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117-479: Tybee Island Light is a lighthouse next to the Savannah River Entrance, on the northeast end of Tybee Island , Georgia . It is one of seven surviving colonial era lighthouse towers, though highly modified in the mid 1800s. The current lighthouse is the fourth tower at this station, though neither of its first two predecessors were lit. The first tower was built at the direction of James Oglethorpe and

234-422: A Hippodamian grid plan . Following Alexander's death in 323 BC, his general Ptolemy Lagides took possession of Egypt and brought Alexander's body to Egypt with him. Ptolemy at first ruled from the old Egyptian capital of Memphis . In 322/321 BC he had Cleomenes executed. Finally, in 305 BC, Ptolemy declared himself Pharaoh as Ptolemy I Soter ("Savior") and moved his capital to Alexandria. Although Cleomenes

351-458: A Roman triumphal column , is one of the best-known ancient monuments still standing in Alexandria today. It is located on Alexandria's ancient acropolis —a modest hill located adjacent to the city's Arab cemetery —and was originally part of a temple colonnade. Including its pedestal , it is 30 m (99 ft) high; the shaft is of polished red granite, 2.7 m (8.9 ft) in diameter at

468-575: A hot steppe climate (Köppen climate classification: BSh ), virtually hot desert climate ( Köppen climate classification : BWh ). Like the rest of Egypt's northern coast , the prevailing north wind, blowing across the Mediterranean, gives the city a less severe climate than the desert hinterland. Rafah and Alexandria are the wettest places in Egypt; the other wettest places are Rosetta , Baltim , Kafr el-Dawwar , and Mersa Matruh . The city's climate

585-402: A rescue service , if necessary. Improvements in maritime navigation and safety, such Global Positioning System (GPS), led to the phasing out of non-automated lighthouses across the world. Although several closed due to safety concerns, Canada still maintains 49 staffed lighthouses, split roughly evenly across east and west coasts. The remaining modern lighthouses are usually illuminated by

702-640: A Diesel generator for backup. Many Fresnel lens installations have been replaced by rotating aerobeacons , which require less maintenance. In modern automated lighthouses, the 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. Later innovations were "Vega Lights", and experiments with light-emitting diode (LED) panels. LED lights, which use less energy and are easier to maintain, had come into widespread use by 2020. In

819-402: A Greek unit of length measuring approximately 180 m or 590 ft). The end of this abutted on the land at the head of the present Grand Square, where the "Moon Gate" rose. All that now lies between that point and the modern "Ras al-Tin" quarter is built on the silt which gradually widened and obliterated this mole. The Ras al-Tin quarter represents all that is left of the island of Pharos,

936-541: A Nile river delta, Alexandria is one of the most vulnerable cities to sea level rise in the entire world. According to some estimates, hundreds of thousands of people in its low-lying areas may already have to be relocated before 2030. The 2022 IPCC Sixth Assessment Report estimates that by 2050, Alexandria and 11 other major African cities ( Abidjan , Algiers , Cape Town , Casablanca , Dakar , Dar es Salaam , Durban , Lagos , Lomé , Luanda and Maputo ) would collectively sustain cumulative damages of US$ 65 billion for

1053-645: A Ptolemaic colonnade and streets in the north-east of the city, but little else. Hogarth explored part of an immense brick structure under the mound of Kom El Deka , which may have been part of the Paneum, the Mausolea, or a Roman fortress. The making of the new foreshore led to the dredging up of remains of the Patriarchal Church; and the foundations of modern buildings are seldom laid without some objects of antiquity being discovered. The most famous mosque in Alexandria

1170-522: A bishop decreed that Paganism must be eradicated. Beneath the acropolis itself are the subterranean remains of the Serapeum, where the mysteries of the god Serapis were enacted and whose carved wall niches are believed to have provided overflow storage space for the ancient Library. In more recent years, many ancient artifacts have been discovered from the surrounding sea, mostly pieces of old pottery. Alexandria's catacombs , known as Kom El Shoqafa , are

1287-436: A filament source. Experimental installations of laser lights, either at high power to provide a "line of light" in the sky or, utilising low power, aimed towards mariners have identified problems of increased complexity in installation and maintenance, and high power requirements. The first practical installation, in 1971 at Point Danger lighthouse , Queensland , was replaced by a conventional light after four years, because

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1404-453: A form of concrete that will set under water used by the Romans, and developed a technique of securing the granite blocks together using dovetail joints and marble dowels . 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

1521-414: 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 . This concentration of light is accomplished with a rotating lens assembly. In early lighthouses, the light source

1638-427: A more powerful hyperradiant Fresnel lens manufactured by the firm of Chance Brothers . While lighthouse buildings differ depending on the location and purpose, they tend to have common components. A light station comprises the lighthouse tower and all outbuildings, such as the keeper's living quarters, fuel house, boathouse, and fog-signaling building. The Lighthouse itself consists of a tower structure supporting

