From Diagrams that changed the world (BBC News):
One of the first to use the visual world to navigate numbers was Florence Nightingale.
Although better known for her contributions to nursing, her greatest achievements were mathematical. She was the first to use the idea of a pie chart to represent data.
Nightingale had discovered that the majority of deaths in the Crimea were due to poor sanitation rather than casualties in battle. She wanted to persuade government of the need for better hygiene in hospitals.
She realised though that just looking at the numbers was unlikely to impress ministers. But once those numbers were translated into a picture – her Diagram of the Causes of Mortality in the Army in the East – the message could not be ignored. A good diagram, Nightingale discovered, is certainly worth 1,000 numbers.
Florence Nightingale had exhibited a gift for mathematics from an early age and excelled in the subject under the tutorship of her father. Later, Nightingale became a pioneer in the visual presentation of information and statistical graphics. Among other things she used the pie chart, which had first been developed by William Playfair in 1801. While taken for granted now, it was at the time a relatively novel method of presenting data.
Indeed, Nightingale is described as “a true pioneer in the graphical representation of statistics”, and is credited with developing a form of the pie chart now known as the polar area diagram, or occasionally the Nightingale rose diagram, equivalent to a modern circular histogram, in order to illustrate seasonal sources of patient mortality in the military field hospital she managed. Nightingale called a compilation of such diagrams a “coxcomb”, but later that term has frequently been used for the individual diagrams. She made extensive use of coxcombs to present reports on the nature and magnitude of the conditions of medical care in the Crimean War to Members of Parliament and civil servants who would have been unlikely to read or understand traditional statistical reports.
“ Nightingale’s achievements are all the more impressive when they are considered against the background of social restraints on women in Victorian England. Her father, William Edward Nightingale, was an extremely wealthy landowner, and the family moved in the highest circles of English society. In those days, women of Nightingale’s class did not attend universities and did not pursue professional careers; their purpose in life was to marry and bear children. Nightingale was fortunate. Her father believed women should be educated, and he personally taught her Italian, Latin, Greek, philosophy, history and – most unusual of all for women of the time – writing and mathematics. “
But while better known for her contributions in the nursing and mathematical fields, Nightingale is also an important link in the study of English feminism. [...]
[Nightingale's essay] Cassandra protests the over-feminization of women into near helplessness, such as Nightingale saw in her mother’s and older sister’s lethargic lifestyle, despite their education. She rejected their life of thoughtless comfort for the world of social service. The work also reflects her fear of her ideas being ineffective, as were Cassandra‘s. Cassandra was a princess of Troy who served as a priestess in the temple of Apollo during the Trojan War. The god gave her the gift of prophecy but when she refused his advances he cursed her so that her prophetic warnings would go unheeded. Elaine Showalter called Nightingale’s writing “a major text of English feminism, a link between Wollstonecraft and Woolf.”