How do we see?

The human eye is shaped like a ball with a bulge in the front. In the middle of this bulge is a hole called the pupil, which is the part we see as the black circle in the middle of the colored iris. The pupil lets in light to the eye. Behind it is the lens, which focuses the picture of what we can see. When light passes through the lens. It is turned upside down, so that an upside down pictures is the image which hits the retina.
The retina is the part of the eye which actually makes sense of what we see. It is sensitive to light, and can sort out all the different colors we see. When light hits the cells of the retina, a chemical change takes place in the cells. This starts message or impulses in the optic nerve at the back of the eye, which takes these messages to the brain. The brain turns the images the right way up, and identifies them as something we can recognize. Have you ever wondered why the pupils of the eyes grow bigger and smaller? This happens according to the amount of light available. In bright light, the pupil closes up to black speck, letting through only enough light to be able to see without damaging the retina. When the light is very dim, the pupil opens up to let in as much light as possible, so that, again, we can
see.

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What is a Dowser?

A dowser is another name for a water-diviner – someone who can tell where there is water lying underground. The dowser uses a whole variety of tools to find the water, but one of the most common is the Y-shaped twig from a hazel tree. The dowser holds the twig by the two prongs of the Y, with the long stem pointing upwards. When the twig is above a spot where there is water beneath the surface of the earth, the stem of the twig will suddenly dip downwards, or in some cases it will twist itself violently out of the hands of the dowser.

Nobody knows exactly how this is done, not even the dowsers themselves, but it may be that they have some special powers which the rest of us don’t possess – it is certainly true that only a very few people can do this.

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Why don’t we all have the same color hair?

Melanin, as brown pigment which gives color to skin, also gives color to hair. Because some people have more melanin, they have darker hair. Hair colors range from blond to black. People who have a shortage of pigment have very pale skin, hair and eyes. They are known as albinos.
Old people have grey hair because as the body gets older it produces less melanin, so the natural hair color fades.

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What are nerves?

Nerves are the organs which tell us what is going on in the world outside our bodies, and which take messages about this world outside our bodies, and which take messages about this world to the brain, which translates the messages into feelings. There are four types of nerve in the body. The first is the one which picks up messages like pain, light, cold and heat. The second type of nerve receives these messages and sends others to parts of the body which cause swift action to be taken. For example if you touch a hot iron, the first type of nerve tells you it is hot, and a spilt second late the second sort of nerve makes your muscles pull your hand away in what is called a reflex action. The third type of nerve takes messages over longer distances in the body, and is the type of nerve which makes our body do the things our brain orders it to do, such as moving parts of the body to perform certain actions. The final sort of nerve is that which transmits messages from the first type, called sensory nerves, to the brain where the messages are translated into feeling. This is why, having touched the iron, we may not feel the pain until just after we have pulled our hand away. We have nerves all over our body, although there are more in certain parts than in others. The central nervous system, through which all messages pass, is composed of the brain and the spinal cord, which is why we have to take special care not to damage our head or backs.

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Which animals and plants are in the most danger?

In this question, the ‘word’ danger does not refer to the danger to which individuals of any species may be subjected. Danger in this case means the danger to which a whole species is liable. In other words, species may be in danger of becoming extinct, and disappearing for ever from the face of the planet. Of course, we can tell from the fossil record that hundreds of species of animals and plants have come and gone throughout the span of life on Earth. In the past, however, those species that have died out have done as a result of natural causes. The animals and plants that disappeared were those that were unable to adapt fast enough to changing conditions or were unable to compete with their rivals for the available food supplies. There are instance, however, such as that of the dinosaurs, in which it is not at all clear why they became extinct. Many dieas have been suggested, but none of them is wholly satisfactory.
For today’s wild life, there is another, more terrible threat to their existence – man. Man is endangering the lives of many species of animals and plants which are unable to adapt to the pressure of man’s increasing numbers and his changes to the natural environment. On the other hand, there are those species that have certainly benefited from man’s activities. In Britain, for example, birds such as the black headed gull have increased in numbers quite dramatically in the last fifty years, adapting well to a semi-urban environment and feeding on man’s waste. Even the fox has been able to survive by adapting to become an urban scavenger in many large cities. Unfortunately, the lack of suitable foods has led to the foxes becoming deformed so that individual probably spends a great deal of their lives in considerable pain.
But man is threatening wild life in many ways. Firstly by his spread further and further into the rural areas, man is reducing the areas in which wild life can live. This also includes the effects of widespread farming where forests and heaths come under the plough and many kilometers of hedges are removed. Secondly, man has hunted many animals to extinction. A good example of this is the destruction of the great auk during the last century or perhaps even more famous the death of the dodo. More recently the fate of many species of the giant sea mammals, whales, has been in the news, as their numbers fall to the more efficient whaler’s harpoon gun with its explosive harpoon. Pollution is also affecting the lives of many animals. Millions of sea birds die very unpleasant deaths as a result of their feathers becoming covered in sticky, black oil waste.
It is sometimes argued that if an animal or plant cannot survive man’s ravages, then this is just the course of evolution. Unfortunately, many beautiful and valuable species, on which man himself depends, may never be seen again.

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What is Unicorn?

On the royal coat of arms of Britain there are two creatures, one on either side of the shield. One animal is, of course, the lion and the other is a strange, horse-like creature with a long elegant horn on its forehead. This is the unicorn. It is a creature of legend, and probably never existed; the tales of it brought back by ancient travelers were probably the result of sighting of rhinoceroses and a good deal of imagination. Nowadays, nobody believes in the unicorn except as a legendary animal, and a heraldic beast, but years ago people did believe in its existence.