1755-583: A navigator with a line of position called a range in North America and a transit in Britain. Ranges can be used to precisely align a vessel within a narrow channel such as a river. With landmarks of a range illuminated with a set of fixed lighthouses, nighttime navigation is possible. Such paired lighthouses are called range lights in North America and leading lights in the United Kingdom. The closer light

1872-419: A new 4th order lens. The main tower was severely damaged in a hurricane in 1871, and developed such serious cracking that a $ 50,000 appropriation was requested for its replacement. Instead a new front tower (which had already been moved twice) was constructed of iron. New keepers dwellings were constructed in 1881 and 1885. The following year the tower was shaken by the 1886 Charleston earthquake , which damaged

1989-512: A number of screw-pile lighthouses. Englishman James Douglass was knighted for his work on the fourth Eddystone Lighthouse. 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

2106-402: 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 transponders so the radar signature of the light is also unique. Before modern strobe lights , lenses were used to concentrate the light from a continuous source. Vertical light rays of the lamp are redirected into

2223-411: 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. South Foreland Lighthouse was the first tower to successfully use an electric light in 1875. The lighthouse's carbon arc lamps were powered by a steam-driven magneto . John Richardson Wigham was the first to develop

2340-461: A seawall, quays and a bridge. Near the beach side of the area, there are the remains of a tower built by Ptolemy II Philadelphus. The tower was an exact scale replica of the destroyed Alexandrine Pharos Lighthouse . Citadel of Qaitbay is a defensive fortress located on the Mediterranean sea coast. It was established in 1477 AD (882 AH ) by the mamluk Sultan Al-Ashraf Sayf al-Din Qa'it Bay . The Citadel

2457-429: A short distance southwest of the pillar, consist of a multi-level labyrinth, reached via a large spiral staircase and featuring dozens of chambers adorned with sculpted pillars, statues, and other syncretic Romano-Egyptian religious symbols , burial niches, and sarcophagi , as well as a large Roman-style banquet room, where memorial meals were conducted by relatives of the deceased. The catacombs were long forgotten by

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2574-415: A single stationary flashing light powered by solar-charged batteries and mounted on a steel skeleton tower. Where the power requirement is too great for solar power alone, cycle charging of the battery by a Diesel generator is provided. The generator only comes into use when the battery needs charging, saving fuel and increasing periods between maintenance. John Smeaton is noteworthy for having designed

2691-415: A successful attempt to erect a 25-ton obelisk in 1999. This followed two experiments to erect smaller obelisks and two failed attempts to erect a 25-ton obelisk. "Pompey's Pillar" is a misnomer , as it has nothing to do with Pompey , having been erected in 293 for Diocletian , possibly in memory of the rebellion of Domitius Domitianus . The structure was plundered and demolished in the 4th century when

2808-469: A system for gas illumination of lighthouses. His improved gas 'crocus' burner at the Baily Lighthouse near Dublin was 13 times more powerful than the most brilliant light then known. 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

2925-408: A system of reflectors and candles, but this was upgraded to oil lamps after it was ceded to the federal government in 1790. A second tower was added to the site in 1822 to form a range . Both towers received Fresnel lenses in 1857, with the lower front tower being equipped with a 4th order lens, while the main tower received a larger 2nd order lens. Confederate forces burned the light in 1862 during

3042-542: Is a popular tourist destination and an important industrial centre due to its natural gas and oil pipelines from Suez . The city extends about 40 km (25 mi) along the northern coast of Egypt and is the largest city on the Mediterranean, the second-largest in Egypt (after Cairo ), the fourth-largest city in the Arab world , the ninth-largest city in Africa , and the ninth-largest urban area in Africa . The city

3159-475: Is built up') existed since the 13th century BC in the vicinity and eventually grew into the Egyptian quarter of the city. Just east of Alexandria (where Abu Qir Bay is now), there were in ancient times marshland and several islands. As early as the 7th century BC, there existed important port cities of Canopus and Heracleion . The latter was recently rediscovered underwater. Alexandria was founded by Alexander

3276-589: Is in the Far West Nile delta area. It is a densely populated city; its core areas belie its large administrative area. Notes: 2020 CAPMAS projection based on 2017 revised census figures, may differ significantly from 2017 census preliminary tabulations. The 14 kisms were reported simply as Alexandria city by CAPMAS in 2006 but given explosive growth definitions, likely informal, may have changed or may be set to change. Same area with 12 kisms existed in 1996. Kisms are considered 'fully urbanised' Alexandria has

3393-537: Is influenced by the Mediterranean Sea , moderating its temperatures, causing variable rainy winters and moderately hot and slightly prolonged summers that, at times, can be very humid; January and February are the coolest months, with daily maximum temperatures typically ranging from 12 to 18 °C (54 to 64 °F) and minimum temperatures that could reach 5 °C (41  °F ). Alexandria experiences violent storms , rain and sometimes sleet and hail during

