Category Science

When was the stethoscope invented?

           A stethoscope is a device used by physicians to listen to the sounds inside the body. Generally, these sounds originate from the heart, lungs, abdomen and the blood vessels. Very often valuable information about the disorders in certain parts of the body can be obtained through observing the change in sounds. For instance, a change in the sounds made by the rushing of blood through the heart valves or by the closing of valves may give important clues to different heart diseases. Similarly, an abnormality in the sounds made by air in the windpipe and airways in the lungs may indicate certain lung disorders.

           Stethoscope was invented by a French doctor, Rene T.H. Laennec, in 1815. It was a one-foot-long hollow wooden cylinder. He put one end of the cylinder on to his patient’s chest and listened to the sounds produced by the heart and the chest through the other end. As he compared such sounds from different patients, he could reach certain conclusions. In 1819, he published these conclusions in the form of a book entitled, De L’ Auscultation Mediate, and soon stethoscope came into general use.

            Since those days, many modifications have been made in its design. A modern stethoscope basically consists of a contact piece called the chest piece. This can be a flat chest piece for high-pitched sounds or a bell-shaped open-ended chest piece for low-pitched sounds. It conducts sounds through two flexible rubber or plastic tubes to a pair of ear pieces which fit into the physician’s ears and excludes other sounds. The chest piece is put in contact with the different parts of the chest and the back. Now, through these sounds the physician gets valuable clues regarding the different diseases the patient might be suffering from. The stethoscope is still the simplest and the most useful means available to doctors to examine the lungs and heart. 

How did the circus begin?

          The Romans were the first to use the word ‘circus’ in the first century B.C. The large open area was called ‘The Circus Maximus’. Here the main attraction was a chariot race. The drivers wore helmets and were wrapped in lengths of bright coloured flowing clothes. The ground was so large as to accommodate around 1, 50,000 people. In those days Rome had other kinds of entertainments also. Jugglers, acrobats, rope-walkers and animal-trainers also entertained people in many ways.

          Eventually all those feats became part of what we call ‘circus’ today.

          After the fall of the Roman Empire, circus went into oblivion for many centuries. The first modern circus came into being in England in 1768, when Philip Astley turned into a trick rider, and he traced the first ring. The name circus was first used in 1782 when the Royal Circus was set up by Charles Hughes. Many showmen found a new outlet in the circus, as did the rope dancers, acrobats, jugglers and others, where it could be seen clearly that nothing was faked. Hence they got much popularity. In the first half of the 19th century many circus sprang up even in the United States.

          Circus is a popular means of entertainment today. It is universally loved by the young and the old. In the modern circus we see many amazing feats like rope-walking, wire-cycling, fire-eating, weightlifting, trapeze and innumerable animal and bird games. Jugglers, acrobats and clowns join in to add to the entertainment.

          The world’s largest permanent circus is Circus Las Vegas, Nevada, U.S.A. This was opened on 18 October, 1968. It covers an area of 11,984 sq. mts. The largest travelling circus is the Gold Unit of Ringling Bros. and Barnum & Bailey Circus. It was used for a show at Sapporo, Japan on 1 July 1988. The largest circus crowd comprised of 52,385 people who attended the performance of “The Greatest Show on Earth” in New Orleans, USA on 14 September, 1975. 

 

Who discovered Australia?

          Australia is the smallest continent but the largest island (piece of land covered with water from all sides) of the world. Its total area is about 8,000,000 sq. km (3,000,000 sq. miles). People during the medieval times talked about the existence of a large continent in the Southern Hemisphere. No one had seen it and people wondered what it was like and whether it was inhabited at all. It was called the ‘unknown southern land’.

          During the 16th century, European countries had been seeking new lands in order to expand their commercial activities. In 1606 the Dutch were the first to visit Australia. Their ship called the ‘Dnyffkin’ anchored off the Northern coast of Australia. When some of its crew went ashore to refill their water casks, they were driven out by the fierce natives. The Dnyffkin sailed away without exploring any other part of the vast continent.

          In 1642 Captain Abel Tasman was sent by the Dutch to explore more about the continent. He sighted the west coast, which he called Van Diemen’s Land (Tasmania). Later he explored New Zealand. In 1770 the English Captain James Cook discovered the South Eastern coast of Australia and named it New South Wales. In 1788 the first English colony was established in the city of Sydney.

          Who, then, were the first inhabitants of Australia?

          Before the arrival of Europeans in the late 18th century the country was first inhabited by the Aborigines who reached Australia from Southern Asia about 20,000 years ago. In 1870 there were about 300,000 Aborigines in Australia. They arrived in two groups; the first group was eventually driven from the south-east into Tasmania; the second was racially quite different which occupied the rest of Australia.

