Longitude

by Dava Sobel

  It was not uncommon for one ship to rely on two or even three chronometers, so that the several timekeepers could keep tabs on each other. Big surveying ships might carry as many as forty chronometers. Records show that when H.M.S. Beagle set out in 1831, bent on fixing the longitudes of foreign lands, she had twenty-two chronometers along to do the job. Half of these had been supplied by the Admiralty, while six belonged personally to Captain Robert Fitzroy, who had the remaining five on loan. This same long voyage of the Beagle introduced its official naturalist, the young Charles Darwin, to the wildlife of the Galápagos Islands.

  In 1860, when the Royal Navy counted fewer than two hundred ships on all seven seas, it owned close to eight hundred chronometers. Clearly, this was an idea whose time had come. The infinite practicality of John Harrison’s approach had been demonstrated so thoroughly that its once formidable competition simply disappeared. Having established itself securely on shipboard, the chronometer was soon taken for granted, like any other essential thing, and the whole question of its contentious history, along with the name of its original inventor, dropped from the consciousness of the seamen who used it every day.

  15.

  In the Meridian

  Courtyard

  “What’s the good of Mercator’s North Poles and Equators,

  Tropics, Zones, and Meridian Lines?”

  So the Bellman would cry: and the crew would reply

  “They are merely conventional signs!”

  —LEWIS CARROLL, “The Hunting of the Snark”

  I am standing on the prime meridian of the world, zero degrees longitude, the center of time and space, literally the place where East meets West. It’s paved right into the courtyard of the Old a Royal Observatory at Greenwich. At night, buried lights shine through the glass-covered meridian line, so it glows like a man-made midocean rift, splitting the globe in two equal halves with all the authority of the Equator. For a little added fanfare after dark, a green laser projects the meridian’s visibility ten miles across the valley to Essex.

  Unstoppable as a comic book superhero, the line cuts through the nearby structures. It appears as a brass strip on the wooden floors of the Meridian House, then transforms into a single row of red blips that recall an airplane’s emergency exit lighting system. Outside, where the prime meridian threads its way among the cobblestones, concrete slab stripes run alongside it, with brass letters and tick marks announcing the names and latitudes of the world’s great cities.

  A strategically placed machine offers to issue me a souvenir ticket stamped with the precise moment—to one-hundredth of a second—when I straddled the prime meridian. But this is just a sideshow attraction, with a price of £1 per ticket. Actual Greenwich mean time, by which the world sets its watch, is indicated far more precisely, to within millionths of seconds, inside the Meridian House on an atomic clock whose digital display changes too fast for the eye to follow.

  Nevil Maskelyne, fifth astronomer royal, brought the prime meridian to this location, seven miles from the heart of London. During the years he lived on the Observatory site, from 1765 to his death in 1811, Maskelyne published forty-nine issues of the comprehensive Nautical Almanac. He figured all of the lunar-solar and lunar-stellar distances listed in the Almanac from the Greenwich meridian. And so, starting with the very first volume in 1767, sailors all over the world who relied on Maskelyne’s tables began to calculate their longitude from Greenwich. Previously, they had been content to express their position as degrees east or west of any convenient meridian. Most often they used their point of departure—”three degrees twenty-seven minutes west of the Lizard,” for example—or their destination. But Maskelyne’s tables not only made the lunar distance method practicable, they also made the Greenwich meridian the universal reference point. Even the French translations of the Nautical Almanac retained Maskelyne’s calculations from Greenwich—in spite of the fact that every other table in the Connaissance des Temps considered the Paris meridian as the prime.

  This homage to Greenwich might have been expected to diminish after chronometers triumphed over lunars as the method of choice for finding longitude. But in fact the opposite occurred. Navigators still needed to make lunar distance observations from time to time, in order to verify their chronometers. Opening to the appropriate pages in the Nautical Almanac, they naturally computed their longitude east or west of Greenwich, no matter where they had come from or where they were going. Cartographers who sailed on mapping voyages to uncharted lands likewise recorded the longitudes of those places with respect to the Greenwich meridian.

