Ch.14 Skyscrapers, Elevators, and Bridges

• Chapter 14 discusses skyscrapers, elevators, and bridges

Skyscrapers

• Skyscrapers are very tall buildings of many stories
• The need for more office space led to building upwards
• Americans were in awe as these buildings, which "scraped the sky," sprung up in cities
• Skyscrapers were made mostly of steel and glass, unlike most houses
• Steel was new, and was lighter and much stronger than iron
• Great lattice-works of frames were welded together from skeletons of these buildings
• Grand Central Station in New York City was called a masterpiece of architectural engineering

Elevators

• Elevators are a platform or compartment in a shaft for raising and lowering people or things to different floors, levels, or stories
• The construction of tall, multi-floored structures increased the need for an easier way to get between floors
• Elevators were originally called “lifts”
• These “lifts” were steam-powered, not like the quiet, electric elevators of today
• Steel is a material made of both iron and carbon

Bridges

• A bridge is a structure carrying a road, path, railroad, or canal across a river, ravine, road, railroad, or other obstacles
• The Mackinac Bridge is approximately five miles long and connects lower Michigan and its Upper Peninsula
• Many cities had been built next to rivers, so getting train tracks across the water was a growing issue
• St. Louis, Missouri, was one place with this problem, as the city had grown up on both sides of the Mississippi River
• James Eads, who built ironclad gunboats for the Union Navy during the Civil War, designed a bridge
• Eads had built a diving bell to explore the Mississippi River, and he knew his bridge would have to go far below the river bed
• The Mississippi has strong currents and churning waters
• Eads knew that a bridge would have to be footed in bedrock far below the surface of the river to stand strong
• The great bridge would have two giant stone towers to support it in the middle of the river
• The towers would be 50 feet above the river, with bases anchored between 86-125 feet below the water

Eads Bridge Construction

• Builders worked in huge airtight "containers” called caissons (CA-sons) to dig down into the bedrock
• Workers in the caissons had to deal with great pressure
• Each shift of workers could only stay down there for 15 minutes at a time and had to come up slowly to adjust to the pressure
• Other great bridges followed, changing America's landscape more
• Mountains and rivers, as well as deserts and plains, could not stand in the way of America's growth

Presidential Fact

• In the 1880s, James A. Garfield became the 20th president
• He served only 200 days in office, the second shortest time
• Garfield was assassinated, unlike William H. Harrison
• His vice president, Chester A. Arthur, then took over the presidency

This lesson covers the history and construction of skyscrapers, the invention of elevators, and the use of steel in building. It explains the need for skyscrapers and how steel and elevators made them practical. Grand Central Station is mentioned as a masterpiece.