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| | The title of the writer is Dagny. Iowa has usually been her house. After becoming out of my occupation for many years I became a courier and I'm performing fairly good monetarily. One of the issues he enjoys most is digital artwork but he's thinking on beginning something new. Check out the newest information on his web site: http://Www.myfitnesspal.com/blog/DietingNewbie/view/-irritable-bowel-syndrome-foods-to-avoid-when-dealing-with-ibs-687335<br><br>my homepage :: [http://Www.myfitnesspal.com/blog/DietingNewbie/view/-irritable-bowel-syndrome-foods-to-avoid-when-dealing-with-ibs-687335 Foods to avoid with IBS] |
| [[File:Aveiro March 2012-13.jpg|thumb|right|275px|The lighthouse of [[Aveiro Lighthouse|Aveiro]], west coast of Portugal]]
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| A '''lighthouse''' is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses and used as an [[aid to navigation]] for [[maritime pilot]]s at sea or on inland waterways.
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| Lighthouses mark dangerous coastlines, hazardous [[shoal]]s, [[reef]]s, safe entries to harbors, and can also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and replacement by modern electronic navigational systems.
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| ==History==
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| {{Main|History of lighthouses}}
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| ===Ancient era===
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| [[Image:PHAROS2006.jpg|thumb|Graphic reconstruction of the [[Lighthouse of Alexandria|Pharos]] according to a 2006 study.]]
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| Before the development of clearly defined [[port]]s mariners were guided by fires built on hilltops. Since raising the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for [[reef]]s and [[promontory|promontories]], unlike many modern lighthouses. The most famous lighthouse structure from antiquity was the [[Lighthouse of Alexandria|Pharos]] of [[Alexandria]], although this collapsed during an earthquake centuries later.
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| The intact [[Tower of Hercules]] at [[La Coruña]] and the ruins of the [[Dubris|Dover]] lighthouse in England give insight into ancient lighthouse construction; other evidence about lighthouses exists in depictions on coins and mosaics, of which many represent the lighthouse at [[Ostia Antica (archaeological site)|Ostia]]. Coins from Alexandria, Ostia, and [[Latakia|Laodicea in Syria]] also exist.
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| ===Modern construction===
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| The modern era of lighthouses began at the turn of the 18th century, as lighthouse construction boomed in lockstep with burgeoning levels of [[Atlantic Ocean|transatlantic]] commerce. Advances in structural engineering and new and efficient lighting equipment allowed for the creation of larger and more powerful lighthouses, including ones exposed to the sea. The function of lighthouses shifted toward the provision of a visible warning against shipping hazards, such as rocks or reefs.
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| [[Image:Eddystone lighthouse00.jpg|thumb|left|upright|[[Eddystone Lighthouse#Winstanley's lighthouse|Winstanley's lighthouse]] at the [[Eddystone Rocks]] marked the beginning in a new phase of lighthouse development.]]
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| The [[Eddystone Rocks]] were a major shipwreck hazard for mariners sailing through the [[English Channel]].<ref>{{citation|first=Samuel|last=Smiles|title=The Lives of the Engineers|year=1861|volume=Vol 2|page=16|url=http://archive.org/stream/livesofengineers02smil#page/16/mode/2up}}</ref> The [[Eddystone Lighthouse#Winstanley's lighthouse|first lighthouse built there]] was an octagonal wooden structure, anchored by 12 iron stanchions secured in the rock, and was built by [[Henry Winstanley]] from 1696 to 1698. His lighthouse was the first tower in the world to have been fully exposed to the open sea.<ref>{{Cite web|url=http://www.britannica.com/EBchecked/topic/340721/lighthouse/72148/The-beginning-of-the-modern-era|title=lighthouse|accessdate=2012-12-17}}</ref>
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| The [[civil engineer]], [[John Smeaton]], rebuilt the [[Smeaton's Tower|lighthouse]] from 1756-59;<ref name="MAJ">Majdalany, Fred: ''The Eddystone Light''. 1960</ref> his tower marked a major step forward in the design of lighthouses and remained in use until 1877. He modelled the shape of his lighthouse on that of an oak tree, using granite blocks. He pioneered the use of "[[hydraulic lime]]," a form of concrete that will set under water, and developed a technique of securing the granite blocks together using [[dovetail joint]]s and marble [[dowels]].<ref name="TRI">{{cite web|url=http://www.trinityhouse.co.uk/interactive/gallery/eddystone.html|title=Eddystone - Gallery|publisher=Trinity House|accessdate=2010-05-03}}</ref> The dovetailing feature served to improve the [[structural stability]], although Smeaton also had to taper the thickness of the tower towards the top, for which he curved the tower inwards on a gentle gradient. This profile had the added advantage of allowing some of the energy of the waves to dissipate on impact with the walls. His lighthouse was the prototype for the modern lighthouse and influenced all subsequent engineers.<ref>{{cite book|title=Minutes of proceedings of the Institution of Civil Engineers|chapter=Note on the Eddystone Lighthouse|author=Douglass, James Nicholas|location=London|publisher=Institution of Civil Engineers|year=1878|volume=vol. 53, part 3|pages=247–248|url=http://books.google.com/books?id=cx4AAAAAMAAJ&pg=PA247}}</ref>
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| [[File:Smeaton's Lighthouse00.jpg|thumb|right|upright|[[John Smeaton]]'s rebuilt version of the [[Eddystone Lighthouse]], 1759. This represented a great step forward in lighthouse design.]]
