ILLUSTRATIONS

Dr. John Snow, 1813–1858. A photograph in the series Literary and Scientific Portrait Club. (Bowerbank J. S. Literary and Scientific Portrait Club. London: Heinz Archive and Library of the National Portrait Gallery.)

Portrait of Sir Edwin Chadwick. (Photograph by J. Delmege. Courtesy of the Wellcome Library, London.)

Robert Koch, 1843–1910, bacteriologist, working in his laboratory at Kimberley, South Africa, 1921. (Photograph by William Osler.)

Vibrio cholerae. (Photograph from Arbeiten aus dem Kaiserlichen Gesundheitsamte, Volume III, 1887. Julius Springer Verlag, Berlin.)

Cryptosporidium. (Photograph courtesy of Dr. Saul Tzipori, Tufts University School of Veterinary Medicine.)

Carrollton Water Treatment Plant. (Photograph by Dr. Robert D. Morris, 2005.)

Collecting water in Mali. (Photograph by João Silva.)