Today we visited the University of Edinburgh’s Centre for Research Collections to look at some original copies of books written by the Scottish engineer and economist William Playfair (1759 – 1823). Playfair’s Commercial and Political Atlas, first written in 1786, is renowned as the book containing the first ever graphs.
Before Playfair’s Atlas, data had to be presented in the form of long lists or tables of numbers, making it very hard to actually use. Playfair’s brother, John, was a mathematician, working during a time period when the geometry of the ancient Greeks was undergoing a revival. John taught his brother that anything that can be expressed as a number can be expressed as a line, and Playfair wondered whether this might lead to an intuitive way of representing the numbers in his data sets. He felt that by using graphical techniques to display data, it would be much easier to make sense of it and discover patterns in it. What he produced were the first examples of line graphs.
As well as being beautiful diagrams, Playfair’s line graphs caught on: By the end of the eighteenth century, a scientific revolution was in full force, with the the visualisation of data becoming increasingly popular. In 1801 Playfair produced an updated version of the Atlas, and in that same year he published another book, the Statistical Breviary, in which he pioneered two new types of chart that we are familiar with today: the pie chart and the bar chart.
Not long after, the pie chart was used by the famous English social reformer and nurse Florence Nightingale to show the causes of death at the hospital where she worked during the Crimean War. She presented this pie chart to government ministers, and this led to improved sanitation in hospitals, helping to change the face of nursing for the better, and ultimately saving many lives.
Find out more about Playfair’s work and how it impacted on modern data science in Week 1 of our course!