William Playfair

Chapter 1 · Millwright to Draughtsman

Learning to draw a quantity

1759 – 1782 · Dundee · East Lothian · Birmingham

William Playfair was born at Dundee in 1759, the fourth son of a minister who died when the boy was thirteen. His elder brother John — later professor at Edinburgh, the mathematician who made Hutton's geology readable — took over his education.

He was apprenticed to Andrew Meikle, the millwright who invented the threshing machine, and then went to Birmingham as a draughtsman and personal assistant to James Watt at the Soho works.

That apprenticeship matters more than any schooling would have. An engineering draughtsman spends his days turning quantities into marks on paper that another person has to read and act on. Dimensions become lengths, and the drawing is trusted to carry them accurately. Playfair absorbed the idea that a measured quantity can live as a distance on a page and be read back off it — which is exactly what a chart does, and exactly what nobody had thought to do with economic data.

His brother's influence is also on record: John had taught him to plot the daily temperature as a line against time on a chart, which Playfair later said gave him the idea.

He left Watt in 1782 to set up as a silversmith and engineer in London. The business failed. It was the first of many.

Why this matters

The idea that quantity can be a length on a page came out of an engineering drawing office, not a mathematics department.

A millwright's apprentice who learned to draw quantities. What would you ask him?

Ask Playfair

• “What did you learn in Watt's drawing office?”
• “Your brother had you plot temperature as a line. What did that suggest?”
• “What is the difference between an engineering drawing and a chart?”
• “What was it like to grow up as the brother of a famous mathematician?”
• “Why did the silversmith's business fail?”

Chapter 2 · The Commercial and Political Atlas

1786, and a page with no numbers on it

1786 · London

In 1786 Playfair published the Commercial and Political Atlas, and its central pages contain something nobody had printed before: the trade of England, over a century, drawn as two lines rising and falling across a page against time, with the space between them shaded to show whether the balance stood for or against the country.

The reader is not asked to do anything. There is no table to work through. The shape of the century is visible in a second, and the direction of the balance is a colour.

He knew exactly what he was claiming. His preface argues that a table is read one figure at a time and immediately forgotten, while an impression made on the eye is retained — and that men who will not sit down to a column of accounts will look at a picture of the same facts. He called it an appeal to the eye.

One chart in the book is a bar chart, and its origin is an accident that reveals the logic. For Scotland he had only a single year's figures, so a line against time was impossible. Instead he drew one bar for each trading partner, their lengths showing the amounts. He apologised for it in the text as inferior, being a picture of quantity without the dimension of time. It is now the most-used chart in the world.

He also had a problem persuading anybody. The book was well received in some quarters and dismissed in others as unserious; the political economists it was meant for were slow to adopt it, and the method took hold on the Continent before it did at home.

Why this matters

The bar chart was invented as an apology for missing data, and its inventor thought it the weakest thing in the book.

A century of trade, drawn as a shape. What would you ask him?

Ask Playfair

• “Why draw the trade instead of tabulating it?”
• “What does the shading between the two lines tell a reader?”
• “Why did you apologise for the bar chart?”
• “Who did you actually want to read this book?”
• “Why were people slow to take it up?”

Chapter 3 · Paris, and the Scioto Affair

The disaster in the middle of the life

1787 – 1793 · Paris · Ohio

In 1787 Playfair moved to Paris, and what followed is the part of his life that is hardest to defend.

He was present at the storming of the Bastille in July 1789, and by his own account took some part in it. More consequentially, he became involved in the Scioto Company, a scheme selling land on the Ohio River to French emigrants. The company sold rights to land it did not own. Roughly six hundred French settlers crossed the Atlantic on the strength of the prospectuses and arrived to find no title, no surveyed plots, and a wilderness; many died. The settlement of Gallipolis exists because of it.

Playfair's exact role is disputed and he later gave accounts that minimised it. What is not disputed is that he was the company's agent in Paris, that he produced the promotional material, and that the material was false. It is a bleak episode and it is part of the record.

He left France as the Revolution turned, and spent the following years in London writing: pamphlets against the Revolution, a continuation of Adam Smith's Wealth of Nations, journalism, and government-funded propaganda including a scheme to forge and distribute French assignats in order to wreck the currency. He ran a bank, which failed. He was imprisoned for debt.

All of this is happening in the same years as the charts, by the same man, sometimes in the same books.

Why this matters

Inventions come from people, and people are not tidy: the man who gave the world its charts also helped ruin six hundred families.

A disaster he never satisfactorily explained. What would you ask him?

Ask Playfair

• “What was your role in the Scioto Company?”
• “What happened to the French settlers who sailed?”
• “Were you really at the Bastille?”
• “Did you forge assignats for the British government?”
• “How do you square all this with the books?”

