March 15th 2013 was the 200th anniversary of Dr. Snow’s birth, the doctor who used visual mapping and discovered the causes of cholera!
As noted by the TED blog, the London School of Hygiene & Tropical Medicine is celebrating the anniversary with a series of events.
What is so special about this map? Visualization expert Prof. Edward Tufte potrays the story and map of Dr. Snow discovery: in 1854 a cholera outbreak was devastating London and causing large number of deaths. He draw a map of the area and plotted the number of deaths with black lines.Do you see any trend?
After mapping the water pumps location, it is quite asy to see that the deaths are concentrated around the Broad Street water pump. And Dr. Snow discovered, through the help of this map, that Cholera is not a viral disease as previosly thought, but is transmitted primarely by contamiated drinking water. The map helped to convince the authories about his theory and thus the handle of the waterpump was removed. The cholera epidemic soon ended.
If you visit London, you can still see the incriminated water pump, which is closed since then, and visit the nearby “John Snow saloon”.