Before the 1940s, scientists wanting to determine the age of fossils and other organic materials relied on relative dating techniques, grouping objects by the estimated date of surrounding rock strata. This method could produce large inaccuracies. Strangely, the ability to date objects more accurately was to originate from outer space. High- energy cosmic rays are constantly bombarding our atmosphere; when they hit, they break up atoms in the stratosphere. A consequence of this is the production of an unstable radioactive form of carbon called Carbon-14 (C-14) from atmospheric nitrogen. American scientist William Frank Libby (1908-1980) reasoned that, as all living creatures are made up of carbon and are constantly replacing this carbon from the atmosphere (plants take it in as carbon dioxide and animals absorb it from plants), all living organisms should have an equal amount of C-14 in their bodies in relation to the proportions occurring in the atmosphere. more...

Pollution is a world problem. Today, whatever little oxygen we inhale, is polluted. No doubt, most of our progress and development is the result of industrial growth and technological advancement of which we feel proud. But it has its evil effect too i.e. pollution. By pollution we mean to destroy the purity of a thing. It is generally used for natural environment i.e. land, water, air. Pollution makes the environment unfit for living. It becomes a health hazard. It brings many diseases, hence it must be checked soon. Land pollution is caused due to dumping and disposal of wastes, application of agro-chemicals in the soil. Deforestation also leads to land pollution. Hence it is necessary to start tree plantation as a social service and national programme. It is the only way which can save humanity. In India, wastes of oil, refineries and atomic plants are dumped into the rivers or more...

Science has made wonders in recent times. It has revolutionized the life in every field such as travel transport, communication, recreation, agriculture, industry, medicine, trade and commerce. We have electricity which has made our life comfortable in various ways. We have atom bomb, a great source of power. Now it is up to us whether we use science for good purposes or take undue advantage of it. No doubt science has placed in the hands of man extremely destructive weapons which may ruin the whole world in seconds but it never compels man nor creates a situation to make use of them. It is our greed and madness for power that urge us to use destructive weapons because we want to  finish each other. Undoubtedly science has contributed a lot towards world peace of which we must be obliged. Science has given quick means of transport and communication which help more...

A tailor sews clothes. He is found in every village and town. No civilized person can do without him. He is a very important member of our society. He earns his living by hard working. He knows no holiday. A tailor depends upon his tools. He requires a few tools. They are-a pair of scissors, a sewing machine, a measuring tape, a sharp needle, a thimble on his middle finger, some thread reels and balls, and an iron press, he puts on thimble on his middle finger to protect it from needle pricks. He also needs a wooden plank and a piece of coloured chalk and a register to note down the measurements of customers. These tools are very necessary for the tailor. He cannot do his work without them. If any one of these tools is missing he cannot do his work. A tailor's shop is generally seen in more...

"The American people never carry an umbrella. They prepare to walk in eternal sunshine." Alfred E. Smith, U.S. politician It was either the Chinese or the ancient Egyptians who first invented the umbrella. Early records from both cultures indicate that umbrellas were used to screen monarchs and people of high standing from the sun. The job of hoisting an umbrella above the emperor was often reserved for the servant of highest rank. The Chinese developed the technology furthest, waxing their paper parasols to provide protection from rain. Around 4,000 years ago, the Chinese also made their umbrellas collapsible, and since then the overall design has changed very little. Making its way to Rome and Greece, the umbrella was used to shade women and even effeminate men from the sun while attending the open-air theater. These umbrellas were made from leather or skins. The umbrella reached England during the reign of more...

Outline : Poor supply of water—many difficulties experienced— cleanliness cannot be maintained properly—fear of diseases spreading— even drinking water sometimes not available.   The problem of water supply in a big city like Delhi is quite acute. It reaches at alarming point during the summer months, when the water taps run dry. There is not a single drop of water. The Yamuna flows at its low level. The water comes just for a while. It leads to a lot of tension and quarrel especially in the streets where there are community taps. People form long queues with their pitchers, pails and buckets. They stand in wait for water for hours together. They are there right from early morning or even earlier. The low lying areas may have a little of water. But what about the houses and localities situated at high places ? There the water reaches very slowly even more...

A journey by train is the cheapest and most comfortable. I had always travelled with my parents. Last Sunday I got a chance to travel alone. My maternal uncle at Allahabad invited us to join the marriage ceremony of his son. My father had no time- So he asked me to go. He gave me some money and many instructions about the ceremonies. I was very glad. I had to go by Delhi Express. I put up my things in a small box and asked the servant to bring a rickshaw for station. I reached the station one hour before the time of arrival of the train. I went to booking office to buy a ticket for myself. There was a great rush. But the people were standing in a queue. I also joined them. At last I purchased the ticket. As soon as I got my ticket, I hired more...

Milk is a liquid food got from animals, like cows, buffaloes, goats and camels. It is white in colour. We commonly use milk got from cows and buffaloes. The milk of goats is good for infants. Milk is very useful to us. It is a wholesome and perfect food. It is the chief food for the infants. It is a food as well as a drink. A man can live only on milk for a long time. If we drink milk along with our regular food, we can be strong and healthy. Many things are made from milk, such as ghee, butter, curd, cheese, cream etc. AH these are very good for health. Different kinds of cakes and sweet meats are made from milk. These are very tasty. Milk is supplied in large cities by villagers of surrounding areas. They carry cans of milk daily in trains and buses. Many more...

A nation cannot prosper if the people are not laborious. Labour is at the source of strength for a nation. A nation that cannot work hard is not respected. A nation of idlers cannot progress and develop. After the Industrial Revolution, the people of Europe learnt to work with tools and machines. They manufactured many things and increased the wealth of their countries. The material prosperity of a country depends on the progress of its agriculture, industry and trade. Ordinary labourers work in fields, mines, mills and factories. Their labour leads to the prosperity and power of the country as a whole. Thus, work is power. For this reason, manual labour is not felt beneath dignity. However in India, the English education at first helped us to become clerks, teachers, lawyers, doctors and some engineers. This education taught the people to feel it beneath their dignity to work with tools more...

The production of aluminum foil via the process of the endless rolling of aluminum sheets cast from moltenaluminum was pioneered at a foil-rolling plant at the foot of the Rhine Falls in the Swiss town of Kreuzlingen in 1910. The plant was owned by the aluminum manufacturing firm J. G. Neher and Sons. The firm had experimented with sheets of pure aluminum, placing them between two heavy, adjustable rollers and filling the interior of the rollers with boiling water. Sheets were passed continuously through the rollers, which were gradually brought closer and closer together until the desired thickness of foil was achieved. Its earliest uses were as wrappers for various tobacco and confectionery products, and with its effectiveness as a barrier to oxygen and light, inhibiting the growth of bacteria, aluminum foil soon supplanted tin as the preferred metal in the wrapping and preservation of foodstuffs. Processes evolved to include more...