My Science School

 

 

The fist practical thermometer or instrument for measuring temperature was invented shortly before the end of the 16th century by the famous Italian astronomer Galileo. It was an air thermometer giving only a rough indication of the degrees of heat and cold, and later he increased its efficiency by using alcohol instead of air.

       The principle on which most thermometer work is that a liquid or gas used for measuring expands or contracts with changes in temperature more rapidly than the glass containing it. Thus when a coloured liquid is confined in a thin glass tube the difference in expansion, as shown by the level of the liquid against a graduated scale, indicates the temperature.

    About 1714 the German scientists Gabriel Daniel Fahrenheit designed a thermometer which, for the first time, used mercury as the measuring agent. He also introduced the scale named after him in which 320 is the freezing point of water and 2120 the boiling point. Mercury is still used in most thermometers because it has a high boiling point (6740) and a low freezing point (-380).

    An alcohol thermometer, still in use in some countries, was made by Rene de Reaumur, a French naturalist, about 1731. About 11 years later Andres Celsius, a Swedish astronomer, used the centigrade scale for the first time, with freezing point 00 and boiling point at 1000.

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The first powered dentist’s drill was made by George Washington’s dentist, John Greenwood, who adapted his mother’s spinning wheel with its foot treadle to rotate his instrument.

    Earlier dentists had operated their drills by means of bowstrings, a method which must have required skill, determination and physical stamina on the part of the dentist, as well as a great deal of courage from the patient. Later drills were operated by turning a handle at the side.

In 1829 James Nasmyth, the Scottish inventor of the steam hammer, used rotary power to improve the efficiency of the drill. A hand-operated drill with a flexible cable was patented by Charles Merry, an American dentist in 1858; and George Harrington, an Englishman, invented in 1864 a drill driven by a clockwork motor.

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Guglielmo Marconi is usually credited with sending the first radio message. Marconi was born in Bologna, Italy; He came to England in 1896 and obtained a British patent for his wireless telegraphy system. In 1897 he established a radio transmitter on the roof of the post office at St Martin’s-Le-Grand in London, and sent a message a distance of a few hundred yards.

       He continued to improve his apparatus, and in 1898 radio was installed aboard a ship at sea, the East Goodwin lightship off the south-east coast of England. In the following year wireless messages were sent across the English Channel.

    The first radio transmission across the Atlantic was on December 12, 1901 from a station on the cliffs at poldhu, in Cornwall, and the message, three dots representing the letter S in the Morse code, was picked up at St John’s in Newfoundland.

     The existence of radio waves was first demonstrated by Heinrich Hertz, a German professor, in 1887. Marconi based his experiments on Hertz’s research.

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The first aero plane ever to fly was built by a French naval officer, Felix du Temple de la Croix. In 1874 his monoplane, powered with a hot-air engine, took off from the top of a hill near Brest in France. It did not get far, just a short hop, but it was a beginning. A few years later, in 1890, Clement Ader of France flew his own plane, Eole, entirely under its own power for about 50 meters. It was a world record.

     The first truly successful aero plane flight was in 1903. In December of that year Orville Wright flew his chain-driven plane Flyer I at a speed of 8m.p.h and at an altitude of 12 feet for 12 seconds in North Carolina, United States. It was several years before the Wrights’ achievements were fully appreciated in America.

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Felix Wankel, a German motor engineer, invented the rotary piston engine which bears his name. Deprived of a university education when his family’s fortune vanished in the German inflation of 1919-20, he went in for car repairing and set up his own business in 1924 at the age of 22.

        Soon he began work at designing a rotary piston engine, an idea which had attracted engineers since the invention of the stream engine. From 1934 to 1936 his research was backed by B.M.W. and from 1936 to 1945 by the German air force. In 1951 he established his own research institute and financed it by working as a consultant.

Wankel succeeded in discovering the secret of effective seals between the rotating pistons and the casing. He also discovered the geometrical form of an engine that could carry out the four-stroke cycle in one chamber without valves, giving a useful high compression ratio. His engine ran successfully for the first February, 1957. N.S.U. began limited production of Wankel engines for a car is 1963, and went into large-scale production in 1967.

