Note : In case of doubt as to proper distance between holes or rows, 

 or depth and strength of charges, try several 10-hole test blasts, with 

 different charges at different distances and depths. 



When wide ditches are blasted requiring two or three rows of holes, 

 the center hole in each of the rows should be primed with a Victor No. 6 

 Electric Fuze. These should be connected together and fired by means 

 of a blasting machine. In some cases, when the rows are not more than 

 36 inches apart, the blast can be effectually made by placing extra holes 

 between the rows midway between the two center holes. The primed 

 cartridge with cap and fuse is then inserted in the center hole of the 

 middle row ; the detonation then will carry by means of the extra holes 

 to the other rows already charged as shown in the diagram below. 



Note : Wasting of earth. The dirt excavated in a ditch blast will fall the way 

 the wind blows. It is better to ditch on a windy day to obviate the possibility of 

 dirt falling back into the ditch. 



o o o o o o o 



O < EXTRA HOLE FOR PRIMER 



0000000 



OOOOOOOOOOO 



O < EXTRA HOLE FOR CARRYING DETONATION 

 OOOOOOOOOO 



O < EXTRA HOLE FOR CARRYING DETONATION 

 .OOOOOOOOOOO 



SHOWING LOCATION OF PRIMER HOLES IN PROPAGATED BLASTING OF 



DITCHES 



Draining Swamps and Ponds 



Swamps and ponds, except where they are close to rivers, lakes or 

 the ocean, are caused by spring or surface water collecting on low ground 

 without a lower outlet. As a rule they are underlaid by a hard clay or 

 other impervious subsoils which prevent the water from sinking. In a 

 great many instances it is impracticable to drain these by surface methods 

 or ditching, yet they can often be permanently dried up by exploding 

 deep charges of dynamite and shattering the impervious subsoil beneath. 

 The number of charges required and depth of same depend of course on 

 the size of area to be drained, the amount of water required to be sunk, 

 and the thickness of the various subsoil strata encountered until the 

 water-absorbing sand or gravel is reached. In order to determine the 

 depth required, a test hole is bored with a dirt auger, which should be 

 pulled up from time to time in order to clean hole out, as also to ascertain 

 the nature of the soil encountered which is readily seen on the spiral 

 thread of the auger. Once the water-absorbing sand or gravel is reached 

 the depth of the hole is noted on the auger shank. This test hole must 

 not be charged, as it is too deep. The hole or holes for charging should 



149 