3510-579: Is located on the eastern side of the northern tip of Pharos Island at the mouth of the Eastern Harbour . It was erected on the exact site of the famous Lighthouse of Alexandria , which was one of the Seven Wonders of the Ancient World . It was built on an area of 17,550 square metres . Persistent efforts have been made to explore the antiquities of Alexandria. Encouragement and help have been given by

3627-419: Is one example. Race Rocks Light in western Canada is painted in horizontal black and white bands to stand out against the horizon. 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 trigonometry (see Distance to the horizon ) as D = 1.22 H {\displaystyle D=1.22{\sqrt {H}}} , where H

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3744-683: Is referred to as the beacon or front range; the further light is called the rear range. The rear range light is almost always taller than the front. When a vessel is on the correct course, the two lights align vertically, but when the observer is out of position, the difference in alignment indicates the direction of travel to correct the course. There are two types of lighthouses: ones that are located on land, and ones that are offshore. Alexandria Alexandria ( / ˌ æ l ɪ ɡ ˈ z æ n d r i ə , - ˈ z ɑː n -/ AL -ig- ZA(H)N -dree-ə ; Arabic : الإسكندرية ; Ancient Greek : Ἀλεξάνδρεια , Coptic : Ⲣⲁⲕⲟϯ - Rakoti or ⲁⲗⲉⲝⲁⲛⲇⲣⲓⲁ)

3861-584: Is the second largest city in Egypt and the largest city on the Mediterranean coast . It lies at the western edge of the Nile River delta . Founded in c.  331 BC by Alexander the Great , Alexandria grew rapidly and became a major centre of Hellenic civilisation , eventually replacing Memphis , in present-day Greater Cairo , as Egypt's capital. Called the "Bride of the Mediterranean" internationally, Alexandria

3978-510: Is the height above water in feet, and D is the distance from the lighthouse to the horizon in nautical miles, the lighthouse range . 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

4095-589: The Battle of Ridaniya in 1517, the city was conquered by the Ottoman Turks and remained under Ottoman rule until 1798. Alexandria lost much of its former importance to the Egyptian port city of Rosetta during the 9th to 18th centuries, and it only regained its former prominence with the construction of the Mahmoudiyah Canal in 1820. Alexandria figured prominently in the military operations of Napoleon 's expedition to Egypt in 1798. French troops stormed

4212-488: The Civil War and removed the lens as they retreated to Fort Pulaski . Reconstruction of the light was begun in 1866 but was delayed by a cholera outbreak. A new tower was constructed atop the first 60 ft (18 m) of the old tower, raising the height of the whole to 154 ft (47 m). This tower was equipped with a 1st order lens. The front beacon was now a 50 ft (15 m) wooden skeleton tower equipped with

4329-553: The Coptic Orthodox Church and the Greek Orthodox Church of Alexandria both lay claim to this ancient heritage. By 641, the city had already been largely plundered and lost its significance before re-emerging in the modern era. From the late 18th century, Alexandria became a major centre of the international shipping industry and one of the most important trading centres in the world, both because it profited from

4446-601: The Florida Reef along the Florida Keys, beginning with the Carysfort Reef Light in 1852. In waters too deep for a conventional structure, a lightship might be used instead of a lighthouse, such as the former 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 . Aligning two fixed points on land provides

4563-640: The Muslim conquest of Egypt in 641 AD, when a new capital was founded at Fustat (later absorbed into Cairo ). Alexandria was best known for the Lighthouse of Alexandria ( Pharos ), one of the Seven Wonders of the Ancient World ; its Great Library , the largest in the ancient world; and the Catacombs of Kom El Shoqafa , one of the Seven Wonders of the Middle Ages . Alexandria was the intellectual and cultural centre of

4680-464: The "moderate" climate change scenario RCP 4.5 and US$ 86.5 billion for the high-emission scenario RCP 8.5, while RCP 8.5 combined with the hypothetical impact from marine ice sheet instability at high levels of warming would involve up to US$ 137.5 billion in damages. Additional accounting for the "low-probability, high-damage events" may increase aggregate risks to US$ 187 billion for the "moderate" RCP4.5, US$ 206 billion for RCP8.5 and US$ 397 billion under

4797-510: The 20th century. These often have a narrow cylindrical core surrounded by an open lattice work bracing, such as Finns Point Range Light . 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 of California. In shallower bays, Screw-pile lighthouse ironwork structures are screwed into

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4914-524: The 4th century AD. This underwater section, containing many of the most interesting sections of the Hellenistic city, including the palace quarter, was explored in 1992 and is still being extensively investigated by the French underwater archaeologist Franck Goddio and his team . It raised a noted head of Caesarion . These are being opened up to tourists, to some controversy. The spaces that are most open are

