Thursday, January 5, 2006

Historical Information Design

View Minard's classic map of Napoleon's disaterous invasion of RussiaView Minard's companion map, of Hannibal's Alpine crossingView Quennevat's map and compare it to Minard's more sophisticated thematic maps.A Thematic Map is not a general map; a general map locates geographic features – mountains, rivers, towns – regardless of their function, for the purpose of observing their relative spatial relationships. The thematic map concentrates on showing geographic phenomena in the context of a narrative theme or themes – the number of possible themes being virtually unlimited, encompassing nearly every possible discipline from the social and economic worlds, geology and religion, population and disease. This genre of information graphic, which first appeared in geological maps in the 1770’s, enhances the effectiveness of the time-series graphic by adding spatial proportions, either in two or three dimensions.

Charles Joseph Minard provides us with the classic model of a thematic map used to describe historical scenarios. His 1869 maps of Napoleon’s 1812AD Russian campaign and Hannibal’s 218BC crossing of the Alps not only dramatically depict their relative subjects visually, but also introduce a variety of graphic methods for future authors of visual texts.

With his Napoleon map, Figurative map of the successive losses in men of the French Army in the Russian Campaign 1812-1813, Minard attempted to graphically demonstrate the devastating loss of life suffered by Napoleon’s Grand Army during its Russian Campaign of 1812, a human catastrophe that he felt was poorly communicated textually. Indeed, as the Franco-Prussian war loomed over 1860’s France, it should be considered that Minard’s message was not just one of historical import, but a contemporary humanistic, anti-war message as well.

The graphic methods Minard employs to portray Napoleon’s Russian campaign are simple, elegant, and descriptive. In the Napoleon map six levels of historical information are being described in one powerful design – geography, time, temperature, the course and direction of the army’s movement, and the quantity of troops remaining with Napoleon’s force. The method Minard uses to demonstrate the diminishing human quantity – gold and black paths, their widths relative to the size of the army at a rate of one millimeter to every 10,000 men – is shown in direct relationship to flanking movements, the crossing of rivers, battles for particular cities and, on the return course, a time series graph of the plummeting temperatures of the Russian winter. This combination of multivariate data creates a visual narrative describing how the 422,000-man French force set out from Poland in 1812, crossing the Polish-Russian border near the Niemen River, dwindled to 100,000 men by the time it arrived at a deserted Moscow. Through battle, attrition, natural frontier, and the harsh calamity of the Russia winter, Napoleon’s Grand Army was so rapidly and completely decimated that by the time it returned in 1813 only 10,000 men remained.

Certainly, the loss of life Minard depicts was not unknown to his contemporaries. But it may have been underappreciated. A look at Minard’s sources for this map reveals numerous sources that, while quantitative and honest, are comparatively ineffective in stressing the totality of the disaster. Minard’s visual text, on the other hand, was appreciated for its visual and humanistic effectiveness both by contemporary and modern critics: Étienne-Jules Marey said that Minard’s Napoleon map “def[ied] the pen of the historian by its brutal eloquence” and Edward Tufte described it as what “may well be the best statistical graphic ever drawn.”

But Minard’s Napoleon map is even more striking when compared to two analogues: A modern, more conventional depiction of Napoleon’s campaign and Minard’s own supplemental map of Hannibal’s march across the Alps.

In Jean Claude Quennevat’s Atlas de la Grande Armée, the Russian campaign is depicted with an almost identical geographic scale but without any of the narrative quality. While such a map is routine in military histories, it lacks the thematic quality necessary to define it as a visual text – no relationships or arguments are proposed, no hypotheses tested. The percipient is left with no appreciation of the loss of human life or of the impact of weather and geography on the army’s retreat. Only the mundane details of movement and siege are overlaid upon the map. Compared to Minard’s depiction of this same campaign, Quennevat’s graphic is an empty chart.

However, by comparison to the Napoleon map’s companion, Figurative map of the successive losses in men of the army that Hannibal drove through Spain into Italy by crossing Gaul, the French disaster is more vividly described and Minard’s graphic methodology justified.

In his Hannibal map, the diminishing-width visualization method is used again, this time to depict the attrition of Hannibal’s 92,000-man force as it passed through Spain, Gaul, and Italy. Whereas the Napoleon map sought to demonstrate the enormous cost of lives as a result of the Russian winter, here the percipient can easily witness the cost in lives as Hannibal’s force is reduced from 46,000 to 26,000 over the course of its 14-day transmission of the Alps. But the Hannibal map’s argument, by itself, is a weaker one. Based on the extant works of Polybius and Larauza’s Histoire critique du passages des Alpes par Annibal, its argument is less dramatic and relies on its sources with less analysis. For instance, Minard makes no “opinion on the point where Hannibal crossed the Alps … adopt[ing] that from Larauza without claiming to justify it.” But when viewed together with the Napoleon map – as the Hannibal map was originally printed – and by juxtaposing the underappreciated French disaster with the famous Carthaginian one, the Hannibal map reinforces the dramatic losses of the French Army.

In both of Minard’s visual texts, the percipient benefits from his graphic philosophy: that “the dominating principle which had characterized his graphic tables and figurative maps was the immediate appreciation by the eyes of the proportions of the numerical results.” These techniques – specifically the use of colored bands to proportionally represent the population of a migrant force over time and distance – are a uniquely French thematic innovation and have been rarely imitated since Minard’s successful use of them in his Napoleon and Hannibal maps. Perhaps this lack of imitation is a result of the technique’s inherent geographic inaccuracy – though geographic precision was not Minard’s principal objective. The oversimplified geographic presentation of eastern Russia is also problematic. So few geographic details are present that many percipients unfamiliar with the region might lack clear understanding. The Hannibal map, by comparison, does an excellent job orienting the percipient both in terms of geography and compass direction.

This is not a repetition of the cliché, “A picture is worth a thousand words,” but instead a reminder that sometimes a thousand words are too many and, too often, unnecessary. fb

1 comment:

Anonymous said...

What a great resource!