Lighthouses have always had two principal functions: to warn of danger from a spot that sailors could see from a safe distance both night and day, and to be guides into harbors or anchorages. Lighthouses also have become symbolic monuments of society’s efforts to reduce the hazards of seafaring. These structures were often constructed under precarious circumstances by skilled builders and were maintained, often at great personal risk, by dedicated keepers.
The dramatic settings and individual histories of lighthouses made them objects of interest to non-seafarers. But advances in technology have rendered many lighthouses obsolete, particularly those that were manned. During the late 20th century, the urge to save these symbols of our nautical heritage prompted the establishment of numerous lighthouse preservation organizations.
Lighthouses in the Ancient World
The first lighthouse on record was built on the island of Pharos. It was built for the purpose of guiding sailors safely into the harbor at Alexandria, Egypt. Alexander the Great founded this port city on the Mediterranean Sea in 332 B.C., and located it on the western edge of the Nile River delta to avoid the heavy silt and sediment loads deposited annually by the great river. Ptolemy, ruler of Egypt after Alexander’s death, authorized the building of the Pharos light in 290 B.C. Alexandria served ships carrying Egyptian grain and armies to ports around the Mediterranean, and proved important to the extension and maintenance of the Roman Empire.
The Pharos lighthouse stood for about 1,500 years, finally falling victim to earthquakes in A.D. 1326. An Arab traveling in 1166 described the lighthouse as follows: the lowest of three stages was a square about 183 feet high with a cylindrical core; the middle stage was octagonal with 60-foot sides and a height of about 90 feet; and the third stage was circular with a height of 24 feet. The total height, including the foundation, was about 384 feet. It was reported to have used fire at night and a sun-reflecting mirror during the day.
The Pharos lighthouse was memorialized on Roman coins, and its name is the base for the word “lighthouse” in Spanish and Italian (faro), Portuguese (farol), and French (phare). Even in Britain before 1600, a lighthouse was called a pharos.
The Romans have been credited with building more than thirty lighthouses throughout their provinces, including one in Spain at Corunna, in France at Boulogne (which survived until 1664), and in England alongside the harbor at Dover.
After the fall of the Roman Empire, no new lighthouses were constructed until the end of the so-called Dark Ages, when trade among ports on the Mediterranean and beyond began to expand. The Italians built a light tower in 1157 at Meloria and at other port cities thereafter, almost all of them harbor lights. It was not until the 15th century that lighthouses began to be installed offshore to warn seamen of hazards to their vessels along routes to the port cities. Alan Stevenson estimated that the number of lighthouses worldwide grew from about 34 in 1600 to approximately 175 in 1800.
Lighthouses in America
The first “lighthouses” in the Americas probably consisted of small fires on hilltops or lanterns displayed from the windows of houses overlooking harbors. In the territory that eventually became the United States, the Boston Light was the first structure generally accepted to be a true lighthouse. It was built in 1715 on Little Brewster Island in Boston Harbor and lighted for the first time in 1716. The British destroyed the lighthouse in 1776. It was rebuilt in 1783 and is still functioning today. Although the Boston Light is considered the nation’s oldest lighthouse, the tower itself is only the second oldest. The oldest tower in the United States is the Sandy Hook Light at the entrance to New York Harbor, built in 1764.
It should not be surprising that the Northeast hosted the majority of the early lighthouses, given the more intensive maritime interests in merchant shipping and fishing in that region, as well as the less-than-friendly nature of the climate and the approaches to the New England coast. The U.S. Lighthouse Service was established in 1789 as one of the first acts of the new federal government, and took over responsibility for the operation of existing lighthouses and the construction and operation of new lights. During the next decade, 12 more lighthouses were built and put into operation.
A chart published in 2001 identifies some 671 standing lighthouses in the United States, including a number of structures that are no longer lighted. The continuing development and application of new technologies have made the historic lighthouse, with its keeper dedicated to maintaining the continued operation of the light and fog signals, obsolete.