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| One such influence was [[Robert Stevenson (civil engineer)|Robert Stevenson]], himself a seminal figure in the development of lighthouse design and construction.<ref name="NLB">{{cite web|url=http://www.nlb.org.uk/HistoricalInformation/StevensonEngineers/Robert-Stevenson/|title=NLB - Robert Stevenson|accessdate=January 28, 2013}}</ref> His greatest achievement was the construction of the [[Bell Rock Lighthouse]] in 1810, one of the most impressive feats of engineering of the age. This structure was based upon Smeaton's design, but with several improved features, such as the incorporation of rotating lights, alternating between red and white.<ref>{{citation|title=John Rennie, 1761–1821: The Life and Work of a Great Engineer|first=Cyril Thomas Goodman|last=Boucher|page=61|year=1963|url=http://books.google.co.uk/books?id=1wu8AAAAIAAJ&pg=PA59&lpg=PA59}}</ref> Stevenson worked for the [[Northern Lighthouse Board]] for nearly fifty years<ref name="NLB" /> during which time he designed and oversaw the construction and later improvement of numerous lighthouses. He innovated in the choice of light sources, mountings, reflector design, the use of [[Fresnel lens]]es, and in rotation and shuttering systems providing lighthouses with individual signatures allowing them to be identified by seafarers. He also invented the movable jib and the balance crane as a necessary part for lighthouse construction.
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| [[Alexander Mitchell (engineer)|Alexander Mitchell]] designed the first [[screw-pile lighthouse]] - his lighthouse was built on piles that were [[screw]]ed into the sandy or muddy seabed. Construction of his design began in 1838 at the mouth of the [[Thames]] and was known as the [[Maplin Sands]] lighthouse, and first lit in 1841.<ref name=Tomlinson>{{cite book|title=Tomlinson's Cyclopaedia of Useful Arts|year=1852-54|publisher=Virtue & Co.|location=London|page=177|editor=Tomlinson|url=http://archive.org/details/cyclopdiaofuse02tomlrich|quote="[Maplin Sands] was not, however, the first screw-pile lighthouse actually erected, for during the long preparation process which was carried on at Maplin Sands, a structure of the same principle had been begun and completed at Port Fleetwood..."}}</ref> However, though its construction began later, the [[Wyre Light (Fleetwood)|Wyre Light]] in Fleetwood, Lancashire, was the first to be lit (in 1840).<ref name=Tomlinson />
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| ===Lighting improvements===
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| [[File:Verre du bec d'Argand.jpg|thumb|left|upright=0.7|[[Argand lamp]] with circular wick and glass chimney. <small>(Illustration from ''Les Merveilles de la science'' [1867-1869] by [[Louis Figuier]]).</small>]]
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| The source of illumination had generally been wood pyres or burning coal. The [[Argand lamp]], invented in 1782 by the Swiss scientist, [[Aimé Argand]], revolutionized lighthouse illumination with its' steady smokeless flame. Early models used ground glass which was sometimes tinted around the wick. Later models used a mantle of [[thorium dioxide]] suspended over the flame, creating a bright, steady light.<ref>http://www.johnmoncrieff.co.uk/shop-2/products.php?cat=32</ref> The Argand lamp used [[whale oil]], [[colza]], [[olive oil]]<ref>"Lamp." ''Encyclopaedia Britannica: or, a dictionary of Arts, Science, and Miscellaneous Literature.'' 6th ed. 1823 [http://books.google.com/books?id=T8wnAAAAMAAJ&pg=PA505&lpg=PA505&dq=%22argand+lamp%22+%22olive+oil%22&source=bl&ots=K9CxKs3AJG&sig=9wwDAF6jlwx9zV-xjvALVg_EKEs&hl=en&ei=rxPdTuOVLMLX0QHpqvXWCg&sa=X&oi=book_result&ct=result&resnum=6&ved=0CFkQ6AEwBQ#v=onepage&q=%22argand%20lamp%22%20%22olive%20oil%22&f=false Web.] 5 Dec. 2011</ref> or other [[vegetable oil]] as fuel which was supplied by a [[gravity feed]] from a reservoir mounted above the burner. The lamp was first produced by [[Matthew Boulton]], in partnership with Argand, in 1784 and became the standard for lighthouses for over a century.