Queen Elizabeth the First was supposed to have possessed a unicorn’s horn, which was worth an enormous sum of money, and the horn was supposed to have healing powers and could protect people against poison. There were special rules and down about how to catch a unicorn. A Young girls was the effective bait, and unicorn would lay its head in her lap while the hunters crept up to do their work. The Unicorn became part of the British coat of arms when Scotland and England were first united under King James the First. Before that England’s heraldic beasts were a lion and a dragon and Scotland’s were two unicorns. Legend has it that the two beasts, the lion and the unicorn, were deadly enemies and that the only way to stop them killing one another.

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Who was Robin Hood?

“He stole from the rich and gave to the poor” is a favourite saying about this notorious outlaw. According to legend, Robin is supposed to have lived in Sherwood Forest with his band of Merry Men, robbing wealthy travelers and giving their gold and jewels to the poor people of Nottinghamshire and Yorkshire. The first written account of him is The vision of piers Plowman, a poem written by William Langland in 1377, and since then legends have grown up, showing Robin as a sort of medieval superhero, although obviously these legends were well known before the poem was written. In spite of these tales, not much is known of the real Robin Hood, and some People even believe that he may be sort of woodland spirit, since Robin was often a name given to spirits, elves and pixies. It is doubtful whether anything will ever be known about the real outlaw Robin Hood, unless some startling evidence is found, proving him to have really been what all the stories say he was.

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What is the most common surname in the world?

In English-speaking countries, the most common surname is what you expect: Smith. But the most common surname in the world is Chang, with a total of more than 80 Million! And the Most common first name in the world? Mohammed!

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What are the Northern Lights?

The Northern Lights, or Aurora Borealis, are seen in the areas near the north pole, but they are also to be seen near the south pole, where they are called the Aurora Australis. Scientists are not sure about what exactly causes the aurorae, but they think that the beautiful rays of dancing pink, green and yellow lights may be caused by sudden discharges of electrical energy from the sun, which hit the high layers of the earth’s atmosphere near the poles. Here the earth’s magnetic field does not protect the atmosphere from the sun’s particles as it does over the rest of the planet, and so we see the lights in these regions. When they do appear, the sky in these regions. When they do appear, the sky may sometime be heard to crackle , just like the noise you hear when san electric spark sometimes jumps between your hand and a glass or metal surface.

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Why don’t newly-born babies have teeth?

When a baby leaves the mother’s womb to live in the outside world, his small stomach does not immediately adapt to a mixed diet. This is why the baby needs his milk. Teeth are not needed for this type of food because the baby does not have to chew. Indeed, they would be in the way as the baby has to suck his food into his mouth. And it would not be very comfortable for the mother to breast-feed a baby who had a mouthful of teeth.
As the baby grows, teeth begin to appear in the gums of his mouth. This stage is called teething, It can be a little painful for the baby and he may cry when his teeth come through. When the baby has teeth he can start to eat solid foods
t is very important to look after a child’s teeth right from the start. This is one reason why babies need milk as the calcium in it helps to make teeth grow healthy and strong.

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What is taste?

Taste is one of the five senses, the others being sight, smell, touch hearing. Our chief organ of taste is the tongue, which is covered with tiny cells or taste buds. These react to different taste and send messages to the brain
You may be surprised to learn that there are in fact only four kinds of taste; sweet, sour, salty and bitter. All the flavours we know are a combination of these four.
Just as there are four kinds of taste, so there are four kinds of taste bud, and these are situated in different areas of the tongue. Only the centre of the tongue has no buds at all, as you will see if you put a little salt on the middle of your tongue. Experiments with other flavours to find the areas of taste buds on your tongue, and then see how placing an ice cube on your tongue affects your sense of taste.

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What is an albino?

An albino is a person or an animal without any colour at all in their skin except red caused by blood vessels. This is quite rare, and means that person has very white skin, white hair and pink or red looking eyes. The red colour appears because there are lots of blood vessels in the eye. Albinos live all over the world – there are albino people in Africa, where rest of their family is the colour you would expect. As well as being striking to look at, albinos also have problems if they live in sunny countries. Because they have no colour in their skin, they also have little or no protection against the harmful rays of the sun, and can burn very easily unless proper care is taken. Albino also have no colour in their eyes, which means that there is little or no protection against strong light, so many albinos have to wear dark glasses for most of the time.

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Why do soldiers wear Khaki?

Soldiers wear khaki for camouflage, or course, to ensure that they blend with their background and make them lees easily spotted by their enemies.
In early times camouflage was not so important to soldiers; fighting at that time was usually hand to hand, and distinctive uniforms were necessary so that the combatants could discriminated between friend and foe. The uniforms were as colorful as possible and were covered with feathers, ribbons and to other decorations to give the fighting men a sense of unity, a feeling of belonging to, and being a part of their own regiment.
But with the invention of the breech-loading gun and long-range artillery, camouflage became very important indeed, as the British soldiers fighting in the American War of Independence found to their cost. Many of the Americans had no uniform as such, and wore their usual hunting shirts, whose neutral colour gave them good protection. The British soldiers, in their red coats and white breeches, presented perfect targets, and were unable to melt into the landscape.
In the 1840s Lieutenant Harry Lumsden was forming a regiment cavalry and infantry in northern India, and was given permission to arm and dress his men as he whished. Since their duties would involve skirmishes with the natives he decided that his men should wear with the natives he decided that his men should wear uniforms the color of the local ground, so that they would be inconspicuous, and cloth specially dyed locally. It was called Kahki after the Urdu word for dusty, and when Lumsden’s regiment went into action in 1849 they were known as the ‘Mudlarks”.
The success of the Khaki camouflage led to all British soldiers being issued with Khaki uniform when they were posted overseas, though colours charged slightly in accordance with the surrounding countryside.
When the First World War started in 1914 some cavalry regiments were their traditional colourful uniforms, but they soon changed to Khaki, the colour of the med in the trenches and the dust of the roads they had to travel.
Today soldiers all over the world dress in Khaki, glad to the protection it affords them. The bright, colourful uniforms that once glamourized war have disappeared.

