Analyzes the formation of the collection of scientific instruments at the Museu Nacional's Biological Anthropology Sector (previously known as the Physical Anthropology Division), Brazil. It focuses on the instruments used for anthropometric measurements. By drawing relations between this collection and other of the institution's biological anthropology collections, as well as the activities of Museu Nacional researchers within their sociopolitical and academic contexts, we arrive at a privileged view of the scientific methods and theories in use in the final decades of the nineteenth century and beginning of the twentieth.