Circumstantial Evidence? …English politician and justice of the peace Sir Edmund Berry Godfrey was found murdered on October 17, 1678. His body had been left in a ditch on Greenberry Hill in London. Three men were arrested and tried for the crime. Their names were Robert Green, Henry Berry, and Lawrence Hill.

At that time opinion in the medical profession was divided as to the cause of cholera. Most doctors favored the theory that it was spread by foul air in the overcrowded quarters of the poor. Others suggested that height above sea level was significant: the higher the altitude, the purer the air. One authority solemnly concluded that people with dark hair were more vulnerable than blonds or redheads. But the grim fact was that no one knew how to prevent or cure the disease.

Snow’s reasoning was simple enough. Cholera, he pointed out, first manifests itself as a stomach disorder; therefore, it was reasonable to conclude that what he called the cholera “poison” had to be swallowed. The major symptoms were vomiting and diarrhea, followed by spasms and cramps in the limbs. People tended not to wash before eating, and anyone in contact with a victim could easily take in leaking privies and overflowing cesspools such as Soho, there was every chance the disease passed directly into the local supply of drinking water.