professor, and draws a moral about the importance of "steadiness and consistency of plan" as well as of "genius". Bruce Berkowitz in 2018 provides a detailed portrait of Playfair as an "ambitious, audacious, and woefully imperfect British patriot" who undertook the "most complex covert operation anyone had ever conceived". Bar chart Two decades before Playfair's first achievements, in 1765 Joseph Priestley had created the innovation of the first timeline charts, in which individual bars were used to visualise the life span of a person, and the whole can be used to compare the life spans of multiple persons. According to James R. Beniger and Robyn (1978) "Priestley's timelines proved a commercial success and a popular sensation, and went through dozens of editions". These timelines directly inspired Playfair's invention of the bar chart, which first appeared in his Commercial and Political Atlas, published in 1786. According to Beniger and Robyn (1978) "Playfair was driven to this invention by a lack of data. In his Atlas he had collected a series of 34 plates about the import and export from different countries over the years, which he presented as line graphs or surface charts: line graphs shaded or tinted between abscissa and function. Because Playfair lacked the necessary series data for Scotland, he graphed its trade data for a single year as a series of 34 bars, one for each of 17 trading partners". In this bar chart Scotland's imports and exports from and to 17 countries in 1781 are represented. "This bar chart was the first quantitative graphical form that did not locate data either in space, as had coordinates and tables, or time, as had Priestley's timelines. It constitutes a pure solution to the problem of discrete quantitative comparison". The idea of representing data as a series of bars had earlier (14th century) been published by Jacobus de Sancto Martino and attributed to Nicole Oresme. Oresme used the bars to generate a graph of velocity against continuously varying time. Playfair's use of bars was to generate a chart of discrete measurements. Graphics Playfair, who argued that charts communicated better than tables of data, has been credited with inventing the line, bar, area, and pie charts. His time-series plots are still presented as models of clarity. Playfair first published The Commercial and Political Atlas in London in 1786. It contained 43 time-series plots and one bar chart, a form apparently introduced