This chapter focuses on the material practices of nineteenth-century science. The sciences made knowledge claims in the service of empire, both implicitly and explicitly. The chapter argues that the nineteenth-century witnessed a significant period of internationalization and expansion that laid the foundations of modern globalized science. Nineteenth-century sciences depended upon practices that both constituted and benefited imperialism. Reconnaissance through mapping, fieldwork and exploration was often integral to global political and military activity. Telegraphy became one of the most important new technologies that made it possible to communicate across vast distances speedily. Ordering globalized scientific knowledge has often been characterized as a process of extraction from the periphery and classification in the metropole; however, this underestimates the extent to which local knowledge was crucial to European attempts at classification. The development of both international congresses and world fairs, for example, provided opportunities for collaboration, showcasing work and conducting national rivalries.