5031-515: The Arabs under the general 'Amr ibn al-'As invaded it during the Muslim conquest of Egypt , after a siege that lasted 14 months. The first Arab governor of Egypt recorded to have visited Alexandria was Utba ibn Abi Sufyan , who strengthened the Arab presence and built a governor's palace in the city in 664–665. In reference to Alexandria, Ibn Battuta speaks of a number of Muslim saints that resided in

5148-576: The Great in April 331 BC as Ἀλεξάνδρεια ( Alexandreia ), as one of his many city foundations . After he captured the Egyptian Satrapy from the Persians , Alexander wanted to build a large Greek city on Egypt's coast that would bear his name. He chose the site of Alexandria, envisioning the building of a causeway to the nearby island of Pharos that would generate two great natural harbours. Alexandria

5265-504: The Great Harbour. The names of a few other public buildings on the mainland are known, but there is little information as to their actual position. None, however, are as famous as the building that stood on the eastern point of Pharos island. There, The Great Lighthouse , one of the Seven Wonders of the World , reputed to be 138 m (453 ft) high, was situated. The first Ptolemy began

5382-507: The Rosetta Gate, but remnants of streets and canals were exposed in 1899 by German excavators outside the east fortifications, which lie well within the area of the ancient city. Alexandria consisted originally of little more than the island of Pharos, which was joined to the mainland by a 1,260 m-long (4,130 ft) mole and called the Heptastadion ("seven stadia"—a stadium was

5499-585: The Serapeum. Nearby, immense catacombs and columbaria have been opened which may have been appendages of the temple. These contain one very remarkable vault with curious painted reliefs, now artificially lit and open to visitors. The objects found in these researches are in the museum, the most notable being a great basalt bull, probably once an object of cult in the Serapeum. Other catacombs and tombs have been opened in Kom El Shoqafa (Roman) and Ras El Tin (painted). The German excavation team found remains of

5616-710: The Society for the Promotion of Hellenic Studies in 1895; and a German expedition worked for two years (1898–1899). But two difficulties face the would-be excavator in Alexandria: lack of space for excavation and the underwater location of some areas of interest. Since the great and growing modern city stands immediately over the ancient one, it is almost impossible to find any considerable space in which to dig, except at enormous cost. Cleopatra VII 's royal quarters were inundated by earthquakes and tsunami, leading to gradual subsidence in

5733-643: The Sultan of Egypt at the time, al-Nasir Muhammad . Ibn Battuta also visited the Pharos lighthouse on two occasions: in 1326 he found it to be partly in ruins and in 1349 it had deteriorated to the point that it was no longer possible to enter. During the Middle Ages , the Mamluk Sultanate provided amenities for European merchants to stay in the port cities of Alexandria and Damietta , so hotels were built and placed at

5850-462: 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. The Argand lamp used whale oil , colza , olive oil or other vegetable oil as fuel, supplied by a gravity feed from

5967-405: The United Kingdom and Ireland about a third of lighthouses had been converted from filament light sources to use LEDs, and conversion continued with about three per year. The light sources are designed to replicate the colour and character of the traditional light as closely as possible. The change is often not noticed by people in the region, but sometimes a proposed change leads to calls to preserve

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6084-486: 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. One such influence was Robert Stevenson , himself a seminal figure in the development of lighthouse design and construction. His greatest achievement was the construction of the Bell Rock Lighthouse in 1810, one of

6201-568: The ancient Mediterranean for much of the Hellenistic age and late antiquity . It was at one time the largest city in the ancient world before being eventually overtaken by Rome . The city was a major centre of early Christianity and was the centre of the Patriarchate of Alexandria , which was one of the major centres of Christianity in the Eastern Roman Empire . In the modern world,

6318-513: The base, tapering to 2.4 m (7.9 ft) at the top. The shaft is 88 ft (27 m) high and made out of a single piece of granite. Its volume is 132 m (4,662 cu ft) and weight approximately 396 tons. Pompey's Pillar may have been erected using the same methods that were used to erect the ancient obelisks . The Romans had cranes but they were not strong enough to lift something this heavy. Roger Hopkins and Mark Lehrner conducted several obelisk erecting experiments including

6435-481: The beam was too narrow to be seen easily. 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. For example, the Scheveningen Lighthouse flashes are alternately 2.5 and 7.5 seconds. Some lights have sectors of

6552-621: The black at the top further down the tower until the illustrated configuration was reached. In 1967 the entire tower was repainted with a white base and a gray top. The gray faded severely and was painted black in 1970. In 1999 a major restoration project was begun under the auspices of the Tybee Island Historical Society , who took possession of the light station in 2002 under the National Historic Lighthouse Preservation Act . As part of this project

