The circumstances surrounding the story of John Snow and the Broad Street pump are explained on this website supported by the Science Museum. Making the Modern World
Putting 'Snow Broad Street Pump ' into Google will bring up even more information.
' Epidemics are among the most dramatic events that humans experience. In historical times, doctors have struggled to explain why they start and end. These days, we understand that diseases like influenza are caused by small infectious particles called viruses which spread from person to person. But can we say when an epidemic can start and explain why they end ?
Epidemiology is the study of the spread of disease
. This article (which does include some A-Level mathematics) on the Plus website tells you more : The mathematics of diseases
And this article gives more background on Understanding Hypotheses .