"The windiest & foggiest place on the... " a Point Reyes Station Travel Page by JLBG

Point Reyes National Seashore, in Marin County, is, by official records, the windiest and foggiest place on the Pacific Coast.

The Miwok Indians were the first inhabitants of the land that is now Point Reyes National Seashore. It seems that in 1579, Sir Francis Drake was the first European that landed on this shore, The coast is very dangerous and so many wrecks took place that a light house was built. It was a very hard work and was first lit in 1870 and retired from service in 1975. It is now a historic building, run by the National Park Service inside %L[http://www.nps.gov/pore/ ]Point Reyes National Seashore%L*.

The lighthouse was equipped with lens and mechanism that had been constructed in France. The lens were Fresnel lens that were developed by Augustin-Jean Fresnel, a French physicist that used the Huygens–Fresnel principle.

I borrow a definition from a technical document:

Fresnel lens were originally developed for lighthouses. The Fresnel lens reduces the amount of material required compared to a conventional spherical lens by breaking the lens into a set of concentric annular sections known as Fresnel zones. For each of these zones, the overall thickness of the lens is decreased, effectively chopping the continuous surface of a standard lens into a set of surfaces of the same curvature, with discontinuities between them. This allows a substantial reduction in thickness (and thus weight and volume of material) of the lens

Since 1813, Fresnel was assistant to François Arago, another physicist, as Head of the French “service des phares et balises” (lighthouses and beacons office). They improved in different ways the lightening systems for lighthouses: use of lamps with a series of concentric wicks fed with oil under pressure, use of various devices to concentrate the light in one direction. A first system of lens was set up on the Arc de Triomphe in 1822 and was seen 32 km away. It was set up on most lighthouses, both in France and abroad. The system was improved to what is now named Fresnel lens in 1843 and in the following years was used worldwide in lighthouses.