6669-458: The centre of the city, close to the point where the Sema (or Soma) of Alexander (his Mausoleum ) rose. This point is very near the present mosque of Nebi Daniel ; the line of the great East–West "Canopic" street is also present in modern-day Alexandria, having only slightly diverged from the line of the modern Boulevard de Rosette (now Sharae Fouad). Traces of its pavement and canal have been found near

6786-406: The choice of light sources, mountings, reflector design, the use of Fresnel lenses , 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. Alexander Mitchell designed the first screw-pile lighthouse – his lighthouse

6903-507: The citizens until they were discovered by accident in 1900. The most extensive ancient excavation currently being conducted in Alexandria is known as Kom El Deka . It has revealed the ancient city's well-preserved theater, and the remains of its Roman-era baths . The temple was built in the Ptolemy era and dedicated to Osiris, which finished the construction of Alexandria. It is located in Abusir,

7020-565: The city on 2 July 1798, and it remained in their hands until the arrival of a British expedition in 1801. The British won a considerable victory over the French at the Battle of Alexandria on 21 March 1801, following which they besieged the city , which fell to them on 2 September 1801. Muhammad Ali , the Ottoman governor of Egypt, began rebuilding and redevelopment around 1810 and, by 1850, Alexandria had returned to something akin to its former glory. Egypt turned to Europe in their effort to modernise

7137-513: The city. One such saint was Imam Borhan Oddin El Aaraj, who was said to perform miracles. Another notable figure was Yaqut al-'Arshi, a disciple of Abu Abbas El Mursi . Ibn Battuta also writes about Abu 'Abdallah al-Murshidi, a saint that lived in the Minyat of Ibn Murshed. Although al-Murshidi lived in seclusion, Ibn Battuta writes that he was regularly visited by crowds, high state officials, and even by

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7254-471: The climate of Alexandria in the year 2050 would most closely resemble the current climate of Gaza City . The annual temperature would increase by 2.8 °C (5.0 °F), and the temperature of the warmest and the coldest month by 2.9 °C (5.2 °F) and 3.1 °C (5.6 °F). According to Climate Action Tracker , the current warming trajectory appears consistent with 2.7 °C (4.9 °F), which closely matches RCP 4.5. Due to its location on

7371-525: The collapse of the Soviet government in 1990s, most of the official records on the locations, and condition, of these lighthouses were reportedly lost. Over time, the condition of RTGs in Russia degraded; many of them fell victim to vandalism and scrap metal thieves, who may not have been aware of the dangerous radioactive contents. Energy-efficient LED lights can be powered by solar panels , with batteries instead of

7488-488: 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. The first Fresnel lens

7605-493: The cooler months; these events, combined with a poor drainage system, have been responsible for occasional flooding in the city in the past though they rarely occur anymore. July and August are the hottest and driest months of the year, with an average daily maximum temperature of 30 °C (86  °F ). The average annual rainfall is around 211 mm (8.3 in) but has been as high as 417 mm (16.4 in) Port Said , Kosseir , Baltim , Damietta and Alexandria have

7722-475: The country. Greeks, followed by other Europeans and others, began moving to the city. In the early 20th century, the city became a home for novelists and poets. In July 1882, the city came under bombardment from British naval forces and was occupied. In July 1954, the city was a target of an Israeli bombing campaign that later became known as the Lavon Affair . On 26 October 1954, Alexandria's Mansheya Square

7839-587: The course of Roman rule in Egypt , the city's name was Latinised as Alexandrēa ad Aegyptum . After the capture of Alexandria by the Rashiduns in AD 641, the name was Arabicised : initial Al- was re-analysed into the definite article ; metathesis occurred on x , from [ks] to [sk] ; and the suffix -eia was assimilated into the feminine adjectival suffix -iyya ( ـِيَّة ). Radiocarbon dating of seashell fragments and lead contamination show human activity at

7956-621: The development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs and promontories , unlike many modern lighthouses. The most famous lighthouse structure from antiquity was the Pharos of Alexandria , Egypt , which collapsed following a series of earthquakes between 956 and 1323. The intact Tower of Hercules at A Coruña , Spain gives insight into ancient lighthouse construction; other evidence about lighthouses exists in depictions on coins and mosaics, of which many represent

8073-450: The distinction of its population's three largest ethnicities: Greek, Egyptian and Jewish. By the time of Augustus , the city grid encompassed an area of 10 km (3.9 sq mi), and the total population during the Roman principate was around 500,000–600,000, which would wax and wane in the course of the next four centuries under Roman rule. According to Philo of Alexandria , in

8190-513: The easy overland connection between the Mediterranean and Red Seas and the lucrative trade in Egyptian cotton . Alexandria was located on the earlier Egyptian settlement, which was called Rhacotis ( Ancient Greek : Ῥακῶτις , romanized :  Rhakôtis ), the Hellenised form of Egyptian r-ꜥ-qd(y)t . As one of many settlements founded by Alexander the Great, the city he founded on Rhacotis

