CLEARING LAND BY BLASTING.

New Zealand Times, Volume XXX, Issue 4448, 22 June 1875, Page 3

CLEARING LAND BY BLASTING.

“It may to many seem strange,” says a United States paper, “that we in America should he able to learn anything about clearing land from Great Britain, but recently some operations in clearing and improving land in the northern part of Scotland have been performed in a manner that is instructive to us. The operations especially referred to are the breaking up and the- removal of stumps, trees, large stones, and rocks by means of dynamite or giant powder. This explosive is a preparation of nitro-glyoerine, rendered perfectly safe in use by admixture with absorbing and diluting substances, and is many times more effective than gunpowder. This powerful explosive has been found to act in a most satisfactory manner, having greater effect, and exerting its force in a more favorable manner than gunpowder, and does not require any tamping. The rending force is so great that the largest stumps are torn into fragments of convenient size for removal, or are lifted bodily out of their bed. One method of applying the explosive. is this - A large hole is bored with a common auger into the centre of a stump, and a charge of giant powder, in a cartridge already prepared to fit the hole, is inserted. An iron tapering screw, made to fit a winch, is then tightly screwed into the hole. The screw has a hole through its centre, by which a fuse is carried to the charge. The charge is exploded, in the usual manner, and the stump is blown to pieces, or lifted out of its place. It may be well to caution those who undertake this work to exercise the greatest care, and to keep a good look out for the screw, as it will sometimes bo blown to a considerble distance if too large a charge is used. Greater useful effect is gained by moderate charges. Excessive charges do very poor execution, either blowing out the screw or a portion of the stump, and leaving the larger portion shattered, but still in a condition which makes their removal very difficult. Another method is as follows : —A hole is punched in the earth beneath the centre of the stump and between two of the largest roots. A cartridge of giant powder is placed at the bottom of the hole with a fuse attached to it. It is stated that the powder when it explodes throws the stump completely from the ground in every case, and frequently splits it into several portions. With common blasting powder this cannot be done. Its explosion is not sufficiently rapid, and the earth is simply removed from the stump. _ But with the many times more rapid and forcible explosion of giant powder the loose earth offers sufficient resistance, and the force of the explosion is exerted directly upwards with the best effect upon the stump or rock. It matters not whether the object to be removed be a stump or a rock, the effect is the same. The force of these nitre-glycerine preparations may be very economically used in breaking large rocks which need removal. Upon a recent occasion we saw a stone of about 10 tons weight, being nearly a cube of six feet diameter, shattered into fragments by a charge of 11b. of giant powder simply placed upon the upper surface of the stone, and covered with a shovelful of earth. The stone was of very hard tough trap-rock, and would have required a day's work of two or three men to break it up with common powder. .