A tower or other structure erected to give guidance and warning to ships and aircraft by either visible or radioelectrical means. The first man-made lighthouse was the Pharos of Alexandria (3rd-c BC). Early lighthouses were erected on land and burnt mainly wood, coal, or oil. Henry Winstanley's Eddystone lighthouse was the first structure (1699) fully exposed to the open sea, while Smeaton's masonry tower, built (17569) on the same site, embodied an important new construction principle, using masonry blocks dovetailed together in an interlocking pattern. Modern lighthouses are generally built of concrete and steel, standing on submerged caissons or steel-piled structures similar to those used for offshore oil and gas rigs. Equipment within the lighthouse includes rotating paraboloid mirrors to create a pattern of flashes. Lights are beamed on and off by an electrical code unit using modern lens equipment driven by an electric motor. As new types of electric lamps become available (eg compact source discharge tube lamps) they are adapted for lighthouse use. Most lighthouses are now automated and self-sustaining. They are monitored from a remote control centre via landline, radio, or (most frequently) satellite link, and powered by electricity, diesel generators, or storage batteries using solar power.
An aid for navigation and pilotage at sea, a lighthouse is a tower building or framework sending out light from a system of lamps and lenses or, in older times, from a fire.
Because of modern navigational aids, the number of operational lighthouses has declined to less than 1,500 worldwide.
Perhaps the most famous lighthouse in history is the Lighthouse of Alexandria, built on the island of Pharos in ancient Egypt.
History
Lighthouses originally contained an open fire.
Design
In order to conserve power, the light is concentrated.
In old lighthouses:
vertically the light is bundled into horizontal directions horizontally the light is bundled into one or a few directions at a time, with the light beam sweeping around; In very old lighthouses, the light source was a kerosene lamp, and the lenses were rotated by a clockwork assembly wound by lighthouse keepers, sometimes as often as every two hours. In more modern lighthouses, electric lights and clock drives were used, generally powered by diesel electric generators.Efficiently concentrating the light from an omnidirectional source of the type used in lighthouses requires a lens of very large diameter.
In modern, automated lighthouses, this system of rotating lenses is often replaced by a very bright light that emits brief omnidirectional flashes (concentrating the light in time rather than space).
In any of these designs an observer, rather than seeing a continuous weak light, sees a brighter light during short time intervals. These instants of bright light are arranged to create a characteristic light pattern specific to the particular lighthouse.
Maintenance
In the United States, lighthouses are maintained by the United States Coast Guard. In Britain and Ireland, those in England and Wales are looked after by Trinity House, those in Scotland by the Northern Lighthouse Board, and those in all of Ireland by the Commissioners of Irish Lights.
Automation
In the beginning of the 20th century Swedish inventor Gustav Dahlén invented the AGA Lighthouse which effectively made lighthouse keepers obsolete. However, for many years lighthouses still had keepers, partly because lighthouse keepers could serve as a rescue service if necessary.
Today there are a few keeper-run lighthouses left in existence;
Often in inaccessible locations, modern lighthouses are much more functional and less picturesque buildings;
Notable Lighthouses
In some locations, lighthouses have become popular tourist destinations and the buildings are being maintained as tourist attractions. See, for example, Cape Hatteras lighthouse
Such an example is the Split Point Lighthouse in Aireys Inlet, Victoria, Australia.
Bengtskär lighthouse is the highest (52 meters) in the Nordic countries.
The Soviet Union built a number of automated lighthouses powered by radioisotope thermoelectric generators in remote locations.
In Brazil, (South America), "Cabo Branco lighthouse" is strategically located in Joao Pessoa at the easternmost point of the Americas at 34º 47' 38" west longitude and 7º 9' 28" south latitude.
Symbology
Lighthouses are used as symbols by certain organizations.
Lighthouses are often interpreted in dreams as beacons of truth or as male fertility and influence.
Range Lights
A problem with a single lighthouse is that it is only a point at night.
Gallery
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The Peggys Point lighthouse in Nova Scotia, Canada. |
Fairport Harbor West Breakwater Lighthouse, Fairport Harbor, Ohio viewed from the Headlands Dunes State Nature Preserve |
Fairport Harbor West Breakwater Lighthouse, Fairport Harbor, Ohio viewed from the Headlands Dunes State Nature Preserve |
Cape Willoughby Lighthouse, Kangaroo Island, South Australia |
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Portland Bill lighthouse, Isle of Portland, Dorset |
Scarborough Harbour Lighthouse, Scarborough, North Yorkshire, England |
A 1999 photo of the Navassa Island lighthouse. |
McClain's State Park Lighthouse, Upper Peninsula, Michigan |
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Point Reyes Lighthouse |
Nauset Light and lightkeeper's house, Eastham, Massachusetts |
Spurn Point Lighthouse, East Yorkshire, England. |
Admiralty Head Lighthouse Inactive, used as interpretive center by a local environmental group |
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Strumble Head Lighthouse, Wales |
Neuwerk Lighthouse, Hamburg, Germany, completed 1369 |
The Eddystone Lighthouse, situated off the coast of Cornwall, England. |
Hunting Island Light House, South Carolina |
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Byron Bay Lighthouse, New South Wales, Australia |
Cape Disappointment Lighthouse |
The tall Bengtskär lighthouse also functions as a museum. |
Cabo Branco Lighthouse, Joao Pessoa, Brazil |
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