Scienza, tecnologia ed economia nelle tecniche di navigazione attraverso i secoli: navigatori “pratici” o cronometri marini?

This article takes its cue from a centuries-old American publication used in the Navy, Nathaniel Bowditch’s The American Practical Navigator, to explore a fascinating page in the history of navigation, specifically concerning the determination of longitude at open sea. Knowing the position of a ship is, in fact, the first prerequisite for safety at sea, and full control of navigation is an essential strategic and geopolitical issue for a nation that wants to be a political, military, and economic power. The first edition of Bowditch’s text dates back to a period (the early 19th century) when the technical evolution of marine chronometers could (chronologically) have supplanted navigation based on the observation of the movement of the stars in the sky. Bowditch’s text, on the other hand, taught how to determine longitude at sea using the so-called ‘celestial methods’. It was so successful in the Navy (especially in the New World) that it became part of the equipment considered indispensable for navigation, as compass or sextant. The authors start from this apparent temporal inconsistency and set out to analyze it on the basis of historical, geographical, economic, and technological factors. There is often a certain reluctance to readily and fully adopt new technological tools; this phenomenon also occurred in the case of the marine chronometer, mainly for economic reasons. After a brief examination of the problem of longitude at sea and the main methods used to solve it, Bowditch’s work and its evolution to the present day are presented; the technical and historical analysis of the marine chronometer, from the time of the Longitude Act (1714) to the present day, highlights the close links and important strategic, technological, and economic significance of the two instruments, whose contribution to the sciences of navigation (and beyond) is worthy of consideration and reflection even today.