How does a thermometer work?

   The thermometer on your wall is a glass tube with a silvery or red or blue line inside. The silvery line is a liquid called mercury. Since the tube is hollow, the mercury can move. It goes up as the room gets warm and down when the room turns cold. A thermometer with a colored line contains a different liquid that behaves in the same way.
    The marks and numbers on the tube measure the height of the mer­cury. If it shrinks down to the 32-mark, you will be shivering, and water will turn to ice. But when the mercury goes up as high as 90, you feel very hot.
Why does the line of mercury grow taller or shorter? Like everything else, mercury is made of tiny particles called molecules. The mer­cury molecules are always moving, bumping into each other and bouncing away. Even when the silvery line remains steady inside the tube, the molecules are shifting around and around. Heat makes them move faster. The fast-bouncing molecules shove each other farther and farther apart. So the mercury takes up more space, and it rises in the tube.
   When the molecules get cold they move more slowly. Now they don't need so much bouncing space. They draw closer together, and the mercury goes down.

What is the Bermuda Triangle?

   It is a triangular area of the Atlantic Ocean, with Bermuda, southern Florida, and Puerto Rico making up its approximate corners. It is also known, more ominously, as the Devil's Tri­angle, because of the numerous ships and airplanes that reportedly have vanished in the region, usually without trace. Some authors have sought to explain the disappearances as due to mysterious weather conditions in the area of the triangle. But this has not been borne out by any evidence.

What part of Siberia doesn't have mountains?

The Urals is a set of mountains that extends from north to south through Russia, which divides the European part of that nation from the Asian part.

But if you travel east from the Urals, you would leave the mountains behind for a long way. Since there are no mountains or hills between the Urals and the Yenisei River, there are about 2,000 kilometers of distance between one and the other.

This region, called the West Siberian Plain, is the largest flat expanse on Earth. Most of this plain is part of the Ob River basin, the fourth longest in the world, with a length of more than 5,000 kilometers.

The total area of the Western Siberian Plain is more than 2,590,000 square kilometers, twice the size of Alaska.

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What is the origin of vanilla?

Vanilla and chocolate have a lot in common. Both are native to Mexico. In fact, when Europeans first tasted vanilla, they tasted it along with chocolate!

When the Spanish explorers arrived in Mexico, the natives offered them a chocolate drink cooled with snow (from the mountains) and mixed with vanilla as a sweetener, since chocolate, by itself, is bitter.

In Europe, too, chocolate was served along with vanilla for more than a century after arriving from the New World. Then people started using sugar instead of vanilla to sweeten the chocolate; vanilla became a flavor on its own.

All the vanilla consumed in the world was grown in Mexico until 1836, when scientists found a way to grow it in other lands. Today, most of the world's vanilla comes from Madagascar and other islands in the Indian Ocean.

Vanilla comes from an orchid - which is the only orchid on Earth that produces a useful product.

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SOME VERY FUNNY FACTS ABOUT MARRIAGE

All over the world, women prefer to marry older men and vice versa.

Marriage is love. Love is blind. Therefore, marriage is an institution for the blind.

After marriage, husband and wife each become one on one of two sides of a coin. They just can't see each other, but they stay together.

A British couple, Percy and Florence Arrowsmith hold the record for the longest marriage in the Guinness Book of Records. The marriage lasted 80 years before the death of Percy Arrowsmith, at 105 years of age in 2005.

Married women seem to have a lower risk of being abused in the home than those who are not married. Regardless of race, education, and age, cohabitants are three times more likely to become violent than married people.

No matter how often a married man changes jobs, he always ends up with the same boss.

In the first year of marriage, the man speaks and the woman listens; in the second year, the woman speaks and the man listens; in the third year, the two speak and the NEIGHBOUR listens.

THE CHILD ASKS: -Dad, how much does it cost to get married? THE FATHER ANSWERS: -I don't know son, I'm still paying for it.

CHILD: Is it true, Dad, that in ancient China a man didn't know his wife until he married her? THE FATHER: That happens everywhere, son.

When a man takes a woman's hand before they are married, it is love; when they are married, it is self-defense.

When a newly married man looks happy, we know why. But when a man with ten years of marriage looks happy, we would like to know why.

It is not true that a married man lives longer than a single man.

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Interesting facts about hurricanes

The hurricane season runs from June 1 to November 30. It is rare, but hurricanes have formed in the Atlantic as early as March or as late as December.

The average life span of a hurricane is 9 days.

Apart from hurricane this natural phenomenon is also known by the names of cyclone and typhoon.