8307-473: The emitted light into a concentrated beam, thereby greatly increasing the light's visibility. 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. French physicist and engineer Augustin-Jean Fresnel developed the multi-part Fresnel lens for use in lighthouses. His design allowed for

8424-468: The entrance into a harbor, such as New London Harbor Light . 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 the clifftop to ensure that they can still be seen at

8541-488: The high-end ice sheet instability scenario. In every single estimate, Alexandria alone bears around half of these costs. Since sea level rise would continue for about 10,000 years under every scenario of climate change, future costs of sea level rise would only increase, especially without adaptation measures. Greek Alexandria was divided into three regions: Two main streets, lined with colonnades and said to have been each about 60 m (200 ft) wide, intersected in

8658-455: The lantern room where the light operates. 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 muntins (glazing 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

8775-470: The largest cities ever built before the Industrial Revolution and the largest pre-industrial city that was not an imperial capital. Due to the constant presence of war in Alexandria in ancient times, very little of the ancient city has survived into the present day. Much of the royal and civic quarters sank beneath the harbour and the rest has been built over in modern times. " Pompey's Pillar ",

8892-593: The largest city in the world and, for some centuries more, was second only to Rome. It became Egypt's main Greek city, with Greek people from diverse backgrounds. The Septuagint , a Greek version of the Tanakh , was produced there. The early Ptolemies kept it in order and fostered the development of its museum into the leading Hellenistic centre of learning ( Library of Alexandria , which faced destruction during Caesar 's siege of Alexandria in 47 BC), but were careful to maintain

9009-477: The least temperature variation in Egypt. The highest recorded temperature was 45 °C (113 °F) on 30 May 1961, and the coldest recorded temperature was 0 °C (32 °F) on 31 January 1994. A 2019 paper published in PLOS One estimated that under Representative Concentration Pathway 4.5 , a "moderate" scenario of climate change where global warming reaches ~2.5–3 °C (4.5–5.4 °F) by 2100,

9126-431: The lens and caused further cracking of the brickwork; these were both however immediately repaired. In 1933 the tower was electrified and the station reduced to a single keeper. The beacon was automated in 1972. Throughout its life the daymark of the tower was modified on numerous occasions. Originally all-white, the base and lantern were painted black in 1887; this was altered in 1914 and again in 1916, each time bringing

9243-531: The light is concentrated, if needed, by the "lens" or "optic". Power sources for lighthouses in the 20th–21st centuries vary. Originally lit by open fires and later candles, the Argand hollow wick lamp and parabolic reflector were introduced in the late 18th century. Whale oil was also used with wicks as the source of light. Kerosene became popular in the 1870s and electricity and acetylene gas derived on-site from calcium carbide began replacing kerosene around

9360-505: The lighthouse at Ostia . Coins from Alexandria, Ostia, and Laodicea in Syria also exist. The modern era of lighthouses began at the turn of the 18th century, as the number of lighthouses being constructed increased significantly due to much higher levels of 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

9477-469: The lighthouse keepers. 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 / 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

9594-468: The local Archaeological Society and by many individuals. Excavations were performed in the city by Greeks seeking the tomb of Alexander the Great without success. The past and present directors of the museum have been enabled from time to time to carry out systematic excavations whenever opportunity is offered; D. G. Hogarth made tentative researches on behalf of the Egypt Exploration Fund and

9711-510: The location during the period of the Old Kingdom (27th–21st centuries BC) and again in the period 1000–800 BC, followed by the absence of activity after that. From ancient sources it is known there existed a trading post at this location during the time of Rameses the Great for trade with Crete , but it had long been lost by the time of Alexander's arrival. A small Egyptian fishing village named Rhakotis ( Egyptian : rꜥ-qdy.t , 'That which

9828-399: The low grounds to northeast and southwest, where it is practically impossible to get below the Roman strata . The most important results were those achieved by Dr. G. Botti, late director of the museum, in the neighbourhood of "Pompey's Pillar", where there is a good deal of open ground. Here, substructures of a large building or group of buildings have been exposed, which are perhaps part of

9945-466: The luminosity of traditional oil lights. The use of gas as illuminant became widely available with the invention of the Dalén light by Swedish engineer Gustaf Dalén . He used Agamassan (Aga), a substrate , to absorb the gas, allowing the gas to be stored, and hence used, safely. Dalén also invented the ' sun valve ', which automatically regulated the light and turned it off during the daytime. The technology

10062-515: The merchants' disposal so that they could live according to the pattern they were accustomed to in their country. Alexandria lost much of its importance in international trade after Portuguese navigators discovered a new sea route to India in the late 15th century. This reduced the amount of goods that needed to be transported through the Alexandrian port, as well as the Mamluks' political power. After

