k;2 ENGINEERING ON THE FARM 



and preparing the hole. An advantage of making the hole 

 with dynamite in preference to digging is the loosening of 

 the hard material for some distance around the hole. This 

 gives the roots of the tree a greater opportunity to spread. 

 Obstructions in drainage channels. Silt bars, ice, and 

 jams in drainage channels are frequently removed with 

 explosive when it would not be possible to accomplish the 

 same result in any other manner. Charges of 60 per cent 

 dynamite, 18 inches apart, in wet ground, can be fired from 

 one primer, the concussion through the ground being 

 sufficient to explode all of the charges. 



SUMMARY 



Definite instructions for the grade, quantity, and exact 

 location of a charge cannot be given for specific blasting 

 work. A certain amount of experimental work must be 

 done if the most economical results are to be obtained. 

 When bowlders are to be removed, the hardness of the 

 rock will determine the quantity and the method. When 

 stumps are to be dynamited, the root formation, the length 

 of time the stump has been dead, and the condition of the 

 soil will be the determining factors. For special work, such 

 as breaking up hardpan, tree planting, and ditching, the 

 manufacturer's instructions should be followed, only such 

 changes being made as local conditions dictate. 



BIBLIOGRAPHY 



Pamphlets on the various uses of explosives on the farm published by 

 Aetna Powder Co., Chicago, Illinois; Du Pont Powder Co., Wil- 

 mington, Delaware. 



