Tuesday, 19 March 2013
Saturday, 16 March 2013
When were the world fairs started?
We do not have definite information about the beginning of the fairs. But in ancient times when there were no means of communication and man had to go long distances in search of articles of daily needs, the traders used to assemble on a fixed day at a fixed place to sell articles of daily use. People used to purchase articles of their needs in exchange for animal hides or grains.
With the advancement in the modes of communication, the commercial importance of the fairs decreased, and they came to be organised for entertainment and on cultural occasions. With the growth of civilization and industrial progress, fairs became the means of demonstrating the progress and achievements of any country. In the 19th century, fairs became symbols of international co-operation and friendship. They began to be called world fairs.
The first world fair was set up in 1851 in the Hyde Park of London. For this purpose a building named 'Crystal Palace' was constructed. The building was made of iron and glass. this fair went on for 141 days and 6 million 39 thousand and 195 people saw it. It was destroyed in a fire in 1936. The first international fair of America was organised in New York in 1853. Twenty-three countries participated in it and five thousand people set up their stalls. But this did not become very successful. After this, America organised a big fair in 1876 on the occasion of the centenary celebrations of American Independence at Pensylvania. America exhibited in this fair articles developed by it. In this very fair Graham Bell demostrated for the first time the telephone developed by him. After this, the world's biggest fair spot was constructed in New York in 1939-40. This was constructed on a piece of land measuring 1216.5 acres. In 1964-65 a world fair was organised at this place, which was visited by 51 million, 6 lakhs, 7 thousand and 37 people. Around 60 million people saw the Expo.' 70 fair organised at Osaka. This fair went on form March 1970 to September 1970. In India the first world fair, Asia-72, was organised at Pragati Maidan in Delhi in 1972 and was visited by millions of people. Now-a-days international book fairs are also held every year.
With the advancement in the modes of communication, the commercial importance of the fairs decreased, and they came to be organised for entertainment and on cultural occasions. With the growth of civilization and industrial progress, fairs became the means of demonstrating the progress and achievements of any country. In the 19th century, fairs became symbols of international co-operation and friendship. They began to be called world fairs.
The first world fair was set up in 1851 in the Hyde Park of London. For this purpose a building named 'Crystal Palace' was constructed. The building was made of iron and glass. this fair went on for 141 days and 6 million 39 thousand and 195 people saw it. It was destroyed in a fire in 1936. The first international fair of America was organised in New York in 1853. Twenty-three countries participated in it and five thousand people set up their stalls. But this did not become very successful. After this, America organised a big fair in 1876 on the occasion of the centenary celebrations of American Independence at Pensylvania. America exhibited in this fair articles developed by it. In this very fair Graham Bell demostrated for the first time the telephone developed by him. After this, the world's biggest fair spot was constructed in New York in 1939-40. This was constructed on a piece of land measuring 1216.5 acres. In 1964-65 a world fair was organised at this place, which was visited by 51 million, 6 lakhs, 7 thousand and 37 people. Around 60 million people saw the Expo.' 70 fair organised at Osaka. This fair went on form March 1970 to September 1970. In India the first world fair, Asia-72, was organised at Pragati Maidan in Delhi in 1972 and was visited by millions of people. Now-a-days international book fairs are also held every year.
Do giants live on earth?
In many parts of Europe and Asia, there are legends of the existence of giants in ancient times. We also read many stories in magazines and newspapers about demons and giants. After reading these stories, one feels that giants exist in some parts of the world. Since many races of pygmies are found on earth,
it is logical to think that there may be races of giants on the earth as well. In fact, giants have existed in myths and story books only. There is no scientific evidence that such people ever actually existed.
Enough variations are noticed in the heights of human beings of the world. Most of the people are of normal heights but the people of some races, such as Eskimos, Lapps and certain Indian tribes in South America, are dwarfs. Some of the native tribes of eastern Africa, have an average height of 2 metres. But they cannot be treated as demons or giants.
In fact, we all know of giants who appear in circuses and side shows. How did they get to be so tall? They are usually the persons suffering from abnormalities. Thy become abnormally tall due to the excess formation of hormones by pituitary gland. The pituitary gland regulates growth. Sometimes, it developes a tumor which makes the gland larger. This larger gland then begins to produce large quantity of hormones. One of these hormones is the growth hormone, which has an effect on the size of the organs and the skeleton of the body.
