Zero Degrees. Geographies of the Prime Meridian

For more than two decades, I have taught that a conference held in Washington, D.C. in 1884 fixed the Prime Meridian in Greenwich, and that until 1911, the French refused to endorse this decision, preferring their own prime meridian in Paris. Although this history is not incorrect, the purpose of Withers’ new book is to say “not so fast!” For one thing, more than one conference took place. The 1883 Rome International Geodetic Association (iga) effectively established the resolutions to which the parties subsequently agreed in Washington. For another, as Withers shows in an interesting chapter at the end of the book, the 1884 conference had a series of “afterlives” in which various interested parties (not just the French) tried to change the outcome.A prime meridian is a line from which degrees of longitude are measured. Although there is an obvious single line of zero latitude (the Equator), any line joining the poles can act as a longitudinal line of zero degrees. If there is “one line to rule the world,” as Withers puts it (5), thereby uniting all the maps, then having that line in your territory would be a coup. In the late nineteenth century, prime meridians were established (or proposed) in nearly two dozen cities—including Paris, Moscow, Washington D.C., New Orleans, Jerusalem (which had no observatory), the Canary Islands, and even the Great Pyramids of Giza. Yet Greenwich’s primacy was, if not inevitable, more than likely, if only because it was already widely adopted (including by the United States since 1850) for nautical purposes.The complexity of choosing a universal candidate from these options, however, involved more than simply politics. Withers shows that three interrelated issues had to be resolved—the location of the prime meridian, the setting of a universal time, and the viability of the metric system as a rational scheme of measurement. At the 1884 conference, the British were concerned that the adoption of Greenwich would lead to the adoption of the metric system, but they were able to deflect this issue bureaucratically. Regarding universal time, astronomical purposes had the day beginning at noon, whereas civil purposes had it beginning at midnight. Withers discusses Sandford Fleming’s 1878 scheme for standard time zones in Chapter 4. The development of telegraphy and the need for standard train timetables (the cause attributed to a collision of two trains in 1853 was one of the trains running “behind time” [159]) made the establishment of a standardized clock essential. But what would be designated as “zero hour”? In an attempt at neutrality, Fleming fixed on the Bering Straits as passing through the least populated terrain, which, when “harmonized” with longitude, could act as an anti-meridian—that is, the meridian opposite the Prime Meridian (163), for which Fleming, using shipping tonnages, identified Greenwich as the leading candidate.Withers’ book is weighted toward the long process that culminated in 1884, devoting chapters to prime meridians prior to 1790, the Americas, and the globalizing of space and time before covering the conference and its aftermath and closing with a short summary of the highlights. The book will be of interest to historians of science, geodesists, geographers, cartographers, and archivists. As Withers explains, since no “prime meridian archive” exists (309), he was forced to delve widely into British, French, Canadian, and U.S. archives. In the end, he manages to untangle the complications surrounding the 1884 conference that ultimately resulted in the adoption of a single prime meridian, at the cost, perhaps, of excessive historical detail.

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