Charles Coquebert de Montbret
This character was charged by Napoleon with drawing up the first precise chart of the linguistic border in Brittany. However its investigation related only to the departments of the Coast-of-North and the Morbihan. The still bilingual Loire-Inférieure however, was isolated of this investigation. However, it is known that a linguistic border separated this department starting from the " saltworks of Herbignac".
Its investigation is very interesting because it shows very a Net retreat of the Breton-speaking territory in Brittany.
In addition to the Brittany, it more generally dealt with all the languages of France.