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Why do we need water?

Very simply – because our bodies are about two thirds water. The human body contains about eleven gallons of water, and as we get rid of our body water by sweating and other means, we must replace it. The water in our bodies is not the same as ordinary drinking water, or course. There are many chemicals in it, which the body needs to grow and repair itself, and the water moves these substances around inside the body so that each part gets the amount it needs. Although on some days you may not drink as much as on others, you take in water from the solid things you eat - vegetables, fruit, meat and bread are about a third water themselves.
Blood is mainly water. About a gallon of all water in our bodies is in the blood, but that level always remains the same, no matter how much you drink.

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What would we do without Coal?

Coal is something which we all need in some way or other. We need coal to produce heat and light for our homes and offices; our industry needs coal to provide many commercial and household goods to export all over the world.
Different types of coal are often found in a coalfield. There are ‘coking coals’, for instance which, when mined, aren’t used for home consumption but are valuable for the belts furnace of a steel works. Then there is anthracite, a hard kind of coal which burns with a very intense heat.
Coal is still mined today by men going down into the earth and risking their lives to bring the coal from the seams up to the surface. Despite a great many new safety measures mining is still a difficult and dangerous job. At least the practice of taking children to work down the mine shafts has ceased now, although pit ponies are sued to pull loads of coal under ground.
There are quite a few mines in Britain, mostly in Wales. Scotland and North-East England. A world famous mining area is the of the Rhur valley in Western Germany.

How is coal made?

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What would we do without Wool?

Wool has kept us warm since ancient times when man first domesticated sheep, and even in this age of synthetic fibers wool still remains a firm favourite with most of us. Britain, especially, has a lot sheep grazing on the hills of Scotland, Wales and Ireland, and has a thriving wool industry.
Britain was very important when it came to wool-producing in the Middle Ages, and a sack of wool became a status symbol of wealth, hence the Lord Chancellor’s seat in the House of the Lords becoming known as the wool sack. All in all, the sheep population of the world is about 970,000,000!
When shorn, the sheep’s fleece is matted and oily and unfit for spinning, so the fleece must be washed and ‘carded’ before going on to the next process. Once spun, the wool goes on to be woven into the woollen clothes and rugs, carpets, etc., we are familiar with in the shops. In the middle Ages the Flemish were celebrated weavers; these days Bradford and Leeds are well known for their fine weaving.

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Why can’t babies walk at birth as some animals do?

From the moment of birth a baby can carry out all natural functions, just like any animal’s offspring. However, unlike other species, a human baby cannot walk straight away. This is party because man walks on two legs whereas animals walk on four legs. So it is more different for babies to learn to walk and they have to crawl on all fours first. Man also has a longer life than most animals and he takes longer to grow into an adult. Therefore, the baby stage lasts longer.
Another point is that offspring of animals often have to start looking after themselves when they are very young, so they need to be able to walk as early as possible.

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Why do we have to pay taxes?

A tax is a sum of money which is paid by the citizens of a country to its government. Some taxes are direct, such as those you pay when you own certain things like a house or a car: others are added on to things you buy like electrical goods, and petrol, or services such as repairs, building work, and restaurant meals. The government then claims the money back from the shops and service operators.
Taxes are the main income of the government and it uses this money to pay for public services such as roads, health, schools, police and national defense. In democratic countries, people usually pay more or less tax according to how much they earn.

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FASCINATING FACTS

Who knows what?
The average woman’s brain weighs around 4 oz lighter than a man’s. The Brain of Neanderthal man was bigger than both.

Super tankers
The rudder of a giant oil tanker could provide parking space for nearly fifty cars if laid on its side.

Windy
Workers on Japanese building sites sometimes use kites to carry bricks up tall buildings.

Slow risers
Some species of snail have been known to sleep continuously for four years.

Bare-faced Piggery
At the turn of the century, a shaved bear dressed in female clothing was exhibited as ‘The Pig – Woman’, a fortune – teller whose grunted replies were prompted by a man beneath the table with a sharp stick.

Wet lot
The average American uses sixty gallons of water every day.

Passing fancy
Inmates who escaped from Sing. Sing prison could rely on change of clothes at the home of millionaire Whitelaw Reid, who kept two suits hanging in an outside barn for that purpose.

Strict Upbringing
Young men in Malagasy Indian tribes must pay their fathers for the right to grow taller than them. While their fathers are alive they cannot shave or eat animal rumps.

Peace on earth
Just under three quarters of the earth’s population live without radio, television, newspapers or telephones.

Museum Piece
A coin described as a ‘Roman sesterce coin from between 135 and 138A.D. was removed from display when a nine-year-old boy recognized it as a plastic medallion given with bottles of Pop.

