Reading Group Guides for the Search for Longitude

The Biggest Peril to Ships for Near of History

By CHRISTOPHER LEHMANN-HAUPT

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LONGITUDE
The True Story of a Lonely Genius Who Solved the Greatest Scientific Problem of His Fourth dimension
By Dava Sobel

irst, is anybody clear on the difference between longitude and latitude? In her elegant history, ''Longitude: The True Story of a Solitary Genius Who Solved the Greatest Scientific Problem of His Time,'' Dava Sobel writes that ''the trick for remembering the departure'' is that ''the latitude lines, the parallels, really practise stay parallel to each other as they girdle the globe'' in a series of concentric circles that are smaller the farther they are from the equator.

Whereas: ''The meridians of longitude go the other way: They loop from the North Pole to the South and back again in great circles of the same size, so they all converge at the ends of the world.'' (Although Ms. Sobel never explains how to remember that it'due south the latitudes and not the longitudes that are parallel, ane trick is to associate the ''a'' sounds in breadth and parallel.)

But the real difference, equally the she notes, is that the zero-degree parallel of breadth is fixed past nature and is the equator, while the zero-degree meridian of longitude is simply wherever science decides to place it (for more than 200 years at Greenwich, England). She concludes, ''This deviation makes finding breadth child'south play, and turns the decision of longitude, especially at sea, into an developed dilemma -- one that stumped the wisest minds of the world for the improve part of homo history.'' In fact, so frustrating was this problem that information technology came to exist thought of equally synonymous with impossibility.

The inability to solve the longitude problem for so long also had dire consequences. If a ship didn't know how far to the e or west it had traveled, then information technology didn't know where land was likely to be, and the unexpected contiguity of land had a manner of causing ships to sink with a frequent loss of human lives. Eventually, Ms. Sobel writes, a especially disastrous wreck at the Scilly Isles, near the southwestern tip of England, ''precipitated the famed Longitude Act of 1714, in which Parliament promised a prize of $:20,000 for a solution to the longitude problem'' (which would be millions of dollars today).

The answer lay in e'er knowing what time information technology was at an agreed-upon zero-top, besides every bit aboard the send (by setting the local clock to noon when the sun was direct overhead). The 2 clock times would so enable the mariner ''to convert the 60 minutes difference into a geographical separation,'' Ms. Sobel writes, since 1 hour of departure in fourth dimension equals 15 degrees of longitude separation.

The problem lay in keeping rails of the starting-point time. No clocks existed that could withstand either the temperature changes or the move of ships at sea. The heavens weren't even so mapped in enough item to summate a remote time from the position of the moon relative to the stars.

Even less promising were crackpot suggestions like taking forth on shipboard a wounded domestic dog that would presumably yelp on cue whenever someone at home would dip a cloth soaked with its claret in a solution of the miraculous ''pulverisation of sympathy.'' (The history of this procedure plays an important function in the plot of Umberto Eco's new novel, ''The Island of the Day Before.'')

Ms. Sobel reveals in her opening chapter that the problem of longitude was eventually solved by i John Harrison, an unschooled woodworker who had the genius to invent a pendulum-free clock that required no oil and ''would carry the truthful time from the dwelling port, like an eternal flame, to whatever remote corner of the world.''

For a moment, the reader is disappointed that Ms. Sobel has given abroad the outcome so apace. Only to feel so is to reckon without her remarkable ability to tell a story with clarity and perfect pacing. The wonder of Harrison is that he seemed to come out of nowhere, without educational activity and without apprenticeship in clockmaking. Nevertheless the clarity of a mind that could dream up the escapement mechanism, among other novel clock parts, was not reflected in his ability to express himself.

Equally Ms. Sobel puts it, ''He wrote with the scrivener's equivalent of marbles in his mouth.'' Describing his first encounter with a potential patron of his piece of work, he wrote, ''Mr. Graham began as I thought very roughly with me, and the which had similar to take occasioned me to get crude too; merely even so we got the ice broke . . . and indeed he became as at last vastly surprised at the thoughts or methods I had taken.''

Others as well were very crude with Harrison. Although his clocks functioned perfectly and made it simple for ocean captains to summate longitude, the people awarding the prize, being astronomers, were increasingly biased toward a solution involving the lunar distance method, even though such calculations took over iv hours to complete and were highly vulnerable to error. Every bit Ms. Sobel tells of Harrison'due south struggles, one wants to hiss the royal astronomers who went so far as to sabotage Harrison's clocks.

Somewhen his son, William, appealed to King George III, who reportedly muttered nether his breath, ''These people have been cruelly treated,'' and said aloud to William, ''By God, Harrison, I volition see you righted.'' But the recognition and money consequently granted Harrison by Parliament were non near equally much proof of his success as the spreading use of his clocks, which eventually were mass produced and finally evolved into today's Swatch spotter.

Ms. Sobel, a quondam science reporter for The New York Times, confesses in her source notes that ''for a few months at the commencement, I maintained the insane thought that I could write this book without traveling to England and seeing the timekeepers firsthand.'' Eventually she did visit the National Maritime Museum in Greenwich, where the iv clocks that James Harrison constructed are exhibited.

She writes, ''Coming face up with these machines at last -- after having read endless accounts of their structure and trial, after having seen every detail of their insides and outsides in still and moving pictures -- reduced me to tears.''

Such is the eloquence of this gem of a volume that information technology makes you sympathise exactly how she felt.

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Source: https://www.nytimes.com/books/97/03/09/bsp/longitude.html

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