Diggers in the Earth

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In almost every kind of work new methods are invented after a while. In quarrying, however, the same old methods are in use. The only difference is that, instead of the work being done by muscle, it is done by compressed air or steam or electricity. Compressed air or steam works the drill and the sledgehammer. The drill is held by an arm, but the arm is a long steel rod which is only guided by the workman. Not the horse-sweep of old times, but the steam derrick and the electric hoist lift the heavy blocks from the quarry. Polishing used to be a very slow, expensive operation, because it was all done by the strength of some one's right arm, but now, although it takes as much work as ever, this work is done by machinery. To "point" a piece of stone, or give it a somewhat smooth surface, is done now with tools worked by compressed air. After this, the stone is rubbed--by machinery, of course--with water and emery, then by wet felt covered with pumice or polishing putty. A few years ago two young Vermonters invented a machine that would saw granite. This saw has no teeth, but only blades of iron. Between these blades and the piece of granite, however, shot of chilled steel are poured; and they do the real cutting.

Granite has long been used in building wherever a strong, solid material was needed; but until the sand blast was tried, people thought it impossible to do fine work in this stone. There was a firm in Vermont, however, who believed in the sand blast. They had a contract with the Government to furnish several thousand headstones for national cemeteries. Cutting the names would be slow and costly; so they made letters and figures of iron, stuck them to the stones, and turned on the blast. If a sand blast is only fast enough, it will cut stone harder than itself. The blast was turned upon a stone for five minutes. Then the iron letters were removed. There stood in raised letters the name, company, regiment, and rank of the soldier, while a quarter of an inch of the rest of the stone, which the iron letters had not protected, had been cut away. By means of the sand blast it has become possible to do beautiful carving even in material as hard as granite.

Granite looks so solid that people used to think it was fireproof; but it is really poor material in a great fire. Most substances expand when they are heated; but the three substances of which granite is made do not expand alike, and so they tend to break apart and the granite crumbles.

A marble quarry is even more interesting than a granite quarry. If you stand on a hill in a part of the country where marble is worked, you will see white ledges cropping out here and there. The little villages are white because many of the houses are built of marble. Then, too, there are great marble quarries flashing in the sunshine. Sometimes a marble quarry is chiefly on the surface. Sometimes the marble stretches into the earth, and the cutting follows it until a great cavern is made, perhaps two or three hundred feet deep. A roof is often built to keep out the rain and snow. It keeps out the light, too, and on rainy days the roof, together with the smoke and steam of the engines, makes the bottom of the quarry a gloomy place. Everywhere there are slender ladders with men running up and down them. There are shouts of the men, clanking of chains, and puffing of locomotives.

Marble is cut out in somewhat the same way as granite, but a valuable machine called a "channeler" is much used. This machine runs back and forth, cutting a channel two inches wide along the ends and back and sometimes the bottom of the block to be taken out.

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