ESHS/HSS Annual Meeting

Longitude Measurements and the Reform of Cartography in Early Modern Europe: the Scientific Correspondence between Giovan Domenico Cassini and Luigi Ferdinando Marsili

• In Event: Scientific Disputes, Cosmological Theories from Scheiner to Cassini: Archival Sources from the 17th Century 2

English Abstract

Not long before the era of longitude measurements taken at sea using the celebrated Harrison chronometers, developed by the mid-18th century, early modern scientists were still tackling with the problem of determining longitude on land. Indeed, even at the end of the 17th century, the challenge of updating ancient maps—whose errors had been propagated from Ptolemy’s Geography through the Renaissance—remained unresolved.
This contribution offers an insight into the issue by focusing on the well-known astronomer Giovanni Domenico Cassini (1625–1712) and Luigi Ferdinando Marsili (1658–1730), the future founder of the Institute of Sciences in Bologna. Recent archival research has brought to light a scientific correspondence between the two, extending from 1695 to 1698. At the time, Cassini was perfecting his method of determining longitude using the satellites of Jupiter from the Observatoire Royal in Paris, while Marsili, travelling through Hungary as a military officer, attempted to apply the method. The instruments, observational data, analyses, and discussions exchanged between the two men—as they emerge from the archival material—will be presented.

Authors

• Eugenio Bertozzi, University of Bologna

• Laura Rigotti, University of Bologna