On our recent visit to Pigeon Point Lighthouse we learned a couple of interesting facts about the large* Fresnel lens on display in the museum:
- The lens, consisting of 1,008 separate prisms, was manufactured in France in 1854 and originally installed in the Cape Hatteras light station. When the Hatteras tower was rebuilt in 1868, the lens was taken down and put into storage in New York. It was shipped to the west coast and put into service at Pigeon Point in 1871.
- The prisms are cleaned once a month using a solution of 2 parts distilled water to 1 part isopropyl alcohol and one drop of Woolite per quart.
*Fresnel lenses are classified in size/focal length as "orders", The modern designation 6th order being the smallest and ranging up to the huge 12' tall hyper-radial lens.
