48 TRANSPORTATION ON LAND BY VEH1CLES:-THE ROADS 



In the usual practice a hole is charged to one third of its depth. A series of holes should be 

 blasted at one and the same time, so as to increase the effect. Powder cans should not be 

 opened with a pick or a chisel. Deep and large holes allow the charge to be placed low, 

 and by this means the effect of the charge is increased. 



A hole 1 inch in diameter and 2 feet deep requires about ',; of a pound of powder. A hole 

 IV2 inches in diameter and 3'/.; feet deep requires about 3 pounds of powder. 



2. Dynamite. Dynamite contains, usually, 75 per cent of nitro-glycerine and 25 per cent of silicic 

 acid. It comes in sticks measuring \'U by 8 inches, and in boxes containing 25 or 50 pounds. 



35 per cent dynamite, at 12'/,> cents per pound, is used for blasting stumps, ice, or lighter 

 rock; 45 to 50 per cent dynamite, at 14 cents per pound, is used in hard rock; 60 to 75 per 

 cent dynamite, at 18 cents per pound, is used for extremely hard rock and for submarine purposes. 



Dynamite freezes at 46 degrees Fahrenheit. It is not easily exploded, like powder, in the 

 course of transportation, and can be used under water. 



Whilst tamping is not required, tamping with moist clay results in economy. 



Dynamite is dangerous particularly when it is partly frozen or during the act of thawing out. 

 It should not be placed in warm water for thawing; it should be placed in a can, and the can 

 should be kept in luke-warm water. Dynamite should not be exposed to the sun, to the camp 

 fire, or to the heat of a stove. Old dynamite, owing to partial decomposition, looses its strength. 

 Oily wrappers prove that some nitro-glycerine has leaked out. Green spots on the wrappers 

 indicate extreme danger in handling. 



3. Caps, fuse, detonators. Caps come in boxes of 100, costing 80 cents. They are attached to 

 the fuse with the help of fuse cutters and cap crimpers. 



The common cotton fuse costs •v3'35 per thousand feet; single -tape fuse for damp soil and 

 double-tape fuse for wet soil and triple-tape fuse for use under water costs between .v4 and 

 j^5"60 per thousand feet. The cap should be placed in the top of the charge and not in its midst. 



Electric detonators are more efficient than caps, for the reason that they cause a simultaneous 

 discharge of a number of holes. 



If a shot fails the crew should wait 30 minutes before touching it. The charge should never 

 be picked out; it should be left alone and a new hole should be drilled at a distance not less 

 than 2 feet from that which has failed to be discharged. 



It is unwise to use two kinds of explosives in one and the same hole. 



(c) Work. The drilling of the rock is obtained either by sledges, steel, and hand labor, or else 

 with the help of air drills. 



in road building, the removal by blasts of small quantities of rock (for ditches, culverts, or cross runs) 

 should be avoided. 



The success of the blast depends on the stratification of the rock, and, above all, on the skill of the 

 workmen. 



In gneiss rock, 3 men will drill by hand 18 feet of 1-inch holes or 10 feet of 2-inch holes in the 

 course of a day. 



V. Transportation of dirt. Dirt is transported with the shovel, with wheel barrows (capacity 2 cubic 

 feet, price .Yr50 for wooden and -v 12 for steel barrows), by scrapers, with and without wheels (capacity 

 5 cubic feet, price ^6 to «v 10, weight 100 pounds), by 2-wheel horse trucks, by temporary railroads with 

 dump cars or flat cars, and by cable transmission. A team load ordinarily consists of I '3 cubic yards of dirt. 



A ton of earth is composed of 21 cubic feet of sand, 



25 cubic feet of coarse gravel, 



28 cubic feet of marl or clay. 

 Transportation of dirt by contract is preferable to transportation by day labor. 



Aside from the influence of dirt quantities, the local ratio prevailing between the cost of manual labor 

 and the cost of team labor must decide whether wheelbarrows, carts, or teams are to be used for the 



