JAMES WATT (1736-1819)

James Watt didn't invent the steam engine. The first steam engine was patented in 1698, the year James Watt's father was born. James Watt improved steam engine's efficiency enormously, making them the versatile workhorse of the Industrial Revolution. In 1764 he was given a model Newcomen engine to repair. The major problem with the Newcomen engine was that three quaters of the steam was wasted in heating the cold cylinder up to 100 degrees before the steam stopped condensing and started generating power. One Sunday afternoon in May 1765 Watt went for a walk on Glasgow Green and suddenly he knew it: the engine needed a separate condenser. Watt was backed with Dr Roebuck, who wanted engine to pump the water out of his coal mines. But this financial backing was interrupted. Afterwards Watt worked with Matthew Boulton (a Birmingham-bases tycoon) and in 1775 the engine worked properly. Boulton & Watt become the most important engineering firm in the country. Watt continued his work, eventually inventing the parallel motion.


ALEXANDER GRAHAM BELL (1847-1922)

Bell was born into a family specialising in elocution. He himself was also teaching people how to speak. In 1863, at the age of 16, he and his brother Melville began researching the machanics of speech. They killed the family cat in order to study the vocal chords in more detail. Bell studied sound and he thought about transmitting speech with electricity. His idea was to make a device that could mimic the human voice and reproduce vowels and consonants. His father has developed a shorthand system called Visible Speech, in which every sound was presented by a symbol. In 1870 a family moved to Canada. Bell was lecturing and demonstrating the Visible Speech system in Boston. He opened his own school to train teachers for the deaf. In 1873 he become a professor of vocal physiology at Boston University. In 1875 he came up with a simple receiver that could turn electricity into sound. In the same year he was garanted the patent for his multiple telegraph. Important accident occured while testing a circuit with one transmitter and two receivers. The transmitter was switched off and Watson was adjusting one of the receivers when Bell heard a note coming from the receiver. He had discovered that the receiver could also work in reverse: instead of making sound when electricity was sent through it, it also made electricity when supplied with sound. The electricity varied with voice. Bell developed his system and submitted his patent on 14th February 1876, just two hours before Elisha Gray, his main rival. The first telephone exchange was built in Connecticut in 1893.
In the Volta Laboratory, in association with Charlec Sumner Tainer, he invented the Graphophone.
In 1885 he acquired land on Cape Breton Island in Nova Scotia. Here he continued his work with deaf people. He made own aircraft wih wings based on triangles, he built forerunner to the iron lung and he experimented with sheep.



JOHN LOGIE BAIRD (1888-1946)

He ripped up a telephone exchange to conect his bedroom to those of his friends across the street. His studies at Glasgow University were interrupted in their final year by the outbreak of war in 1914. At the end of the war he set himself up in business, with mixed results. He successfully sold medicated socks, but his jam factoty and soap projects failed. In 1922 he applied himself to creating a television. His firts apparatus sat on a washstand. He also used a tea chest, a biscuit tin, an old cupboard, scrap-wood, string and sealing wax. On 26th January 1926 he gave the world's first demonstration of true television. In 1927 his television was demonstrated of telephone line between London and Glasgow. One year later his company achieved the firts transatlantis television transmission between London and New York. He also gave the first demonstration of both colour and stereoscopic television. But Baird's mechanical system was rapidly becoming obsolete as electronic systems were developed, chiefly by Marconi in America.
Although Baird is chiefly remembered for mechanical television, in 1930 he demonstrated big-screen television in London and he televised the first live transmission in 1931 and the following year he demonstrated ultra-short wave transmission.


ALEXANDER FLEMING (1881-1955)

Alexander Fleming was a farmer's son from Ayrshire in Scotland. He moved to London at 13 and later trained as a doctor. In 1928 Fleming was research assistent to Sir Almroth Wright working on bacteria. He accidentaly discovered a mould on a set of culture dishes, which were being used to grow the staphylococci germ. Fleming noticed that where there was a mould the germs had stopped developing. The mould was penicillin. Fleming tested the penicillin on animals, with no ill effects, and he also used it to cure colleague's eye infection. Fleming has discovered the first antibiotic. But it was the scientists Howard Florey and Ernst Chain, who developed penicillin further. Chiefly after their research penicillin could be produced as a drug. At first supplies of penicillin were very limited, but by World War II. it was being mass-produced by the American drugs industry and given to all soldiers before active service.

Maturita.cz - referát (verze pro snadný tisk)
http://www.maturita.cz/referaty/referat.asp?id=2113