Florida has had more hurricanes than any other state in the United States. More than 60 have played there since 1900.

The 'perfect storm' of 1991, made famous by the book and film, was created from the remains of Hurricane Grace.

Hurricanes turn clockwise in the Southern Hemisphere and counterclockwise in the Northern Hemisphere.

Hurricane Katrina killed at least 1,836 people, making it the deadliest hurricane in the United States since Hurricane Okeechobee in 1928.

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How does welding work?

Welding is a method that permanently joins two pieces of metal. Heat is applied to two of the metal edges or surfaces, usually with a gas torch or electric welding tool.

However, when large surfaces are to be welded, large machines are used. The heat applied by the machines melts the two surfaces or edges until they melt into one piece.

During the welding process, the heated metal must be protected from oxygen and nitrogen in the air, as these gases cause the weld to be weak and brittle. This protection is provided by spraying other gases into the metal during the welding process.

Once the two pieces of metal are welded together and the weld cools and hardens, the assembly is as strong as any other part of the metal. Welding is used in the manufacture of cars, buildings, bridges, airplanes, and large electrical appliances.

The heat generated by welding is often more than 1,500° Celsius.

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Some facts about soap

Maybe you've ever felt that it wasn't necessary to use a soap to wash your hands and that with just water you could wash just as well. Most kids think that way. But water can only remove part of the dirt from the surface of the skin, but water and soap together clean better.

If you look under the microscope at a cross section of the skin, you will see that it has many hollow areas or valleys, where particles of grease and dirt can be penetrated. Water alone can get some of that dirt out, but when water hits the grease, there's not much it can do against it.

But if you add soap to that same water it has a totally different action. The action of mixing soap and water sends air into the water and forces it to spread, as it creates bubbles. A bubble is actually an air balloon with a thin outer cover of soap and water.

While the bubbles appear to be very delicate and weak, they actually function as countless powerful magnets. Just as magnets attract metal to them, soap bubbles pick up dirt and pull it out of the skin. The dirty bubbles are then washed away by the stream of water, leaving the skin clean.

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What is Optometry?

   Optometry is a profession specializing in the protection and improvement of vision. The optometrist is one who practices the art and science of vision care. He is trained and licensed to make tests to determine the person's visual skills, especially in relation to his specific needs. When visual errors are found, he prescribes and provides any corrective lenses or visual training needed for adequate and comfortable sight.
   The roots of the profession of optometry lie in the development of research in physics, mathematics, and optics, as well as in physiology and psychology. Modern optometry, however, really dates from the 19th century, when such men as Thomas Young, Herman von Helmholtz, Eduard Jaeger, and others, were busily engaged in Europe in measuring the eye and inventing instruments for testing sight. The results of their research are found in the applications used today. Development in the field of refraction led to the refractive testing of the eye, or optometry, as it is now known.
   The word "optometry," in the sense of "diagnosis of refractive error" first appeared in 1870, and in the next thirty years optometry slowly evolved as a specialized vocation.

What is Galvanizing?

    Galvanizing is the coating of iron or steel with a thin layer of zinc to protect it from rusting, or oxidation. The iron or steel is protected by the zinc and by a thin layer of zinc oxide that forms on the zinc surface. It is further protected by an electrical reaction between zinc and iron that acts when the zinc coating is broken or scratched. Under these conditions the zinc is oxidized in place of the iron, and the exposed iron does not rust.
   In the United States most galvanized products, such as telegraph wire, garbage cans, and roofing and siding for buildings, are galvanized by the hot dipping method. In this process, iron or steel sheets are dipped into molten zinc. The zinc combines with the iron or steel to produce a protective layer of zinc-iron alloy overlaid by a layer of zinc. The entire coating is usually from 0.0002 inch to 0.004 inch thick.
   Electrogalvanizing, a less costly process, produces a thinner, less durable zinc coating. Here the iron or steel is placed in a solution of zinc or zinc salts. A strong electric current is passed through the solution to deposit a layer of 99.99 percent pure zinc on the surface of the steel or iron.
    Sherardizing is a process used to galvanize small items, such as nails or bolts. These are placed in a rotating drum containing fine zinc dust. The drum is heated to a temperature from 350 °C to 370 °C. (660 °F to 700 °F.), well below the melting point of zinc. As in hot dipping, a layer of zinc-iron alloy forms on the surface of the iron or steel.
   Large objects are often zinc-coated by being sprayed with molten zinc. This does not result in true galvanizing, since an alloy is not formed with the zinc.
   Galvanizing is named for Luigi Galvani, an 18th- century Italian physician who performed early experiments in electricity.

