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Democratus, a Greek philosopher, first put forward his ideas about the composition of matter. The whole universe was made of tiny, invisible particles, he suggested and called these particles Atoms. To confirm his views, no experimental explanations could be put forward and thus his ideas were debated for hundreds of years.

Each chemical element is made up of identical atoms, a British chemist, John Dalton in 1808 suggested from his experimental work. Dalton also suggested that elements are different because they are each made of different types of atoms. According to him the atom was the smallest part of an element which cannot be cut or divided further. His views came to be known as Dalton's atomic theory but was rejected by later workers.

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Thomas Alva Edison, an American inventor, after two years of ceaseless toil was the first to make practical electric bulb in 1879. His problem was to find a filament that would slow when current is passed through it, without getting burnt. He spent about 40,000 dollars and fruitless experiments. He tried many substances including a hair from the beard of one of his workers. After trying about 6,000 materials, he used a filament of carbonised cotton thread which continuously glowed for 40 hours in a vacuum. A district in the center of New York was lighted with Edison's bulbs, by 1882.

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In 1876, Alexander Graham Bell, a Scottish- born American inventor and teacher invented the telephone. Graham Bell taught deaf people how to speak and gave music lessons. He studied how sounds are emitted by vibrating objects. He invented a form of electric telegraph that sent signals as musical notes made by vibrating needs. This idea led Graham Bell to devise a way of sending and receiving the frequencies present in the human voice. His first telephone message was to his assistant. The instrument has been greatly improvised since the bells time, though the principle of the modern telephone remains the same.

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In 1863, because of the discovery of radio waves by James Maxwell, listening to music, songs, news etc, could be possible. In 1888, Heinrich Hertz could send and receive these radio waves in his laboratory. At about 3,00,000 km per second these radio waves move. For broadcasting, these radio waves can carry sound and picture signals.

In 1894, Sir Oliver Hedge gave the first practical demonstration of radio. To a distance of 55 meters he sent a marse code message. An Italian engineer Guglielmo Marconi at about the same time managed to transmit a message over two kilometers. It was Marconi who invented radio. In 1896 he came to England and established radio as practical and an important means of communication. An experimental radio broadcasts had begun by 1910 and in USA in 1915 an experimental radio station was opened.

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The Scottish television pioneer John Logie Baird demonstrated the first television system in 1926. He rotated a disc with holes in it and transformed light from picture into lines. He effected brightness variations into electric signals with the help of photoelectric cell. In his receiver the signals made a bulb vary in brightness. The viewers saw a faint, fuzzy image through roles in another spinning disc. The system was soon replaced by a higher quality fully electronic system.

In U.K., Germany and USA in 1939 the television broadcast began. In 1950's the Colour Television was experimented and in the last couple of decades became popular. Television owes it's transmission of pictures to radio waves and sound from transmitters and their reception in receiver sets. Nowadays for transmitting signals of sound and pictures in the form of radio waves, satellites are used.

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One of the most important technical inventions of the 20th century is the computer. In 17th century the work on calculating devices began when a french mathematician, Blaise Pascal, built the first mechanical calculating machine. It consisted of a series of cogs connected to dials. It was then that Joseph Jacquard built an automatic loom in 1805 in which the patterns were controlled by the punched cards. These cards are still used in computers. Charles Baggage was the first to attempt make a real computer in 1833. He set out to make what he called an Analytical Engine and this was to be first general programmable computer. But because the engineering of the time was not good enough, it could not be completed.

To make the United States census calculations hundreds of times faster, Herman Hollerith used a punched card system in 1890. It was then during the Second World War in 1946, the US computer ENIAC was built. A German engineer Konrad Zuse, at around the same time built a machine using a similar approach. The same team that built ENIAC, built the UNIVCI in 1951, first mass-produced computer.

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In 1929, an English test pilot, Frank Whittle invented the jet engine. The British Air Ministry initially rejected his idea and so he set up his own company and built and tested the first engine on ground by 1937. An experimental aircraft with a Whittle engine made its first flight in 1941. The latest modern high-speed aircraft are powered by the jet engines.

In the jet engine there are many sets of fans. The first set at the front of the jet engine spin and suck air into the engine. There are more fans inside the engine, which compress the air and force it at high pressure into the combustion chamber. In the combustion chamber, liquid fuel heats the air that expands and rushes towards the tail of the engine. As it streams out, a turbine in the way rotates and drives the fans at the front.

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The invention of paper was first made in China which was one of the greatest discoveries of Han dynasty in China about 105 A.D. Paper was made using fibres from the mulberry tree by the Han people. The idea is said to have come from someone watching wasps building their nests from tiny wood chips. Almost two thousand years ago the principle used is followed even today but with the use of different raw materials. Old Silk, hemp or mulberry bark is what the Chinese used. The papermaking was cheap since these materials were available in plenty.

The raw material was collected and mixed with water. To make a sort of paste, this was trodden and then mixed with potash. This mixture was steamed and pulped over a furnace. In a bath of clear water was this mixture placed and mesh frames were dipped into it. When dried in the sun the mixture covering the frames formed into sheets of paper. Paper was of utmost importance due to the good governess in china and government officials used it to keep records.