The aim of the AmateurS project is to write collectively a history of amateurs in science echoing the questions raised by contemporary participatory and citizen science and by sciences in the digital era. This history will take into account new perspectives formulated within the Science Studies and within social and cultural history. Our research is based on two hypotheses: 1° Looking at the past enriches our understanding of the present, by bringing continuities to light as much as by revealing the discontinuities emphasized in most surveys focusing on the 20th Century and on the present. 2° A transdisciplinary approach enhances our understanding of amateur activities in science. This project brings together historians of three scientific fields: two (astronomy and archaeology) are taken into account in many classical historical studies, one (medical sciences) is more original in this perspective, even though it is central in contemporary participatory and citizen science. The project is organized according to 3 research lines (WP) and one transversal theme. WP 1 - Figures of the amateur This WP relies on the production and the interpretation of a database collecting all the French publications (books and periodicals) displaying the word "amateur" in their title, between 1850 and 1950. Two sets (corpus) of sources (texts and images) will be extracted from the database, allowing the team to analyse the whole range amateur practices, the place of scientific activities among these practices, and the scientific fields favored by amateurs. Free access to the database will be granted to scholars and the general public at the end of the project, through a specifically designed digital platform. WP 2 - A subjective history of the amateur's worlds Identities and self definitions will be studied from a perspective "from below". The aim of this WP is to capture the amateurs' point of view on the science they practice, on their own identity as scientists, on their relations with the "professionals" and with other practioners they consider illegitimate. In this WP we will focus on two topics studied at a micro-historical scale: 1° conflicts shifting the boundaries between "amateurs" and "professionals", as well as instances of consolidation of these boundaries; 2° the social worlds and the personal networks of the amateurs. WP 3 - Practices and know-how This WP focuses on the material productions of the amateurs (instruments, experimental devices, scale models, images, etc.). In this WP we focus on the practical gestures and on the know-how which are mobililized by amateurs in the production of material devices, on the uses of these devices and on their circulation among a broader public. Transversal theme : Women as amateurs We will confront the results of our history of amateurs in science with the perspectives developed in the historiography of women in science.