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Science Makes a Better Lighthouse Lens

Science Makes a Better Lighthouse Lens

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The first Fresnel lens, installed in the elegant Cardovan Tower lighthouse on France's Gironde River in 1822, was visible to the horizon, more than 20 miles away. Sailors had long romanticized lighthouses. Now scientists could rhapsodize, too. "Nothing can be more beautiful than an entire apparatus for a fixed light," one engineer said of Fresnel's device. "I know of no work of art more beautifully creditable to the boldness, ardor, intelligence, and zeal of the artist."

Fresnel lenses soon shone along the ragged coastlines of Europe, but surprisingly, America was slower to see the light. As mariners came to depend on Europe's powerful new lights, they complained bitterly about the puny lamps lighting America's coasts. Despite the clear superiority of Fresnel lenses, the parsimonious bureaucrat in charge of federal lighthouses, Stephen Pleasanton, considered the cost prohibitive. Finally, the uproar became so great that in 1838 Congress launched an investigation. It was not until then that Congress coughed up the cash to import a few Fresnel lenses. The first were installed in 1841 inside the two towers at Navesink Lighthouse, overlooking the approach to New York Harbor.

Only after 1852, when the United States created a Lighthouse Board made up of eminent scientists and mariners, including Joseph Henry of the Smithsonian and Alexander Bache of the U.S. Coast Survey, did the great lenses really begin to light America's coastline. By the Civil War, nearly all lighthouses in the United States had Fresnel lenses. It was shortly after the Civil War, however, before a beehive of prisms first shone from the Bolivar Light watching over Galveston. A Fresnel lens, similar to the one on display at NMAH, was still in use there in September 1900, when waves from the Gulf of Mexico began pounding the coast.

Late in the morning of September 7, the U.S. Weather Station in Galveston learned by telegraph that a hurricane had just ripped across Florida and was somewhere over the Gulf. The next day, a telegrapher wired Washington, D.C. that Galveston was going under. Thousands died. Among the survivors were 125 people who found safety in the lighthouse. Keeper H. C. Claiborne exhausted a month's supply of food feeding the crowd. When the tower swayed in the wind, disabling the machinery that rotated the lens, Claiborne turned the lens by hand crank and kept the Bolivar Light shining through that terrible night.

With time, Galveston recovered. The Bolivar Light served the city until 1933, then was replaced by another light on the south side of Galveston. The museum's lens served through the Galveston hurricane of 1915, then retired with the lighthouse and was stored by the U.S. Department of the Interior until it was transferred to the Smithsonian in 1976. By then, Augustin Jean Fresnel, who lived only a short while after inventing his great device, had been dead for nearly a century and a half. Along with the lens, Fresnel left behind his theories of light, which form the basis of modern optics. Today, the principle behind the Fresnel lens is used in the headlights of cars and in the flashing lights on police and emergency vehicles. And in a few older lighthouses around the country, and the world, Fresnel's elegant beehives still shine.

By Bruce Watson


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