ESHS/HSS Annual Meeting

Analog Sines and Signs of Analogy – Some Clever Instrumental Ways to Lessen Trigonometric Ardor

• In Event: Contested Success and Celebrated Failure: The Practice of Mathematical Instruments in Varied Settings II

English Abstract

This paper follows a geometrical idea — a diagram for reading sines and cosines — across several instruments and contexts, from Islamic sine quadrants to Renaissance artifacts. Beginning with an anonymous astrolabe from ca. 1500 (Museu de Marinha, Lisbon) that displays such a diagram not often found on European astrolabes, it traces the motif through Petrus Apianus’s Instrumentum primi mobilis (1534) and a brass version signed by Egnatio Danti (1568, Museo Galileo); the latter instrument has recently been studied by Giorgio Strano and Gaia Gugini, who also showed how it relates to other instruments, including a quadrant by Thomas Gemini. Examining these instruments through the lenses of making, use, and patronage highlights how the same trigonometric device served distinct aims — epistemic, ornamental, or courtly — and depended on different criteria of success. By comparing these reappearances, the paper asks how a seemingly stable diagram could travel and transform, revealing the plural categories that sustained the practice of “doing geometry”.

Authors

• Samuel GESSNER, Centro Interuniversitário de História das Ciências e da Tecnologia, University of Lisbon

• Michael Korey, Mathematisch-Physikalischer Salon (Staatliche Kunstsammlungen Dresden)