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| [[South Foreland Lighthouse]] was the first tower to successfully use an electric light in 1875. The lighthouse's [[arc lamp|carbon arc lamps]] were powered by a steam-driven [[magneto (generator)|magneto]].<ref>{{cite book |last=Baird |first=Spencer Fullerton|title=Annual record of science and industry |publisher=Harper & Brothers|location=New York|year=1876|pages=460|accessdate=2009-09-06}}</ref> [[John Richardson Wigham]] was the first to develop a system for [[coal gas|gas]] illumination of lighthouses. His improved gas 'crocus' burner at the [[Baily Lighthouse]] was 13 times more powerful than the most brilliant light then known.<ref name=cil>{{cite journal| title=John Richardson Wigham 1829–1906 | url=http://www.commissionersofirishlights.com/media/35546/Beam_2006.PDF#page=23 | publisher=Commissioners of Irish Lights | journal=BEAM | volume=35 | date=2006-7 | pages=21–22}}</ref>
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| The vaporized [[oil burner]] was invented in 1901 by [[Arthur Kitson]], and improved by David Hood at [[Trinity House]]. The fuel was vaporized at high pressure and burned to heat the mantle, giving an output of over six times the luminosity of traditional oil lights. The use of gas as iluminant became widely available with the invention of the [[Dalén light]] by Swedish engineer, [[Gustaf Dalén]]. He used [[Agamassan]] (Aga), a [[Substrate (materials science)|substrate]], to absorb the gas allowing safe storage and hence commercial exploitation. Dalén also invented the '[[sun valve]]', which automatically regulated the light and turned it off during the daytime. The technology was the predominant form of light source in [[lighthouses]] from the 1900s through the 1960s, when electric lighting had become dominant.<ref>[http://www.aga.com/web/web2000/com/WPPcom.nsf/pages/History_SunValve History - The Sun Valve<!-- Bot generated title -->]</ref>
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| ===Optical systems===
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| [[File:Fresnel lighthouse lens diagram.png|thumb|right|Diagram depicting how a spherical [[Fresnel lens]] collimates light.]]
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| With the development of the steady illumination of the Argand lamp, the application of optical lenses to increase and focus the light intensity became a practical possibility. [[William Hutchinson (privateer)|William Hutchinson]] developed the first practical optical system in 1763, known as a [[catoptrics|catoptric]] system. This rudimentary system effectively collimated the emitted light into a concentrated beam, thereby greatly increasing the light's visibility.<ref>{{Cite web|url=http://www.britannica.com/EBchecked/topic/340721/lighthouse/72152/Oil-lamps|title=Lighthouse|publisher=Encyclopedia Britannica|accessdate=2014-01-06}}</ref> The ability to focus the light led to the first revolving lighthouse beams, where the light would appear to the mariners as a series of intermittent flashes. It also became possible to transmit complex signals using the light flashes.
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| French physicist and engineer [[Augustin-Jean Fresnel]] developed the multi-part [[Fresnel lens]] for use in lighthouses. His design allowed for the construction of lenses of large [[aperture]] and short [[focal length]], without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. A Fresnel lens can also capture more oblique light from a light source, thus allowing the light from a lighthouse equipped with one, to be visible over greater distances.
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| The first Fresnel lens was used in 1823 in the [[Cordouan lighthouse]] at the mouth of the [[Gironde estuary]]; its light could be seen from more than {{convert|20|mi|km}} out.<ref>Watson, Bruce. [http://libproxy.uncg.edu:2088/servlet/BioRC "Science Makes a Better Lighthouse Lens."] ''Smithsonian''. August 1999 v30 i5 p30.
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| produced in ''Biography Resource Center''. Farmington Hills, Mich.: Thomson Gale. 2005.</ref> Fresnel’s invention increased the [[luminosity]] of the lighthouse lamp by a factor of 4 and his system is still in common use.
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| ===Recent===
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| The advent of electrification, and [[automatic lamp changer]]s began to make lighthouse keepers obsolete. For many years, lighthouses still had keepers, partly because lighthouse keepers could serve as a rescue service if necessary. Improvements in maritime navigation and safety such as the [[Global Positioning System]] (GPS) have led to the phasing out of non-automated lighthouses across the world.<ref>[http://www.nps.gov/history/maritime/keep/keep19th.htm Lighthouse Keepers in the Nineteenth Century<!-- Bot generated title -->]</ref> In Canada, this trend has been stopped and there are still 50 staffed light stations, with 27 on the west coast alone.<ref>[http://www.fogwhistle.ca/bclights]</ref>
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| Remaining modern lighthouses are more functional and less picturesque; usually they use solar-charged batteries and have a single stationary flashing light sitting on a steel skeleton tower.<ref name="Crompton"/>
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| ===Famous lighthouse builders===
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| [[Image:James Douglass portrait.jpg|thumb|right|200x200px|[[James Nicholas Douglass|Sir James Douglass]] was a prolific lighthouse builder and designer in the late 19th-century.]]
