BLASTING (ante). The of blasting are essentially the same here as in Europe; but the developments of mining, railroad building. and improvements in navigation, have rendered necessary some very extensive operations. The most tumor tent was, perhaps, the removal of the reefs in the East river, at Hallett's point, near New York, known as the "HelIgate improvement." The rock to be removed extended more than 100 yards into the river, greatly narrowing the channel and rendering navigation extremely difficult. The plan of operation was to sink a large square shaft on the Island shore from which the rock projected, and to run into the rock at a proper depth long galleries radiating from the place of entrance like the lines of an expanded fan. The entrance shaft was nearly 100 ft. square, and its bottom was 32 ft. below low water. Nearly 20 tunnels were bored in all directions, extending from 200 to 240 ft., and all were connected by lateral galleries. All the excavated rock was hauled to the entrance and hoisted to the surface. The work was completed in Sept., 1876, and made ready for blasting with more than 52,000 pounds of explosive material in many thousands of holes drilled forthe purpose. The explosives were dynamite, rendrock, and vulcun powder. The firing was by electricity. On the given day a quarter of a million people found their way to points on land and water where the explosion could be seen. When the eventful
moment arrived. gen. Newton, the engineer in charge, took the hand of his little girl, a mere infant, and with it pressed down the key by Which the battery was fired. 'there was a rumbling or shakim. of the ground, the rising of a great mass of water from 20 to 40 ft. in the air, a few small stones thrown a little higher, an immense mass of smoke, and all was over. Millions of tons of rock had been shattered, and yet the noise and the shock were less than would have attended the simultaneous discharge of half a dozen field-pieces in the open air. There was so much doubt and iemorance about the possible effect of this explosion that many people living one, two, and threemiles away left their houses and took positions in the open air, through fear of wide-spread ruin. The work was completed successfully, and after dredging out the broken stone the navigation of the channel was greatly improved. In previous years much has been done in the harbor of New York by surface-blasting, i.e., lowering to the face or to some crevice of a rock cans filled with nitro-glycerine and exploding it by electricity, the effect being to gradu ally wear away the rock. The great work of the Sutra tunnel (q.v.) was another triumph for American engineering.