Hello, XLZPTZ Speaking
There is enough telephone cable under New York to reach Venus.

Cheeky Monkey
An art student in Pretoria who submitted a chimpanzee’s picture instead of his own was awarded a pass mark by examiners.

Larger than life
Western sets in old Holly wood movies were built smaller than in real life to make the cowboys look big.

Vintage stuff
The word vinegar comes from the French VIN aigre, meaning sour wine.

Not cats and Dogs
During a freak storm in France, thousand of small toads rained down on the startled population.

Thick-Skinned
Although toads are capable of surviving 10,000 mg. of fluoracetic acid, as little as 1 mg. will kill a dog.

Spider Dressing
High-Class barbers in Roman time used to dress the cuts of their clients spiders’ webs soaked in vinegar.

Early Start
Female children in the Tiwi Islands in the Pacific are engaged they are born. They are married at birth to the adult of their parents’ choice.

Deep freeze
A Lizard discovered inside a block of a ice buried 33 ft. below ground level in Siberia, was found to be alive.

Going up
The three astronauts who spent twelve weeks in space on the sky lab mission had grown two inches taller by the time they returned to Earth.

Sweet teeth
One third of the world’s boiled sweets are eaten in Britain.

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Why do some Plugs spark when disconnected?

The electricity supplied to a building travels round a circuit in cables under the floor and back to the main supply point. A Plug socket is a point where there is a deliberate break or gap in that circuit. When you plug something in, the circuit is complete, and the electric current passes through the apparatus, making it work.
If you pull the plug out when the current is switched on, the contact surface of the plug pins gets smaller as it is pulled out. The ends of the pins heat up very quickly and then the remaining electricity in them jumps across the gap between the pins, which we see as a spark. You should always switch off a plug before disconnecting it.

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Why do you put water in Car Radiators?

When Petrol is burnt in a car engine it gives off a lot of heat, which affects the various parts of the engines. Although the heat only rises slowly it could cause the engine to seize up. So these parts have to be cooled by water which circulate around the engine is special channel.
The water first passes through the radiator which is made up of lots of thin pipes, kept cool by the air which blows against them as the vehicle is moving. The cooling action is also helped by a fan turned by the engine. This water is carried around the rest of the engine to cool it down. Heat is transferred to the water which returns to the radiator and is cooled again.

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How do Telephones work?

The way that Telephones work is similar in some ways to television, but the transmission uses an electric current rather than air waves, and telephones transmit only sound, not pictures.

When you speak on the Telephone, the microphone inside the mouthpiece transforms the sound waves into electrical impulses. These are transmitted through the telephone cable to the ear piece of the other person’s receiver. This turns the impulses into sounds which are nearly identical to those made by the caller, so that it is like listening to the actual voice of the person talking.

Years ago, and still today in some isolated places, you had to ask the operator or at the telephone exchange to connect your telephone with someone else’s in order to speak to them. Nowadays, thanks to the progress of electronics, the connection is made automatically, even to countries on the other side of the world.

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How an Electronic Calculator Works?

The operations of an electronic calculator are not only very quick, they are also very basic. Most of the calculations are done using simple addition and subtraction, and a number system which has only two numbers, 0 and 1.
This binary (two-state) number system is used in calculators and other electronic devices, because they operate on a system of electronic switches, which at any time can only be in one of two states; off or on. In the Binary code, ‘off is represented by 0, and ‘on’ by 1.
The calculator keyboard uses our usual (decimal) numbers, from 0 up to 9, on its keys, but when a key is pushed down, the calculator understands this in the binary equivalent, which is fed through a ‘switch point’ situated under the key, and from there into the heart of the calculator – the ‘chip’.
This is a tiny integrated circuit, an incredible network of electronic components in a piece of Silicon, itself smaller than a Do stage stamp.
The chip carries out the binary operations at the speed of light, and its answers are sent back to the display, and its answers are sent back to the display. The Calculator converts binary into decimal again, using a ‘decoder’ (a circuit based on switches),and these decimals appear on the display panel, using LED, or light emitting diode, segments.
The space for each unit on the display has seven such segments, plus a decimal point, and each LED gives off a reddish glow when required. Different combinations of these segments light up any decimal number from 0 up to 9, as the chip instructs through the switching circuit.
The chip adds in the standard binary way: 0+1 = 1; 0+) = 0’ and 1=1 = 0 (equivalent of 2). And it subtracts by reversing this procedure.
The operations of multiplication and division are carried out by continued addition and subtraction, respectively. For example, to multiply 43 by 17, the calculator adds 43 seventeen times. This may seem show to us, but electronically the answer is arrived at almost immediately.
Just try dividing 1,089 by 33, and see how long you take! How would the calculator solve this one? And because it works electronically, it can do harder sums in about the same amount of time. It would divide 582.31 by 34.9 as soon as add two and two!

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Which language is spoken by most people?

Over 500 million people speak one of the Mandarin Chinese dialects. Chinese is unlike most other languages as it has no alphabet, but uses instead several thousand characters or symbols, each of which conveys one complete idea. Each character has only one syllable, and most words are made up of two or more characters. A character can change its meaning by the way its pronounced or by changing its position in a sentence, It is only in the last hundred years that ways have been invented to write Chinese in the Roman alphabet.

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Why is playing important?

