It has been said that Florence
Nightingale was the first to use diagrams for presenting statistical data.
This is not true, of course, but she may have been the first to use them
for persuading people of the need for change.
Edward Tufte does not mention Nightingale in his book on
the history of graphics1, and he says that
this famous 1869 chart by Minard of Napoleon's dwindling army as it
marched to Moscow and back in 1812/13 may be the best statistical graphic
Minard's diagram includes a temperature
chart which misleadingly suggests that Napoleon's army froze to death. It
shows the falling temperature during the retreat from Moscow, but most of
the army was lost during the advance (300,000 men, vs. 90,000 in the
retreat). Nightingale herself studied this catastrophe, and concluded that
Napoleon's army - like most others - had died of disease2.
Like Minard's, Nightingale's most famous graphics
illustrated what she called the "loss of an army" - the British army sent
to the Crimea. She published them ten years before Minard's. Hers also
were more topical and conveyed a call to action - they were prescriptive
rather than descriptive. She used recent data to persuade the Government
to improve army hygiene.
Although she was before Minard, there were others before
her. The best-known pioneer of statistical graphics was William Playfair,
who published what must be the first "pie chart" in 18013. It was in a graphic showing that, by comparison
with other countries, the British paid more tax. The vertical line to the
left of each circle is the population (left scale) and the vertical line
to the right is the tax revenue (right scale). In this selection of four
of Playfair's countries, Britain is the only one in which the tax line is
higher than the population line:
Playfair used this graphic to argue for lower taxes. So
you could say that, unlike Minard, his graphics are prescriptive. But
Playfair's graphics are merely comparisons. They do not demonstrate what
would happen if you reduced taxes. They look good but make you ask "so
what?" They do not illustrate cause-and-effect - what Nightingale called a
Before going into Nightingale's graphics, let's look at
the state of statistical science in her day. There was a great revolution
in this area in Nightingale's time. In 1837 the General Registry Office at
Somerset House, led by William Farr who later helped Nightingale with her
Crimean statistics, began to systematically record births, deaths, and
marriages in the UK. This gave people the opportunity to examine new cause
and effect relationships using registration statistics.
The years of struggle and the visit to
For example, Florence Nightingale and her sister
Parthenope attended the 1847 meeting of the British Association for the
Advancement of Science in Oxford. There, they may have seen a report from
a Government Actuary, F. G. P. Neison, which showed that counties in which
people were better educated had a lower crime rate. This was an argument
in favour of higher taxes to finance public education, countering the
propaganda of Playfair against high taxes. Neison knew that opponents of
his theory would claim that it was prosperity, not education, that reduced
the crime rate. So he found counties that had both a relatively high
income and a relatively low education, and showed that at least a part of
the variation in crime rates was due to education:
Neison estimated the level of education in each county by counting the
proportion of people getting married there who were able to write their
name on the marriage certificate. Statistics relied much more on ingenuity
and less on complicated formulae in 1847!
Social improvers like Florence Nightingale eagerly seized
on results like Neison's which showed how mankind could combat social
evils. Part of her interest in statistics was related to her Unitarian
faith. Unitarians believed that mankind has the power to continuously
improve itself by observation and the use of reason.
After the Crimean War (1854-56), Nightingale created a
number of spectacular graphics designed to show how improvements in
building hygiene could save many lives. These appear in five different
- Appendix 72 of the report of the Royal Commission that Nightingale
organised after the war, published in 1858.
- Mortality of the British Army (1858), a private edition by
Nightingale of the above Appendix, with exactly the same content but
with better layout than that used by Government printers. She produced
2000 copies of this book. P>
- A Contribution to the Sanitary History of the British Army
(1859). Nightingale published this anonymously to answer a
pamphlet4 that claimed that she had
exaggerated the number of deaths in the war. She showed that the Army's
own figures, released in late 1858, showed that on the contrary she had
underestimated. The graphics in the Contribution used the same
statistics as in No. 2 but with different graphic presentation, as we
- Notes on Matters Affecting the Health of the British Army
(1858). This was a confidential report to the Government, that
Nightingale printed privately and sent to a number of people. This
contains two of the three graphics from No. 3.
- England and Her Soldiers (1859) by Harriet Martineau.
Nightingale encouraged Martineau to write this book about the war and
gave her copies of the graphics used in No. 3.
Most of the graphics used in Nos. 1 and 2 are similar to
those previously used by her adviser William Farr in his
Registrar-General's Annual Reports. They are mostly what we might call
"100% area" or "100% stacked bar".
There is also one "honeycomb" graphic showing how densely
soldiers are packed in camp (a device which Farr had already used for
illustrating urban density), and two other graphics that are highly
original. The first is what Nightingale called the "bat's wing" which is
very gloomy to look at and also misleading.
The circle on the right has 12 sectors
going clockwise representing the first 12 months of the war. The circle on
the left is the second 12 months. The superimposed dark shapes show the
monthly death rates. The diagram illustrates how the Sanitary Commission,
sent out in the middle of the war, dramatically reduced the death rate.
The length of the radial line in each month is
proportional to the death rate, but both the text and the appearance imply
that it is the shaded area that is proportional to the death rate, rather
than the length of the radial lines. Florence recognised this error and
inserted an erratum slip, but then replaced this diagram in later
documents (nos. 3, 4, and 5 listed above) with what I will call the
This "bat's wing" and its successor are so different from
any diagrams that Farr did before that they may be Nightingale's own
invention. The other highly original chart is what I will call the "Lines"
- a bar chart showing how soldiers in peacetime, living in their barracks
in England, were dying at a faster rate than civilians in the cities
There is a black bar in each of four age ranges, and a longer red bar.