What is freedom of speech?

    Freedom of speech is the right of a person to express his opinions on all subjects without fear of punishment or reprisal. Freedom of speech is closely related to other civil liberties, such as freedom of assembly, freedom of religion, and freedom of the press. It is a basic concept of a free society and is sometimes explicitly written into national constitutions, as it is in the First Amendment to the U.S. Constitution and in the French Declaration of the Rights of Man. In other countries, freedom of speech, although largely unprotected by formal written guarantees, is supported by the common law of the land, as in Great Britain and Canada. Freedom of speech operates best in a democratic society, where the people have the regular opportunity to discuss and make choices between opposing policies and can change their leaders by means of the vote. On the private level, freedom of speech guarantees the right of an individual to disagree with his neighbor on vital issues of the day without fear of being punished.

What is fuel injection?

Fuel injector

   Fuel injection is the direct injection of liquid fuel into the combustion chamber of an internal-combustion engine. Fuel injection is used primarily in compression ignition engines, such as the diesel engine. Fuel Injection systems are also used in some spark ignition engines, including the gasoline engine.
   The typical fuel injection engine has a separate fuel injection mechanism for each cylinder. The mechanism consists of a high-pressure pump, a nozzle, and a valve fitted into the wall of the cylinder. During the compression stroke the pump forces a small amount of fuel through the nozzle into the cylinder, where it ignites and burns. The nozzle sprays the fuel evenly through the air in the cylinder. The valve allows the fuel to enter but prevents the compressed fuel-air mixture from backing up into the fuel system.
   When a fuel injection system is used in a gasoline engine, it may completely replace the conventional carburetor. Alternatively, the fuel may be injected into the stream of air entering the cylinders, in a device called the injection carburetor. The principal advantage of a fuel injection system over the conventional carburetor and intake manifold system in a spark ignition engine is that it provides a more even distribution of fuel to the cylinders.
   Reaction engines, such as the turbojet engine, also use the fuel injection technique. In such engines the fuel is injected into the combustion chamber, where it burns continuously.

What is flame photometry?

   Flame photometry is a method of chemical analysis based on measurement of flame coloration. Many chemical elements cause characteristic flame colorations. By measuring the light emitted by such colored flames, the amounts of such elements present in substances can be determined. Although flame photometry is most frequently used to determine amounts of sodium and potassium, the technique can be applied to determine about 48 different elements. Flame photometry is of particular use in the analysis of body fluids and tissues. However, it can be applied to the analysis of many other substances.

What is liquefied gas?

   All gases may be changed into liquids by the combined effects of lowering their temperature and allowing them to expand from a sufficiently high pressure.
   Before air is liquefied it must first be freed from dust, moisture, and carbon dioxide which, at the low temperatures used, would solidify and thus obstruct the expansion valves. The remaining gas is compressed and allowed to expand in a series of three or four cycles, the pressure becoming successively greater. The cooling effect of the final expansion becomes great enough to lower the temperature to —191 °C., at which point the gas begins to change into a liquid. Liquid air thus made may be separated into oxygen and nitrogen by fractional distillation, nitrogen (bp — 195.8 °C.) boiling off first and leaving liquid oxygen (bp —182.9 °C.). Both oxygen and nitrogen are prepared commercially in this way. Liquid air may also be used to produce high vacua, to maintain very low temperatures and to dry and purify gases.
   Liquid air is considerably richer in oxygen content than is gaseous air. It is a nonconductor of electricity, supports the combustion of fuels immersed in it, and has a pale blue color. A coil of lead wire immersed in liquid air becomes elastic, due to the low temperature. Liquid oxygen is strongly magnetic. It is used with fuels to propel ROCKETS and rocket bombs.
   Hydrogen (bp -252.7 °C.) and helium (bp -269 °C.) are the gases most difficult to liquefy. The former yields the lightest known liquid, its specific gravity being only 0.07. Many gases are liquefied before being marketed because liquids are easier to handle and occupy less space than gases. Chlorine, ammonia, sulfur dioxide, and carbon dioxide are among the commercial gases sold in liquid form.
   Hydrocarbon gases from oil wells, as well as those produced in the cracking of petroleum, may be liquefied and sold in steel cylinders, for heating and lighting to residents who do not have access to natural or manufactured gas.
   Other liquefied hydrocarbon gases, such as ACETYLENE, are important industrial fuels. The vaporization of some liquefied gases, such as ammonia, sulfur dioxide, METHYL CHLORIDE, and FREON, produces the cooling effect used in many refrigerators.

