Florence Nightingale, the Lady with the Lamp, without the lamp.
It's much less easy to find famous women from history than it is to find famous men. That's chiefly because society expected women to stay at home and keep house, and content themselves with being the wives and mothers of the men doing the more interesting stuff. Not that all men did interesting stuff, of course. For most, like Lucy's father and brother in The Shimmer on the Glass, work involved a lot of hard labour in order to earn just enough money to make ends meet. They had next to no time for pleasure, and their lives were plainly little better (and occasionally a lot tougher) than the women's, who had the physical labour of doing all the washing, cleaning and cooking, which was much more difficult than it is today.
For rich young men, however, the world was a much more exciting place than for wealthy young women, who were educated in arts and languages only so that they could marry well. They certainly weren't expected to have a career of any sort and couldn't hope to do anything that was either interesting or useful. At least they didn't have the drudgery and financial worries of the poor, but goodness, life must have been dull!
Florence Nightingale was brought up in exactly this sort of household - her parents were rich, and the family travelled around Europe. But they were very conventional too, and they were set against her becoming a nurse. When she was twenty-four, however, Nightingale decided that she had to follow her calling from God to help people, in spite of her family's anger. She turned down a proposal of marriage from an eligible young man who had been courting her for nine years - which can't have thrilled her parents - and began to educate herself in the science of nursing.
She is most famous for saving the lives of wounded and sick soldiers in the Crimean War. Nightingale arrived in the Crimea in November 1854 with 38 women she had trained as nurses. The conditions she found in the Army Hospital in Scutari were horrifying: the staff were overworked, the wards were overcrowded, the sewers were blocked, there was poor ventilation, not enough medicine or food, and no attention to hygiene. Ten times as many soldiers died from infections and diseases - typhoid, dysentery, and cholera - as from the wounds they'd got in battle.
Nightingale wrote to The Times in London, asking the British government to do something. The government responded by asking Isambard Kingdom Brunel to design pre-fabricated wards, which were sent out to the Crimea. These reduced overcrowding and provided much improved sanitation (eg. sewers and clean water) and ventilation. Nightingale's hygiene practices, such as hand-washing, also reduced the spread of infection. Altogether, she is credited with reducing the mortality rate from 42% to 2% - only 2 soldiers out of every 100 now died, rather than 42! The nickname 'Lady with the Lamp' comes from the ward rounds she would make at night after the doctors had gone, checking on her patients by the light of her lamp.
Nightingale's fame for her work in the Crimea was so great that a fund was set up while she was still working there to provide money for nurses to be trained. Lots of people gave generously, and on her return, Nightingale used the money to set up a training school at St. Thomas' Hospital. She spent the rest of her life building and organising the nursing profession, which didn't exist before. She died in her sleep aged 90, having saved countless lives as well as improving the lives of the huge numbers of poor people by campaigning for better living conditions for them.