Blasting
Aiton's Encyclopedia (1910)
Important: Safety Warning
This page contains instructions involving gunpowder or other explosive or pyrotechnic compositions. Preparing explosives as described has caused severe injuries and deaths, and is illegal in most places.
This information has been left in for historical purposes but should not be acted upon.
the process of removing obstructions by the use of explosives. Quarrymen save themselves labor by drilling holes and filling them partially with charges of powder. One end of a piece of fuse is placed in the powder and the hole is filled up to the surface with loose sand or with scraps of rock tamped down solid. The free end of the fuse is then fired and the quarryman retires to a safe position, which he is able to do before the fire reaches the powder. The sudden explosion throws off a mass of rock, doing work that would otherwise cost days of labor. In lieu of a fuse electric circuits may be employed. The ends of the wires are separated slightly; in leaping the gap the spark ignites the powder. A number of charges may be ignited at the same instant in this way, cracking off long strips of rock as neatly as though done with a saw. Nitro-glycerin and gun cotton are too dangerous, but dynamite or silicious earth, saturated with nitro-glycerin, may be used for the purpose. In 1843 three dynamite charges of 6,000 pounds each were fired simultaneously to blow up a portion of the Dover cliff required in the construction of a breakwater. Miners employ dynamite in loosening ore and coal, and in digging tunnels. Farmers put a cartridge of dynamite under a stump to throw it out of the ground. A dangerous reef known as Hell Gate , in the East River between New York City and Long Island , was removed by charging twenty tunnels with over twenty-five tons of dynamite and powder. Several million tons of rock that had long been a menace to shipping were thrown out in a single explosion. During the siege of Port Arthur by the Japanese immense blasts of dynamite were used that literally tore the faces off the mountains, and rendered expensive fortifications worthless. See Powder ; Dynamite
What Has Changed in the Last Century
Aiton's 1910 account treats dynamite as the last word in blasting, and the editor's note calls Nobel's 1867 patent the thing that changed everything. It has since been almost entirely displaced: since the 1950s the bulk of commercial blasting has used ANFO, a cheap mixture of ammonium nitrate prills and fuel oil, along with related emulsion slurries, and dynamite is now rare enough that some manufacturers have stopped making it. The spark-gap firing described here gave way to electric detonators and then to non-electric shock-tube systems and electronic detonators timed to the millisecond, so a face is broken by dozens of charges firing in a programmed sequence rather than all at once. Two details in the old text are worth correcting: the 1843 Dover cliff blast (Round Down Cliff) used gunpowder, since dynamite did not yet exist, and the Hell Gate work culminated in the Flood Rock explosion of 1885.
Written for this edition, 2026.