DYNAMITE
The use of dynamite has become as much an art as a science. Sixty years ago, dynamiters placed explosives around a building which they wanted to demolish, or destroy. When they blew it up, the environment was covered with pieces of bricks and rocks. This doesn’t  happen anymore.

Today we can control explosions because scientific blasting techniques (new methods of causing an explosion) have been developed in recent years. Nowadays, holes are made in the base of a building and these are filled with enough dynamite to knock out destroy – the building’s supports and make it fall down.

 

Dynamite has  become the most efficiently controlled source of releasable energy available. Therefore, it is the most often used explosive. More than a billion pounds of dynamite is exploded by blasting experts annually in the United States, most of it in mines and quarries, i.e. places where stone for building purposes is taken from the ground.

Other  increasingly important areas in which this explosive is used are construction work (roads, bridges, buildings, etc.), gas and oil-well drilling, recovering iron from sunken ships, and fire-fighting. Controlled explosions are mostly used in areas of dense population. For example, subway construction crews in New York often use  dynamite underground without the people above being aware of it.

In an explosion, the solid particles inside a dynamite stick are immediately transformed into hot expanding gases, which force and powerfully push aside rocks, steel or anything nearby. One of the examples of blasting with precision occurred in 1944,  when engineers built a 13-mile tunnel through a Colorado mountain.

Starting on opposite sides of the mountain, they met in the middle with great accuracy — only a one centimeter error at the point where the two parts of the tunnel joined. Another example is Gutzon Borglum’s use of dynamite to form the faces of Washington,  Jefferson, Lincoln, and Theodore Roosevelt in the rocks at Mount Rushmore, in South Dakota. Many dynamiters claim that precision blasting became an art in July of 1930 at the Saguenay River Power Project, Quebec.

 

A power station had been built, but to provide water for it, they needed to turn  the water from the river into another channel. Ordinary methods had failed so Sam Russell, a blasting expert, was asked for advice. He had a brilliant idea. He built a cement block weighing 11,000 tons. He said that he was going to drop u into the river and thus block, or stop, the flowing water. Many people thought he was mad, but Russell calmly put 1,000 pounds of dynamite into holes under the cement block. When the dynamite detonated, the block moved into the right place with a roar that could be heard miles away.

QUESTIONS
A. What do the following refer to?
1. ‘these’ (line 8):
2. ‘they’ (line 26):
3. ‘it’ (line 38):
B. What do the following mean?
1. ‘blasting’ (line 6):
2. ‘quarries’ (line 13): 3. ‘precision’ (line 24):

 

C. Mark the best choice. Line 42, a ‘roar’ is probably a(n) .

a) machine b) loud noise c) explosive material d) cement block

D. Mark the statements as True (T), False (F) or No Information (Nl).

 

1. When dynamite was first used, people did not place the explosive in holes in the base of a building.

2. The United States uses more dynamite than any other country.

3. Most of the dynamite that is being consumed in the United States is used
in construction work.

4. Controlled explosions can be used underground in cities.

5. The use of dynamite in the opening of the tunnel in Colorado was
unsuccessful because there was a major error in calculation.

6. Borgium used dynamite to construct a tunnel at Mount Rushmore.

7. When Sam Russell first explained his plan for blocking the water, everybody thought it was an excellent idea.

 

E.

1. Why is dynamite the most often used explosive?
2. What happens inside a dynamite stick when it explodes?
3. Why was it necessary to change the direction of the Saguenay River?

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