Since its foundation in 1794, the Conservatoire des Arts et Métiers has been both a place of professional education and of demonstration of machines used in the production process. That raises the question of the transmission of technical knowledge to different audiences, as well as the issue of knowledge legitimization. At the Conservatoire, thanks to the system of chairs, knowledge is constructed not in regards to academic disciplines, but according to know-how. Two sorts of audiences were progressively distinguished. On the one hand, an audience composed of training professionals; in this case, knowledge is legitimate since it allows the trainee to be an efficient worker. On the other hand, the general public, for whom are set up public conferences and the Museum of Arts and Crafts; in this case, knowledge is legitimate because it educates the audience. However, in both cases, these aims are subordinated to the national industrial progress.JEL Codes: I23