Technology and Lighthouses – The Light
The purpose of a lighthouse’s light is to provide a mariner at sea with a fixed point of reference to aid his ability to navigate in the dark when the shore or an offshore hazard cannot be seen directly. The distance at which such a light can be seen depends on the height and intensity of the light. The brighter the light and the greater its height above the sea, the farther it can be seen. Of course, when the weather is bad—with rain, snow, or fog—visibility can be greatly reduced.
The earliest lights were wood-burning fires. Large, visible fires required vast quantities of wood, which tended to burn quickly. During the early 1500s, coal began to be used for fires in lighthouses. Coal had the advantage of burning more slowly and brightly than wood. However, it also required more care to keep its fire bright, particularly during bad weather. Enclosing the fire with glass windows resulted in soot on the glass, which reduced the visibility of the light. Adding reflectors to increase the visibility also resulted in deposits of soot on the reflecting surfaces, which reduced their effectiveness.
Candles were used in some lighthouses. Although not as bright as coal fires, candles produced less soot and ash, and were more easily contained within a lantern, which kept the flame steadier. Some lighthouses used a dozen or more candles and reflectors to make the light more visible, but in bad weather, still-brighter lights were needed.
Lamps burning oil were the next step in the attempt to improve the visibility of the lights. A variety of wick types were used in these lamps: flat, solid and round, and multiple wicks in a single oil reservoir (known as “spider lamps”). A lamp using a hollow, circular wick was invented by a Frenchman, Ami Argand, in 1781. The design allowed air to flow along both the inside and outside of the wick, which greatly enhanced the brightness of the flame. This lamp was often fitted in the center of a large (18- to 20-inch) parabolic reflector, and was widely used in England and France.
In the United States, an unemployed ship captain, Winslow Lewis, patented his version of the Argand lamp and parabolic reflector after demonstrating its superiority to the spider lamp at the Boston Light. He was awarded a contract to install his lamp system in the nation’s lighthouses, a task he completed in 1815.
In 1822, the Frenchman Augustin Fresnel invented a lens that captured and focused a much larger fraction of the light emitted by the lamps than did reflectors, hence producing a much brighter light. These Fresnel lenses were quickly adopted in England, France, and other European seafaring nations.
In the United States, however, Winslow Lewis worked successfully to ensure that his system remained the preference of the Lighthouse Service. He was supported in this effort by Stephen Pleasanton, the fifth auditor of the Treasury Department, who was in charge of the lighthouses. In 1838, as a result of complaints and criticisms from maritime interests, Congress directed that Captain Matthew Perry be sent to Europe to examine the lighthouses there and to purchase two Fresnel lenses.
Working in France, Augustin Fresnel developed lenses that enveloped a light source in all directions in what has been described variously as a “barrel,” “glass keg,” or “gigantic beehive of prisms.” By combining the reflecting (light-bouncing) and refracting (light-bending) characteristics of prisms above and below the light source, with a strong magnifying lens at the level of the light source, the light was concentrated in a narrow horizontal sheet of light.
Fresnel lenses were generally made in seven orders, or sizes, depending on the intensity of light desired. The first-order lens was the largest in common use (about 10 to 12 feet tall and 6 feet in diameter) and was used for seacoast lights that needed to be seen from the greatest distances. The sixth-order lens was much smaller and used in harbors. There was also a three-and-a-half-order lens, used mostly in the United States along the Great Lakes.
The design of the lens also accommodated different light characteristics, which allowed mariners to distinguish one lighthouse from another. The characteristics included the color(s) of the light, whether it was a fixed or a flashing light, and, if flashing, the frequency of the flashes. For a flashing light, the magnifying layer at the center of the lens was replaced by a number of bull’s-eyes spaced around the circumference, the number determined by the desired frequency of the flash and the speed of the rotation of the lens. The rotating lens would be floated in a pool of mercury, or mounted on wheels and driven around by clockwork mechanisms. Color, or dark intervals, would be created by introducing colored glass or opaque sheets into the appropriate lens locations.
