The Astronomer Royal, the Hydrographer and the time ball: collaborations in timesignalling 1850-1910

摘要

This paper examines the relationship between the Admiralty and the RoyalObservatory, Greenwich, by studying the roles of the Hydrographer and the AstronomerRoyal as they worked together on the problem of communicating accurate time to ships. Thecollaboration between the Astronomer Royal and the Hydrographer directed the developmentof time balls and other visual signals throughout their period of use in Britain and its colonies.This paper focuses on the time ball and clock developed by the Astronomer Royal WilliamChristie and the Hydrographer William Wharton as a key example of significant and pro-ductive collaboration between the two institutions. The paper also highlights the importanceof the telegraph system to visual time signals. The ability to drop a time ball at a distance froman observatory created significant opportunities to improve the time signal service to marinersand stimulated further innovation in this field.