Des Cartes
Generates Aux Cartes Spectates
Translation of text: Charles De Fourcroy
From Palsky (1996): Des Chiffres et
des Cartes, p.51-52
(translated by Daniel J. Denis)
April 7, 2002
CHARLES
DE FOURCROY
Much progress in the field should be attributed to works published at the end of the 18th century and beginning of the 19th century. Among these, one of the most remarkable is Essai d'une table poléométrique by Charles de Fourcroy, dated 1782. De Fourcroy is without a doubt, one of the first to employ proportional geometric figures to translate and compare quantities representing the occurrence of urban surfaces: "If we have the surfaces (i.e., areas) of all the cities/villages in the table, or the proportions representing these cities, transformed into cross-sections, each of equal extension, and each on the same scale; then if we successively put one on the other, from the largest to the smallest, and joined all by one of their angles; these squares would overlap relative to their size, and the whole would form a kind of table that visually represents an idea of the actual proportion that can be found between the surfaces of these different cities. We could as well find in this table two cities of equal size, cut their squares diagonally, and have the table represent only half of each; which essentially means the same. Such is the attached figure, which requires no further explanation" (figure 15).
The Table poléométrique highlights more specifically, by the strict use of the variation in size, the cartographic works of engineers of bridges and roads from 1840 to 1870. Graphic innovation goes hand in hand with demographic preoccupations, with a concern for the urban settlements: "Many new cities formed in France under the reign of Louis XV [...]. I don't know if in these circumstances we know exactly why these cities grew so much in size, but perhaps it is due to two new war cities [...] with the necessary size-increase of many other cities. An opinion of this kind seemed to me to require some data or evidence". Or again: "There must exist between the surface of a city and the number of inhabitants a certain proportion more advantageous than all other, where it constitutes the most suitable population, a question I have not addressed, though it is not of immediate curiosity." It is thus as much by the graphic, as it is with thought, the action of "voluntary geography", that Fourcroy precedes the creators of modem cartography, a cartography adapted to the quantitative information in the following century.
The Table established by Fourcroy signals a fundamental moment in the evolution of the graphical method. We see the passage to the abstract, to fictitious features. By these proportional triangles, the author constructs an image that does not return/relate to its original existence. As J. Bertin notes, "you would have had to be in the 14th century to foresee at Oxford, and the 18th century to discover with Charles de Fourcroy, that the two dimensions of the sheet of paper could represent something other than just visible space. It was, in reality, going from a simple representation to a "system of signs" which was complete, independent, and possessed its own laws and properties, this is to say, its own "semiologie." Charles de Fourcroy's table contributes in freeing the graphic from the usual interpretation of the world. The center of interest is close to that of Noel-Laurent Duchemin, but the world of expression is fundamentally novel. In addition, the graph is an applied graph. It facilitates the bringing together of, and comparing of new information.
We
can mention that in this first example, a geometric surface does not translate
to an extent the urban surfaces, even if the demographic concerns/details are
subjacent. There remains to show that the style can express all numerical data.
It is difficult to measure the real influence of the poleometric
table, but another work confirms for us, through diagrams, graphical
translation of statistics.