Friday, December 7, 2012
In the McCurdy Family Maritime Gallery, MOHAI Public Historian Lorraine Mc Conaghy looks into the giant seven foot tall Fresnel lens on display in the Maritime room at the new Museum. For 73 years, this lens focused the flashing beacon of the lighthouse on Smith Island, at the southern entrance to Puget Sound's Rosario Strait. A light was established on Smith Island in 1857, warning mariners of hazard. This prismatic lens was manufactured in Paris in 1884, and was in use on Smith Island until 1957. The lens was developed in the mid-19th century by French engineer Augustin-Jean Fresnel, and replaced the heavy solid lens with a lighter and brighter concentric series of faceted prisms surrounding the central "bulls-eye." At the heart of the rotating Fresnel lens system was a brilliant light source - in the 1880s, a lard oil lamp, after 1910, an incandescent oil vapor lamp, after 1930, an electric light.
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