The beauty of diagrams. Part 4, Florence Nightingale.

The fourth in a six-part series in which mathetmatician Marcus du Sautoy explores the stories behind some of the most familiar scientific diagrams. This part features Florence Nightingale's 'rose diagram' which showed for the first time that hospitals can kill. It was designed to persuade that British government that sanitation needed to be improved in British hospitals. This would go on to save countless lives.