Due to the fact that the closer spacing of holes and more expensive 

 dynamite are required, this method is usually somewhat more expensive 

 than when the electrical method is employed. It must be remembered 

 that cold weather checks the action of Du Pont N. G. 60% Dynamite 

 and it is necessary to use larger charges and put the holes closer together 

 than in warm weather. This work can be done best when the tempera- 

 ture of the water or earth is above 50 degrees Fahr., and is not recom- 

 mended for lower temperatures. 



For ditches with a width at the top greater than 6 feet two or three 

 rows of holes are required. The holes should be the same distance apart 

 in the rows, the same depth and charged with the same quantity and 

 kind of dynamite as for narrower ditches. The following table shows the 

 spacing of the rows and charge per hole required for various size ditches : 



Table of Charges for Blasting Ditch Without 

 a Blasting Machine 



In order to enable the blaster to calculate the amount of dynamite 

 required to cut various size ditches, the following table used in conjunc- 

 tion with either of the preceding tables should prove very useful : 



I rod = i6| feet. 



10 rods = 165 feet or 55 yards. 



yi mile 1320 feet or 440 yards or 80 rods. 



Yz mile = 2640 feet or 880 yards or 160 rods. 



If longer ditches or larger charges are required, multiply the above 

 figures by two, three or four, according to the number of rows. 



148 



