William Playfair (1759 - 1823) was a Scottish engineer and political economist remembered for his innovations in the presentation of quantitative information through graphs and charts. He invented the time series graph or line chart, the bar chart, and the pie chart.
“Familiarity has dulled our sense of the importance of Playfair's diagrams and it is easy to underestimate the ingenuity that was required to invent them.”
Ian Spence (Historian)
Dmitri Mendeleev ****(1834 - 1907) was a Russian chemist who developed the periodic classification of the elements. Mendeleev published his first periodic table of the elements in 1869. Mendeleev found that, when all the known chemical element were arranged in order of increasing relative atomic mass, the resulting table displayed a recurring pattern of properties within groups of elements. In his version of the periodic table of 1871, he left gaps in places where he believed unknown elements would find their place.
