Antique navigation tools soar in valueBy Christa Worthington, N.Y. Times News Service
Nowadays, fixing longitude and latitude at sea can be done with the click of a button through satellite navigation. But that removes the human factor in pinpointing one's place on earth -- something always present when mariners used instruments of celestial navigation like 19th-century sextants in brass and 18th-century octants in ebony and ivory.
Used in tandem with marine chronometers until World War I, these hand-held relics of nautical adventure are increasingly sought by collectors, mainly yachtsmen and interior decorators, and have been gaining in value.
Prices at a recent sale of maritime ephemera at Christie's in London were double the estimates. Antique sextants and octants can bring $1,400 to $4,000 and as much as $8,000 when made by a well-known manufacturer.
"They are beautiful because they are working things," says John Badley, the senior director of Sotheby's in London and author of "Nautical Antiques and Collectibles."
Often fashioned with platinum or gold scales, sextants belonged to the ship captains, who carried them in custom-made mahogany cases. "They were something he got when he was a midshipman, and he went from boat to boat with it," Badley said. "When he was retired, it would have been passed on down the family." (Octants were even carved in relief on the gravestones of New England sea captains, as if to chart their way to heaven.)
The sextant, which measures one-sixth of a circle, has remained the most accurate manual instrument for charting by the stars since it was invented in 1757 by John Bird, an English instrument maker.
Knowing how to use a sextant is still the measure of seamanship: merchant vessels are required to have one aboard, along with a timepiece for calculating longitude, in the event of electronic failure. Until the 19th century, octants, which measure one-eighth of a circle, steered whalers around the globe.
Since Ptolemy, finding latitude, the distance north or south of the equator, has been relatively easy -- a matter of using an instrument like a sextant to measure the altitude of the pole star or the sun against the horizon.
Finding longitude (the meridians drawn from North Pole to South Pole) with any precision at sea was more difficult, and for centuries impossible, subjecting sailors to the luck of dead reckoning. (To do so required comparing the time aboard ship with that of some known longitude and thereby determining the distance traveled east or west.)
Embarrassed when four warships were wrecked against the rocks of the Scilly Isles off the coast of England because of navigational error, the British Parliament issued the Longitude Act of 1714, offering 20,000 pounds to anyone who could find a workable method of determining longitude at sea.
The solution came from a scorned carpenter, John Harrison, who perfected a precision marine chronometer in 1760. His struggle inspired Dava Sobel's 1995 surprise nonfiction best seller, "Longitude."
Another Englishman, Jesse Ramsden, refined the sextant in 1768 by developing a machine that could systematically mark the measures on its arc, making it more accurate and less expensive to produce. Used together to read longitude and latitude, the sextant and chronometer helped to build the British Empire and remained the most reliable system of navigation until radio and quartz technology replaced them.
Old chronometers set in mahogany boxes can range in price from $1,000 to tens of thousands of dollars.
Earlier instruments are rare and quite valuable. "Bizarre and eccentric" is how Charles Miller of Christie's in London describes some 15th- and 16th-century nautical devices. The cross staff -- a wooden, rectilinear rule -- caused sailors to go blind by having them look into the sun. It was replaced by the back staff, which allowed the navigator to sight with the sun behind him.
These can sell for $5,000 to $15,000 or more. They can be found along with rarities like the astrolabe, the first instrument of celestial navigation, through specialist dealers like Tesseract of Hastings-on-Hudson, N.Y., which publishes an extensive catalogue.
"Scientific instruments are coming into their own as benchmarks of our civilization," says William Andrewes, the David P. Wheatland Curator of the Collection of Historical Scientific Instruments at Harvard University.
Predominantly British, "the market for maritime ephemera is still immature in the U.S.," but is growing, said Justin Cobb, a consultant to Skinner, the Boston auction house that sells nautical artifacts as Americana.
Indeed, the challenge of navigating open water continues to intrigue. Right now, two seagoing movies, "Titanic" and "Amistad," and a best-selling nonfiction book, "The Perfect Storm,"about a New England fishing crew lost at sea, only add to the romance.
"It's part of the tradition and feeling of the sea to be able to use the sky," said Don Treworgy, associate director of the Mystic Seaport Museum in Connecticut, who teaches celestial navigation. With foresight, he has begun collecting outmoded instruments of radio and satellite navigation for the museum -- though his heart is elsewhere.
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