      The rotary piston engine challenges the usual internal combustion engine, using reciprocating pistons, because it offers reduced size, weight, vibration, noise and production costs for comparable thermal efficiency. It is considered suitable for industrial, marine and aeronautical uses.

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Clyde Tombaugh, a young American research student, made the last discovery of a planet while working in 1930 at the Lowell Observatory, Arizona state College. This planet is Pluto, the ninth one in order of distance from the sun, 3,670 million miles away.

    Although Tombaugh, who was 26 at the time, was the first astronomer to see Pluto, its existence had been suspected by Percival Lowell, builder of the observatory at Flagstaff, Arizona. Lowell began searching for the planet in 1905, the year before Tombaugh was born. He observed that there was a difference between the predicted and actual positions of Uranus, and this led him to conclude that there must be another planet. His final calculations about “panel X” were published in 1914, but he had still not found the planet when he died two years later.

    Another American, W.H Pickering, took up the search, concentrating on the irregular movements of the planet Neptune. He saw a clue in the movement of comets, which seem to be attracted by large planets. Here were 16 known comets whose paths took them millions of miles beyond Neptune. Which is 2,800 million miles from the sun, and Pickering was convinced that they were being attracted by a still more distant planet.

   In 1919 yet another hunt was begun by Milton Humason at Mount Wilson Observatory, Pasadena, California. Instead of mathematical calculation, Humason tried photograph. He took two pictures of a series of stretches of the sky, with a gap of one or two days between exposures. In such photographs stars stay still, but planets change position.

    When Tombaugh discovered Pluto, it became clear that Humason had photographed the planet twice. Once it had been masked by a star, and the second time its image had coincided with a flaw in the photographic plate. The main difficulty in the search had been that Pluto was extraordinarily faint. Pickering formed the opinion that it was not Lowell’s planet X, but that a huge planet remains to be discovered.

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The hydrofoil, a boat supported clear of the water by underwater wings called hydrofoils, was invented by an Italian, Forlanini, in 1898. In 1918 a hydrofoil, powered by an aircraft engine, gained the world’s water speed record. The commercial hydrofoils now used in Europe are based on the work of German engineers who carried out research into the design of high-power, lightweight engines.

       In the early 1950s hydrofoils were developed in the United States, Canada and Russia using high-powered gas turbines. They are used for both military and commercial purposes.

     Since water is 775 times heavier than air, very small hydrofoil wings will support relatively heavy boats. But, since operating in water puts great loads on boats, the hulls are usually built of high-strength steel.

    The object in raising the hull of the hydrofoil from the water is to avoid the resistance caused by friction and drag. This means the power needed to drive the boat at high speeds is cut by half. Another result is that the hydrofoil travels smoothly in quite rough water, and is not slowed down.

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The first flight by a jet-propelled aircraft was made in Germany on August 27, 1939. Its engine was designed by Hans-Joachim von Ohain, who had conceived the idea while a student at Gottingen University in Lower Saxony. Unknown to von Ohain, the British inventor and aviator Frank Whittle had thought of the idea some years earlier. But his engine did not have its first flight until May 14, 1941.

    Briefly, a jet engine takes in air from the atmosphere, compresses it, and uses it in burning fuel. The mixture of hot gases is then expelled through a nozzle in a powerful backward jet which propels the aircraft forwards.

     This forward thrust is the effect of a scientific principle first explained by the English scientist Sir Isaac Newton (1642-1727). He pointed out that with every action there is a reaction which is equal but opposite to it. Thus when a gun is fired, the forward movement of the shell is matched by the backward recoil of the barrel. In a similar way the reaction to the jet exhaust drives the engine forward. The thrust is obtained by the pressure of the jet against the inside of the nozzle and not, as many people suppose, by the exhaust gases “pushing” against the atmosphere.

