Fresnel Lighthouse Lens
Grade Range: K-12
Resource Type(s): Artifacts, Primary Source
Date Posted: 3/27/2012
In the early nineteenth century, lighthouses in the United States were considered inferior to those in France and England. American mariners complained about the quality of the light emanating from local lighthouse towers, arguing that European lighthouses were more effective at shining bright beams of light over long distances. While American lighthouses relied on lamps and mirrors to direct mariners, European lighthouses were equipped with compact lenses that could shine for miles.
In 1822, French scientist Augustin-Jean Fresnel was studying optics and light waves. He discovered that by arranging a series of lenses and prisms into the shape of a beehive, the strength of lighthouse beams could be improved. His lens—known as the Fresnel lens—diffused light into beams that could be visible for miles. Fresnel designed his lenses in several different sizes, or orders. The first order lens, meant for use in coastal lighthouses, was the largest and the strongest lens. The sixth order lens was the smallest, designed for use in small harbors and ports.
By the 1860s, all of the lighthouses in the United States were fitted with Fresnel lenses. This lens came from a lighthouse on Bolivar Point, near Galveston, Texas. Galveston was the largest and busiest port in nineteenth-century Texas. Having a lighthouse here was imperative – the mouth of the bay provided entry to Houston and Texas City, as well as inland waterways. The Bolivar Point Light Station had second and third order Fresnel lenses over the years; this third order lens was installed in 1907. Its light could be seen from 17 miles away.
On 16-17 August 1915, a severe hurricane hit Galveston. As the storm grew worse, fifty to sixty people took refuge in the Bolivar Point Light Station. Around 9:15 PM, the light’s turning mechanism broke, forcing assistant lighthouse keeper J.B. Brooks to turn the Fresnel lens by hand. By 10 PM, the vibrations from the hurricane were so violent that Brooks began to worry the lens might shatter. He ceased turning the lens, trimmed the lamp wicks and worked to maintain a steady light through the night. The next morning, Brooks left the lighthouse to find Bolivar Point nearly swept away by the water.
Bolivar Point Light Station used this Fresnel lens until 1933. It was donated to the Smithsonian Institution by the National Park Service.
Science Standards (Grades 3-5)
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United States History Standards (Grades 5-12)