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Technological Innovations
Twin Lights holds a prominent place in American maritime history as the site of the first use of the Fresnel Lens. In 1841, two of these revolutionary lighthouse lenses were installed: a “first-order” light in the South Tower and a “second-order” light in the North Tower. Developed by French physicist Augustine Fresnel, they were far superior to any navigational lighting apparatus being used in the United States at that time.
The lenses resembled glass beehives and consisted of a series of prisms that surrounded a central light source. They were classified into seven sizes called orders. Seacoast lights like Twin Lights usually received a first or second order lens. With the installation of these Fresnel lenses, Twin Lights became the best coastal lighthouse in America.
An enormous electric-arc bivalve lens, measuring nine feet in diameter, replaced the South Tower beehive light in 1898. In order to illuminate this new lens, the Lighthouse Service built an electric generator house on site. It was one of the brightest navigational lights ever used in the United States. The beacon was visible for 22 miles and, under certain conditions could be seen reflecting in the night sky seventy miles away. The light was so bright that the North Tower was taken out of service not to be re-lit until 1962, when a smaller commemorative light was placed there.
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