By Robert Lamb

http://www.howstuffworks.com

To witness the incredible power of steam, you don't have to look any further than the eruption of geysers or the explosion of gasses that occurs when lava reaches the ocean. Early man witnessed such sights and has long sought to control the power of steam through technology ranging from the basic tea kettle to the modern nuclear power plant. (248 no spaces)

Regardless of the level of technology involved, steam power comes down to one basic principle: When water is heated to the point of vaporizing, the vaporized water takes up more space than the liquid water did. This is because solids, liquids and gases are each held together by different levels of molecular forces. In solids, the molecules are compact. In liquids, they're further apart. And in gasses, like steam, they're even further apart. (372 no spaces)

If you heat a can of soup in a fire, the liquid contents will vaporize and eventually expand to the point where the can will explode to release the pressure inside. When this pressure is used to perform a particular task - like turning a turbine or causing a kettle to whistle -- steam technology is harnessing steam power. The methods of heating, containing, channeling and using steam have changed, but the basic principle remains the same. (366 no spaces)

Learning to harness the power of steam has been a long process. Greek mathematician Hero theorized the use of steam technology in the second half of the first century. However, it would be well over 1,600 years before the first practical steam engine was created. The age of steam that followed shaped the course of history by powering the Industrial Revolution, transforming the global shipping industry and revolutionizing modern warfare. (371 no spaces)

In this article, we'll look at how steam technology developed over the centuries and how our understanding of steam power changed the world. (118 no spaces)

The earliest known records of steam technology can be traced back to Alexandria in AD. 75. It was there that the mathematician Hero, also known as "Heros" or "Heron," wrote three books on mechanics and the properties of air and presented plans for a simple steam engine. (224 no spaces)

Hero's design called for a hollow sphere with bent tubes emerging from either side of it. This mechanism was then filled with water and mounted above a fire. As the heat caused the water inside the sphere to vaporize, steam was forced to vent through the two tubes. This steam-powered propulsion caused the sphere to rotate. (268 no spaces)

Hero's method for transforming steam power into motion was the foundation for later steam technology. However, a great number of scientific advancements were necessary before the concepts behind his steam turbine could be put to practical use. Although people like Leonardo da Vinci toyed with the idea of steam power (the inventor suggested in 1495 that steam power could fire a projectile). (331 no spaces)

In 1606, Giovanni Battista della Porta of Naples recorded his theories about the role of steam in creating a vacuum. He theorized that if water converted to steam inside a closed container resulted in increased pressure, steam condensed to water inside a closed chamber would result in decreased pressure. This new understanding of steam played a vital role in future developments. (321 no spaces)

In 1679, French scientist and mathematics professor Denis Papin managed to turn della Porta's theory into reality. Papin expanded on this device by adding a sliding piston to the top of a closed cylinder full of water. When heated, the expanding steam pushed the piston up. As the steam cooled and became liquid again, the resulting vacuum pulled the piston back down. (307 no spaces)

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TASKS

1. Describe how steam engine works, using the words: boiler, combustion chamber, condenser, heat-exchanger, liquid, valve, working fluid, coal уголь.

2. Match the words with their definition:

1) steam engine

2) to vaporize

3) to convert

4) pressure

5) sliding piston

6) expanding steam

a) трансформировать, преобразовывать

b) расширяющийся пар

c) паровой двигатель

d) испаряться

e) давление

f) скользящий поршень

3. Compare and describe 3 forms of matter (water): solid, liquid and gas.