The Granite Monthly Volume . 27; A New Hampshire Magazine (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 Excerpt: ... quarryman. After sufficient powder has been placed in the hole, the remaining portion of it is filled with sand or loam, allowing for air space, and tamped down tight with the tampingbar, the fuse is lighted, and the quarrymen retire to a safe place to await the result of the explosion. Dynamite cartridges are also used for blasting. Frequently the charge fails to explode, and again the skill of the quarryman is shown in re moving the old charge so as to insert a new one. This operation is one of the most dangerous parts of quarrying, as a spark of fire caused by friction often explodes the charge, and the quarrymen engaged in the work, having no time to escape, are killed or maimed for life by such explosions. Where there is steam power in a quarry, the holes have been blown out by steam, thus avoiding danger of explosion. Much depends upon how the blast is made. In the first place the directions in which a blast will break any kind of rock from the drill hole are but three, and some'.imes four, unless the explosive be too quick and forcible in its action. The limited number of directions in which the rock is most liable to break is determined by the structure of the rock and the shape of the drill hole. Quick-acting explosives like dynamite have a tendency to shatter the stone. Coarse gunpowder is preferred by many, but this is seldom used further than to detach large masses, which are split into smaller pieces by means of wedges and half-rounds. Sometimes a number of holes are drilled on a line and fired by means of electricity. Some large operations in blasting have been done with tunnels, as at Graniteville, Mo., and Long Cove, Me. In every locality the structure of the rock must be studied to take advantage of the cleavage and natural joints. There m...