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| [[John Smeaton]] is noteworthy for having designed the third and most famous [[Eddystone Lighthouse]] but some builders are well known for their work in building multiple lighthouses. The Stevenson family ([[Robert Stevenson (civil engineer)|Robert]], [[Alan Stevenson|Alan]], [[David Stevenson (engineer)|David]], [[Thomas Stevenson|Thomas]], [[David Alan Stevenson|David Alan]], and [[Charles Alexander Stevenson|Charles]]) made lighthouse building a three generation profession in Scotland. Irishman [[Alexander Mitchell (engineer)|Alexander Mitchell]] invented and built a number of screwpile lighthouses despite his blindness. Englishman [[James Nicholas Douglass|James Douglass]] was knighted for his work on lighthouses.
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| [[United States Army Corps of Engineers]] Lieutenant [[George Meade]] built numerous lighthouses along the Atlantic and Gulf coasts before gaining wider fame as the winning general at the [[Battle of Gettysburg]]. Colonel [[Orlando M. Poe]], engineer to [[General William Tecumseh Sherman]] in the Siege of Atlanta, designed and built some of the most exotic lighthouses in the most difficult locations on the U.S. Great Lakes.<ref>[http://www.nps.gov/history/maritime/keep/architect.htm Architects, Engineers and Contractors<!-- Bot generated title -->]</ref>
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| French merchant navy officer [[Marius Michel Pasha]] built almost a hundred lighthouses along the coasts of the [[Ottoman Empire]] in a period of twenty years after the [[Crimean War]] (1853–1856).<ref name="hnet">{{cite web |url=http://www.h-net.org/reviews/showrev.php?id=11049 |publisher=Humanities and Social Sciences Net Online |title=Review of Thobie, Jacques, L'administration generale des phares de l'Empire ottoman et la societe Collas et Michel, 1860-1960. H-Mediterranean, H-Net Reviews. January, 2006 | author=Guigueno, Vincent |accessdate=2010-09-20}}</ref>
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| ==Lighthouse technology==
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| ===Power===
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| In a lighthouse, the source of light is called the "lamp" (whether electric or fueled by oil) and the concentration of the light is by the "lens" or "optic". Originally lit by open fires and later candles, the [[Argand lamp|Argand hollow wick lamp]] and parabolic reflector introduced in the late 18th century.
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| [[Whale oil]] was also used with wicks as the source of light. [[Kerosene]] became popular in the 1870s and electricity and carbide ([[acetylene gas]]) began replacing kerosene around the turn of the 20th century.<ref name="Crompton"/> Carbide was promoted by the [[Dalén light]] which automatically lit the lamp at nightfall and extinguished it at dawn.
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| ===Lens===
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| {{see also|Fresnel lens}}
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| [[File:Cape Meares Lighthouse lens - Oregon.jpg|thumb|[[Cape Meares Lighthouse]]; first-order Fresnel lens]]
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| Before modern strobe lights, [[Lens (optics)|lenses]] were used to concentrate the light from a continuous source. Vertical light rays of the lamp are redirected into a horizontal plane, and horizontally the light is focused into one or a few directions at a time, with the [[light beam]] swept around. As a result, in addition to seeing the side of the light beam, the light is directly visible from greater distances, and with an identifying [[light characteristic]].
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| This concentration of light is accomplished with a rotating lens assembly. In early lighthouses, the light source was a [[kerosene lamp]] or, earlier, an animal or vegetable oil Argand lamp, and the lenses rotated by a weight driven clockwork assembly wound by [[lighthouse keeper]]s, sometimes as often as every two hours. The lens assembly sometimes floated in [[mercury (element)|liquid mercury]] to reduce friction. In more modern lighthouses, electric lights and motor drives were used, generally powered by diesel electric generators. These also supplied electricity for the lighthouse keepers.<ref name="Crompton"/>
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| Efficiently concentrating the light from a large omnidirectional light source requires a very large diameter lens. This would require a very thick and heavy lens if a conventional lens were used. The [[Fresnel lens]] (pronounced {{IPAc-en|f|r|eɪ|ˈ|n|ɛ|l}}) focused 85% of a lamp's light versus the 20% focused with the parabolic reflectors of the time. Its design enabled construction of lenses of large size and short focal length without the weight and volume of material in conventional lens designs.<ref name=mhp/>
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| Fresnel lenses are ranked by <!-- "order" should be linked somewhere useful -->''order'', a measure of refracting power, with a first order lens being the largest, most powerful and expensive; and a sixth order lens being the smallest. The order is based on the focal length of the lens. A first order lens has the longest focal length, with the sixth being the shortest. Coastal lighthouses generally use first, second, or third order lenses, while harbor lights and beacons use fourth, fifth, or sixth order lenses.<ref name=ll/>
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| Some lighthouses, such as those at [[Cape Race Lighthouse|Cape Race]], Newfoundland, and [[Makapuu Point Light|Makapuu Point]], Hawaii, used a more powerful [[hyperradiant Fresnel lens]] manufactured by the firm of [[Chance Brothers]].