  In 1884, at the International Meridian Conference held in Washington, D.C., representatives from twenty-six countries voted to make the common practice official. They declared the Greenwich meridian the prime meridian of the world. This decision did not sit well with the French, however, who continued to recognize their own Paris Observatory meridian, a little more than two degrees east of Greenwich, as the starting line for another twenty-seven years, until 1911. (Even then, they hesitated to refer directly to Greenwich mean time, preferring the locution “Paris Mean Time, retarded by nine minutes twenty-one seconds.”)

  Since time is longitude and longitude time, the Old Royal Observatory is also the keeper of the stroke of midnight. Day begins at Greenwich. Time zones the world over run a legislated number of hours ahead of or behind Greenwich mean time (GMT). Greenwich time even extends into outer space: Astronomers use GMT to time predictions and observations, except that they call it Universal Time, or UT, in their celestial calendars.

  Half a century before the entire world population began taking its time cues from Greenwich, the observatory officials provided a visual signal from the top of Flamsteed House to ships in the Thames. When naval captains were anchored on the river, they could set their chronometers by the dropping of a ball every day at thirteen hundred hours—1 P.M.

  Though modern ships rely on radio and satellite signals, the ceremony of the ball continues on a daily basis in the Meridian Courtyard, as it has done every day since 1833. People expect it, like teatime. Accordingly, at 12:55 P.M., a slightly battered red ball climbs halfway up the mast to the weather vane. It hovers there for three minutes, by way of warning. Then it ascends to its summit and waits another two minutes. Mobs of school groups and self-conscious adults find themselves craning their necks, staring at this target, which resembles nothing so much as an antiquated diving bell. It’s a far cry, indeed, from the glitz of Times Square on New Year’s Eve.

  This more frequent, oddly anachronistic event has a genteel feel. How lovely the red metal looks against the blue October sky, where a stout west wind drives puffs of clouds over the twin observatory towers. Even the youngest children are quiet, expectant.

  At one o’clock, the ball drops, like a fireman descending a very short pole. Nothing about the motion even suggests high technology or precision timekeeping. Yet it was this ball and other time balls and time guns at ports around the world that finally gave mariners a way to reckon their chronometers— without resorting to lunars more than once every few weeks at sea.

  Inside Flamsteed House, where Harrison first sought the advice and counsel of Edmond Halley in 1730, the Harrison timekeepers hold court in their present places of honor. The big sea clocks, H-1, H-2, and H-3, were brought here to Greenwich in a rather dishonorable fashion, after being rudely removed from Harrison’s house on May 23, 1766. Maskelyne never wound them, nor tended to them after testing them, but simply consigned them to a damp storage area where they were forgotten for the rest of his lifetime— and where they remained for another twenty-five years following his death. By the time one of John Roger Arnold’s associates, E. J. Dent, offered to clean the big clocks for free in 1836, the necessary refurbishing required a four-year effort on Dent’s part. Some of the blame for the sea clocks’ deterioration lay with their original cases, which were not airtight. However, Dent put the cleaned timekeepers back in their cases just as he’d found them, inviting a new
round of decay to commence immediately.

  When Lieutenant Commander Rupert T. Gould of the Royal Navy took an interest in the timekeepers in 1920, he later recalled, “All were dirty, defective and corroded—while No. 1, in particular, looked as though it had gone down with the Royal George and had been on the bottom ever since. It was completely covered—even the wooden portions—with a bluish-green patina.”

  Gould, a man of great sensitivity, was so appalled by this pitiful neglect that he sought permission to restore all four (the three clocks and the Watch) to working order. He offered to do the work, which took him twelve years, without pay, and despite the fact that he had no horological training.

  “I reflected that, so far as that was concerned, Harrison and I were in the same boat,” Gould remarked with typical good humor, “and that if I started with No. 1 I could scarcely do that machine any further harm.” So he set to right away with an ordinary hat brush, removing two full ounces of dirt and verdigris from H-1.

