EXPLOSIVE 





Alter E, I. <lu Pon( '!«• Ni-iiii,iirM <V. Co. 



PlG. [65. Co/7 oA leading wire to 

 carry from the blasting machine 



to the charge 



Since the win: near the point of explosion Is broken and 

 destroyed al each firing, a section of cheap insulated wire 

 is used to connect the main lead wires with the fuse win 

 In conecting up Hie circuil I he 



insulation at the end of the 

 wire should be scraped 

 back and the wires securely 

 twisted together. In wet grass 

 or on wet ground the con- 

 nection should be wrapped 

 with insulation tape; in dry 

 worka small piece of wood laid 

 under the wire at this point will frequently serve to prevent 

 short-circuiting. The connection with the lead wire should 

 not be made until all is ready for firing. The circuit can 



then be completed by the operator at, 



the machine. As soon as the shot has 

 been fired, the machine should be dis- 

 connected and remain so until the next 

 shot is ready for firing. 



Electric firing is generally considered 

 safer and less liable to misfire than the 

 safety fuse. It has an added ad van ta^" 

 in that a number of shots may be fired at the same instant. 

 In hard blasting a number of charges fired at one time will 

 give much better results and require less explosive than if 

 the shots occur at intervals. 



Misfire. When; a safety fuse is used, misfire; 

 may be due to one of the following causes: frozen 

 dynamite, poor fuse, fuse slipped out of the cap, 

 wet cap, or cap pulled out of the primer. When 

 a safety fuse fails to burn, the source of trouble 

 may be a space in the core where there is no 

 (oiiofinsu- powc jei\ The fuse is likely to smolder along until 

 to cover bare the powder core is again ignited and a delayed 

 J(nn wor U k Wet explosion results. In electric firing misfire may 



After B. 1 <)u Pool 



rli: '.<■!,, ••urn <fc Co. 



Pig. 166, si>(Kil of con- 



nei lingwirr t<> connect 



the fuse in the circuit 



AfUrr E. I. 'In 



Pont dcNemoun 

 <fc Co, 



Fig. 167. 



13 