Some adults think that when children play they are wasting their time and that it is more important to study. They couldn’t be more wrong. Children need to play both by themselves and with others as they develop their personalities this way. Babies, especially, learn through playing, and children’s games change as they grow up, until they reach an age where they are gradually replaced by other activities and pastimes. Adults do not play in the same way as children, but they also need leisure interests – more than ever now that working hours are less – both to amuse themselves and to relax.

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Why is it better to eat at set times?

The process of digesting food takes a certain amount of time. It makes sense to eat at set times, leaving a sufficient amount of time between each meal for the stomach to digest the food. The Stomach juices have to break down the food, so that it can be absorbed by the body.
Naturally, the times and sizes of meals vary from society to society, and habits and customs tend to decide these.

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What alphabet is used by deaf People?

Understanding what somebody else is saying when you are deaf can be an impossible task, making the deaf person feel isolated and alone. Dumb people, unable to speak, are similarly denied the basic human medium of communication. Finger spelling is a method of talking to someone using a signaling code, similar to semaphore. The two-handed method used in Australia. Britain, Burma, India and some other countries, utilizes relative positions of the hands and fingers to spell different letters. It is quicker to learn than the one-handed method and can be seen more clearly at a distance.

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Is there life on other planets?

Ever since man has been aware of worlds beyond our own, he has begun to wonder whether he is alone in the Universe. Do other races of creatures very different or perhaps quite similar to ourselves exist on distant planets? This desire to explore beyond the confines of our world and to imagine what possible life forms could exist on other planets has let science fiction writers to describe all kinds of strange creatures. In the first men on the Moon, H. G.Wells tells of a species living in the craters and caves of the Moon that he calls the Selenties. These creatures resemble giant, intelligent ants. Of course, we are aware today that no such creatures exist and there never has been any form of life on the Moon, least of all the ‘Man in the Moon’. There have been other creatures from the Pages of science fiction such as the Mekons with tiny green bodies and huge heads whom Dan Dare met in his space travels in the Eagle comic. More recently, television has brought the terrifying, war-like Daleks who confronted Doctor Who in the programmed of the same name.
These are just a few of the imaginary men from outer space, but what are the possibilities of actual life forms? The first point to make is that there is little to be gained from trying to picture weird and wonderful creatures sprouting radio antennae from their heads and breathing liquid ammonia. We should try to confine ourselves to examining whether or not there is any chance of living systems much like our own somewhere else in the universe. It must also be remembered, however, that a living world elsewhere could be more or less developed than our own. In other words it could still be at the stage of a ‘primordial soup’ of primitive life forms or thousand of years more advanced than our own world.
Scientists have attempted to calculate how many galaxies there are in the Universe and how many solar systems are contained within these galaxies in a effort to work out how many planets there might be similar to our own. Even the most cautious would probably agree the number of planets in the Universe similar to our own probably runs into the thousands. This means that the chances are heavily in favour of there being many other worlds just like our own in which there are plants and animals and humans breathing air made of oxygen, nitrogen, carbon dioxide, and a few others gases.
Are these intelligent creatures trying to make contact with us using radio waves? Some people think so, but of course, they may be thousands of light years away so that by the time we received any message, they could be extinct. The possibility exists that we have already been visited by spacemen and that such wonders of the world as the Pyramids of Egypt were constructed with their help. Perhaps soon we shall know more of the creatures from outer space.

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How is man exploring outer space?

From earliest times men have dreamed of traveling in space, exploring new worlds, reaching for the stars – an apparently impossible dream. Then rocket research which took place during World War II gave a great impetus to space travel for which rocket propulsion is essential. After many experiments the first major break-through came in April 1961 when a Russian, Yuri Gagarin, spent 108 breath-taking minutes in space. Three weeks later Commander Alan Shephard of the U.S. Navy also journeyed into out space. The greatest milestone so far passed was in July 1969 when two more Americans, Neil Armstrong and Edwin J. Aldrin Jr. stepped on to the moon.

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Why do we keep food in a fridge?

Food goes bad because bacteria, mould and microbes attack it. This happens more quickly in warm temperature, where as cold interrupts and even stops this process. So food will keep fresh for longer in a fridge.
Nowadays, there are enormous refrigerated rooms, fro string meat and vegetables which can then be eaten in perfectly good condition at any time of year. The technique of keeping foods refrigerated is most important in transporting fish from the sea to the markets where they are sold.

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Why do people look so big on a film screen?

When we pass light through a film on to a screen a little distance away, we obtain a picture which is larger than the film itself. This is because there is a magnifying lens at the ends of the projector. The size of the image depends on the distance between the projector and the screen, and on the focusing power at the end of the projector. Projectors also have a system of lenses which help to make the picture clearer and sharper.

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Why did Columbus sail westwards?

Christopher Columbus was an Italian from Genoa living in Portugal. Although in the fifteenth century most people still believed that the world was flat, others, including Columbus, had come to believe it was round. If this was so, he argued, a ship could sail around the globe and return to its original starting point. Thus the shortest route to the spice Islands of the East Indies would by sailing Westwards. He sought support for his theory but it was rejected again and again. Finally, after years of disappointment, he gained the help of Ferdinand and Isabella, the king and queen of Spain. In August 1492, three small ships set sail from Spain, their bows pointing westwards across the wide, unknown Atlantic. They were the Santa Maria, the Nina and the Pinta. On 12 October land was sighted. Columbus was convinced that it was an island off the coast of India. When other islands came into view he named them the ‘Indies’. His ‘mistake’ was nevertheless a vitally important event in the discovery and exploration of the west.

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Why Australians are called “Diggers”?

