Total Pageviews

Wednesday, October 31, 2007

What is a lightship?

A lightship is like a floating lighthouse. It anchors in one spot to warn shipping of such nearby dangers as sand banks or dangerous currents. At night it projects a powerful beam of light. The lamp is fitted in such a way that the beam stays steady, even if the ship is being tossed about by waves. Lightships also have their name painted on each side, so that during daylight hours ships can use them to check their own position.

Read more...

Thursday, October 25, 2007

What kinds of tools did early man use?


Some animals and birds make use of tools. There are some good examples among the birds. For example, the song thrush commonly feeds on snails which it opens by flying up with the shell in its bill and dropping the snail on convenient stone. The bird often uses the same stone on a number of occasions so that it may become littered with broken shells.
The stone is often referred to as a thrush’s anvil. The members of the shrike family often make use of thorns on which they impale their prey. But man more than any other animal has taken advantage of his large brain capacity to increase his power to hunt, kill, build his homes, and so on.
It is man’s ability to hold things in his hand with has enabled him to make such use of tools, where other animals have had to rely on their strength and agility, their teeth and their claws. Man’s first tools and weapons were stones which he had picked up. He chose stones that had been worn and sharpened by the weather into shapes that could be used as clubs or for cutting and scraping. As you might imagine the right shaped stones were not always easy to find, so that in time man learned to fashion primitive tools to a constant design that suited his purpose.
Many of the early men were carnivorous, that is, they fed largely on meat. This meant that a lot of the stones that have been positively identified as prehistoric implements were designed to kill animals, and then to scrape the flesh off the bones of the victim. Tools of prehistoric man could be made of bone, tooth, or more frequently stone, and in particular, flint. Flint was chosen because it breaks to give a flake with a very sharp, hard edge that could be used as, say, an axe. At first, these primitive weapons would be held directly in the hand. Eventually, however, man learned how to attach these axe-heads to a wooden shaft, and the power of the weapon was increased.
As he became more experience in making stone tools, the tools became more and more advanced in their design so that soon he was making blades, scrapers, and even arrowheads. Arrowheads were a great advance because they meant that for the first time man could kill his prey without putting himself to the risk of approaching what could be a very dangerous animal. Of course, these weapons could also be used to wound and kill other men.

Read more...

Tuesday, October 23, 2007

Are all deserts hot?


The definition of a desert is a place where the lack of moisture makes it impossible for anything but a few special life forms to grow. This applies not only to hot places, like the Sahara and the Gobi deserts, but also to very cold places too. Because all or most of the moisture there is turned to ice, almost nothing can grow there, which makes it a desert. So, you see, a great deal of the Artic is desert as well as the hot places people think of as being deserts.

Read more...

Monday, October 22, 2007

How are Clouds formed?

Clouds are formed when warm moist air rises into the sky. When it reaches a certain height, the warm air cools down and the water vapor in it condenses in to small drops of water, forming clouds. There are several different types of cloud. The ones which are highest are usually made up of drops of ice, and are the thinnest. These are called cirrostratus and cirrocumulus clouds. Lower clouds are called altostratus and altocumulus clouds. Lower still are the stratocumulus clouds and the nimbostratus clouds – these are the thick and shapeless rain clouds- and the lowest of all are the stratus clouds, which are seen as fog over high, mountains regions. Thunder clouds are called cumulus and cumulonimbus clouds, and these are the fat, cauliflower shaped ones.

Read more...

Friday, October 19, 2007

Is fresh air really fresh?

How many times have you heard someone say, ‘I think I’ will go out for a breath of fresh air”? Have you ever stopped to think what this means in our industrialized world? Of course, if you happen to be living high up among the mountains where there is little or no industry and few people your chances of finding fresh air are quite good. But what of the build-up areas of Britain and Europe or America? Even if you have not experienced it yourself, we expect you have heard of smog. This word is a mixture of the words ‘smoke’ and ‘fog’, which is very apt because smog really is smoky fog. London was once famed for its ‘pea-soupers’, that is, fog containing so much, sulfurous waste that it resembled the yellowish green color of pea soup and was almost as difficult to breathe and see through. These smogs usually occurred during the early months of winter when the fogs that would normally be present at that time of year became contaminated with all the smoke from cars and factory chimneys.

It is interesting to note how much influence pollution of the air, at first by smells of household waste and later by pollution, has influenced the distribution of people in cities like London. As you probably know, London has an ‘East end’ and ‘West end’ until quite recently the East end has been by far the poorer half of the city. This is because winds usually blow from west to east carrying the dirty air with them. People who could afford to choose where they wanted to live went to the western side leaving the smelly east for those with smaller incomes. In Los Angeles, in America, which is also famed for its smog’s, the prevailing winds are from east to west so that the London situation is reversed.