Chapter 4 · Cutting the Circle

The Statistical Breviary, 1801

1801 · London

In 1801 Playfair published the Statistical Breviary, a short book comparing the European powers — their areas, populations and revenues — and in it he did something new again.

He drew each country as a CIRCLE, sized so that its area represented the country's extent. Then, for the Turkish Empire, he divided the circle into sectors to show how much lay in Europe, in Asia and in Africa. That is the first pie chart.

The design carries two quantities at once, which is the clever part and the part usually forgotten. The size of the circle says how big the whole is; the sectors say how it divides. Two circles side by side can therefore be compared as wholes and as compositions in the same glance. He added lines beside the circles for population and revenue, so a reader could see at once whether a country's revenue was large or small for its size.

He was frank in the preface that he was not a mathematician and that he offered the method as a way of making information stick. He also anticipated the standard objection — that a picture cannot be exact — and answered it: nobody remembers the exact figures from a table either, and a reader who takes away a correct impression has gained more than one who takes away nothing.

The Breviary sold poorly. Playfair went on drawing charts for the rest of his life, including the famous chart of the price of wheat against wages from 1565 to 1821, published two years before his death.

Why this matters

The pie chart was designed to carry two things at once — the size of the whole and the shares within it — and half of that design is routinely thrown away.

The first circle ever cut into shares. What would you ask him?

Ask Playfair

• “How did you come to divide a circle into slices?”
• “Why size the circles differently?”
• “What do you say to somebody who calls a picture inexact?”
• “Does it matter that you were not a mathematician?”
• “What is the wheat and wages chart trying to show?”

Chapter 5 · The Long Wait

Poor at his death, universal a century later

1801 – 1823, and after · London · Paris

Playfair's inventions did not take hold quickly, and he knew it. In Britain the reaction to graphical presentation was suspicion: political economy was a serious business conducted in tables, and pictures looked like a shortcut. On the Continent the reception was warmer — Alexander von Humboldt used and praised his methods, and German and French statisticians took them up decades before the British did.

He kept trying schemes. He attempted to extort money from Lord Archibald Douglas over a family secret and was prosecuted for it; he fled to Paris to escape the judgment and lived there in poverty for some years. He wrote a study of the causes of the decline of wealthy nations, and continued to produce charts.

He died in London in February 1823, poor, and his obituaries did not mention the charts.

What happened afterwards is that the methods became the air everybody breathes. By the middle of the nineteenth century the line graph was standard in official statistics; by the twentieth, bar charts and pie charts were how quantity was discussed in newspapers, boardrooms and classrooms. Every graph a school student draws is one of his three inventions. Almost nobody knows his name.

The most useful thing about the life is what it shows about invention. Playfair was not a mathematician, was not particularly rigorous, was frequently dishonest, and failed at nearly everything he attempted. He also thought hard about one question that nobody else was asking — what will a reader actually take in and keep? — and answered it well enough to change how the world looks at numbers.

Why this matters

His charts became universal a century after he died poor, which is a lesson about how long a good idea can take to be believed.

Poor at his death, and now unavoidable. What would you ask him?

Ask Playfair

• “Why did Britain resist your charts and the Continent take them up?”
• “Did you know what you had invented?”
• “What happened with Lord Archibald Douglas?”
• “What is the one question you kept asking about a reader?”
• “Does it matter that nobody knows your name?”

What Playfair changed

The line graph, the bar chart and the pie chart all appear for the first time in two books by William Playfair, published in 1786 and 1801, and between them they are now the visual vocabulary in which quantity is discussed everywhere in the world. The practice of shading between two curves to show a balance is his. So is the idea of sizing a shape so that its area carries a total. His central argument — that a reader keeps what the eye takes in at once and forgets what a table makes them work through — is the founding claim of information design.

A debate that continues

His part in the Scioto Company, which sold Ohio land it did not own to about six hundred French emigrants, is documented and disgraceful, and his own later accounts minimised it. He attempted to extort money from Lord Archibald Douglas and was prosecuted. He was not a mathematician and made no mathematical claims; the histogram, often confused with his bar chart, is a later and different instrument that he had no hand in.

Keep exploring — ask Playfair

• “Is an impression that is roughly right worth more than a figure that is exactly right and forgotten?”
• “Can an invention be separated from the character of its inventor?”
• “Why did the most useful chart in the world begin as an apology?”

Related lives

• Adolphe Quetelet — The Average Man
• James Watt — Who Found Where the Steam Was Wasted
• Florence Nightingale — The Lady with the Lamp

Related themes

Charts and data presentation · Political economy · Information design