Charts recording the temperature and mortality rates in London, UK, for every week of the 11 years between 1840 and 1850. The outer area of the chart shows mortality. Black areas are when weekly deaths exceeded the average and yellow areas are when weekly deaths were below the average. The inner area shows temperature. Red areas are when weekly mean temperatures exceeded the mean temperature for the years 1771-1849 and black areas are when they were lower than this. This chart was printed in the 'Report on the mortality of cholera in England, 1848-49' by the British epidemiologist William Farr (1807-1883).