Captain Perry’s direction from Congress was to purchase a first-order fixed lens and a second-order revolving lens. These were installed in 1840 in the twin towers of New Jersey’s Navesink Light Station at the entrance to New York Harbor, and both performed very well. Despite this, only three light stations in the United States were equipped with Fresnel lenses by 1851, each directed by a special act of Congress. Stephen Pleasanton felt the lens needed more testing. Congress responded in 1851 by establishing a board to investigate all aspects of aids to navigation.
The investigating board found that the existing lighthouses south of Navesink were virtually useless for mariners because of the inadequate intensity and range of their lights. It also reported that the few Fresnel-equipped stations were greatly superior to any other mode of illumination and were much more economical to operate than the best system of reflectors and Argand lamps. On the basis of the board’s report, Congress reorganized the Lighthouse Service and established a Lighthouse Board to administer the aids to navigation. It also directed that Fresnel lenses be installed in all new lighthouses and in existing lighthouses whose lighting apparatus needed to be replaced. Within ten years, all U.S. lighthouses had been equipped with Fresnel lenses.
The Argand light-reflector system required as many as thirty lamps to provide adequate light, while the Fresnel-equipped lighthouses needed only one lamp. The several designs of lamps used in early U.S. lighthouses were all variants of the Argand lamp in their use of concentric wicks, but they differed from the Argand, and from each other, in how the oil was fed to the wicks.
The fuel originally used was whale oil, thick for summer use and thinner for winter. But in more northerly locations, even the thinner oil congealed from the cold and required warming to enable it to flow properly. A switch to sperm-whale oil provided a higher quality fuel that burned well, but it became increasingly expensive as fewer sperm whales were caught. The less-expensive rapeseed oil used to fuel French lighthouses was phased out after a brief period of use in the United States when it became clear that American farmers were not growing an adequate supply of the wild cabbage from which the oil was obtained.
The Lighthouse Board’s committee on experiments, headed by Joseph Henry of the Smithsonian Institution, resumed experiments with lard oil, which was cheap and readily available but had a tendency to burn poorly. Henry’s experiments revealed that the oil would burn well if it was preheated, and by 1867 lard oil was being used exclusively in the larger lamps. In the 1870s, examination of kerosene as a fuel led to its adoption in 1878 as the fuel for the smaller lamps.
The last step in the search for a better oil light involved the development of a wickless, incandescent, oil-vapor lamp in which the kerosene was vaporized under pressure and transported to a mantle where it burned with a bright glow.
Experiments in lighting lighthouses with electric lamps began in England in 1859 and in France several years later. The U.S. Lighthouse Board kept abreast of these developments and carried out some experiments. Probably the most visible electrically illuminated lighthouse in the United States was the Statue of Liberty, lighted by arc lamps in 1886. For a variety of reasons, including the great expense of installing and operating generators and maintaining the early electric lamps, only a few additional lighthouses were electrified in the United States before the turn of the century.
The potential advantages of electrifying lighthouses drew increasing attention in the United States during the early 20th century. Adoption of electric light sources remained slow, however, because many lighthouses were not conveniently accessed by power lines, and it was not until the 1920s and 1930s that those lighthouses could be provided economically with generators to supply the needed electricity.
Once electrified, the lighthouses could be automated. The advantages were several: electric lights could be turned on and off by a timer switch, the clean nature of the light eliminated the need for daily cleaning of lenses and maintenance of lamps, and the mounting of multiple lamp bulbs allowed burned-out lamps to be automatically replaced. The need for resident keepers could not be justified economically, as electrified lighthouses could be maintained by visits on a weekly basis.
In 1939, responsibility for U.S. aids to navigation was assigned to the U.S. Coast Guard, and the Lighthouse Bureau, which had succeeded the Lighthouse Board, was abolished. Since the mid-20th century, further technological developments have made the visible aids to navigation increasingly less significant to mariners. These developments include the establishment of radio beacons and the loran (long-range navigation) system, which uses radio signals to let mariners know where they are; and the GPS (Global Positioning System), which relies on receivers that interpret special satellite signals to determine position within a matter of a few feet anywhere.