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| In recent times, many Fresnel lenses have been replaced by rotating [[aerobeacon]]s which require less maintenance. In modern automated lighthouses, this system of rotating lenses is often replaced by a high intensity light that emits brief omnidirectional flashes (concentrating the light in time rather than direction). These lights are similar to obstruction lights used to warn aircraft of tall structures. Recent innovations are "Vega Lights", and initial experiments with [[light-emitting diode]] (LED) panels.<ref name="Crompton"/>
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| ===Light characteristics===
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| {{see also|Light characteristic}}
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| <!-- Deleted image removed: [[File:Light house in USA beach.jpg|thumb|right|Light house in [[USA]] beach]] -->
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| 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 [[light characteristic]] or, pattern specific to a lighthouse.<ref>[http://www.uscgboating.org/safety/aton/abbreviations.htm Aids To Navigation Abbreviations]</ref> For example, the [[Scheveningen Lighthouse]] flashes are alternately 2.5 and 7.5 seconds. Some lights have sectors of a particular color (usually formed by colored panes in the lantern) to distinguish safe water areas from dangerous shoals. Modern lighthouses often have unique reflectors or [[Racon|Racon transponders]] so the radar signature of the light is also unique.
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| ==Building==
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| ===Design===
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| [[Image:Split Rock Lighthouse architect design.png|thumb|right|Architect's design of [[Split Rock Lighthouse]]]]
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| [[Image:Finnish Lighthouses 1909.JPG|thumb|right|Architecture of 1909 lighthouses in Finland]]
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| For effectiveness, the lamp must be high enough to be seen before the danger is reached by a mariner. The minimum height is calculated by trigonometric formula <math alt="d is 1.17 times the square root of H"> d = 1.17 \sqrt {H} </math> where ''H'' is the height above water in feet, and ''d'' is the distance to the horizon in nautical miles.<ref>[http://www.boatsafe.com/kids/distance.htm How far is the horizon?]</ref>
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| Where dangerous shoals are located far off a flat sandy beach, the prototypical tall masonry coastal lighthouse is constructed to assist the navigator making a landfall after an ocean crossing. Often these are cylindrical to reduce the effect of wind on a tall structure, such as [[Cape May Light]]. Smaller versions of this design are often used as harbor lights to mark the entrance into a harbor, such as [[New London Harbor Light]].
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| Where a tall cliff exists, a smaller structure may be placed on top such as at [[Horton Point Light]]. Sometimes, such a location can be too high, for example along the west coast of the United States, where frequent low clouds can obscure the light. In these cases, lighthouses are placed below clifftop to ensure that they can still be seen at the surface during periods of fog or low clouds, as at [[Point Reyes Lighthouse]]. Another victim of fog was the [[Old Point Loma lighthouse]], which was replaced in 1891 with a lower lighthouse, [[New Point Loma lighthouse]].
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| As technology advanced, prefabricated skeletal iron or steel structures tended to be used for lighthouses constructed in the 20th century. These often have a narrow cylindrical core surrounded by an open lattice work bracing, such as [[Finns Point Range Light]].
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| Sometimes a lighthouse needs to be constructed in the water itself. Wave-washed lighthouses are masonry structures constructed to withstand water impact, such as [[Eddystone Lighthouse]] in Britain and the [[St. George Reef Light]] off California. In shallower bays, [[Screw-pile lighthouse]] ironwork structures are screwed into the seabed and a low wooden structure is placed above the open framework, such as [[Thomas Point Shoal Lighthouse]]. As screw piles can be disrupted by ice, steel caisson lighthouses such as [[Orient Point Light]] are used in cold climates. [[Orient Long Beach Bar Light]] (Bug Light) is a blend of a screw pile light that was converted to a caisson light because of the threat of ice damage.<ref>[http://www.nps.gov/history/maritime/constype/constype.htm Lighthouse Construction Types<!-- Bot generated title -->]</ref>
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| In waters too deep for a conventional structure, a [[Lightvessel|lightship]] might be used instead of a lighthouse, such as the former [[United States lightship Columbia (WLV-604)|lightship ''Columbia'']]. Most of these have now been replaced by fixed light platforms (such as [[Ambrose Light]]) similar to those used for offshore oil exploration.<ref>[http://www.nps.gov/history/maritime/ltshipmain.htm Lightships of the U.S.]</ref>
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| <gallery>
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| Image:Eddystonelighthouse.jpg|[[Eddystone Lighthouse]], one of the first wave-washed lighthouses
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| Image:Adziogol hyperboloid Lighthouse by Vladimir Shukhov 1911.jpg|[[Hyperboloid structure|Hyperboloid]] design [[Adziogol Lighthouse]] by [[Vladimir Shukhov|V.G.Shukhov]], [[Ukraine]], 1910
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| </gallery>
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| ===Components===
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| [[Image:Lighthouse lantern room with Fresnel lens.png|thumb|Lighthouse lantern room from mid-1800s]]
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| While lighthouse buildings differ depending on the location and purpose, they tend to have common components.
