Graphics Reference
In-Depth Information
Escaping Flatland
Although some attempts to display more than two variables simultaneously had oc-
curred earlier in multiple time series (Playfair,
; Minard,
), contour graphs
(Vauthier,
) and a variety of thematic maps, (e.g. Berghaus (
)) a number of
significant developments extended graphics beyond the confines of a flat piece of
paper. Gustav Zeuner [
-
] in Germany (Zeuner,
), and later Luigi Per-
ozzo[
-
]inItaly (Perozzo,
) constructed
-Dsurface plotsofpopulation
data.
he former was an axonometric projection showing various slices, while the
latter (a
-D graph of population in Sweden from
-
by year and age group)
was printed in red and black and designed as a stereogram.
Contour diagrams, showing isolevel curves of
-D surfaces, had also been used
earlierinmappingcontexts(Nautonier,
-
;Halley,
;vonHumboldt,
),
buttherangeofproblemsanddatatowhichtheywereappliedexpandedconsiderably
over this time in attempts to understand relations among more than two data-based
variables, or where the relationships are statistical, rather than functional or mea-
sured with little error. It is more convenient to describe these under Galton, below.
By
, the idea of visual and imaginary worlds of varying numbers of dimensions
found popular expression in Edwin Abbott's (
) Flatland, implicitly suggesting
possible views in four and more dimensions.
Graphical Innovations
With the usefulness of graphical displays for understanding complex data and phe-
nomena established, many new graphical forms were invented and extended to new
areas of inquiry, particularly in the social realm.
Minard (
) developed the use of divided circle diagrams on maps (showing
both atotal, byarea, and subtotals, bysectors,with circlesforeach geographic region
on the map). Later he developed to an art form the use of flow lines on maps of width
proportional to quantities (people, goods, imports, exports) to show movement and
transport geographically. Near the end of his life, the flow map would be taken to its
highest level in his famous depiction of the fate of the armies of Napoleon and Han-
nibal, in what Tute (
) would call the 'best graphic ever produced.' See Friendly
(
)forawiderappreciationofMinard'swork.
he social and political uses of graphics is also evidenced in the polar area charts
(called 'rose diagrams' or 'coxcombs') invented by Florence Nightingale [
-
]
to wage a campaign for improved sanitary conditions in battlefield treatment of sol-
diers (Nightingale,
). hey let no doubt that many more soldiers died from dis-
ease and the consequences of wounds than at the hands of the enemy. From around
the same time, Dr John Snow [
-
] is remembered for his use of a dot map of
deaths from cholera in an
outbreak in London. Plotting the residence of each
Image: http://math.yorku.ca/SCS/Gallery/images/stereo
.jpg
Zeuner used one axis to show year of birth and another to show present age, with number
of surviving persons on the third, vertical, axis giving a
-D surface. One set of curves thus
showed the distribution of population for a given generation; the orthogonal set of curves
showed the distributions across generations at a given point in time, e.g. at a census.
