Spring has arrived, and with it, daylight saving time. As the clocks go forward an hour in the UK, as they did earlier this month in the US, we’re taking a look at how Greenwich became the home of time. A new book by Geographer Royal for Scotland, Professor Charles Withers, asks the question, how did the prime meridian, a singular world-ruling feature, come to be sited in southeast London? Why was it chosen over Washington, Paris, or Beijing? The passage below, excerpted from the prologue of Zero Degrees: Geographies of the Prime Meridian, explains how the choice of Greenwich to mark 0° longitude would go on to solve complex problems of global measurement that had engaged geographers, astronomers, and mariners since ancient times.
In November 1883, a sixty-seven-year-old English sailor addressed a letter to the world’s geographical societies. There are, he began, “some things that belong to all mankind.” What William Parker Snow had in mind was nothing less than a single prime meridian, a global base point or line to be used by all nations. From such an agreed point of terrestrial measurement, he reasoned, navigators and geographers could plot their voyages and align their maps, and perhaps astronomers could even chart the heavens, all using a standard point of earthly reference. One prime meridian for the world and only one, stressed Parker Snow, would be of “vast benefit to Science and Humanity.”
His appeal for a uniform base of measurement was rooted in personal experience. Born in 1817 in Poole, England, William Parker Snow was a sailor, an author, a sometime Patagonian colonist, a historian of the American Civil War, and, important to his own self-image, a veteran of Arctic exploration. He was also reputed to be psychic and lived, as one contemporary remarked, “on the edge of the Fourth Dimension.” Parker Snow’s supposed otherworldly powers, revealed in a dream in January 1850, convinced him (but few others) of the location of the ill-fated Franklin expedition that was lost in the Arctic in 1847–1848. As a young man, Parker Snow had himself nearly perished at sea during a storm when his vessel had a close encounter with another ship that had derived its mid-ocean position and course from an initial meridian different from his own.