Galileo Galilei, le « mesureur du temps » et les longitudes: Une interprétation nouvelle de l’instrument proposé par Galilée en 1637

Abstract

Galileo Galilei, The Problem of Longitudes and the “Time Measurer”: A New Interpretation of the Instrument Proposed by Galileo in 1637 The determination of any position on the Earth’s surface occupied lengthily (and still does) the human ingenuity and Galileo Galilei was no exception to this rule. In the early seventeenth c., although latitude was safely determined, longitude was a difficult problem to solve, especially when the position to define was that of a ship. The challenge of finding a way to determine longitudes was of prime importance for the European maritime and warlike countries. Whoever managed to make transatlantic journeys with the greatest efficiency and speed would become the master of new territories and of new products to be commercialised. Galileo took an active part in this matter. In 1610 he discovered four Jovian satellites and saw through this discovery a solution to the longitude problem. Later he invented an instrument that would contribute to the perfection of astronomical observations and participate to the longitude solution. The aim of this paper is to present a detailed analysis of this outstanding instrument, a unique pendulum conceived by Galileo Galilei at the end of 1637, and to propose a new interpretation.