Today, many industrial countries have introduced ‘Clean Air Acts’ preventing the burning of ordinary coal in homes in certain areas and controlling the amount of smoke that factories can release. This means that some areas, such as London, Certainly have air containing much lees dust and dirt, and smogs are almost a thing of the past. In general, however, the air in our countries is far from fresh. The millions of cars on the road pour vast quantities of poisonous carbon monoxide gas into the atmosphere. It has even been suggested that if supersonic flight became popular, with the ‘planes flying at such hi8gh altitudes. The upper atmosphere could be affected in such a way as to permit deadly cosmic rays to reach the Earth.

The next time that you see some plants or trees next to a busy road, take a closer look at the leaves. You will probably find that they are covered with a film of black, oily dust. Remember that this is the same air that we are all breathing.

Read more...

Thursday, October 18, 2007

What are ores, and where might you expect to find them?

You must realize that the Earth provided us with all the raw materials swallowed up by our industries. Many of these materials are minerals. The word ‘mineral’ is used to denote any substance obtained by mining. It is clear that the words mine and mineral have similar origins. You might expect that minerals would be spread throughout the Earth, and indeed, this does happen. Occasionally, however, minerals may accumulate in sufficient quantities for man to be able to remove them comparatively easily. When this situation arises, the deposits are usually known as ores or ore bodies. The minerals associated with the ores that have no real economic value are usually referred to as gangue minerals, the consequent scarcity of them, and improved methods of mining and refining, material that was once thrown on the spoil heaps can now provide valuable sources.

Ores can occur in a variety of ways. With ores or iron, for example, the same ore can arise as a result of different methods of concentration. Many ores other than iron are formed in association with magma tic process. If you remember the way in which magma cools and forms crystals. It will come as no surprise to you to learn that metals such as chromium and nickel result from the settling into bands of the relevant crystals as the magma cools. There are often watery solution charged with minerals coming from magmas and these also provide supplies of metals such as mercury or copper. Both these minerals are in short supply, and in fact, deposits of mercury are almost completely confined to areas in Spain. Not all ores have been formed by igneous activity, however. Important deposits of iron in England have resulted from concentration by sedimentary process. Deposits known as placers are typical sedimentary ores. Of course, oil and coal must be considered as economic minerals and these have obviously resulted from sedimentation.

The sea may one day provide much of the world’s minerals. It has been known for some time that there is great richness of gold in the sea but as yet it has not been worthwhile nor even possible to exploit this mineral wealth. Even uncommon metals like vanadium, which is used for the nosecones of spacecraft, is concentrated in the blood of an unexciting sea animal – the sea cucumber.

Read more...

Wednesday, October 17, 2007

Where and what are the galaxies?


Our galaxy, vast island of stars though it is, is only one of millions of similar galaxies scattered throughout space as far away as we can see through our telescopes. The nearest galaxies to our galaxies are two small satellite galaxies called the Magellanic clouds. They can be seen only in the southern hemisphere, and look like pieces torn out of the Milky Way. A large nearby galaxy is the Andromeda galaxy, which can be seen with the naked eye as a faint patch. It is over 2 million light – years away.

Galaxies come in many shapes. Many are spiral. Elliptical galaxies look like globular clusters of stars, and irregular galaxies such as the Magellanic Clouds have no particular structure. About a hundred million galaxies can be seen with the largest telescopes. Galaxies, like stars, tend to form clusters and our galaxy is one of a cluster of over tweny7 that include the Andromeda Galaxy.

Read more...

Tuesday, October 16, 2007

Why is the time different in other countries?


The time it takes for the Earth to make one rotation has been divided into 24 parts, known as hours. This division was made to give us a fixed unit of time.

We take as a reference point the moment when the Sun is at its highest point in the sky (when the sun is at its highest point in the sky (when the shade is at its minimum).This is called mid-day, or noon.

However, this does not happen at the same moment on each part of the Earth because the Earth is turning all the time. Therefore, when it is mid-day in London it will be seven o’clock in the morning in some parts of the United States of America. Because the USA is such a large country, there are even time difference between some of the States.

Read more...

Monday, October 15, 2007

What is a rack railway?


Ordinary railway lines usually look as they are laid on level ground. In reality most stretches of railway track have a slight gradient, so that during a journey of any reasonable length, a train will be running up and down a number of very gradual slopes. However, there is a define limit to the degree of steepness a train can manage going up hill before its wheels start to skid on the tracks. In mountainous areas especially, it is not always possible to avoid gradients which a normal train simply could not climb, even by carrying the track through deep cuttings and tunnels. To overcome this difficulty rack railways have been built. Locomotives intended to run over such sections of track have a toothed, or cog, wheel fitted between the normal running wheels. This connects with third rail, also toothed, fitted to the track itself. This is the rack, its cog wheel engages the rack rail and so holds the train to the track with no risk of skidding.

