 12 feet and the distance between the 

 rows 10 feet. The holes in the adjacent rows are not placed 

 opposite each other, but alternately, as indicated in the diagram : — 



0000 

 00000 



In each hole a single 2-oz. cartridge of "cheddite" is 

 exploded. Where there are roots of heavier bushes the holes 

 are made deeper and the amount of charge is increased. The 

 explosion not only loosens the soil to such an extent that the 

 scrub can easily be pulled up, but it also breaks and loosens 

 the subsoil. For tree planting the hole should be from 3 

 to 4 feet in depth, and the charge 6 to 10 ozs. of " gelignite " or 

 7 to 12 ozs. of " cheddite." This should make a hole sufficiently 

 large for planting the tree, or will loosen the soil so that it can 

 easily be removed. The hole should be left for 24 hours before 

 planting. 



A demonstration of the method, as applied to the breaking 

 up of the subsoil on land to be used for fruit culture, was 

 recendy given on land at the Hall of Aberuthven, belonging to 

 the Blair Estates Company, by Messrs G. P. Berry and W. Bruce 

 of the Edinburgh and East of Scotland College of Agriculture. 

 Holes in rows were bored to the depth of about 2h feet. The 

 distance between the holes was 9 feet and between the rows 

 also 9 feet ; 2 ozs. of cheddite were exploded in each hole. The 

 demonstration was highly successful, the ground being cracked 

 and fissured for a considerable distance round each hole A 

 year or two must elapse before the full effect on the fertility 

 of the land can be judged. 



It is difficult to lay down any very definite rules as to the 

 amount of explosive to be used, so much depends on the nature 

 of the soil. The soil referred to above was a fairly heavy clay. 



