To break up a boulder weighing approximately a ton, a one-inch 

 hole eight inches deep, charged from half to two-thirds full of Red Cross 

 Extra Dynamite, is required. Smaller boulders require holes from four 

 to six inches in depth, which, if necessary, can be filled full of Red Cross 

 Extra Dynamite, and no tamping used. 



Snakeholing 



In this method of breaking boulders the dynamite is placed in holes 

 underneath them just as in stump blasting. The hole is made with a 

 crowbar or dirt auger in such a direction that the charge of dynamite 

 will be against the center of the lower side of the boulder. If the 

 boulder is hollow or flat underneath, the explosion of the charge will 

 break it in pieces and throw it out of its bed. If the lower side is round 

 or bulging the boulder will be heaved out, but will not be so well broken. 

 When this occurs the large pieces may be broken by mudcapping. Care 

 should be taken when the charge is placed to leave no means by which the 

 force of the dynamite may be wasted. If it has not been thoroughly 

 tamped, or if it is too near the surface of the ground and not in the 

 proper position beneath the boulder, the dynamite may blow the dirt out 

 and leave the boulder untouched. 



Red Cross 40% Extra Dynamite should be used when breaking up 

 boulders in this way. Only from one-half to two-thirds the quantity 

 that would be required to mudcap the same boulder is needed, provided 

 it has a hollow or flat side underneath. Less dynamite is required in 

 damp, heavy soil than in light or sandy soil. 



Caution: Blockholing and snakeholing boulders are the most 

 dangerous operations in agricultural blasting, because pieces of rock are 

 often thrown great distances. Hence it is necessary to get joo to 400 feet 

 away before the blast. To reduce the risk from flying stones, especially 

 when blasting near a dwelling, cover the boulder with a number of leafy, 

 branchy boughs. These tend to retard the flying stones the same as the 

 rope blankets used by contractors in blasting in cities. 



The quantity and strength of dynamite required naturally depends 

 on the size and shape of the boulder. The "grain" and kind of rock are 

 also important points. Red Cross Extra Dynamite 40% or Du Pont 60% 

 N. G. Dynamite is best for blasting boulders. The following table gives 

 approximately the number of 1J4 x 8-inch cartridges to blast boulders 

 of different sizes, so that they will be broken into pieces small enough 

 for one man to handle, provided the boulders are mostly above the 



surface of the ground. 



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