Iron is a very hard metal, of which so many useful things are made that the present age is sometimes called the Iron Age. A specially strong kind of iron is called steel, of which machines, tools and weapons of many kinds, including ships, locomotives, motor cars and bicycles, ploughs, knives and swords, are made. In recent times steel, along with cement, has been much used in constructing the largest buildings of our great cities.

India is famous for its iron and steel. Over two thousand years ago Alexander the Great received a gift of Indian steel from certain chiefs of the Punjab. About A.D. 415 the famous iron pillar now in Delhi was set up by Kumaragupta I. It is over 23 feet in height and weighs over six tons. Some Indian swords and daggers have been made from the iron found in fragments of meteors which have fallen on to the earth.

Iron is found in the earth in the form of iron ore. Before it can be used, this iron ore has to be smelted.
By this process the metal is melted away, and what is left is called slag. In districts where iron is found' we see great heaps of this dirty dark-coloured slag. Now-a-days it is used in making roads.

Since the invention of railways iron and steel have-been used for the making of rails. If you look at a map of India you will see how railways cross the country in many directions. From Trivandrum and Dhanushkodi in the far south to Chaman on the Afghan frontier and Tinsukia near the border of China, these railways run without a break. The rails are fastened together so tightly that even an earthquake does not always tear them apart. You can imagine what a great deal of labour has been required to make so many thousand miles of railroad.

The blood of human beings and animals contains a certain amount of iron, which is necessary to health. They obtain it from green vegetables, which absorb it from the earth. When people have too little iron in their blood, they have to take it in the form of medicine. So when we say that a man has a constitution of iron it is true in two ways,—he has much iron in his system, and his muscles are very strong and hard.