ROUGH CONVEKSION. 



261 



has been poured into the bore-bole, the fuse, made of tarred 

 yarn surrounding- a thin column of powder, is inserted, and then 

 the rest of the powder. The remainder of the bore-hole is then 

 filled with earth or clay as a tamping, and firmly raramed-down. 



The portion of the fuse 4-6 inches long, which protrudes 

 beyond the hole, is lighted with a match, and in 1-2 minutes 

 the explosion follows. 



iii. Blasting Siiiiwps hy Dynamite. 



Dynamite is a more powerful explosive than gunpowder, and 

 is obtainable in cartridges, resembling brown stearine candles 

 encased in thick paper. It becomes hard at temperatures of 

 45" to 50" Fah., and cannot be heated above 140 Fah. without 

 danger. It will not explode, unless it be at least as soft as wax, 

 and must therefore be slightly warmed during winter. 



According to the size of the stump 1*7-2 grams (1-1"12 

 drams) of dynamite are required for every centimeter in the 

 diameter of the stump, so that cartridges of 70 to 100 grams 

 suffice for stumps of 0*50 to 0*70 meters in diameter \j.e., 2^ to 

 3i ounces for diameters of 1 foot 8 inches to 2 feet 3 inches. — 

 Tr.], provided the wood is not too difficult to split. 



The dynamite-cartridge (p) in fig. 133, is then placed in the 



