76 THE APPLE 



then the gases will force their way through this weak spot and 

 will escape without doing as much work as they should. 



It must be remembered then that in order to have a charge of 

 dynamite do good work it must be so placed that the holding-in 

 pressure is as nearly as possible the same at the top and on all 

 sides of it. If a charge of dynamite explodes properly, the change 

 into gases is almost instantaneous, although some kinds of dyna- 

 mite explode — or "detonate," as it is often called — more rap- 

 idly than others. 



Dynamite is exploded by a detonator. There are two styles of 

 detonators — one known as a blasting cap, and the other as an 

 electric fusee (pronounced /use'). Both are small copper cylin- 

 ders about \ inch in diameter and from il to 2\ inches long, 

 which contain a small quantity of a very powerful explosive. 

 This explosive is quite sensitive to heat and shock, and a hard, 

 sharp blow may explode it ; therefore detonators must be carefully 

 handled. 



The heat to detonate a blasting cap is provided by the spark 

 from a piece of fuse, one end of which has been pushed into the 

 open end of the blasting cap, and fastened there by crimping the 

 blasting cap on it with a cap crimper. When the other end of 

 the fuse is lighted, it burns through slowly, and when the fire 

 reaches it the blasting cap explodes. 



Preparing caps and fuse. Placing the detonator in the cartridge 

 of dynamite is called priming it, and the cartridge with the deto- 

 nator in it is called the primer cartridge or primer. When the 

 charge consists of more than one cartridge the primer should 

 generally be loaded last or next to the last. 



The first steps. The first step in the preparation of the primer, 

 when using fuse and blasting cap, is to examine your dynamite 

 and see that it is not frozen. Frozen dynamite is hard and rigid ; 

 when thawed it is soft. Next examine your fuse ; see that it is not 

 stiff and brittle ; if in this condition, it is advisable to warm it 

 slightly before a fire until it becomes pliable. Take your cap 

 crimpers and cut the required length from the roll ; the cut 

 should be made squarely across and not diagonally. Sometimes 

 in the cutting the end becomes flattened, thereby making the end 

 of the fuse too large to enter the blasting cap. This end should 



