'Map Showing Deaths from Cholera in Broad Street, Golden Square and the Neighbourhood from 19th August – 30th September', from Cholera Inquiry Committee. Report on the Cholera Outbreak in the Parish of St James, Westminster during the Autumn of 1854, London. J Churchill, 1855. Wellcome Library, London.
Snow prepared this version of the Broad Street map for a report to go before the Board of Health. The map shows his original and innovative contribution to the field of disease mapping. The subtle inclusion of a dotted black 'Voronoi' line indicating the equidistant walking points between pumps helped to demonstrate Snow's theory that the Broad Street pump was the origin of the epidemic.