Early in the 1800s, gold was discovered in Australia. Most of the ‘Strikes’ were in the vicinity of the Blue mountains near Bathurst. In 1851, a prospector named Hargraves – Who had been in California during the gold-rush two years earlier discovered rich traces of gold in Summer Hill Creek. The news spread rapidly and within two months the whole are was swarming with prospectors. The fact that there was gold to be had sent men digging in other areas, especially around Melbourne. In time the cities were deserted and ships lay empty in the harbours, for everyone seemed bitten by the lust for gold. Town sprang up overnight and were soon the scenes of rioting and bloodshed. The army has to be called in and a battle took place between soldiers and diggers. The incident became known as the battle of Eureka Stockade. By 1856, however, the day of the ‘amateur’ digger was almost over. Deep shafts had to be sunk to reach the gold and such mines had to be run by companies. But, in memory of the gold-flush days, Australians are still sometimes called “Diggers’.

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What is a Cyclone?

Very simply, a cyclone is a kind of storm, and storm is air which is moving quickly from one Place to another.

A storm begins when a mass of warm, moist air from the equator meets a mass of cold, dry air from the northern hemisphere. The two masses of air will not mix- instead they form a front, which is just the name of the boundary where the two meet. The air in them continues to move, and the warm air rises above the colder air, becoming cooler as it does so. Then the moisture which was in the mass of warm air condenses and forms clouds.

Meanwhile, at the center of the storm, the air pressure begins to fall, and winds blow round this area of low pressure. In the northern hemisphere, the winds blow in the anti-clockwise direction, and this means that the warm air moves north round the eastern side of the storm, and the cold air moves south around the western side.

So a cyclone is just another word for a low pressure area. Such cyclones can be enormous, sometimes about a thousand miles in diameter.

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What is a Nebula?

One of the most stroking objects in the sky is the Great Nebula in the constellation of Orion. It can be seen as a faint greenish patch with the naked eye just below Orion’s Belt, but through binoculars or a telescope it is seen as a mass of glowing gas. Nebulae are large clouds of dust and gas in space. Many produce their own light, and others are illuminated by stars. Some are dark, and we see them as black clouds or bands against the stars. Many luminescent nebulae are formed when stars explode into supernovae. The remains of the star move out through space as an expanding shell of glowing gas. Nebulae are among the most striking sights in the heavens. Photographs show them to have beautiful colours, but these colours may not show in a telescope.

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What are Quasars?

The word quasar is short for quasi-stellar object, which means an object that resembles a star. But quasars are not like ordinary stars. Many are thought to be near the edge of the observable universe and moving away from us at nearly the speed of light. But quasars produce intense amounts of light and radio waves, and may be as much as 200 times as bright as an ordinary galaxy. And they appear to be much smaller than a galaxy-about one light-year across. No one can account for how quasars produce such immense amounts of energy. Perhaps they are much nearer, much larger, and not moving so fast.

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How fast can a dog run?

Some breeds of dog can run much faster than others, and the fastest dog of all is the greyhound. A fully grown greyhound can run at the astonishing speed of about 56 k.p.h., that is, at nearly a kilometers a minute. Because greyhounds runs so fast, greyhound racing is a popular sport. At a Greyhound racing track, the dogs are put in a series of boxes called traps. Then an electrically-driven imitation hare starts to move round a rail running beside the track. As the hare runs past the traps, the doors are released and in their excitement the dogs rush out in pursuit. As in horse racing, people place bets on which dog will be first past the winning post.

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Where is Pampa?

The Pampa is a region of grassland in Argentina. It runs inland from the town and cities, such as Buenos Aires on the Atlantic coast, and stretches for hundreds of miles up to the foothills of the Andes. The Pampa is very like the great plains, or prairies, of north America which stretch across the states of Texas, Kansas and Nebraska. Like the prairies, the Pampa is most famous for its cattle ranches, and the cowboys which look after the herds of cattle as they roam across the plains. One of Argentina’s most important exports is beef, which comes from the huge cattle ranches which are situated on the Pampa.

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What is a king crab?

The King crab, or horseshoe crab, is not really a crab at all. In fact it is not even a crustacean but a very primitive arthropod which belongs to a group of its own. From fossil evidence we know that king crabs were abundant in seas about 175 million years ago. The few species that survive today are virtually unchanged from those early ancestors and for this reason they are sometimes called 'living fossils'.
King crabs have some unusual features. They are about a foot across, have heavy domed shell divided by a joint across, have a heavy domed shell divided by a joint across the middle, four pairs of walking legs and a long spiky tail. The bony mouth extends between the bases of the legs which help in chewing up the food. These characteristics, together with their gills and mouthparts, tell us that the King crab is actually descended from the forerunners of another group of arthropods adapted for life on land-the arachnids. These include the scorpions, spiders, mites and ticks, and daddy long legs or harvest men.