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| A light station comprises the lighthouse tower and all outbuildings, such as the keeper's living quarters, fuel house, boathouse, and [[fog horn|fog-signaling]] building. The Lighthouse itself consists of a tower structure supporting the lantern room where the light operates.
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| The lantern room is the glassed-in housing at the top of a lighthouse tower containing the lamp and lens. Its glass storm panes are supported by metal ''[[Astragal]]'' bars running vertically or diagonally. At the top of the lantern room is a stormproof ventilator designed to remove the smoke of the lamps and the heat that builds in the glass enclosure. A [[lightning rod]] and grounding system connected to the metal cupola roof provides a safe conduit for any lightning strikes.
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| Immediately beneath the lantern room is usually a Watch Room or Service Room where fuel and other supplies were kept and where the keeper prepared the lanterns for the night and often stood watch. The clockworks (for rotating the lenses) were also located there. On a lighthouse tower, an open platform called the gallery is often located outside the watch room (called the Main Gallery) or Lantern Room (Lantern Gallery). This was mainly used for cleaning the outside of the windows of the Lantern Room.<ref>{{cite web |url=http://www.nps.gov/history/maritime/ltcomp.htm |title=Light Station Components |publisher=nps.gov }}</ref>
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| Lighthouses near to each other that are similar in shape are often painted in a unique pattern so they can easily be recognized during daylight, a marking known as a [[daymark]]. The black and white barber pole spiral pattern of [[Cape Hatteras Lighthouse]] is one example. [[Race Rocks Light]] in western Canada is painted in horizontal black and white bands to stand out against the horizon.
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| ===Range lights===
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| {{main|Range lights}}
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| [[Image:NantucketRangeLites.jpg|right|thumb|Range Lights in [[Nantucket, Massachusetts]], indicating the observer is left of the desired channel]]
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| Aligning two fixed points on land provides a navigator with a [[line of position]] called a range in the U.S. and a [[navigational transit|transit]] in Britain. Ranges can be used to precisely align a vessel within a narrow channel such as in a river. With landmarks of a range illuminated with a set of fixed lighthouses, nighttime navigation is possible.
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| Such paired lighthouses are called [[range lights]] in the U.S. and leading lights in the United Kingdom. The closer light is referred to as the beacon or front range; the furthest away is called the rear range. The rear range light is almost always taller than the front.
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| When the vessel is on the correct course, the two lights line up vertically. But when the observer is out of position, the difference in alignment indicates the proper direction of travel to correct the course.
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| ==Maintenance==
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| In the United States, lighthouses are maintained by the United States Coast Guard (USCG).<ref>[http://www.nps.gov/history/maritime/light/admin.htm Lighthouses: An Administrative History]</ref>
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| Those in England and Wales are looked after by [[Trinity House]]; in Scotland, by the [[Northern Lighthouse Board]]; and in Ireland by the [[Commissioners of Irish Lights]]. In Canada, they are managed by the [[Canadian Coast Guard]]. In Australia, lighthouses are conducted by the [[Australian Maritime Safety Authority]].
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| The Soviet Union built a number of automated lighthouses powered by [[radioisotope thermoelectric generator]]s in remote locations. They operated for long periods without external support with great reliability.<ref>[http://www.atomicinsights.com/sep96/materials.html AEI: September 1996, RTG Materials<!-- Bot generated title -->]</ref> However numerous installations deteriorated, were stolen, or vandalized. Some cannot be found due to poor record keeping.<ref>[http://www.bellona.no/en/international/russia/navy/northern_fleet/incidents/37598.html Radioisotope Thermoelectric Generators - Bellona<!-- Bot generated title -->]</ref>
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| ==Preservation==
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| As lighthouses became less essential to navigation, many of their historic structures faced demolition or neglect. In the United States, the [[National Historic Lighthouse Preservation Act]] of 2000 provides for the transfer of lighthouse structures to local governments and private non-profit groups, while the USCG continues to maintain the lamps and lenses. In Canada, the [[Nova Scotia Lighthouse Preservation Society]] won heritage status for [[Sambro Island Lighthouse]], and sponsored the [[Heritage Lighthouse Protection Act]] to change Canadian federal laws to protect lighthouses.<ref>{{cite web
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| | url = http://www.heritagecanada.org/eng/featured/current.html
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| | title = Lighthouse Bill Protecting Our Lighthouses – The Icons of Canada's Maritime Heritage
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| | publisher = Canadian Heritage Foundation
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| | work = Featured Heritage Buildings
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| | author = Douglas Franklin
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| | accessdate = 2008-06-10
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| }}</ref>
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| Many groups formed to restore and save lighthouses around the world. They include the [[World Lighthouse Society]] and the [[United States Lighthouse Society]].<ref>[http://uslhs.org Welcome to The United States Lighthouse Society]</ref> A further international group is the Amateur Radio Lighthouse Society, which sends amateur radio operators to publicize the preservation of remote lighthouses throughout the world.<ref>[http://arlhs.com/ Amateur Radio Lighthouse Society<!-- Bot generated title -->]</ref>
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| ==Popular culture and symbolism==
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| [[Image:SplitPoint 0072.jpg|thumb|right|[[Split Point Lighthouse]], used in the popular Australian TV series ''Round the Twist'']]
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| Visiting and photographing lighthouses are popular hobbies as is collecting ceramic replicas. Some lighthouses are popular travel destinations in their own right, and the buildings maintained as tourist attractions. In the U.S., National Lighthouse and Lightship Weekend is celebrated on the first weekend of August, and [[International Lighthouse and Lightship Weekend]] on the third weekend. Many lighthouses are open to the public and amateur radio operators communicate between them on these days.
