Unit1JohnSnowwasawell-knowndoctorinLondon-sofamous,indeed,thatheattendedQueenVictoriatoeasethebirthofherbabies.Buthebecameinspiredwhenhethoughtabouthelpingordinarypeopleexposedtocholera.Thiswasthemostdeadlydiseaseofitsday.Neitheritscause,noritscurewasunderstood.Somanythousandsofterrifiedpeoplediedeverytimetherewasanoutbreak.JohnSnowwantedtousehisknowledgetohelpsolvethisproblem.Heknewitwouldneverbecontrolleduntilitscausewasfound.Hegotinterestedintwotheoriesexplaininghowcholerakilledpeople.Thefirstsuggestedthatcholeramultipliedintheairwithoutreason.Acloudofdangerousgaswouldfloatarounduntilitfounditsvictims.Thesecondsuggestedthatpeopleabsorbedthisdiseaseintotheirbodieswiththeirmeals.Fromthestomachthediseaseattackedthebodyquicklyandsoontheaffectedpersonwasdead.Hebelievedinthesecondtheorybutneededtoprovehewascorrect.SowhenanotheroutbreakhitLondonin1854,JohnSnowwasreadytotestthesetwotheories.Asthediseasespreadquicklythroughthepoorneighbourhoods,JohnSnowbegantogathertheinformation.Hefoundthatintwoparticularstreets,thecholeraoutbreakwassoseverethatmorethan500peoplehaddiedin10days.Hedeterminedtofindoutwhy.Hemarkedonamapwhereallthedeadpeoplehadlived.Hereitis:Themapgaveavaluableclueaboutthecauseofthedisease.ManyofthedeathswerenearthewaterpumpinBroadStreet(especiallynumbers16,37,38and40BroadStreet.)JohnSnowalsosawthatsomehouses(suchas20and21BroadStreetand8and9CambridgeStreet)hadhadnodeaths.Hediscoveredthatthesefamiliesworkedinthepubat7CambridgeStreet.TheyweregivenfreebeerandsohadnotdrunkthewaterfromtheBroadStreetpump.Itseemedthewaterwastoblame.Next,JohnSnowlookedintothesourceofthewaterforthesetwostreets.Hefoundthatitcamefromtheriver,whichhadbeenpollutedbythedirtywaterfromLondon.ImmediatelyJohnSnowtoldtheastonishedpeopleinBroadStreettoremovethehandlefromthewaterpumpsoitcouldnotbeused.Soonthediseasebegantoslowdown.JohnSnowhadshownthatcholerawasspreadbygermsandnotinacloudofgas.Inaddition,hefoundtwootherdeathsinanotherpartofLondonthatwerelinkedtotheBroadStreetoutbreak.Awoman,who...
