The Beauty of Diagrams

Can a diagram save lives? Florence Nightingale is best known as the Lady of the Lamp, who cared for thousands of soldiers in appalling conditions during the Crimean War of 1854-6. What is less well-known is that she was a superb statistician, and the first to use a statistical graphic as a call to action.

After the war, Nightingale wrote a passionate report on why the soldiers had died in such large numbers and it revealed the astonishing fact that out of 18,000 deaths, 16,000 had been due to infectious diseases in hospital rather than battle wounds. The report included her revolutionary and controversial 'Rose Diagram', whose message was potent and direct - hospitals can kill. The diagram was designed to persuade the British government that, if sanitation in hospitals was improved, many deaths could be avoided. Nightingale's pioneering diagram was a catalyst in the creation of better and cleaner hospitals that would go on to save thousands of lives.

In the last hundred years, one diagrammatic image stands above all others. It represents a scientific breakthrough that has been voted the most significant in the 20th century, more important than penicillin or the first working computer.

The double helix shows us what the structure of our DNA looks like. Francis Crick and James Watson announced their discovery in Nature magazine in April 1953, and their article included a diagram of the structure by Odile Crick. The image she drew has become so well known and loved that we now find it in a whole range of consumer products - there are double helix ties, dogs chews and even a perfume.

So has the image of the double helix become so divorced from its original scientific setting that no one knows what it really is or what it stands for?

When the unmanned space probe Pioneer 10 took off from Cape Canaveral in March 1972, it had on board a remarkable diagram. The Pioneer Plaque was designed to communicate fundamental facts about Earth and its inhabitants to life on other planets. In carefully engraved graphic images and mathematical symbols, the plaque would reveal the Earth's location in the solar system and show extra-terrestrial intelligent life what human beings looked like.

But how could one single diagram do all that - what do you put in and what do you leave out? With its naked human figures, the plaque sparked arguments amongst feminists and conservatives.

So was it, in the end, a great intellectual game or was it the most enterprising, artistic and scientific diagram of all time, perhaps even the ultimate diagram?