When excess of this hormone is produced body keeps on growing. In such a case, the height of the individual may go up to 2 1/2 metres. This condition is known as giantism.
it is logical to think that there may be races of giants on the earth as well. In fact, giants have existed in myths and story books only. There is no scientific evidence that such people ever actually existed.
Enough variations are noticed in the heights of human beings of the world. Most of the people are of normal heights but the people of some races, such as Eskimos, Lapps and certain Indian tribes in South America, are dwarfs. Some of the native tribes of eastern Africa, have an average height of 2 metres. But they cannot be treated as demons or giants.
In fact, we all know of giants who appear in circuses and side shows. How did they get to be so tall? They are usually the persons suffering from abnormalities. Thy become abnormally tall due to the excess formation of hormones by pituitary gland. The pituitary gland regulates growth. Sometimes, it developes a tumor which makes the gland larger. This larger gland then begins to produce large quantity of hormones. One of these hormones is the growth hormone, which has an effect on the size of the organs and the skeleton of the body.
When excess of this hormone is produced body keeps on growing. In such a case, the height of the individual may go up to 2 1/2 metres. This condition is known as giantism.
What causes an echo?
When we speak loudly in a big empty hall or in a temple, we hear our own sound repeatedly. This is called echo. An echo can also be heard by shouting near a deep ditch or a well. The thunder of clouds, is another example of echo.
We know that sound travels from one place to another in the form of waves. The velocity of sound in the air is (340 metres 1100 ft) per second. When we speak, the sound waves emanating from our mouth spread out in all the directions. When these waves meet a wall or some other obstacle in their way, they are reflected back. These reflected waves are heard by us as an echo. Hence echo is produced when sound waves are reflected by some obstacle.
To hear an echo, it is essential that the obstacle reflecting the sonund waves must be situated at least 17 metres or 55 feet from us. This is because, the effect of sound persists on our ears for one-tenth of a second. If some sound signal has reached the ears and within one tenth of a second another sound signal reaches our ears, it will not be distinguished because during this period the effect of the earlier sound is persisting in the ear. Sound travels about 34 metres or 110 ft in one-tenth of a second. As such, if the object reflecting the sound waves is situated 17 metres away from the speaker, the time taken for the sound to travel this distance, from the speaker's mouth to the object and back to him would be one-tenth of a second and the reflected sound can be distinguished by our ear as an echo.
All objects do not reflect sound. There are some materials like wood, jute, cardboard etc. which absorb sound.
Today we find that in modern buildings the architects use methods and materials which reduce echoes and favour good sound transmission. Auditoriums are now built with rounded corners and few large flat surfaces. This prevents sound waves from being reflected to any one position. They are scattered in many directions and the only sounds heard are those sent out from the source. Some fibre boards having many holes are used for making rooms sound proof. By the use of these materials the sound waves are either absorbed or scattered so the production of echo is reduced.
We know that sound travels from one place to another in the form of waves. The velocity of sound in the air is (340 metres 1100 ft) per second. When we speak, the sound waves emanating from our mouth spread out in all the directions. When these waves meet a wall or some other obstacle in their way, they are reflected back. These reflected waves are heard by us as an echo. Hence echo is produced when sound waves are reflected by some obstacle.
To hear an echo, it is essential that the obstacle reflecting the sonund waves must be situated at least 17 metres or 55 feet from us. This is because, the effect of sound persists on our ears for one-tenth of a second. If some sound signal has reached the ears and within one tenth of a second another sound signal reaches our ears, it will not be distinguished because during this period the effect of the earlier sound is persisting in the ear. Sound travels about 34 metres or 110 ft in one-tenth of a second. As such, if the object reflecting the sound waves is situated 17 metres away from the speaker, the time taken for the sound to travel this distance, from the speaker's mouth to the object and back to him would be one-tenth of a second and the reflected sound can be distinguished by our ear as an echo.
All objects do not reflect sound. There are some materials like wood, jute, cardboard etc. which absorb sound.
Today we find that in modern buildings the architects use methods and materials which reduce echoes and favour good sound transmission. Auditoriums are now built with rounded corners and few large flat surfaces. This prevents sound waves from being reflected to any one position. They are scattered in many directions and the only sounds heard are those sent out from the source. Some fibre boards having many holes are used for making rooms sound proof. By the use of these materials the sound waves are either absorbed or scattered so the production of echo is reduced.
