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.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account