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Good reasons to read books

Reading helps to feel more confident.
Help to travel around the world in the cheapest way.
Develop your personality.
Provide food for thoughts.
Reading make you laugh and think.
Draw you towards perfection.
Stimulate creativity.
Brings out writing talent.
Helps in communicating.
Clear your vision.
Satisfies your curiosity.
Help you make more choices.
Help you to build literary talent.
Book reading do not require any special device to teach.
Increase your attention span.
Books are fruitful pastime
Books can be used any time anywhere.
Provides entertainment when others fail.
Reading makes you powerful.
Helps you to know the ' whys and hows ' of everything.
Helps you to create and spread fun.
Help you to travel across time intelligently.
Keep you updated with facts and figures.
Spreads love, affection and knowledge.
Make the best of friends.
Take you to intellectual environment.
Helps you to feel the world around you.
Entertain your mind.
Broaden your horizon.
Books bring nature to your doorstep.
Books bring about a personality change.
Increases comprehension.
Books do not require company.
Books are stress busters.
Develop a sense of belonging to people around you.
Provides mental and physical relaxation.
Act as a communication tool.
Books are intellectually satisfying activity.
Provides spiritual experience.
Provide emotional strength.
Build your self esteem.
Encourage your imagination to soar.
Make you smarter and wiser.
Books help you grow.
Takes you to a world of dreams.
Change your life and vision.
Helps in achieving life goals.
Books develop wonderful experience.
Books transform lives.
Books inspire, books motivate, books build nations.

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What’s the Difference between a star and Planet?

A star is a huge ball of hot, glowing gases, which whirls in space. All stars are made up of the same two gases, hydrogen and helium, and they shine by their own light, which is produced as a result of atomic reactions in their centre, causing great heat.

Planets are different. A Planet is much smaller and more solid than a star. It does not shine by its own light, because it is not nearly hot enough to produce that light. Instead, it shines by the light of the nearest star.

Our sun is a star, and in its solar system there are nine planets-Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.

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What is Ultrasound Scanning.

Ultrasound scanning is used to analyze the structure of internal organs, muscle and their size. Ultrasound scanning (Obstetrical ultrasound) is commonly used to scan and analyze the pregnancy period. Ultrasound scanners operating frequency is between two to eighteen mega hertz. Lower frequencies also uses in scanning to get deeper image from body. The Ultrasound scanner operators are called sonographers. A gel is applied on the body of patient before scanning, a probe called transducer produces ultrasound frequency. This probe directly placed on the patient and ultrasound passes from the transducer through the applied water based gel to body. Mainly ultrasound scanning is used to observe the development of fetus during pregnancy. Another applications of ultrasound is in Dental section to clean tooth, cancer treatment, surgery, eye treatment etc.

The working principle of ultrasound scanner : It produces a wave and analyze the echo of that wave, especially how strong the echo was and how long the echo to be received. From these things it produces a digital image as output.

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What is MRI Scan

Magnetic Resonance Imaging (MRI) Scan is the latest system to scan and analyze the functions of human body. Normally MRI scanning is used to find brain diseases. MRI is used to scan all organs in our body very successfully. But MRI scanning is harmful to pregnant ladies. MRI Scanning is more secure than X-rays and CT scan. An electromagnetic radiation is used in MRI scanner. If atoms comes in a high electromagnetic field the nucleus of each atom produces radio signals, these signals are fed to a computer and creates an image of internal body parts. The good cells and weak cells produces different type of radio waves. Working of MRI scanner is depend upon the different types of radio waves from the cells. In 1977 Raeymond V Damadian make a MRI scanner and he named it as Indomitable.

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What does the future have in store for our planet?

This question has many parts to it. We know, for example, that eventually our star, the Sun, will die and in doing so will destroy the Earth. The very distant future, then means the end of the Earth, but this will not occur for many millions of year and need not concern us here. It has also been suggested that our climate is changing and that we are at the beginning if another Ice Age, but opinion is divided. It is enough to say that large scale changes to the planet as a whole take place so slowly when compared to our short life span that they may go unnoticed, disguised by the much more rapid changes which man is causing to his own life and that of all other living creatures on Earth.

The usual way of attempting to ‘see’ into the future is to look at the way changes have occurred in the past up to the present day and then try to project into the future, but this is not easy because it is not always possible to anticipate the effects of a particulars set of circumstances. Try a simple experime4nt. Draw two lines on a piece of paper at right angles to one another to form the axes of graph. The graph could represent, say, the rate at which a hot water bottle cooled after it was placed in your bed. Suppose one axis represented temperature and the other time. Suppose also that you had measured the temperature on two occasions so that you could plot two points on your graph. These could be joined by a straight line, and if you wanted to know the temperature of the bottle sometime later, you would simply project that straight line to the required point in time. But, if, in the meantime, someone removed the blankets from the bed, the bottle would cool much more quickly and your prediction would be wrong.

The subject of many science fiction stories deals with ideas of what conditions might be like in years to come. Some suggestions seem to be widely far fetched, but a hundred years ago who would have believed in the possibility of supersonic flight or submarines that can stay under the Arctic ice for two years without surfacing, or even in satellites circling Venus? On the other hand in the heyday of the motor car a few years ago, most of us would have laughed at the idea of fuel shortage. How do we know what the world’s population might be in a hundred or even twenty years time? Can we predict whether science and technology will be able to find solutions to the problems of overcrowding, food shortage, and pollution choking our rivers and seas, or the ever-decreasing numbers of wild animals and plants with the accompanying dangers to our own species. Will be able to able to take a rocket to a distant planet as easily as we can now take a bus to the next town, or will we return to more rural living, each community growing its own food and making clothes by hand? Then there are the danger of nuclear war. If man is to survive in peace and plenty, the watchword seems to be to try to foresee the consequence of any action rather than wait and see, by which time it may be too late.

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Why don’t we see the Moon on some Nights?