What is mimicry?

   Mimicry is the resemblance of an animal to another animal or plant or to its surroundings. This resemblance, which often helps to protect the animal, is usually based on a similarity of color or structure.
   Many examples of mimicry may be found among insects. The dead leaf butterfly of India, when resting, has the color and shape of a dead leaf and is therefore not disturbed by its enemies. People are often afraid of the harmless hover fly because it looks like a stinging wasp. The viceroy butterfly is rarely eaten by birds because it resembles the bad-tasting monarch butterfly. The walking stick looks just like a small twig. Spider mites that live among moss look just like part of the moss plant.
   Many other animals also have protective coloring or structure. Young deer and some baby birds blend with their environment. The stripes of the tiger blend with the tall grass. Many nocturnal spiders are black and therefore difficult to see at night. Tree frogs are green. Arctic animals are often white. Protective coloring not only protects these animals from their enemies, but it also makes it possible for them to prey on other animals more easily. For example, the white fur of the polar bear, who has few enemies, enables it to approach its prey, the seal, unseen.
   Animals do not plan a color or shape for themselves. Their protective coloring and structure is the result of selective evolution. Through the ages the animals with the most effective protective coloring and structure have survived the longest and therefore have been able to reproduce more of their kind.
   After many generations of breeding, more and more members of their species were born with the coloring and structure necessary for their survival.

Who was Attila?

In 433 Attila and his brother Bleda became joint rulers of the Huns, wild tribes living in southeastern Europe. Eleven years later Attila had Bleda killed. Then he set out on a march of conquest. After conquering lands to the east and south, he started westward. Attila was so cruel a warrior that he was known as the "scourge of God."
At first his army swept everything before it. But Flavius Aetius, a great Roman general, joined forces with Theodoric, the king of the Visigoths, and met Attila and his army at Chalons. The fighting was so fierce that legends say the dead warriors continued the battle in the sky. About 250 thousand men were killed. In the end Attila was defeated.
In 453 Attila was preparing to march on Italy. But suddenly, just before his troops were ready to set out, he died.
The body of Attila was put in a coffin of gold. The gold coffin was put in a coffin of silver. The silver coffin was put in a coffin of iron. Men were sent to bury Attila. When they came back they were killed. No one must ever know Attila's burial place.

What is counterfeiting?

   Counterfeiting is the crime of making false money in the form of paper currency, coins, or government bonds. It is also a crime to possess or exchange counterfeit money knowingly. The most prevalent type of counterfeiting is that of paper currency. However, most counterfeit bills are recognizably different from genuine bills. Some require careful examination and may be discovered only by trained experts.
   Counterfeiting has existed since money first replaced barter as a means of trade. In early England, counterfeiting consisted of imitating the king's seal or his gold and silver coinage. The act was considered treason and was punishable by death.

What is Collectivism?

   Collectivism is a political and economic system in which the means of production and distribution are owned collectively and are used for the benefit of the community as a whole. Most collectivist societies are based either upon a desire for economic equality or upon religious principles.
   Collectivist societies have existed since ancient times, usually on a small scale. A monastery is an example of a collectivist community. Collectivism on a national scale in modern times is based either upon the socialist theory of the moderate Second International, to which the Socialist parties of western Europe belong, or upon the revolutionary theories of the Third (Communist) International, which incorporated the ideas of Karl Marx.

What is Voice?

   Voice is sound made by the vocal organs of people and some animals. Ideas and feelings can be communicated from one being to another by means of the voice. For example, the voice of a chattering robin warns other birds to stay away from the nest. The voice of a barking dog may indicate that a stranger is near. The voice of a crying baby may indicate hunger or sickness. As human babies grow, they learn to use the voice to speak.
   No two voices are exactly the same, so the sound of the voice identifies the speaker. Males usually have deeper voices than females. They have longer vocal cords. The singing voice expresses a wider range than the speaking voice. Some voices are uninteresting because they do not vary in tone. This evenness of pitch is known as monotone.

What are organic compounds?

   Chemical compounds containing carbon are defined as organic compounds. Most of the organic compounds also contain hydrogen, and a large number contain oxygen. Many contain nitrogen, sulfur, phosphorus, and other elements. The branch of chemistry now known as organic chemistry grew out of earlier studies of substances obtained from living organisms.
   Natural organic compounds are found in plant and animal tissues. Familiar organic substances include sugar, fat, and petroleum.