Historic time period: 1801–1861
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More About Lighthouses
Waterways can't be simply explored and mapped. They must also be marked, inspected, and continually maintained to ensure watercraft safety. River bottoms, shorelines, and harbors change continuously, sometimes from one day to the next—introducing a new danger where none existed before. Coastal and river travel are safe today largely because decades of vigilance and work. The U.S. Army Corps of Engineers, the U.S. Coast Guard, and its forerunner, the U.S. Lighthouse Service, have kept them so.
In fog or deep night, a lighthouse's beam warns ships away from dangers such as shorelines, shallow waters, and underwater rocks. Because the exact locations of lighthouses are marked on charts, the lights help seafarers figure out where they are. In the past, lighthouses keepers lived in lighthouses to make sure the lights were shining every night. Today, many lighthouses are run by computers.
Lighthouse Lenses
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.
The Lighthouse on Bolivar Point, Texas
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 1917, 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.
For More Information on Lighthouses
- To find the closest lighthouse, consider using the National Parks Service Web site specifically about lighthouses you can visit or a Coast Guard Web site.
- Visit the general Coast Guard Web site on lighthouses for more activities and images.
- For additional information on lighthouse lenses and an explanation of the different orders, check out the National Parks Service Web site.
