deaths: locations of 578 deaths
 pumps: locations of 13 water-pumps

These data consist of the locations of 578 
deaths from cholera, and the position of 13 water pumps (wells). Each
coordinate point in the file "cholera.deaths" specifies the address 
of a person who died from cholera. When many points are associated 
with a single street address, they are "stacked" in a line away 
from the street so that they are more easily visualized. This is 
how they are displayed on John Snow's original map. The dates of 
the deaths are not recorded.

The significance of the map is that, by closing the Broad Street 
pump by removing its handle, Dr. Snow supposedly stopped the epidemic, 
and demonstrated that cholera is a water-borne disease. This was not 
previously understood. The map is the most famous and classical 
example in the field of medical cartography. 

For more details, an informative source is:
A. Cliff & P. Haggett, 1988, Atlas of Disease Distributions, Blackwell,
Oxford, ISBN 0-631-13149-3

Adapted from:
Waldo Tobler
National Center for Geographic Information and Analysis
Geography Department
University of California
Santa Barbara CA 93106-4060

tobler@geog.ucsb.edu
1/10/94

Data and  text were downloaded from:
   http://ncgia.ucsb.edu/Publications/Software/cholera/