Diggers in the Earth

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This quarry had been given up and allowed to fill with water; but it was a granite country, and farther down the road there was another, where scores of men were hard at work. This second quarry was part-way up a hill; or rather, it was a hill of granite which men were digging out and carrying away. When they began to open the quarry, much of the rock was covered with dirt and loose stones, and even the granite that showed aboveground was worn and broken and stained. This is called "trap rock." The easiest way to get rid of it is to blast with dynamite and then carry away the dirt and fragments. Next comes the getting out of great masses of rock to use, some of them perhaps long enough to make the pillars of a large building.


_Courtesy Jones Brothers Company._

The first thing to do is to strip off the soil from the stone. Then, as the blocks are cut out, the big derrick lifts and loads them on waiting cars.]

Now, granite is a hard stone, but there is no special difficulty in cutting it if you know how. In the old days, when people wished to split a big boulder, they sometimes built a fire beside it, and when it was well heated, they dropped a heavy iron ball upon it. King's Chapel in Boston was built of stone broken in this way. To break from a cliff, however, a block of granite big enough to make a long pillar is a different matter, and this is what the men were doing. First of all, the foreman had examined the quarry till he had found a stratum of the right thickness. He had marked where the ends were to come, and the men had drilled holes down to the bottom of the stratum. Then he had drawn a line at the back along where he wished the split to be, and the men had drilled on this line also a row of holes. Next came the blasting. If one very heavy charge had been exploded, it would probably have shattered the whole mass, or at any rate have injured it badly. Instead of this, they put into each hole a light charge of coarse powder and covered it with sand. These were all fired at the same instant, and thus the great block was loosened from the wall. Sometimes there seems to be no sign of strata, and then a line of horizontal holes must be drilled where the bottom of the block is to be. After this comes what is called the "plug-and-feather" process. Into each hole are placed two pieces of iron, shaped like a pencil split down the middle. These are the "feathers." The "plug" is a small steel wedge that is put between the iron pieces. Then two men with hammers go down the line and strike each wedge almost as gently as if it was a nut whose kernel they were afraid of crushing. They go down the line again, striking as softly as before. Then, if you look closely, you can see a tiny crack between the holes. There is more hammering, the crack stretches farther, a few of the wedges are driven deeper and the others drop out. The block splits off. A mighty chain is then wound about it, the steam derrick lifts it, lays it gently upon a car, and it is carried to the shed to be cut into shape, smoothed, and perhaps polished.

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