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| Lighthouses are popular icons on vehicle license plates. [[Barnegat Lighthouse]], [[Tuckerton Island Lighthouse]], [[Thomas Point Shoal Light]], [[Saybrook Breakwater Light]], [[White Shoal Light (Michigan)|White Shoal Light]], and [[Biloxi Light]] are so depicted.<ref>http://www.sunherald.com/306/story/114405.html</ref>
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| To recognize the role of lighthouse keepers in maritime safety, the U.S. Coast Guard named a class of {{convert|175|ft|m|0|sing=on}} [[USCG coastal buoy tender|coastal buoy tenders]] after famous U.S. lighthouse keepers. Fourteen ships in the class were built between 1996 and 2000.<ref>[http://www.uscg.mil/datasheet/175wlm.asp USCG: About Us - Aircraft & Cutters<!-- Bot generated title -->]</ref>
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| Due to their function as beacons of safety, organizations choose lighthouses as a symbol. The lighthouse is the symbol of Lighthouse International, a U.S. organization for the blind.<ref>[http://lighthouse.org Lighthouse International]</ref> Lighthouses are often interpreted in dreams as beacons of truth or as male fertility and influence.
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| Lighthouses were once regarded as an archetypal [[public good]], because ships could benefit from the light without being forced to pay. One reason the Confederacy broke off from the United States was the former's opposition to most taxpayer-funded internal improvements; yet even the Confederate States Constitution explicitly allowed public funds to be spent on lighthouses.<ref>[http://www.yale.edu/lawweb/avalon/csa/csa.htm The Avalon Project : Constitution of the Confederate States; March 11, 1861<!-- Bot generated title -->]</ref>
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| A widely disseminated urban legend tells of a radio conversation between a U.S. or British naval vessel and what is believed to be another ship on a collision course. The naval vessel insists the other ship change course, but the other ship continues to insist the naval vessel do so. After the captain of the naval vessel identifies himself and demands a course change, the other party responds with, [[Lighthouse and naval vessel urban legend|"I'm a lighthouse. It's your call"]].
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| The Disney film ''[[Pete's Dragon]]'' featured a lighthouse and the resulting Helen Reddy song ''[[Candle on the Water]]'' alludes to it. The Australian television series ''Round the Twist'' also involved a family living at [[Split Point Lighthouse]]. The long-running American soap opera ''[[Guiding Light]]'' has featured a lighthouse in many of its opening title segments, and the fictional [[Springfield (Guiding Light)|Springfield, Illinois]] has a lighthouse situated near the town.<ref>[http://lavender.fortunecity.com/indemnity/439/gl.html ''The Guiding Light''] Retrieved 16 July 2009.</ref>
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| Their isolated and mysterious nature makes lighthouses a frequent setting of horror and suspense films, as well as adventure video games. Recently, a lighthouse played a pivotal role in Martin Scorsese's ''[[Shutter Island (film)|Shutter Island]]'', and was featured in the final shot of the film.
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| An island with a lighthouse is the setting of [[Tove Jansson]]'s novel ''[[Moominpappa at Sea]]'' and the isolated nature of the lighthouse surrounded by the sea also is a reference to the states of mind of the main characters of the novel.
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| [[St. Anthony's Lighthouse]] at St. Anthony's Head near Falmouth, Cornwall was featured in the title sequence of the children's live action puppet television program series ''Fraggle Rock'' created by Jim Henson.
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| ''[[The Adventures of Portland Bill]]'' was a British stop motion animated children's television series made in 1983. Set in a fictional lighthouse, the name its main character was a reference to the [[Portland Bill Lighthouse]] in [[Dorset]]. Many of the other characters were plays on the names of coastal regions, made familiar to the wider public by the [[BBC Radio 4]] [[Shipping Forecast]].