  Tragic events in Gould’s own life inured him to the difficulty of the job he had volunteered for. Compared to the mental breakdown he suffered at the outset of World War I, which barred him from active duty, and his unhappy marriage and separation, described in the Daily Mail in such lurid detail that he lost his naval commission, the years of attic seclusion with the strange, obsolete timepieces were positively therapeutic for Gould. By putting them to rights, he nursed himself back to health and peace of mind.

  It seems only proper that more than half of Gould’s repair work—seven years by his count—fell to H-3, which had taken Harrison the longest time to build. Indeed, Harrison’s problems begat Gould’s:

  “No. 3 is not merely complicated, like No. 2,” Gould told a gathering of the Society for Nautical Research in 1935, “it is abstruse. It embodies several devices which are entirely unique—devices which no clockmaker has ever thought of using, and which Harrison invented as the result of tackling his mechanical problems as an engineer might, and not as a clockmaker would.” In more than one instance, Gould found to his chagrin that “remains of some device which Harrison had tried and subsequently discarded had been left in situ.” He had to pick through these red herrings to find the devices truly deserving of salvage.

  Unlike Dent before him, who had merely cleaned the machines and sawed off the rough edges of broken pieces to make them look neat, Gould wanted to make everything whir and tick and keep perfect time again.

  While he worked, Gould filled eighteen notebooks with meticulous colored-ink drawings and elaborate verbal descriptions far clearer than any Harrison ever wrote. These he intended for his own use, to guide him through repetitions of difficult procedures, and to save himself the needless repetition of costly mistakes. The removal or replacement of the escapements in H-3, for example, routinely took eight hours, and Gould was forced to go through the routine at least forty times.

  As for H-4, the Watch, “It took me three days to learn the trick of getting the hands off,” Gould reported. “I more than once believed that they were welded on.”

  Although he cleaned H-1 first, he restored it last. This turned out to be a good thing, since H-1 was missing so many pieces that Gould needed the experience of exploring the others before he could handle H-1 with confidence: “There were no mainsprings, no mainspring-barrels, no chains, no escapements, no balance-springs, no banking-springs, and no winding gear . . . Five out of the twenty-four anti-friction wheels had vanished. Many parts of the complicated gridiron compensation were missing, and most of the others defective. The seconds-hand was gone and the hour-hand cracked. As for the small parts—pins, screws, etc.— scarcely one in ten remained.”

  The symmetry of H-1, however, and Gould’s own determination, allowed him to duplicate many absent parts from their surviving counterparts.

  “The worst job was the last,” he confessed, “adjusting the little steel check-pieces on the balance-springs; a process which I can only describe as like trying to thread a needle stuck into the tailboard of a motor-lorry which you are chasing on a bicycle. I finished this, with a gale lashing the rain on to the windows of my garret, about 4 P.M. on February 1st, 1933—and five minutes later No. 1 had begun to go again for the first time since June 17th, 1767: an interval of 165 years.”

  Thanks to Gould’s efforts, the clock is still going now, in the observatory gallery. The restored time-pieces constitute John Harrison’s enduring memorial, just as St. Paul’s Cathedral serves as monument to Christopher Wren. Although Harrison’s actual remains are entombed some miles northwest of Greenwich, in the cemetery of St. John’s Church, Hampstead, where his wife, the second Elizabeth, and his son, William, lie buried with him, his mind and heart are here.

  The Maritime Museum curator who now cares for the sea clocks refers to them reverently as “the Harrisons,” as though they were a family of people instead of things. He dons white gloves to unlock their exhibit boxes and wind them, early every morning, before the visitors arrive. Each lock admits two different keys that work in concert, as on a modern safe deposit box—and reminiscent of the shared-key safeguards that prevailed in the clock trials of the eighteenth century.

  H-1 requires one deft, downward pull on its brass-link chain. H-2 and H-3 take a turn with a winding key. That keeps them going. H-4 hibernates, unmoving and untouchable, mated for life with K-1 in the see-through cave they share.

