Jean-Noël HALLÉ (1754-1822), Napoleon's first physician, promoter of vaccinia and hygiene teaching. Autograph letter signed to the doctor Jean-Louis Bagot (1727-1794), who was mayor of Saint-Brieuc. 3 pp. in-4. Paris, 12th May 1780. On the epidemiological survey carried out in Brittany at the request of the Société Royale de Médecine [Bagot had been appointed by the King as physician for the epidemics of Brittany]. "Happy to be in a position to admire your work in discharging the duty imposed on me by the Royal Society [of Medicine] in handing over to me all that concerns the correspondence of the province of Brittany, I hasten to express to you all the esteem which your lights and your zeal have inspired in this company. In the details that you present, we can follow with pleasure the march of nature, well felt and expressed with clarity and precision. The description of St Brieuc that you put at the head of your correspondence is undoubtedly sufficient for the purpose that you propose to fulfil entirely. But in addition to the study of epidemic diseases and the different constitutions peculiar to each town and each canton, one of the aims of the society, by bringing together the topographical descriptions of each region, is to form a general topography of the different provinces that make up France [...]". An engraved portrait is included.