Some rack railway lines pass through mountainous regions such as Alps. Other have been built to carry passengers to the actual summits of mountains, such as Snow-don in North Wales, and Mount Washington and pike’s peak in the United States.

Read more...

Sunday, October 14, 2007

Can trains run without rails?


For many years railway engineers have been thinking about new kinds of track for trains to run along. The parallel metal rail tracks with which we are familiar are not very efficient by modern standards. Because wheels are needed to move the trains along, a good deal of power is lost through friction in the moving parts. Ordinary railway tracks also set a limit to the speed that trains can go, especially round curves. They take up a lot of room, and they are expensive to build and keep in good repair.

Some trains, such as those operated on the Paris Metro, run very efficiently on rubber tyres. Other even more interesting advances in this field have been the experiments with monorail systems. Monorail means ‘one rail’, and several types of train have been designed which are suspended from an elevated monorail track. Spectacular results, in terms of speed and comfort, have been achieved.

Yet other trains have been built which sit astride a single metal or concrete track and slide along it. Called aero-trains, they have been designed to move like hovercraft. An even more advanced idea is to suspend a train from a monorail by magnetizing the rail. In all these cases there is hardly any friction to overcome, and much greater safety.

New forms of motive power are also being considered, including jet propulsion. The day may come when trains will be able to move almost as fast as aircraft

Read more...

Saturday, October 13, 2007

Why is the British flag called the ‘Union Jack’?


The Union Jack, the official flag of Britain since 1801, is really three separate flags in one, for it combines the English Cross of St.George, the Scottish cross of St Andrew and the Irish cross of St Patrick, England, Scotland and Ireland were originally Independent countries, and the Union Jack symbolizes the fact that they now from the United Kingdom, another name for Britain. Although generally known as the Union Jack, this is incorrect because it is the term for a flag flown only from the jack staff in the bows of a ship to indicate it is a man-of-war. Through popular use, however, the Union Jack gas become the accepted name for the flag.

Read more...

Friday, October 12, 2007

What is the origin of the Marathon race?

The Marathon is a long, grueling race which traditionally closes the Olympic events. It is taken from the amazing achievement of the Greek runner Pheidippides, who ran over twenty-six miles in for hours, taking news to Athens of the Persians’ defeat at the Battle of Marathon in 490 B.C.

Read more...

Thursday, October 11, 2007

Who are the Cossacks?

Many Hundreds of years ago, Russia was full of different tribes and races of people who had made their way from the great plains, or steppes, and mountain ranges of Asia. One of these races – the Cossacks – settled along the banks of the River Don which flows into the Sea of Azov, near the Black Sea. At the same time. They bred a special kind of horse which was noted for its great strength and stamina, and they became splendid horsemen. Their reputation as riders and warriors grew over the years, and they came to be looked upon as some of the finest cavalry soldiers in the world.

Sometimes the former Russian rulers, the tsars, used the Cossack cavalry to crush rebellions among the peasants. At other times the Cossacks were the pride of the Russian army, and could always be relied upon to strike fear into the hearts of the enemy. They were especially effective during Napoleon’s invasion of Russia in 1812, attacking his lines of communication and pursuing his armies during the terrible winter retreat. The German army also came to fear the Cossacks regiments during the Second World War.

Today the Cossacks are as famous as ever. They give exciting riding displays. They have also formed a choir which gives concerts all over the world.

Read more...

Tuesday, October 9, 2007

What is an electrocardiograph?


When a doctor takes a pulse he is felling the patient’s hear-beat. If the heart is beating faster than normal it may be a sign – like a rise in temperature – of illness somewhere in the body. For signs of illness in the heart itself a more careful check is usually needed.

The working of the heart is controlled by electrical impulses, and each part of its-the various valves where blood flows in a out – produces its own electrical wave pattern. By attaching electrical terminal points to the outside of the chest and connecting these to an electrocardiograph, these wave patterns can be observed. For when the electrocardiograph is switched on, an automatic device like pen moves up and down over a special sheet of graph paper, recording each wave impulse. This shows exactly the pattern of each complete heart beat. If anything is wrong with the heart, it will be shown by irregularities in these patterns. The pattern sheets or electrocardiograms can then be kept by doctors and compared over a period of time, which is extremely useful in the treatment of heart illness.

Read more...

How do astronauts ‘walk’ in space?


If an astronaut leaves his spacecraft during a journey, he cannot walk about in the ordinary way. There is nothing but empty space. There is not even any gravity to pull him in one particular direction. He can only guide himself by the same means as the spacecraft itself – by rocket propulsion. So when astronauts do leave their spacecraft during a flight – perhaps to help in docking operations with another spacecraft – they carry specially designed hand rockets with them. If they point the rocket exhaust in one direction, and give the engine a burst of power, they will move in the opposite direction. In this way they can steer themselves.

