How  glass was first made :

Modern eyeglass lenses are usually made of tough plastic. In the ancient world, glass was the only material through which light could pass easily. The Phoenicians and Egyptians made glass more than 3,000 years ago. An old story tells how some Phoenician sailors lit a fire on a sandy beach and rested their cooking pots on blocks of saltpeter. The heat from the fire fused the silica in the sand with the saltpeter to make glass. People in Syria discovered how to blow glass into different shapes by about 100 B.C.E.

Glass was very expensive. Few houses had glass windows, and only wealthy people drank from glass goblets. Metal was cheaper. The Ancient Greeks used glass flasks filled with water as ''burning glasses,'' to focus the rays of the sun to light a fire.

The book : Great Inventions (Science)

The Number: 4228

                                                                                    The Author : Brian Williams.

The reader : Nargis Al –shabibi.