Invention of Glass

Have you ever heard of

any accidental invention? What do you think is

glass made of? What are some

of the uses of glass?

Thousands of years ago, some fishermen

camped for the night on

a sandy beach. After they went

to sleep, the hot coals from

their campfire glowed far into

the night. In the

morning one of the men noticed

a strange lump in the ashes. 

camped for the night on

a sandy beach. After they went

to sleep, the hot coals from

their campfire glowed far into

the night. In the

morning

morning one of the men noticed

a strange lump in the ashes. 

had never seen a stone like it before. Puzzled, he picked it up and ned it off. As he turned it over in his hands, he saw that the "ght of early morning shone right through it. He was sure that it 

d not been on the beach the night before. Could the fire somehow have made this odd substance? 

 

Legends say that this may be the way that people first discovered glass. Glass is formed when sand is mixed with certain chemicals in a very hot fire. Perhaps by accident, all of these materials were mixed with the sand on that beach. As time passed by, people found many uses for this new substance. Hundreds of years ago, castles had only high, narrow openings in their cold stone walls. Because the wind and weather blew in through them, they were called "wind's eyes.” This is where the English word "window" came from. Wealthy people like kings began to use glass to cover these holes in the walls. At that time, glass was hard to make and very expensive. Even kings could not afford glass for every window in their places and forts. Most of people used animal skins, pieces of cloth, or oiled paper. But these coverings did not let in much light, and no one could look out through them. Over the years glassmaking improved a great deal. Today glass is so clear like crystal that you can hardly tell it is there. Houses can have many large windows. Some city skyscrapers look as though they are built almost entirely of glass. Glass windows are used in vehicles as well as buildings. Automobiles, buses, trains, and planes have windows made of safety glass. When this glass is hit hard, it cracks. But it does not shatter into pieces which could injure passengers. This is because safety glass is made like a sandwich. A layer of clear plastic is cemented between two sheets of glass. When safety glass is broken, the shattered pieces of glass stick to the plastic. Glass is helpful, too in building submarines and spaceships. The glass lised is very tough. It will not break under great pressure of water, the cold of outer space, or the extreme heat when coming back into the earth's atmosphere. Even astronauts' spacesuits are made 

objects made of glass, lenses are probably the most important. 

is a specially curved piece of glass that bends light rays. Lenses Finke things look either bigger or smaller than they really are. 

The first lenses were used in glasses to help people see better. Then in 1809 an Italian scientist named Galileo put two glass lenses inside a fube. With one lens at each end, he looked at the sky through this first telescope. He could see things in the solar system that no one had ever seen before. He discovered the rings around Saturn and the moons around Jupiter. In 1675, a Dutchman, Anton van Leeuwenhoek, found another way to use lenses. He made an instrument called a microscope. Through it, he could see tiny creatures swimming about in a drop of water. For the first time, he learned of forms of life that could not be seen by the eye alone. His discovery led people to find out about germs that cause disease. More than two thousand years ago, people had learned how to blow hot melted glass into the shape of bottles. For a long time, these glass containers were scarce and expensive. They had to be blown one at a time. Today there are millions of glass bottles, jars, and water-glusses. In a modern factory, machines can make hundreds of them in a : minute. Millions of bottles and jars are thrown away every year. Now 

people have discovered ways to recycle glass in order to use it over again. When old glass is melted down, it can be made into new bottles or into building materials, like bricks. These glass bricks are Solid and do not let light shine through. They look a lot like ordinary clay bricks. 

Td glass is also used to pave roads. Glass can be ground up and ed with asphalt, a road-surfacing material. The groundup glass 

O sharp edges. It makes a tough surface that engineers think maylast longer than other materials. 

has no sharp edges. 

In future we may all be driving on glass roads and living in houses made of glass. Many other uses will also be found from this interesting material!