  Coming face-to-face with these machines at last— after having read countless accounts of their construction and trial, after having seen every detail of their insides and outsides in still and moving pictures— reduced me to tears. I wandered among them for hours, until I became distracted by a little girl about six years old, with a tussle of blond curls and a big Band-Aid angled above her left eye. She was viewing an automatically repeating color animation of the H-1 mechanism, over and over, sometimes staring intently at it, sometimes laughing out loud. In her excitement, she could hardly keep her hands off the small television screen, although her father, when he caught her at this, pulled them away. With his permission, I asked her what it was she liked so much about the film.

  “I don’t know,” she answered. “I just like it.”

  I liked it, too.

  I liked the way the rocking, interconnected components kept their steady beat, even as the cartoon clock tilted to climb up and then slide down the shaded waves. A visual synecdoche, this clock came to life not only as the true time but also as a ship at sea, sailing mile after nautical mile over the bounding time zones.

  With his marine clocks, John Harrison tested the waters of space-time. He succeeded, against all odds, in using the fourth—temporal—dimension to link points on the three-dimensional globe. He wrested the world’s whereabouts from the stars, and locked the secret in a pocket watch.

  Acknowledgments

  Thank you, William J. H. Andrewes, the David P. Wheatland Curator of the Collection of Historical Scientific Instruments at Harvard University, for first introducing me to the lore of longitude, and for hosting the Longitude Symposium in Cambridge, November 4-6, 1993.

  Thanks, too, to the editors of Harvard Magazine— especially John Bethell, Christopher Reed, Jean Martin, and Janet Hawkins—for sending me to the Longitude Symposium and publishing my article about it as the cover story in the March/April 1994 issue.

  Thanks also to the judges of the Council for the Advancement and Support of Education, Publications Division, for awarding my longitude article their 1994 Gold Medal for the best feature in an alumni magazine.

  Special thanks to George Gibson, Publisher of Walker and Company, for reading that article, seeing it as the beginning of a book—and calling me out of the blue to say so.

  And to Michael Carlisle, Vice President of the William Morris Agency, thank you so much for representing this project with more than your usual flair.

  Sources

  Because this book is intended as a popular account, not a scholarly study, I have avoided using footnotes or mentioning, in the body of
the text, most of the names of the historians I have interviewed or the works I have read and relied on for my own writing. I owe them all many thanks.

  The speakers at the Longitude Symposium (Harvard University, November 4-6, 1993) represent the world’s experts in their various subject matters, from horology to history of science, and they all contributed their knowledge to this slim volume. Will Andrewes comes first alphabetically and actually. Jonathan Betts, Curator of Horology at the National Maritime Museum in Greenwich, England, also gave generously of his time and ideas. In addition to their guidance before the fact, Andrewes and Betts both read the manuscript, and made many helpful suggestions to keep it technically correct.

  I also wish to single out Owen Gingerich of the Harvard-Smithsonian Center for Astrophysics, who collected the also-ran solutions to the longitude problem outlined in Chapters 5 and 6, and termed them “nutty.” Gingerich uncovered the facts of the “powder of sympathy” approach by obtaining a rare copy of the pamphlet Curious Enquiries from his friend John H. Stanley, Head of Special Collections at the Brown University Library.

  Other symposium speakers, in alphabetical order, are Martin Burgess of the Harrison Research Group and the British Horological Institute; Catherine Cardinal, Curator of the Musée International d’Horlogerie in La Chaux-de-Fonds, Switzerland; Bruce Chandler of the City University of New York; George Daniels, former Master of The Worshipful Company of Clockmakers; H. Derek Howse of the Royal Navy (retired); Andrew L. King, clockmaker of Beckenham, Kent; David S. Landes, Coolidge Professor of History and Professor of Economics at Harvard; John H. Leopold, Assistant Keeper in the British Museum; Michael S. Mahoney of Princeton University; Willem Morzer Bruyns, Senior Curator of Navigation at the Rijksmuseum Nederlands Scheepvaartmuseum in Amsterdam; horological illustrator David M. Penney of London; precision watchmaker Anthony G. Randall of Sussex; Alan Neale Stimson of the National Maritime Museum, Greenwich; Norman J. W. Thrower, Professor of Geography Emeritus at U.C.L.A.; author and historian A. J. Turner of Paris; and Albert Van Helden, Chairman of the History Department at Rice University.