The Eiffel Tower and the Hoover Dam are shown.
Marvels of Engineering

It’s hard to imagine two more different structures than the Eiffel Tower and Hoover Dam. For one thing, the Eiffel Tower is in Paris, France, and Hoover Dam is on the border between Nevada and Arizona. The Eiffel Tower is elegant and delicate looking, but Hoover Dam looks like a huge slab of concrete. The Eiffel Tower was made of many parts put together. But the concrete for Hoover Dam was poured at the site. The Eiffel Tower was built for a fair and was not intended to remain in place for long. Hoover Dam was built to allow water to be used in desert country and to create electricity. Everyone expected it to remain in place for many, many years.



Even though these two structures are so different, there are similarities. Each required great effort to complete. Each also necessitated the involvement of many workers. The workers on each faced many challenges and difficulties, and each was built in a series of steps. Each is huge but was built quickly, considering the amount of labor involved.



All of the Eiffel Tower’s parts were made in a factory near Paris. Each piece had to be the right size and shape. Smaller parts were put together and then joined to form a larger piece. These large pieces were put together at the site of the tower. Bolts held together the pieces made at the factory. At the tower, these bolts were pulled out and replaced with hot rivets. Teams of people worked to take out the bolts and put in the rivets.



Hoover Dam was built to replace one that had been washed away, but it was built in a new place. Four tunnels were blasted through rock to cause the Colorado River to flow in new directions. Then the river’s canyon walls had to be cleared. From great heights, workers dangled from ropes. With only air below their feet, they prepared the area for great concrete walls. Far underneath them, the area for the foundation was cleared of mud and loose rock. When this was finished, tons of wet concrete were poured into a gigantic form. For thirty months, concrete was poured until the work was done. Across the Colorado River stood a dam 700 feet tall. When the water was allowed to rush through tunnels, it passed through giant rotary engines, and as their parts whirled, they created electricity.



Making electricity and using water to irrigate dry land were both practical purposes for Hoover Dam. But the Eiffel Tower had no original purpose but to be beautiful. The man who designed it, Gustave Eiffel, looked for a practical use for it. The tower was more than a thousand feet tall, and it was a perfect place for a radio antenna. So, a radio station was built on the tower.



Both the Eiffel Tower and Hoover Dam are popular tourist attractions. Each is considered a marvelous example of engineering skill.

This question has two parts. First, answer part A. Then, answer part B.

Part A

What is the purpose of the first paragraph of the article?

A.
to tell where the Eiffel Tower and Hoover Dam are located

B.
to show just how different the Eiffel Tower and Hoover Dam are

C.
to explain what is meant by the phrase “marvels of engineering”

D.
to describe how one type of material was used to make different structures

Part B

Which detail from the text best supports your answer in part A?

A.
“It’s hard to imagine two more different structures . . .”

B.
“Everyone expected it to remain in place for many, many years.”

C.
“Each piece had to be the right size and shape.”

D.
“Teams of people worked to take out the bolts and put in the rivets.”