My Science School

               Leonardo de Vinci (1452-1519) was thought until recently to have been the first to design a parachute. But drawings have now been found that were made five years before da Vinci’s sketches, possibly by an engineer in Siena central Italy.

               However, the first man to make and successfully use a parachute was a Frenchman, Andre Garnerin (1770-1825), who stretched cloth across a bamboo framework and parachuted from a balloon over Paris in 1797. It was an uncomfortable descent as the fabric was too thick o spill out any wind, and the parachute came down swinging violently like a pendulum. Garnerin was is a tiny basket, to which he clung tightly until his rough landing on the plain of Monceau. The parachutes of those days were developed from the crude canvas devices used to descend from hot air balloons.

               Modern parachutes are made of pure silk or good-quality nylon in small panels and have a small pilot parachutes which open first and helps to pull out the main parachute.

            The first boat ever to be moved by steam power was designed by a Frenchman Jacques Perier and tested on the Seine in Paris in 1775. But the first really successful steamboat was built by Perier’s fellow countryman, the Marquis Claude de Jouffroyd’Abbans. His craft which was 141 feet long and equipped with straight-paddled side wheels travelled several hundred yards against the current on the Saone at   Lyons on July 25, 1783.

              Among early American pioneers was James Rumsey who in 1786 drove a boat at four miles an hour on the Potomac River, propelled by a jet of water pumped out at the stern. Between 1786 and 1790 John Fitch experimented in the Delaware River at Philadelphia with different methods of propulsion, including paddle wheels a screw propeller and steam-driven oars.

              The first to apply successfully the principle of steam to screw propellers was John Stevens whose boat, equipped with two propellers was John Stevens whose boat, equipped with two propellers, and crossed the Hudson River in 1804. However, his achievements was soon eclipsed by Robert Fulton’s 150-foot long paddle wheeler Clermont which in 1807 covered the 150 miles from New York to Albany in 30 hours at a maximum speed of five miles an hour. With Fulton in command on the Hudson, Stevens looked elsewhere, and in 1808 his new boat, the Phoenix, sailed out of New York harbor to become the first steamboat ever to go to sea.

              Both Stevens and Fulton were following in the steps of the Scottish inventor William Symington who in 1802 constructed a steamboat in Scotland, the Charlotte Dundas, which was used as a tug on the forth and Clyde Canal. The Charlotte Dundas was a paddle-wheel steamer used this method of propulsion.

          The earliest wheels so far discovered were found in graves at Kish and Susa, two ancient Mesopotamian cities. These wheels are believed to date from 3,500 B.C. they were made from three planks, clamped together with copper clasps. This kind of wheel also existed in ancient times in Europe and the Near East. No one is sure where the wheel was invented, but this archaeological evidence suggests it was probably In ancient Mesopotamia

            A wheel with proper spokes was not invented until after 2,000 B.C. there are records of this wheel in northern Mesopotamia, central Turkey, and north-east Persia. By the 15th century B.C., spoked wheels were being used on chariots in Syria, Egypt, and the western Mediterranean.

           The solid wheel was used mostly in farming. Tripartite wheels- wheels with three spokes- were being used in the Bronze age in Denmark, Germany and Northern Italy for carts.

          The invention of the wheel made it possible for people to transport heavy objects much more easily. It also enabled them to travel farther and trade with each other more easily, and so find out about other countries and customs.

Picture credit: google

               The first ride able bicycle was made by Kirkpatrick Mac Milan of Dum-friesshire, Scotland, in 1839, although an attempt to construct one had been made by Jean Theson at Fontainebleau, France, in 1645.

               Before this, crude machines had been made, which had no farm o f steering and had to be propelled by publishing the feet against the ground. Machines of this type appear on bas-reliefs in Babylon and Egypt and on frescoes in Pompeii. In England, a stained glass window, dated 1580, in the church of Stoke Poges, Bucking hamshire shows a cherub astride such a machine.

               But all these machines seem to have been four-wheeled. The true bicycle belongs to the 19th Century.

               Macmillan’s bicycle was driven by rods attached from pedals to a sprocket on the rear wheel. The first chain-driven bicycle was produced by Tribout and Meyer in 1869. In this year the first bicycle show-in Paris and the first bicycle road race –from Paris to Rouentook place.

              An Englishman, James Starley, of Coventry in Warwickshire, is known as “the father of the cycle industry”. In 1871 he introduced a bicycle with a large driving wheel and a smaller trailing wheel. This was the “ordinary” bicycle, known to everyone as the penny-farthing. In 1874 a chain-driven bicycle with two wheels of equal diameter was designed by H.J. Lawson. This is known as the safety bicycle and became enormously popular from about 1885 when the Rover safety bicycle was built by John K. Starley, James’s nephew.

             The pneumatic tyre - in other words, a tyre filled with air-was invented in 1888 by John Boyd Dunlop, a veterinary surgeon of Belfast, Northern Ireland. By 1893 the design of the bicycle had been developed into the modern diamond frame with roller-chain drive and pneumatic-tyred wheels.

The first contact lenses were made by A.E. Fick in 1887, but were not successful. During the early part of this century opticians tried to produce extremely thin shell-like lenses to fit closely over the eye. An impression was taken of the eye and a glass shell made which, with a suitable fluid under it, covered most of the eye. After 1938, plastic was used instead of glass, and in about 1950, smaller lenses were introduced which covered only the cornea and floated on a layer of tears. These lenses, only 7 to 11 mm in diameter and 0.1 to 1mm thick can usually be worn all day without being removed.

    Besides being invisible, contact lenses provide a much wider field of vision than spectacles. They are more practical for use in active sports because they are not easily lost or broken, and they can be tinted for use as sunglasses. But contact lenses are not effective in all cases of eye trouble. They are also expensive, and some people find difficulty in learning to wear them.

    As research continues, even smaller and more flexible lenses are being developed.

Picture credit: google

 

 

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google

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.

Picture credit: google