          Today, Australia is among the highly developed countries of the world. Its inhabitants are self-sufficient in almost every respect. It has many distinctive features. Two-third of its land is a desert. It is, however, rich in minerals like gold, tungsten, manganese, cobalt, lead and zinc. Its unique wild life includes animals like kangaroo, koala and birds like emu, black swan. The plants like giant eucalyptus and bottle tree are found here in abundance.

 

Who invented the shoes?

          The primitive man who lived in caves had to make his way through rocks. To protect his feet he probably covered them with bags of grass, strips of animal hide or even flat pieces of wood. These were fastened to the soles of the feet by crude thongs (crude straps) bound around the ankles. These were the first shoes.

          Among the civilized people, Egyptians were the first to make shoes. They used pads of leather or papyrus (a tree with thick stem) which were bound to the feet with two straps. In order to protect the toes, its front was sometimes turned up. Samples of shoes, made around 2000 B.C. have been found in Egypt.

          In some cold countries, people developed a different kind of shoes. They were bags padded with grass and tied around the feet. 

         As far as the modern shoes are concerned, their origin can be traced back to the crusades. Crusades were the military expeditions by the European Christian countries to recover the Holy land from the Muslims in the Middle Ages. These crusaders went on long-drawn wars and had been on their feet. So it became necessary to make shoes that would last long. Gradually, fine leather shoes of attractive designs began to appear in Italy, France and England.

           The designs of shoes have always been subject to changes according to the fashion. For example, in the 16th century people preferred shoes with broad toes. In the 17th century high heels came into fashion. Kings and nobles also ordered some special changes in the designs of their shoes.

           With the development of modern techniques, many varieties of shoes are now being made. Besides leather, rubber, plastic and canvas are also being used in shoes. Plastic-covered shoes which do not need any polishing have come into fashion. Rexin-top sports shoes have become the most popular throughout the world. Today there is a wide range of shoes to choose from according to one’s needs and taste. 

How do fish breathe inside water?

               We see many kinds of fishes in ponds, lakes, rivers and seas. They cannot survive outside water. Whenever somebody gets drowned in water he quickly dies of asphyxia caused by obstructed breathing. On the contrary, the fish survives only in water and dies when taken out of it. Now the question arises: how does it breathe inside water? 

               Except the lungfish, all other fishes breathe by means of their gills. They do not have lungs like human beings nor do they breathe through their noses. They have peculiar process of respiration. They take some water in their mouths for the purpose of respiration. This water flows over the gills and comes out through the openings behind the cover of gills. The oxygen in water is absorbed by the cells of the gills. Since the surface area of the gills is quite large, the amount of oxygen absorbed is also considerable. The oxygen gets mixed in the blood and is circulated throughout the whole body. That is how it purifies the blood. Carbon dioxide produced in its body is brought by the circulating blood to the gills where it gets dissolved in water and passes out. In this way, the cycle of respiration in the fishes continues.

               If the water is dirty, the fishes sometimes come up to the surface of water and take air in for breathing. However they do not use gills for this purpose. The fish is a cold-blooded creature. It is also sensitive to touch, taste, smell etc. It has different organs for these functions. Scientists have already studied more than 20,000 species of fishes.

How are bats different from birds?

           According to the available fossil records, bats are in existence on the earth for more than 60 million years. They are found everywhere in the world except the poles. There are different varieties of bats. Scientists have so far studied more than 2,000 kinds of bats. It is a peculiar creature which flies and yet not regarded as a bird. But why is it so?

          Bats come under the category of mammals. Mammals are those animals whose females give birth to the young and suckle them. Secondly, unlike birds they don’t have feathers on their bodies but have hair. Bat is the only mammal which has wings for flying and the wings measure from 15 cms to 2 mts when spread.

          Most of the bats live on insects and worms. In tropical areas they live on fruits and flowers only. There are some other kind of bats which feed on the blood of other animals and birds – they are called the vampire bats. Due to this characteristic of some bats, people fear bats in general. The teeth of vampire bats are as sharp as needles and they even attack human beings and suck their blood.

          Bat has another peculiarity – while resting it hangs itself upside down with its head facing downward and its legs holding tightly the branch of the tree. The formation of its limb is such that it cannot stand erect. Another feature of bat is that it can fly at night as they produce high-pitched sounds which bounce off nearby objects and this ‘echo’ is picked up by the bat’s large ears which conveys the presence of obstacles.

          The largest bat is the Flying fox with a body length of over 40 cm. Bats have, normally, a lifespan of 20 years.