Magnetic influence on chronometers, 1798–1834: A case study

This paper examines the investigations carried out between 1798 and 1834 to determine whether, and how, magnetism affected the rate at which marine chronometers gained or lost time. There were persistent claims that chronometers systematically altered rate between those determined on land and those at sea, and magnetism was thought by some to be the most likely cause. Others disputed any rate difference at all. The experiments carried out to determine the influence of magnetism and those carried out to determine if there was a difference between land and sea rates of chronometers will be considered. The data will be re-analysed in an attempt to extract additional information to clarify the answers to these questions. The influence these experiments had on certain navigational practices will be discussed briefly.