10179-421: The metal cupola roof provides a safe conduit for any lightning strikes. 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

10296-485: 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. Stevenson worked for the Northern Lighthouse Board for nearly fifty years during which time he designed and oversaw the construction and later improvement of numerous lighthouses. He innovated in

10413-402: The number of operational lighthouses has declined due to the expense of maintenance and the advent of much cheaper, more sophisticated, and more effective electronic navigational systems. Before the development of clearly defined ports , mariners were guided by fires built on hilltops. Since elevating the fire would improve visibility, placing the fire on a platform became a practice that led to

10530-414: The project, and the second Ptolemy ( Ptolemy II Philadelphus ) completed it, at a total cost of 800  talents . It took 12 years to complete and served as a prototype for all later lighthouses in the world. The light was produced by a furnace at the top and the tower was built mostly with solid blocks of limestone. The Pharos lighthouse was destroyed by an earthquake in the 14th century, making it

10647-458: The sea. The function of lighthouses was gradually changed from indicating ports to the providing of a visible warning against shipping hazards, such as rocks or reefs. The Eddystone Rocks were a major shipwreck hazard for mariners sailing through the English Channel . The first lighthouse built there was an octagonal wooden structure, anchored by 12 iron stanchions secured in the rock, and

10764-451: 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. Skeletal iron towers with screw-pile foundations were built on

10881-496: The second longest surviving ancient wonder, after the Great Pyramid of Giza . A temple of Hephaestus also stood on Pharos at the head of the mole. In the 1st century, the population of Alexandria contained over 180,000 adult male citizens, according to a census dated from 32 AD, in addition to a large number of freedmen, women, children and slaves. Estimates of the total population range from 216,000 to 500,000, making it one of

10998-541: The siege of Atlanta, designed and built some of the most exotic lighthouses in the most difficult locations on the U.S. Great Lakes . 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). In a lighthouse, the source of light is called the "lamp" (whether electric or fuelled by oil) and

11115-457: The site of the actual lighthouse having been weathered away by the sea. On the east of the mole was the Great Harbour, now an open bay; on the west lay the port of Eunostos, with its inner basin Kibotos, now vastly enlarged to form the modern harbour. In Strabo 's time (latter half of the 1st century BC), the principal buildings were as follows, enumerated as they were to be seen from a ship entering

11232-516: The surface during periods of fog or low clouds, as at Point Reyes Lighthouse . Another example is in San Diego , California : the Old Point Loma lighthouse was too high up and often obscured by fog, so it was replaced in 1891 with a lower lighthouse, New Point Loma lighthouse . As technology advanced, prefabricated skeletal iron or steel structures tended to be used for lighthouses constructed in

11349-587: The third and most famous Eddystone Lighthouse , but some builders are well known for their work in building multiple lighthouses. The Stevenson family ( Robert , Alan , David , Thomas , David Alan , and Charles ) made lighthouse building a three-generation profession in Scotland. Richard Henry Brunton designed and built 26 Japanese lighthouses in Meiji Era Japan, which became known as Brunton's "children". Blind Irishman Alexander Mitchell invented and built

11466-455: The tower was repainted in the 1916–1966 black-white-black daymark. The beacon is still a functioning navigational aid, still using its original lens. The site is open to the public and retains its keepers houses and auxiliary buildings as well as the lighthouse tower. Lighthouse Lighthouses mark dangerous coastlines, hazardous shoals , reefs , rocks, and safe entries to harbors; they also assist in aerial navigation . Once widely used,

11583-483: The traditional light, including in some cases a rotating beam. A typical LED system designed to fit into the traditional 19th century Fresnel lens enclosure was developed by Trinity House and two other lighthouse authorities and costs about € 20,000, depending on configuration, according to a supplier; it has large fins to dissipate heat. Lifetime of the LED light source is 50,000 to 100,000 hours, compared to about 1,000 hours for

11700-476: The turn of the 20th century. Carbide was promoted by the Dalén light , which automatically lit the lamp at nightfall and extinguished it at dawn. In the second half of the 20th century, many remote lighthouses in Russia (then Soviet Union ) were powered by radioisotope thermoelectric generators (RTGs). These had the advantage of providing power day or night and did not need refuelling or maintenance. However, after

11817-523: 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. 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

11934-643: The weight and volume of material in conventional lens designs. Fresnel lighthouse lenses are ranked by 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. Some lighthouses, such as those at Cape Race , Newfoundland, and Makapuu Point , Hawaii, used

12051-468: The western suburb of Alexandria in Borg el Arab city. Only the outer wall and the pylons remain from the temple. There is evidence to prove that sacred animals were worshiped there. Archaeologists found an animal necropolis near the temple. Remains of a Christian church show that the temple was used as a church in later centuries. Also found in the same area are remains of public baths built by the emperor Justinian,