There are several reasons why we do not see the Moon on some nights. The moon does not give out its own light but reflects light from the Sun. Therefore, when the Earth comes between the Sun and the Moon. It casts a shadow over the Moon. This is known as an eclipse. When the Moon moves between the Earth and the Sun only its far side is lit by the Sun’s rays. The side facing Earth is in total darkness. We call this a ‘new’ Moon. Finally, on nights when the sky is over cast, the clouds hide the moon from us.

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Where do budgerigars live in the wild?

The parakeets are a widespread group of small old World parrots. Best Known is the Grass Parakeet or Budgerigar which is popular as a cage bird in so many homes. Budgerigars come from Australia. Large, chattering flocks feed among the grasses of the wide, inland plains. They eat the seeds of a variety of grasses, the fresh shoots of plants and any small insects they may discover while foraging. If you keep a budgie, do not be surprised if its snaps at a fly or other insects, for it is merely supplementing its diet like its wild relatives. Wild budgerigars are predominantly grass green in color with yellow head and blue tails. They make a spectacular sight as they flock each morning and evening to drink at a waterhole.

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Which tree’s berries are used to flavor gin and can be used in cookery?

The juniper. This evergreen tree is small and resembles a gorse bush with its spiky needles and fragrant grey bark. Juniper wood is used for small decorative carving and inlay, but it is the berries which make it useful. These are distilled into oil of juniper, which is then used in perfumery and exotic cookery. Another of its uses was in medicine, but nowadays its main function is to flavor gin.

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Does a comet foretell disaster?

Before we can answer this question, we must look at exactly what a comet is. As you probably know, a comet looks rather like a star with a long, milky ‘tail’ stretching across the sky. In fact these ‘ tails’ are not tails at all because they always point away from the Sun and do not trail behind.

A comet seems to be made up of three main parts. The nucleus in the center of the star-like part is composed mainly of ice and dust particles, surrounded by a coma of much smaller particles and gas. The coma results from the melting of the ice and other substances as the comet approaches the Sun on it’s extremely stretched out elliptical orbit. The Sun’s radiation also tends to force some of these tiny pieces of ice away from the comet and out into space, which explains why the tail is always directed away from the Sun.

A Scientist called Halley, after whom a particularly bright comet is named, discovered how comets moved. He also predicted when some comets which had already been seen would return. For example, Halley’s Comet made its closest approach to Earth for 76 years as predicted in 1986.

Why are comets associated with disaster? It is true that a comet appeared before the Norman conquest of Britain in 1066, and that two more comets were seen before the Great Fire of London in 1666 and the Great Plague in the previous year, but in world terms these cannot be regarded as major events. Perhaps it is the result of people’s belief that what happens in their own country is of world importance that has led to this idea that comets predict disaster. On the other hand, it has been suggested that the Star of Bethlehem that told of the birth of Christ was in fact a comet. It does seem unlikely, however that a body of ice and gas moving around the sky in a quite regular orbit can have anything to do with the events here on Earth. This particularly true of comets because they have such a low density. Although they may have a diameter of as much as 128000 Kilometers they do not have enough gravitational pull to affect the bodies they pass. In fact, their own orbits may be completely changed.

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How long has man been walking the Earth?

Ever since the philosopher and naturalists, Charles Darwin, and his contemporaries including Wallace, suggested that man had evolved from apes, there has been a continuous, and almost frantic quest for evidence of our ancestors. Of course, where we come from has always been a fascinating question, but it is only comparatively recently that systematic searches have been made for traces of ancient men by such eminent scientists as L.S.B. Leakey and still more recently by his son, Richard. As you might imagine, the idea that man came from monkeys brought with it a great deal of public outcry, and in fact, modern research has shown that man did not descend directly from apes but that the apes and man evolved from a common ancestor.

As you know the first thing that monkeys, apes and man have in common is that they all have backbones, so that they all vertebrates. Many characteristics in man have arisen from living in trees. We share them with other primates, as monkeys, apes and man is known. If you suddenly found that you has to live in a tree, what do you think the most use-full adaptations would be? There would bot be much point in having hoofs like a horse which help the horse to run fast. You would need to be able to hold on to the branches, however, as our hands are well able to do. If you wanted to jump from branch to branch, you would have to be able to judge distances. You would need stereoscopic vision, that is, two eyes positioned at the front of your head, not at the sides as in a fish. You are unable to smell the traces of scent that a dog can, but you do have a much enlarged brain. It is the growth of the brain that has enabled man to leave the comparative safety of the trees and compete with the other ground-dwelling animals that are stronger, have better hearing and sense of smell, can run faster and have warm coats to protect them from the extremes of climate.

As you might expect, because man and apes have developed from a common ancestor, it is not easy to tell when the remains of the primates that have found are of men-like apes or ape-like men. But between ten and fifteen million years ago a creature which has been called a Ramapithe-cus lived in parts of Africa, Asia, and Europe. This may have been the ancestor of man and the other apes, though recent evidence suggests that out ancestor was another creature, the ancestor of the orangutan. However, the groups became increasingly diverse until the first creature that could be called human arrived. This was around four million years ago.

How "Ida" named new fossil help the study about human origins?

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What is the importance of Plants in life’s framework?

It is only when we stop to think that we realize the importance of land plants to us. We eat them in our cereals and vegetables, we make use of them for fibers like cotton, we depend on them for many drugs such as penicillin. But even when we eat meat, we must remember that the animals which produce the meat probably lived on Plants.

Plants are nature’s producers. From sunlight, oxygen, and other foods from the soil, plants manufacture the foods upon which all animals ultimately depend. It is worth noting that it was with the rise of land plants in the Devonian, that land animals also began to evolve.

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