FIG. 117. BLASTING STUMPS ELECTRICALLY 



Blasting by Electricity 



Large boulders and large stumps with spreading roots can often be 

 blown out and broken up more thoroughly and with less dynamite if it is 

 distributed in several charges in different places under the boulder or 

 stump and all of these charges exploded at one time. Groups of stumps 

 standing close together can also be blasted in this way. In order to dig 

 a ditch satisfactorily it is always necessary to explode a number of 

 charges simultaneously. In well sinking and other kinds of blasting it 

 is of advantage to explode a number of charges at one time, as each tends 

 to help the other. The only way in which several charges some distance 

 apart can be exploded at exactly the same time is by the electric method 

 of blasting. Electric blasting may, of course, if so desired, be applied to 

 all of the work described in this Handbook, but it is generally unneces- 

 sary and more expensive, except in the blasting just described. 



The equipment for blasting by electricity, in addition to dynamite, 

 consists of 



Electric Fuzes Leading Wire 



Connecting Wire Blasting Machine 



When the charges of dynamite have been primed with electric fuzes 

 and tamped as already described, the two electric fuze wires extend from 

 the ground over each charge. These two wires should be separated and 

 one of them connected to one of the wires of the next electric fuze on 

 one side and the other one should be connected in the same way to one 

 of the wires of the electric fuze in the hole on the other side. This should 

 be continued until all of the charges are connected in a row with one 

 free wire extending from the first charge and another extending from 

 the last charge. This is called "connecting in series." If the holes are 

 too far apart for the electric fuze wires to reach between them, pieces of 

 connecting wire will have to be used to connect the electric fuze wires in 

 adjoining charges. 



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