Read more...

Who found the Red Cross?

The Red Cross was found by a Swiss, Jean Henri Dunant, after he had witnessed the terrible plight of the wounded at the Battle of Solferino in 1859, Five years later, in 1864, the first Geneva convention was called to establish a code of conduct for nations at war, and Dunant obtained the convention’s agreement that both wounded soldiers and medical services should be treated as neutrals.

The flag chosen to represent the international medical service that grew out of dunant’s work was a red cross on a white background, this being the reverse colours of the Swiss flag. It also gave the organization its name. In Muslim countries, however, the flag is a red crescent on a white background, to distinguish it clearly from the Christian symbol of a crucifix.

Read more...

Monday, October 8, 2007

Where is the world’s oldest underground railway?

The first city to build an underground railway was London. Once the route was planned, a great trench was cut along the streets, the railway tracks were laid and the trench was covered over again, to restore the road and create a railway tunnel underneath. This method of tunnel making is called cut and cover.
The original route of the London Underground was nearly four miles long and ran from Paddington Station to Farringdon Street in the City of London It was opened 1863. The first trains were hauled by steam engines, and the smoke in the tunnels made the journey very unpleasant. But as the world’s first underground railway it was a cause of great excitement and regularly carried 30,000 passengers a day.
Further sections of steam operated underground railway soon followed. Then in 1890 the first really deep-tunnel or ‘tube’ railway was built in London. For this new tube railway, electric locomotives were built. The first trains they hauled had no windows, because windows were thought to be unnecessary if the train was only to travel through a tunnel deep under the ground. The train guard called out the name of each station as the train arrived at it.

Read more...

Saturday, October 6, 2007

Why some gardens are called ‘Botanical’ Gardens?


Private and public gardens and parks are created to make our surrounding more pleasant. The purpose of ‘botanical garden is to provide the right setting for making a scientific study of different kinds of plants. Botanical gardens contain greenhouses which enable exotic plants to be grown. There are also laboratories for study and experiments, and libraries.
Botanical gardens are usually open to the public, so we are given the opportunity to see plants which we wouldn’t normally see in our own country. One of the most famous is Kew Garden in England where you can seen a wide variety of plants and trees from many countries.

Read more...

Friday, October 5, 2007

How can we hear the sea in a shell?

Sad to say, it isn’t really the sea which you can hear when you hold a shell up to your ear, even though it may sound exactly like it. What is really happening is this… All sounds move through the air on vibrations of air called sound waves. We cannot see sound waves moving, but even the tiniest sounds being made in a room will have their own sound waves. There is air too, of course, in the spiral cavity inside the shell, and when sound waves enter they make this air vibrate as they bounce backwards and forwards off the inner wall of the shell. The result is a deep rumbling sound from the air which is resounding inside the shell. This sound reminds us of the sound of waves beating on a shore. It is in just the same way as this that air, vibrates inside the ‘resonator’, of musical instruments, making the sounds of the notes being played.

Read more...

Thursday, October 4, 2007

How is fog formed?

Water vapor is always around us in the atmosphere, in varying amounts according to pressure and temperature. When the temperature drops suddenly, these water vapor particles condense on the dust specks in the air, and this produces the haze we call ‘fog’.
‘Smog’ is a combination of smoke and fog. And is a particular menace in the industrial cities of America, but surprisingly it is Athens in Greece which suffers badly from smog. Smog eats away at the classical Greek building there, such as the Parthenon, at an amazing rate, causing serious damage.

Read more...

Wednesday, October 3, 2007

Why is the word love used in tennis?


Long ago, no score was indicated on French tennis scorecards by an egg-shaped zero. This was known as “I’oeuf”, the French word for egg, and the English-speaking players used the same word, but in this case it should like love, and has been called love ever since.

Read more...

Tuesday, October 2, 2007

Who Invented tennis?

The indoor game of ‘real’ tennis was played in the middle ages. During the 19th century it over flowed on to the lwn where players made up their own rules. In 1874 Major Walter Wing field invented rules for lawn tennis. Even by 1890, however, ‘real’ tennis rackets were still being used.

Read more...

Monday, October 1, 2007

What are the Olympic Games?


The Olympic Games is the biggest sporting event in the world. It takes place every four years, each time in a different country. Amateur sportsmen and women from over 100 nations take part. There are about 20 sports, of which the most important are track and field athletics.

The idea for these competitive events came from Ancient Greece. And the spirit of the games has always been one of true sportsmanship; that is, fair competition, without the aid of cheating in any form. However, competition is so fierce these days that it is hard for competitors to live up to these ideals.

Read more...