Rock blasting, a practical treatise |
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acid action adopted angle battery black powder blasting blow bore-hole carbonic oxide cartridge cellulose centre charge chemical compound clay combustion consists cotton cubic cubic foot cutting edge Darlington degree depth detonator diameter direction dislodged dynamite effect electric fuse employed explosive agent favourable feet fired force developed friction frictional machines gases Göschenen Gothard tunnel grains gun-cotton gunpowder hammer handle heading Hence hydrogen ignition increased kieselguhr labour latter least resistance length lines of least lines of rupture machine boring machine drill means mixture molecules nitrate nitro-glycerine nitrogen operations oxygen pellet piston placed Plate portion position powder pressure pricker produce proportion quantity of heat rapid removed rock ROCK BLASTING safety fuse saltpetre sand scraper shaft shot-holes shots shown in Fig sides sledge space steel striking face substance sufficient suitable surface tamping temperature tension tion tool tree tunnel unkey unsupported faces weight wires
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Página 89 - ... the greater will be the force developed. This fact shows that overcharging is not only very wasteful of the explosive, but that the atmosphere is more noxiously fouled thereby. The same remark applies even more strongly to guncotton and the nitro-glycerine compounds. The careful experiments of Messrs. Noble and Abel have shown that the explosion of gunpowder produces about 57 per cent. by weight of solid matters, and 43 per cent. of permanent gases. The solid matters are, at the moment of explosion,...
Página 6 - FIG. 4. the force of the blow, and therefore it is made as short as possible. For this reason, several lengths are employed in boring a shot-hole, the shortest being used at the commencement of the hole, a longer one to continue the depth, and a still longer one, sometimes, to complete it. To ensure the longer drills working freely in the hole, the width of the bit should be very slightly reduced in each length. It has already been remarked that the diameter of the stock is less than, the width of...
Página 173 - ... and thrown out a crater from the rock, he signals for the stone chains to be lowered to him, which being done, he proceeds to sling the large pieces of broken rock one after the other, as they are hoisted up by steam and deposited on deck. All the pieces large enough to sling being thus removed, he signals for the tub and shovel, and upon their being lowered to him, proceeds to shovel into the tub the small fragments, and to have them hoisted up and piled on deck until the surface of the rock...
Página 174 - ... contractor, expressly for this work, was placed in position and tried. Several imperfections were found at the first trial, which prevented its efficient working. While these were" being remedied a trial was made of surface blasts, placed in and around the rock in the positions most favorable for their action. These proved to be entirely without effect; no seams or breaks were made by them in the smooth surface of the rock. The submarine drilling machine being soon perfected, was put in operation,...
Página 108 - ... force. Charges of an explosive compound of uniform strength produce effects that vary as the weight of those charges, that is, a double charge will move a double mass. And, as homogeneous masses vary as the cube of any similar line within them, the general rule is established that charges of powder capable of producing the same effects are to each other as the cubes of the lines of least resistance. Generally, the quantity of black blasting powder requisite to overcome the resistance will vary...
Página 177 - ... in which the presence of seams could be more readily detected and the character of the strata observed, so that the most favorable positions for the next blasts, to produce the greater effect, could be selected. Sometimes the craters following the strata ran under or left an overhanging " face," in which case a large charge placed under its projecting edge, (see Fig.
Página 174 - The result was much better, bnt not what was desired. The presence of the body of water, from twenty-three to thirty-three feet in depth, seemed to diminish largely the ordinary explosive effect of gunpowder upon rock, as seen in blasts in the open air. Trial was then made of the patent safety blasting powder, manufactured by the Oriental Powder Company of Boston, the proportions having been so modified as to increase its strength for our special use. This produced the desired effect. The rock was...