Lighthouses continued . . .
One innovation during the Pleasonton years had been the use of lightships—vessels moored in shallow water or near shoals where a lighthouse could not be built. The first lightship in the United States was installed at Willoughby Spit, Virginia, in 1820 but soon moved to Craney Island near Norfolk, Virginia, and quickly followed by four more in Chesapeake Bay. Like other navigational aids, lightships suffered during the Pleasonton administration—vessels were wooden, not designed for heavy seas, poorly equipped, manned by landsmen, and lacked relief ships (Noble 1997:129–32).
The U. S. Lighthouse Board also made many technological improvements, including the installation of Fresnel (Fruh-NEL) lenses. Developed in the 1810s by Frenchman August-Jean Fresnel and installed in French lighthouses in the early 1820s, the lenses were composed of concentric circles of prisms that directed the light to a central bullseye which concentrated it, resulting in a far brighter light than that from any other contemporary lens. By the Civil War, all U. S. lighthouses had Fresnel lenses (Noble 1997:22–25; NPS 2001).
Other technological improvements concerned lighthouse construction,lightships, buoys, and lamps. Screwpile and sunken caisson foundations were introduced in this period as well as lighthouses in wave-swept locations built of interlocking stones (Witney 1975:37–40, 44–45). Screwpile lighthouses replaced many lightships in Chesapeake Bay, and by 1889 the total number of lightships had dropped to 24. But with the development of iron steam-powered ships, the number again increased until there were 56 lightships in 1909 (Noble 1997:130; Flint n.d.:3). The lighthouse board replaced earlier copper-clad wooden buoys with iron ones, color-coding all buoys and other markers. Buoys still used bells and later whistles, the latter first introduced in 1876. Gas-lighted buoys began to be used in 1882. Improvements were also made to fog signals. Mechanically rung fog bells were introduced in the 1850s, later replaced by steam whistles, reed-trumpets, and siren-trumpets. Changes to navigational aids were published in the Notice to Mariners, a supplement to the Light List, which recorded all aids, their locations, and characteristics (NPS 2001). At the end ofthis period, the incandescent oil vapor (IOV) lamp was introduced. Similar to a huge Coleman lamp but fueled by kerosene, the lamp produced a far brighter light than earlier ones without increasing fuel consumption (Noble 1997:34).
By 1910, there were 11,713 navigational aids of all types of which 1,397 were major lighthouses (compared to 297 in 1852), too cumbersome for the administrative structure set up in 1852. Furthermore, Congress wanted lighthouses controlled by civilians rather than the military. In 1910, Congress abolished the old lighthouse board and created the Bureau of Lighthouses under the Commerce Department, to which lighthouses had already been transferred in 1903. (Noble 1997:30–32; NPS 2001)
U.S. Coast Guard (1939–present)—In 1939 the U.S. Lighthouse Service was transferred to the U.S. Coast Guard. Under the Coast Guard, especially with the Lighthouse Automation and Modernization Program (LAMP) beginning in the mid-1960s, automation proceeded apace. Lightships began to be replaced by structures similar to oil drilling platforms in the 1960s and by large navigational buoys (LNBs) in the 1970s. The last lightship (Nantucket I) was decommissioned in 1985, and by 1990 all lighthouses had been automated except Boston Light. (Noble 1997:38–40, 146–47; NPS 2001)
Prepared by Nancy S. Seasholes, 2009
Did You Know?
On September 1, 1905, Elliot Hadley lit the most powerful light in Massachusetts at the top of Graves Lighthouse, now in Boston Harbor Islands National Recreation Area. The first-order Fresnel lens aided in navigation and allowed for safe passage into Boston Harbor. More...