Fresnel Lens

Apostle Islands National Lakeshore includes seven light stations with a total of nine lighthouses, constructed between 1856 and 1915. Architecturally and historically significant, they also contained a technological marvel of the 19th century, the Fresnel lens. Designed by the French physicist, Augustin Fresnel, the lens is a series of prisms that bend and magnify the central light source, producing a beam of light that can be seen for miles.

Most of the original Fresnel lenses are lost, but there are two in the park's museum collection, the Devils Island Lens and this one from Michigan Island. This 3 ½ order Fresnel lens was installed in the Michigan Island Lighthouse in 1869. When a second, taller tower was erected at the station, in 1929, the lens was moved to the new tower. In 1972 the Coast Guard removed the lens, replacing it with a molded plastic fixture, and transferred it to the National Park Service. It is on display at the Bayfield Visitor Center.