Dr John Snow
A Model of Disease Transmission
I gave a "farewell address" to the last meeting of the directed study
class in Computational Science at Virginia Tech, 05 May 2009.
The talk was titled
Dr John Snow - A Model of Disease Transmission
and the emphasis was on the invention and defense of a model of
A PDF version is available as
The John Snow web site
maintained by the UCLA School of Public Health at
The Strange Case of the Broad Street Pump,
University of California, 2007,
The Ghost Map,
Peter Vinten-Johansen, Howard Brody, Nigel Paneth,
Stephen Rachman, Michael Rip,
Cholera, Chloroform, and the Science of Medicine:
A Life of John Snow,
Oxford University Press, 2003,
TeX "Source Code"
The LaTeX file used to create the presentation employs the
an imaginative piece of artwork showing the spread of cholera,
which also illustrates the belief that it was spread through
a map of the world, showing the spread of cholera during the
an image of a 3D cube, to illustrate Euler's Formula for
a "mountain" plot of the diamond points shows the generators
as peaks, and the diagram lines as straight valleys, generated
a pixel plot of the Delaunay triangulation of the diamond points,
VORONOI_PLOT, using the L1 distance. Some "mistakes" in the
plot are actually caused by the fact that for the L1 distance,
the boundary can consist of an area, rather than a line, that
is, for certain generators, a relatively huge (and area filling)
number of points can be equidistant from two generators. The plotting
routine doesn't spot this, but its results suggest what is happening.
shows that, without the correct organizing principle, the
explanation for the cholera death data can be invisible.
a map of the Golden Square area, where a highly localized
outbreak of cholera occurred in 1854, from the John Snow
archive and research companion site at
a detail of the Golden Square map, showing the suspected
pump, and a dotted line around its "neighborhood", from
the John Snow archive and research companion site at
an image of Dr John Snow.
a photograph of the John Snow memorial in Broad Street,
which is a replica of the pump he identified as the source
of the epidemic.
a map of the locations of pumps and deaths in the Golden Square
a drawing of the Broad Street Pump, suggesting how local women
collected water in pumps for use at home.
Last revised on 05 May 2009.