12168-567: The year 38 AD, disturbances erupted between Jews and Greek citizens of Alexandria during a visit paid by King Agrippa I to Alexandria, principally over the respect paid by the Herodian nation to the Roman emperor , which quickly escalated to open affronts and violence between the two ethnic groups and the desecration of Alexandrian synagogues. This event has been called the Alexandrian pogroms . The violence

12285-437: 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 keepers, sometimes as often as every two hours. The lens assembly sometimes floated in 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

12402-459: 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. The civil engineer John Smeaton rebuilt the lighthouse from 1756 to 1759; his tower marked a major step forward in the design of lighthouses and remained in use until 1877. He modeled the shape of his lighthouse on that of an oak tree , using granite blocks. He rediscovered and used " hydraulic lime ",

12519-662: Was built on piles that were screwed 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. Although its construction began later, the Wyre Light in Fleetwood, Lancashire, was the first to be lit (in 1840). Until 1782 the source of illumination had generally been wood pyres or burning coal. The Argand lamp , invented in 1782 by

12636-465: Was called Alexándreia hḗ kat' Aígypton ( Ἀλεξάνδρεια ἡ κατ' Αἴγυπτον ), which some sources translated as "Alexandria by Egypt", as the city was, at that time, in the periphery of Egypt proper (the area beside the Nile ). Some of the Alexandrian and Greek populaces, e.g., Hypsicles , also referred to the city as Alexándreia hḗ prós Aígypton ( Ἀλεξάνδρεια ἡ πρός Αἴγυπτον , "Alexandria near Egypt"). In

12753-411: Was constructed of wood; erected in 1736, it was felled by a storm in 1741. The following year a replacement was erected, this time of stone and wood, but still without illumination; instead, it was topped with a flag pole. This tower succumbed to shoreline erosion. The third tower was constructed in 1773 by John Mullryne, a brick tower originally 100 ft (30 m) in height. It was first fitted with

12870-589: Was devastated by a tsunami ( 365 Crete earthquake ), an event annually commemorated years later as a "day of horror". In 619, Alexandria fell to the Sassanid Persians . The city was mostly uninjured by the conquest and a new palace called Tarawus was erected in the eastern part of the city, later known as Qasr Faris, "fort of the Persians". Although the Byzantine emperor Heraclius recovered it in 629, in 641

12987-472: Was founded originally in the vicinity of an Egyptian settlement named Rhacotis (that became the Egyptian quarter of the city). Alexandria grew rapidly, becoming a major centre of Hellenic civilisation and replacing Memphis as Egypt's capital during the reign of the Ptolemaic pharaohs who succeeded Alexander. It retained this status for almost a millennium, through the period of Roman and Eastern Roman rule until

13104-409: Was intended to supersede the older Greek colony of Naucratis as a Hellenistic centre in Egypt and to be the link between Greece and the rich Nile valley. A few months after the foundation, Alexander left Egypt and never returned to the city during his life. After Alexander's departure, his viceroy Cleomenes continued the expansion. The architect Dinocrates of Rhodes designed the city, using

13221-502: Was mainly in charge of overseeing Alexandria's early development, the Heptastadion and the mainland quarters seem to have been primarily Ptolemaic work. Inheriting the trade of ruined Tyre and becoming the centre of the new commerce between Europe and the Arabian and Indian East, the city grew in less than a generation to be larger than Carthage . In one century, Alexandria had become

13338-565: Was quelled after Caligula intervened and had the Roman governor, Flaccus, removed from the city. In 115 AD, large parts of Alexandria were destroyed during the Diaspora revolt , which gave Hadrian and his architect, Decriannus , an opportunity to rebuild it. In 215 AD, the emperor Caracalla visited the city and, because of some insulting satires that the inhabitants had directed at him, abruptly commanded his troops to put to death all youths capable of bearing arms. On 21 July 365 AD, Alexandria

13455-502: Was the predominant light source in lighthouses from the 1900s to the 1960s, when electric lighting had become dominant. 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 developed the first practical optical system in 1777, known as a catoptric system. This rudimentary system effectively collimated

13572-401: Was the site of a failed assassination attempt on Gamal Abdel Nasser . Europeans began leaving Alexandria following the 1956 Suez Crisis that led to an outburst of Arab nationalism . The nationalisation of property by Nasser, which reached its highest point in 1961, drove out nearly all the rest. Alexandria is located in the country of Egypt, on the southern coast of the Mediterranean. It

13689-588: Was used in 1823 in the Cordouan lighthouse at the mouth of the Gironde estuary ; its light could be seen from more than 20 miles (32 km) out. Fresnel's invention increased the luminosity of the lighthouse lamp by a factor of four and his system is still in common use. The introduction of electrification and automatic lamp changers began to make lighthouse keepers obsolete. For many years, lighthouses still had keepers, partly because lighthouse keepers could serve as

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