An unusual compass, on which east and west are reversed, provides insight into the dynamics guiding our understanding of artifacts. By examining how such compasses were used in Tokugawa Japan (1600–1868), the benefits they brought, and how users knew how to read them, this article uncovers the cognitive factors that shape our interaction with technology. Building on the methodological approach of the distributed cognition theory, the article claims that reverse compasses allowed the user to conserve cognitive effort, which was particularly advantageous to Tokugawa-period mariners. Moreover, the article shows that even non-professional Tokugawa Japanese had a relatively easy time reading reverse compasses due to similarity between the compasses’ orientation and Tokugawa timekeeping practices. Building on the bodily and cognitive habits they had developed through the practices of keeping time, users could identify and interpret cultural cues embedded in the structure of reverse compasses.

Ludwik Antoni Birkenmajer (1855-1929), following along the paths pioneered by Leopold Prowe, Maximilian Curtze, Franz Hipler, and J. L. E. Dreyer, joined them as trailblazers of Copernican scholarship in the nineteenth century. Educated in the classics and mathematics, Birkenmajer began by examining more closely the Cracow background to Copernicus's development and studying his works and annotations in books he owned or read. Birkenmajer contributed many discoveries that eventually became common knowledge, and his studies loomed over Polish research on Copernicus into the 1970s. Focusing on historical context and his original insights, the essay reminds readers of his contributions (sections 1–2), relates them to discussions of Copernicus's precursors (section 3), to the debate about Maragha precedents (section 4), his reading of the Uppsala Notebook (sections 2 and 5), and his account of the origin of Copernicus's heliocentrism (section 6). By means of a more critical assessment of his interpretation, the essay revises earlier accounts, rescuing the original insights that mark Birkenmajer's most important contributions to current debates and his efforts to reconstruct Copernicus's path to heliocentrism.

This paper aims at understanding the concept of convention in mechanics as a notion transferred from the field of jurisprudence. This enables us to clarify it as a new epistemic category having a pertinent role in the transformation of mechanics in the nineteenth century. Such understanding permits a separation from linguistic and arbitrary conventions, thus highlighting its epistemic features and not transforming fundamental principles into mere arbitrary agreements. After addressing the main references in the literature discussing the role of convention in mechanics, we analyze its classical use as a concept originating from law. Then we explain its use by Carl G. Jacobi, Ferdinand F. Reech, and J. Henri Poincaré. Here we also show how their uses conform to the features analyzed regarding conventions in jurisprudence. Finally, we try to explain how the use of this concept, among other factors, contributed to the transformation of mechanics.