The great Gallic league. J Dassié. Page 5.
Mr. Clos-Arceduc , engineer as a geographer head of the I.G.N. (National Geographic Institute) approached the problem by very an other method : it is while seeking to answer the question: " a national road having with the compartmental neighbor of the relations implying his seniority, could one find a second criterion making it possible to affirm that it covers a Roman way? ". "The remark, during a walk, that four points of "Le chemin de Saint Mathurin" marked in a characteristic way (bushes, cross, crossroads) were equidistant, gave body to the idea to use such coincidences ".
We summarize this method of analysis on card under the name of " topographic remanence ".
Daniel Jalmain, in 1970, presented to the International Conference on the Archaeological Cartography the results of his investigations on the ways between the Seine and the Loire. He quoted like an indisputable obviousness, the existence of one Gallic league of 2450 meters on the Ablis-Blois axes and Sens-Chartres (Bib.).
Chevallier (1970,1972 and 1997)
During his seminar of Historical Topography and Photo-interpretation, at the " High Studies in Social Sciences University", professor Chevallier, relaying Clos-Arceduc, was made the defender of the plurality of the values of leagues in Gaule. He was based to the measures of distances starting from the routes, but also on the topographic remanence, in which he recognized a singular effectiveness.
In the foreword of the work of D. Jalmain (Bib.) it writes " But, that does one note? That the Romans in Gaule used three systems of measurement: the Roman mile, one league of 2222 meters, is one thousand and half mile, which perhaps goes up with a Greek measurement, and a Gallic mile of 2420 meters approximately, obviously former on their arrival, perhaps the grandmother of the great royal league. Each time the administration Roman, more flexible and more realistic than one believes it, was in front of an established structure, anchored in the customs, it was seen obliged to respect it or compromise. " Chevallier practically thus describes the genesis of the romanized " league ".
Fig. 2. The Roman way Pons-Guimps controls and orders the compartmental one. Photograph n° 76018-22 © J Dassié.