Returning in heavy fog from a mediterranean skirmish with the French on the night of October 22, 1707, four British warships were dashed to pieces on the coastal rocks of the Scilly Isles. Although Admiral Sir Clowdisley Shovell had been warned of danger the day before by a common seaman with his own dread reckoning of their cloudy passage, "such subversive navigation by an inferior was forbidden in the Royal Navy." So the sailor was hanged on the spot for mutiny, the fleet sailed on, and 2,000 troops drowned. Sir Clowdisley himself would wash ashore, where he was murdered on the beach by a woman who wanted his emerald ring.
So begins Longitude (Sunday, July 9; 8 p.m. to midnight; A&E), the absorbing docudrama based on Dava Sobel's terrific little science book of the same name published by Penguin. To sail the seas, we must see the world in imaginary lines like the Arctic Circle and the Tropic of Cancer. Lines of latitude are a constant series of shrinking concentric circles, mapped since Ptolemy, with the Equator marking the zero-degree parallel. So the sun commands: "Any sailor worth his salt," Sobel explains, "can gauge his latitude well enough by the length of the day, or by the height of the sun or known guide stars above the horizon."
Whereas meridians of longitude loop, from the North Pole to the South and back again, in great circles of the same size, converging at the ends of the earth. One degree of longitude equals four minutes all over the world, "but in terms of distance, one degree shrinks from sixty-eight miles at the Equator to virtually nothing at the poles," Sobel writes. To calculate your longitude at sea, you need to know what time it is onboard ship and also, at that very same moment, the local time in your home port. Zero degrees longitude, the prime meridian, could be anywhere -- and has been, from the designated home ports of Rome to Paris to Jerusalem to Philadelphia to St. Petersburg. Since the eighteenth century, we've most of us agreed to accept London as our home port and Greenwich mean as our local time, all because in eighteenth-century London a mechanic named John Harrison made the first seaworthy clock.
Sir Clowdisley lacked a reliable watch, and probably the brains as well to know he needed one. But his hanging of the common seaman who dared to calculate on his own is also conveniently symbolic. Longitude is as much about class as it is about science. It wonders out loud about who gets to be brilliant. The disaster of 1707 was the culmination of four centuries of bad luck, lost loot, and rampant scurvy so distressing to everybody from Galileo to Isaac Newton to the kings of France to the British East India Company, in a high-seas age of exploration, trade, plunder, and piracy, that in 1714 the British Parliament offered a king's ransom of £20,000 (several million dollars in today's currency) for a "Practicable and Useful" means of determining longitude. A Board of Longitude was established to assess any bright ideas. It took John Harrison more than 50 years to get his clock accepted by this board -- because he was neither a member of the Royal Society nor an astronomer nor a gentleman.
On television, he is Michael Gambon. And his loyal son William is Ian Hart. And his lifelong nemesis, Nevil Maskelyne, is Samuel West. (You may recognize the astronomer Maskelyne if you are a loyal reader of Thomas Pynchon. But I will get to Mason & Dixon in a minute, and to Umberto Eco's The Island of the Day Before. Longitude has a wonderful literary pedigree.) Adding to the bare-bones elegance of Sobel's book -- like a fine eighteenth-century timepiece itself, a sort of Mozart cuckoo clock -- director-screenwriter Charles Sturridge fleshes out the part of Rupert Gould (played by Jeremy Irons as if he were J. Robert Oppenheimer), who in the twentieth century would recover and refurbish not only Harrison's ingenious mechanisms but also his reputation. Thus these four hours flash forward and back from workbenches in two different eras. In both locations, women (Gemma Jones, Barbara Leigh-Hunt, Anna Chancellor) get short shrift. Like the latitudes, they are fixed, maybe even equatorial, while the men are loopy all over the place.
To be sure, the Board of Longitude had to consider a number of mad ideas, chief among them "Powder of Sympathy." "This miraculous powder," Sobel tells us, "could purportedly heal at a distance. All one had to do to unleash its magic was to apply it to an article from the ailing person. A bit of bandage from a wound, for example, when sprinkled with powder of sympathy, would hasten the closing of that wound" wherever the patient happened to be, with of course some pain involved. And so the notion of sending wounded dogs to sea; and then, ashore every day at noon, dipping their left-behind bandages in the Digby sympathy solution. The dog's yelp onboard would be a time cue for the captain: "The Sun is upon the meridian in London."
But mostly their minds were already made up that the solution would come from "lunar observations" by their established scientists, the mapping of the stars by such pet astronomers as Maskelyne, and the publishing of manuals and charts for navigators to consult, whenever, of course, the weather permitted. (John Harrison himself, despite his intimate acquaintance with pendulums, was notoriously prone to motion sickness, which made the high-seas testing of his "chronometers" a wretched trial.)
This accounts for the eighteenth-century craze for the "Transit of Venus" eclipse, which sent engineers like Charles Mason and Jeremiah Dixon off to Cape Town with their "Snouts," and Maskelyne himself to St. Helena. To give the prize to a village clock-maker, a very rude peasant indeed, would insult British science, Cambridge University, and the glorious twinship of privilege and credentials. Ultimately, King George III had to intercede on Harrison's behalf, and by then he was 80 years old and his grown son was feeling neglected.
It's an enthralling story, inside the official buildings, onboard the tall ships, deep down among the oak wheels and boxwood axles of Harrison's first clock -- his "grasshoppers" and his "gridirons," his "springing set of seesaws, self-contained and counterbalanced to withstand the wildest waves." My advice is to buy and read Sobel's paperback. Then, acquainted with the problems and personalities, watch the docudrama, where you'll actually see the fabulous clocks and get to seethe at the Board of Longitude. And then go on to read Eco's novel, which is full of Paris meridians, lunar parallaxes, the moons of Jupiter, and the Powder of Sympathy. And then finish up with Pynchon, in whose Mason & Dixon our heroes meet up with mad Maskelyne on St. Helena and first begin to intuit that somebody else is pulling their strings, that they serve an imperial puppet master for whom longitude is calculated in spices and slaves.