Meanings of Practice, Morals of Error: The Case of Gago Coutinho’s Salmoiraghi Theodolites

Abstract

This paper is about an unsuccessful scientific instrument. Since its conception, the four theodolites Portuguese naval officer, geographer, and later aviation pioneer Carlos Viegas Gago Coutinho (1869–1959) ordered from the Italian maker and engineer Angelo Salmoiraghi (1848–1939), which were used in surveying missions to the African colonies, caused problems and disagreements. From the user’s perspective, the instruments were poorly manufactured; from the maker’s perspective, the user’s incompetence was to blame. By focusing on a well-documented set of scientific instruments, I will analyse social features concerning scientific practice, material culture, and instrument trade. I will show how the meaning of an adapted and untrustworthy instrument changed during practice; how a crisis between distanced user and maker, concerning design, precision, and error, developed; and how a clash for scientific and professional authority intertwined moral and scientific attributes.