The black bar is the number of civilians who die each year, and the red is
the number of soldiers. There are a number of curious overtones to this
graphic, which may just be a coincidence.
First, the title "Lines" (in ornate script in the
original) makes it sound like a poem, as in Lines on the Death
of Bismarck. There are four pairs of bars, when actually the message
is clear from one pair alone. There seems to be a kind of repetition, as
in a chorus. This effect is increased by the words, repeated at the end of
each line, English Men, English Soldiers ... It sounds like a
Second, the red bar for the soldiers would certainly make
some people think of the "Thin Red Line" which had become famous in the
Crimean War when a two-deep row of red-jacketed British infantrymen
stopped a Russian heavy cavalry charge, something that was thought to be
impossible. The thin red lines on Nightingale's chart represented these
same heroic soldiers who were now dying unnecessarily because of bad
hygiene in their barracks.
Perhaps this graphic is a visual poem by Arthur Hugh
Clough, who was Nightingale's secretary at the time that she produced
The variation of death rates due to differences in
hygiene was very important to reformers like Nightingale because it showed
that even the civilian death rate could probably also be improved
by better hygiene. One of Farr's rules of thumb was that if something
varied widely from place to place, it could probably be reduced to zero.
This is an example of the army being used as a controlled environment for
testing social theories, which was very common in Victorian times.
This "Lines" graphic is probably the most influential of
Nightingale's diagrams because it dealt with a situation that was still
going on. The "bat's wing", on the other hand, described a wartime
catastrophe which was now history so that the army could claim that it
wouldn't happen next time. It was probably the "Lines" diagram that
Nightingale particularly wanted to frame and send for hanging in the
offices of the Army High Command, as a rebuke6.
However, it is the last graphic - the successor to the
"bat's wing" which I will call the "wedges" - that Nightingale is most
famous for. Strangely enough, the name that many people give it is wrong.
This graphic is not what Nightingale referred to as the "coxcomb"!
In this diagram, Nightingale
resolved the problem of the "bat's wing" by using areas to
represent the variation in the death rate, instead of the length of radial
lines. The blue wedges, representing death by sickness, are far bigger
than those representing wounds. The message of this graphic is twofold:
first, most of the fatalities during the war were from sickness and
second, improvements in hygiene dramatically reduced the death rate.
Nightingale used this diagram instead of the "bat's wing"
in documents 3, 4, and 5. But why do I say that this is not the "coxcomb"?
What did Nightingale mean by the word "coxcomb"?
A coxcomb is the ostentatious red crest on the top of a
cockerel's head. Nightingale used the word to describe the 2000 copies she
had printed of No. 2 - her Mortality of the British Army. This
booklet, a reprint of an annex containing diagrams, text, and tables, was
the "coxcomb" of the enormous Royal Commission report, the colourful and
ostentatious part that people would actually take notice of. In her letter
of Christmas Day 1857 to Sidney Herbert (the President of her Royal
Commission) Nightingale used the word "coxcomb" in this more thoughtful
sense, referring to a book consisting of text, tables, and graphics:
"Dear Mr. Herbert,
I send you one of the "coxcombs" There are
300 of these
1700 of the vulgar sort
I have also the proof of the Appendix copy of it for your report. In
this form, printed Tables & all in double columns I do not think
anyone will read it. None but scientific men ever look into the Appendix
of a Report. And this is for the vulgar public. The only good of having it
in the Appendix at all is for the sake of the last line on the cover of
the coxcomb: "Reprinted from the ... [sic]"7
She never used the word to refer to a diagram. The
"coxcomb" booklet that she was referring to in December 1857 did not even
include the colourful "wedges" diagram, because that didn't appear until
late in 1858. The booklet to which she was referring, published at the
beginning of 1858, included the old bat's wing diagram which was
erroneous and which she replaced by the wedges later that year.
Sir E. T. Cook's biography of Nightingale in 1914 first
used the word "coxcomb" for the late 1858 "wedges" diagram:
"England and her Soldiers, by Harriet Martineau, 1859. Miss
Nightingale's "coxcomb" diagrams were reproduced in this
It is easy to see why the error has persisted: the
diagram resembles the crest of a helmet.
In briefly surveying Nightingale's statistical diagrams
this paper is guilty of the superficiality which Nightingale predicted,
because it has focused on the coxcomb of her report and ignored the real
issues of substance. For example: was her conclusion justified? Did
sanitary improvements reduce the mortality, or was it the reduction of
trench duty as some army doctors claimed? And the most important question
of all: did she achieve real success with these arguments, in terms of
reducing the mortality of the population as a whole?
These questions will eventually be answered by a more
thorough evaluation of material in Nightingale's archives and elsewhere.
1. The Visual Display of Quantitative Information.
Graphics Press UK, P.O. Box 8, Godalming, Surrey, GU7 3HB
2. BL Add.
MSS 43394, f116
3. Playfair, William, The Statistical Breviary,
4. [Hall, Sir John, and others] Observations of a
Non-Commissioner, n.p., n.d. 
4. Mulhauser, Frederick L., The
Correspondence of Arthur Hugh Clough. Oxford: Clarendon, 1957
Bishop, W. J., and Sue Goldie, A Bio-Bibliography of Florence Nightingale.
7. BL Add. MSS 43394, f210. 25/12/1857. ff 215 and 219
also refer to the "coxcombs" as books. Appendix 72 of the Royal Commission
report was printed in double columns, but her Mortality of the British
Army is single column. From her letter, it appears that there were 300
8. Cook, Life of Florence Nightingale, vol. 1, p. 386.
Possibly the only book which more correctly associates the word "coxcomb"
with the "bat's wing" diagram is Sue Goldie's Florence Nightingale in the
Crimean War (1987), p. 94.