A rare, perhaps unprecedented, renovation project is pumping new life into the historic but deteriorating little Point Cabrillo Lighthouse that has stood sentinel since 1908 on the awesomely beautiful and rugged headlands of California’s Mendocino Coast north of San Francisco.
Nearly a generation ago, the powerful beam of the lighthouse’s classic Fresnel lens went dark and ceased to sweep and probe the foggy, treacherous seas offshore. The lens was shut down in the early 1970s when the U.S. Coast Guard attached an ungainly little automated beacon to the roof of the lighthouse where it has flickered ever since.
But now, an unusual collaborative effort spearheaded by a private conservation group and joined by the Coast Guard, the state of California, and a team of volunteers is bringing the Fresnel back to life. The renovation project, which will refurbish the lighthouse as well as the lens, is expected to cost more than $200,000. The target date for completion is August 7 of next year, National Lighthouse Day. Renovators have gingerly lifted the Fresnel lens from the lighthouse lantern room, piece by numbered piece, bolt by numbered bolt, and placed it in a ground-floor room for painstaking restoration. The lantern room itself may come off so its corroded facade can be restored.
Officials of the North Coast Interpretive Association (NCIA), the private organization that manages the lighthouse and is leading the refurbishment effort, say they know of no other Fresnel lens that has been removed from its lantern room, renovated, and put back in operation.
The lens, designed early in the 19th century by a sickly genius who had the temerity to challenge the optics theories of Newtonand the audacity to be rightrevolutionized lighthouse lighting.
Before Augustin Jean Fresnel invented his lens in 1822, lantern rooms of lighthouses around the world were equipped with parabolic reflectors, sometimes dozens of them, each reflector with its own lamp that had to be carefully tended. These were an inefficient and relatively weak lighting source.
The Fresnel lens employs only a single lamp and a system of prisms in a brass frame. The prisms bend the lamp’s rays into sheets of light, casting beams out to sea as far as 22 miles, more than twice the distance of the older reflector systems.
In 1822, when Fresnel was 34 years old, only five years before he would die of consumption, he saw his lens installed in the famous lighthouse at the mouth of France’s Gironde River. Soon all of Europe used the Fresnel lens to make dangerous waters safer for shipping. By 1852, the lens was employed in the United States as well.
While modern navigation no longer depends on the Fresnel, of course, its optic principles are still very much alive. Automobile headlights and taillights, for example, use plastic versions of the Fresnel lens.
"It’s not dead technology," said Julia McIver, ex-ecutive director of NCIA. "And this lens just happens to be one of the more beautiful examples of that technologyIt is the heart of the lighthouse."