These examples of traditional thematic cartography reveal patterns and relationships among data elements literally mapped into two dimensions.
René Descartes (1596–1650). Discours de la méthode: Pour bien conduire sa raison, & chercher la vérité dans les sciences. Plus La dioptrique. Les météores. Et La géométrie.
This image appeared in René Descartes’ ‘Les Météores’, published in 1637 as part of his extraordinarily influential work Discours de la méthode. Descartes’ visualization describes how water vapour moves in the air under different conditions. These descriptions are of hypothetical data based on his experience and imagination rather than any measurements. Hence, this image is more diagram than data visualization: perhaps it is a proto-visualization. This illustrates an important difference between data visualizations and diagrams. If Descartes had collected the data he plotted, rather than hypothesizing them, his diagram would have been a data visualization proper instead of proto.
August Crome (1753–1833). Ueber die Grösse und Bevölkerung der sämtlichen europäischen Staaten: ein Beytrag zur Kenntniss der Staatenverhältnisse, und zur Erklärung der neuen Grössen-Karte von Europa. Leipzig: Weygand, 1785.
August Crome’s ‘Groessen Karte von Europa’ extends the idea of thematic cartography into greater abstraction. This ‘map’ depicts population and area statistics for the countries and states in Europe. The large, superimposed squares that dominate the visualization represent the relative area of each state or country, abstracted into squares for ease of comparison. (The units are ‘Q.M.’ for ‘Quadrat-Meilen’ or ‘square miles’). Crome includes population statistics in columns to the left and right of the squares.
Alexandre Parent-Duchâtelet (1790–1836). De la prostitution dans la ville de Paris, considérée sous le rapport de l'hygiène publique, de la morale et de l’administration. Paris: J.B. Baillière, 1836.
Choropleths involve the mapping of a continuous or categorical variable onto geographic regions. The shapes of shaded areas are determined by political or regional boundaries. The shading within each political boundary is determined by the value of the variable. In this figure created in 1836 by French researcher and civil servant Alexandre Parent-Duchâtelet, the shapes are the borders of the French provinces and the level of shading represents the number of Parisian sex workers who were from that province. This was part of an 8-year, interview-based study that led to legislation that controlled the lives of sex workers and regulated sex work in France. The results also challenged many myths of the day about sex workers, including that most of them were not from the area around Paris.
George H. Swanston (1814–1872). The World in Hemispheres: With Comparative Views of the Heights of the Principal Mountains and Basins of the Principal Rivers on the Globe. Edinburgh: A. Fullarton, 1852.
Swanston’s lovely map includes scaled, comparative depictions of the lengths and areas of the globe’s principal river basins. The beautiful line chart at the bottom, with the lines drawn as mountains, is innovative and fascinating. The x-axis represents latitude, and the y-axis represents altitude. Note that the chart is not a bar chart. It is a line chart. Despite appearances, the relative areas occupied by each mountain can’t be meaningfully compared. But the mountains have width for a reason: they show how higher elevations can accommodate greater biodiversity at latitudes further from the poles. And notice the whimsical puffs of smoke denoting volcanoes.
William C. Woodbridge (1794–1845). Rudiments of Geography, on a New Plan, Designed to Assist the Memory by Comparison and Classification. Hartford: O.D. Cooke, 1829.
Woodbridge’s ‘Comparative Heights of Mountains’ is only forty years older than Swanston’s similar chart, but it is much more rudimentary and seems to hail from a different era. Woodbridge’s visualization is a one-dimensional graph, with the y-axis representing elevation. There is no x-axis. Instead, the various mountains are arrayed for ease of display. This technique is called ‘dodging’: data points are shifted slightly in order to draw elements on top of one another.
Lorin Blodget (1823–1901). Climatology of the United States, and of the Temperate Latitudes of the North American Continent. Philadelphia: J.B. Lippincott, 1857.
This is a superb example of thematic cartography. The graphic plots contour lines indicating precipitation levels (isohyets) over a large part of the northern hemisphere. Lorin Blodget’s Climatology of the United States was the first and most influential work in American climatology. The maps display the data cleanly and elegantly and in such a way that patterns are instantly visible, despite the monumental effort to collect, analyze, and synthesize the data lurking in the background. This is an early and immediately recognizable step on the road to the modern weather map.
Charles E. Goad (1848–1910). Beaverton, Ontario (Ontario County). Toronto: Charles E. Goad Company, 1910.
Budgen’s The Passage of the Hurricanein the previous section presages fire insurance maps of the late eighteenth and early nineteenth centuries. These maps were made to assist insurance companies in assessing and underwriting the risk of fire to buildings in municipalities and communities. The map of Beaverton, Ontario displayed here was created by the Charles E. Goad Company, the largest producer of fire insurance plans in Britain and Canada. The map meticulously plots building locations, uses, construction materials, roads, and other features with a view to insurance financing and claims, for use before a calamity. This is insurance industry data viz.
Alvin J. Johnson (1827–1884). Johnson’s New Illustrated (Steel Plate) Family Atlas: With Descriptions, Geographical, Statistical, and Historical. New York: Johnson and Browning, 1861.
Before standardized time zones solved the problem (thank you, Sir Sandford Fleming!) knowing what time it was from city to city around the world was a tricky business. This beautiful but bewildering visualization showed the relative time in dozens of cities when it was noon in Washington DC–it was 11:50 a.m. in Toronto. (The precise manner in which the cities are sorted eludes explanation.) The chart is a precursor to those displays of clocks one sometimes sees in airports or financial institutions showing the current times in New York, Zurich, Beijing…
