The two files cholera_deaths.txt and cholera_pumps.txt relate to the
   London cholera epidemic of 1854.

   cholera_deaths.txt: spatial coordinates (x,y) of the residence of 
                       each cholera victim within an approximately
                       square area of Soho, London

    cholera_pumps.txt: spatial coordinates (x,y) of public water-pumps
                       within the same area