WEATHEROUTLOOK/GETTY CHAOS: Snow is forecast for large parts of Britain today Last night the bitter temperatures wreaked havoc on the nation, with snow and ice falling after a Met Office warning. The weather service has since issued a fresh "be aware" warning of snow and ice to cover large parts of the country.
In 1854 John Snow mapped the cholera outbreaks around Soho. His map made apparent how the cholera cases were linked to the local water supply. This is probably one of the first "data" maps created to systematically find a solution to a problem.