     The jet engine, whether turbojet, turboprop, ramjet or turbofan, weights less than a piston engine of comparative power and can be much more streamlined.

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Alexander Graham Bell (1847-1922) invented and patented in 1876 the first telephone that was of any real practical use. In 1874 he said: “if I could make a current of electricity vary in intensity precisely as the air varies in density during the production of sound, I should be able to transmit speech telegraphically.” This is the principle of the telephone.

      On March 10, 1872, the first historic message was telephoned to Thomas A Watson, Bell’s assistant, who was in another room: “Mr. Watson, come here; I want you.”

     Bell’s first machine gave electrical currents too feeble to be of much use for the general public. In 1877 the American scientist Thomas A. Edison (1847-931) invented the variable-contact carbon transmitter, which greatly increased the power of the signals.

    The telephone was immediately popular in the United States, but Bell found little interest in Britain when he visited the country in 1878. Then Queen Victoria asked for a pair of telephone and the royal interest resulted in a London telephone exchange being formed in 1879 with eight subscribers.

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          A museum is an institution that collects, studies, exhibits and conserves objects for cultural and educational purposes. They are of several kinds. There are museums devoted to art, science, history, industry and technology.

          The word ‘museum’ comes from the Greek word Mouseion which means ‘temple of the Muses’. The Muses were the goddesses of the arts. One of the first institutions, called Mouseion was founded in Alexandria, Egypt in the 3rd century B.C. Its aim was to collect information that might be of some interest to the scholars. The scholars used to live and carry out their research there. The museum displayed a collection of art pieces and antiquities like statues, astronomical and surgical instruments, elephant tusks and hides of rare animals.

          Later kings and nobles started having their own museums by collecting art objects and antiques from different parts of the world. However, these were private museums, meant only for their families and friends.

          After the French Revolution the doors of the French museums were opened to the general public. In 1793, during the revolution, the Republican Government established a national museum in Lauvre, Paris. For the first time in the 19th century buildings were specially designed for this purpose. One of the first buildings in Europe was the Atles Museum in Berlin, Germany. It was constructed in 1830.

          Today, we have museums in almost all the big cities of the world. They are visited by thousands of people everyday. The oldest museum in the world is the Ashmolean Museum in Oxford which was built in 1679. The largest museum in the world is the American Museum of Natural History in New York. It was founded in 1874. The largest and the most visited museum in the United Kingdom is the British Museum which was opened for public in 1759. Bombay, Madras, Delhi and other big cities in India have museums devoted to different subjects. 

          Shorthand is a system of writing fast using characters, abbreviations or symbols for letters, words or phrases. Other names for shorthand are stenography (little or narrow writing), tachygraphy (swift writing) and brachygraphy (short writing). Because of its obvious usefulness, today it is widely used in business, industry and other professions of the world.

          Most historians trace back the origin of shorthand to the Greek historian Xenophon who used an ancient Greek system to write the memoirs of Socrates. Marcus Tullius Tiro of Rome invented the Latin shorthand far back in 63 B.C. He also compiled a dictionary of shorthand. 

          However, the systematic development of shorthand took place in the 17th century. John Willis is considered the father of modern shorthand. Later the industrial developments brought in a demand for stenographers in the business. During the 18th century several shorthand systems were developed but the one developed by the English stenographer Samuel Taylor in 1786 was adapted in French, Spanish, Portuguese, Italian, Swedish, German, Dutch, Hungarian and other languages. Sir Isaac Pitman developed the modern system based on Taylor’s system in 1837. It consisted of 25 single consonants, 24 double consonants and 16 vowel sounds.

          Irish born John Robert Gregg developed another system in 1888 which was based on circles, hooks and loops. In 1893 this system was introduced in U.S.A. In the present century rapid strides have been made in this field.

           Nowadays many machines are also available which can record fast speeches. Stenotype machine was invented by Ward Stone Ireland, a U.S. stenographer and court reporter, around 1906. This machine is used for recording speeches. It is especially employed for conference and court reporting.

           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. 

          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. 

          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.

 

          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.