The largest single block of stone in the world is in Mount Olga National Park, Northern Territory, Australia. It is Ayers Rock. This huge monolith is over 2.5 km long and rises 348 m above the sand and gravel plains of the Great Plateau. It is oval-shaped and is built of water-worn pebbles of granite cemented by finer sands. Aboriginal …

Long ago, only the very wealthiest people could afford a proper chair to sit in. Poorer folk used rough benches, stools or the floor. At meals, therefore, the lord or lady of the manor used the chair, while the less important people used the benches. At meetings today, the person who is in charge of keeping order is said to …

The lead in exhaust fumes come from the petrol used to drive internal-combustion engines. Crude oil straight from the wells is thick, black and sticky. It has to go through a complicated refining process before it can be used as fuel for the engines of cars, lorries, buses and aircraft. During refining, various substances are added to improve the petrol …

Certain cells of the body store surplus food in the form of fat or animal starch. This is released from storage, when there is not enough food in the blood to supply the energy demands of the body. Few of the things we eat can be used directly by the body cells. They must be changed chemically before they can …

Wherever you live, television pictures come to you from broadcasting stations located in various cities around the country. But they may get to you in several different ways. Many programs are transmitted from a local television mast. They go to the mast from the broadcasting stations along cable or via radio links. Then from the mast, the programs come to …

Grains of sand are really very tiny particles of rock. It takes time and a special kind of weather to turn rock into sand. Rain, frost, and wind can do the job. On beaches, the tide hitting against the rocks forms sand. Salt water, too, forms sand by dissolving minerals in the rocks. Since rocks are made up of minearals …

Lichens are found throughout the world, often occupying areas where no other plant can become established. They are found in their greatest numbers in the Alpine and Arctic regions, where they are the dominant form of vegetation. Lichens are the products of two distinct groups of plants. Together fungi and algae (seaweed is an algae) combine to produce lichens. Most …

Cork is the thick and spongy bark of the cork oak tree. These trees don’t grow to be very tall but they have quite thick trunks. Taking the cork bark off the tree can only be done every ten years, but about forty-five pounds, or about twenty-two kilograms of cork can be stripped off one tree at a time, so …

Nowhere-it simply changes into other substances. That is what burning does to everything. The moment you put a match to the wick, you start a change in the candle by turning the solid wax into a liquid. The liquid wax rises to the wick by an irresistible process called capillarity, the simplex example of which is the way blotting paper …

Cowrie shells are widely distributed and possibly the favourites among shell collectors because of their polished enamel-like surfaces and their beautiful colored patterns. The cowrie appears in all the warmer seas of the globe. But the great cowries, the tiger cowrie and the orange cowrie are natives of tropical regions. They crawl slowly, browsing on weeds, and are shy creatures …