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Unit 1 Great scientists Reading JOHN SNOW DEFEATS “KING CHOLERA” John Snow was a well-known doctor in London-so famous,indeed,that he attended Queen Victoria to ease the birth of her babies.But he became inspired when he thought about helping ordinary people exposed to cholera.This was the most deadly disease of its day.Neither its cause,nor its cure was understood.So many thousands of terrified people died every time there was an outbreak.John Snow wanted to use his knowledge to help solve this problem.He knew it would hever be controlled until its cause was found. He got interested in two theories explaining how cholera killed people.The first suggested that cholera multiplied in the air without reason.A cloud of dangerous gas would float around until it found its victims.The second suggested that people absorbed this disease into their bodies with their meals.From the stomach the disease attacked the body quickly and soon the affected person was dead. He believed in the second theory but needed to prove he was correct.So when another outbreak hit London in 1854,John Snow was ready to test these two theories.As the disease spread quickly through the poor neighbourhoods,John Snow began to gather the information.He found that in two particular streets,the cholera outbreak was so severe that more than 500 people had died in 10 days.He determined to find out why.He marked on a map where all the dead people had lived.Here it is:The map gave a valuable clue about the cause of the disease.Many of the deaths were near the water pump in Broad Street(especially numbers 16,37,38 and 40 Broad Street).John Snow also saw that some houses(such as 20 and 21 Broad Street and 8 and 9 Cambridge Street)had had no deaths.He discovered that these families worked in the pub at 7 Cambridge Street.They were given free beer and so had not drunk the water from the Broad Street pump.It seemed the water was to blame. Next,John Snow looked into the source of the water for these two streets.H