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| ==Gallery==
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| <gallery widths="180px" heights="180px">
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| Image:Joao Pessoa Paraiba Farol do Cabo Branco2.jpg|[[Ponta do Seixas|Cabo Branco Lighthouse]] in João Pessoa, Brazil is a major attraction at the easternmost inland point of the Americas
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| Image:Old Lighthouse Waitemata Harbour.jpg|A rarer type of lighthouse on stilts in the [[Hauraki Gulf]] of New Zealand. Mostly protected by nearby islands, Bean Rock lighthouse lights the way into the [[Waitemata Harbour]].
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| Image:LeuchtturmVonMaspalomas.jpg|Lighthouse "El Faro", [[Maspalomas]], [[Gran Canaria]].
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| File:Lobito Lighthouse.jpg|Lighthouse "Lobito" in [[Lobito]], [[Angola]]
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| File:Knarrarósviti Lighthouse.jpg| The [[Knarraros lighthouse|Knarrarósviti Lighthouse]] is a two-staged tower, built in 1938-1939, located near the town of [[Stokkseyri]]. [[Iceland]].
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| File:Vypin Lighthouse.jpg|The Vypin Lighthouse at [[Kochi]], [[India]]. The structure (built in 1979) has an unusual cross section.
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| File:Rawley_Point_Lighthouse,_June_1,_northern_view.jpg|The [[Rawley Point Light]]house near [[Two Rivers, Wisconsin|Two Rivers]], [[Wisconsin]] at [[Point Beach State Forest]] shows an example of an octagonal skeletal structure.
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| File:Peggys Cove Nova Scotia 01.jpg| [[Peggys Point Lighthouse]], [[Nova Scotia]], [[Canada]]
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| File:The light at Gullringnes in Vardø.jpg|Small non-attendant lighthouse at Gullringnes in [[Vardø]], North [[Norway]].
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| </gallery>
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| ==See also==
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| *[[List of lighthouses and lightvessels]]
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| *[[Day beacon]]
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| *[[Lens lantern]]
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| *[[Pintsch gas]]
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| *[[Pharology]]
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| ==References==
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| ;Notes
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| {{Reflist|33em|refs=
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| <ref name="Crompton">Crompton & Rhein (2002)</ref>
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| <ref name=mhp>{{cite web
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| | url = http://www.nps.gov/history/maritime/light/admin.htm
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| | title = Lighthouses: An Administrative History
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| | work = Maritime Heritage Program – Lighthouse Heritage
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| | publisher = U.S. National Park Service
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| | accessdate = 2008-06-10
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| }}</ref>
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| <ref name=ll>[http://www.nps.gov/history/maritime/lens/lens.htm Lighthouse Lenses and Illuminants]</ref>
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| }}
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| ;Bibliography
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| * Bathurst, Bella. ''The lighthouse Stevensons''. New York: Perennial, 2000. ISBN 0-06-093226-0
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| * Beaver, Patrick. ''A History of Lighthouses''. London: Peter Davies Ltd, 1971. ISBN 0-432-01290-7.
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| * Crompton, Samuel, W; Rhein, Michael, J. ''The Ultimate Book of Lighthouses''. San Diego, CA: Thunder Bay Press, 2002. ISBN 1-59223-102-0.
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| * Jones, Ray; Roberts, Bruce. ''American Lighthouses''. Globe Pequot, 1998. 1st ed. ISBN 0-7627-0324-5.
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| * Stevenson, D. Alan. ''The world's lighthouses before 1820''. London: [[Oxford University Press]], 1959.
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| ;Further reading
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| * Noble, Dennis. ''Lighthouses & Keepers: U. S. Lighthouse Service and Its Legacy''. Annapolis: U.S. Naval Institute Press, 1997. ISBN 1-55750-638-8.
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| * Putnam, George R. ''Lighthouses and Lightships of the United States''. Boston: Houghton Mifflin Co., 1933.
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| * Weiss, George. ''The Lighthouse Service, Its History, Activities and Organization''. Baltimore: Johns Hopkins Press, 1926.
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| ==External links==
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| {{Commons|Lighthouse|Lighthouses}}
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| *[http://books.google.com/books?id=sygDAAAAMBAJ&pg=PA66&dq=Popular+Science+1931+plane&hl=en&ei=ESQHTd47iL2cB5fYkeYN&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEIQ6AEwCDgK#v=onepage&q=Popular%20Science%201931%20plane&f=true "Lighthouses Of Strange Designs, December 1930, Popular Science]
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| *{{cite rowlett|index}} Research tool with details of over 14,700 lighthouses and navigation lights around the world with photos and links.
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| [[Category:Lighthouses| ]]
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| {{Link FA|nn}}
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| {{Link FA|no}}
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