Victoria was Queen of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death. On 1 May 1876, she adopted the additional title of Empress of India. Victoria was the daughter of Prince Edward, Duke of Kent and Strathearn, the fourth son of King George III. Both the Duke and the King died in 1820, Victoria was raised under close supervision by her mother, Princess Victoria of Saxe-Coburg-Saalfeld, she inherited the throne at the age of 18, after her father's three elder brothers had all died, leaving no surviving legitimate children. The United Kingdom was an established constitutional monarchy, in which the sovereign held little direct political power. Victoria attempted to influence government policy and ministerial appointments. Victoria married her first cousin Prince Albert of Saxe-Coburg and Gotha in 1840, their nine children married into royal and noble families across the continent, tying them together and earning her the sobriquet "the grandmother of Europe". After Albert's death in 1861, Victoria avoided public appearances.
As a result of her seclusion, republicanism temporarily gained strength, but in the latter half of her reign, her popularity recovered. Her Golden and Diamond Jubilees were times of public celebration, her reign of 63 years and seven months was longer than that of any of her predecessors and is known as the Victorian era. It was a period of industrial, political and military change within the United Kingdom, was marked by a great expansion of the British Empire, she was the last British monarch of the House of Hanover. Her son and successor, Edward VII, initiated the House of Saxe-Coburg and Gotha, the line of his father. Victoria's father was Prince Edward, Duke of Kent and Strathearn, the fourth son of the reigning King of the United Kingdom, George III; until 1817, Edward's niece, Princess Charlotte of Wales, was the only legitimate grandchild of George III. Her death in 1817 precipitated a succession crisis that brought pressure on the Duke of Kent and his unmarried brothers to marry and have children.
In 1818 he married Princess Victoria of Saxe-Coburg-Saalfeld, a widowed German princess with two children—Carl and Feodora —by her first marriage to the Prince of Leiningen. Her brother Leopold was Princess Charlotte's widower; the Duke and Duchess of Kent's only child, was born at 4.15 a.m. on 24 May 1819 at Kensington Palace in London. Victoria was christened by the Archbishop of Canterbury, Charles Manners-Sutton, on 24 June 1819 in the Cupola Room at Kensington Palace, she was baptised Alexandrina after one of her godparents, Emperor Alexander I of Russia, Victoria, after her mother. Additional names proposed by her parents—Georgina and Augusta—were dropped on the instructions of Kent's eldest brother, the Prince Regent. At birth, Victoria was fifth in the line of succession after the four eldest sons of George III: George, the Prince Regent; the Prince Regent had no surviving children, the Duke of York had no children. The Duke of Clarence and the Duke of Kent married on the same day in 1818, but both of Clarence's legitimate daughters died as infants.
The first of these was Princess Charlotte, born and died on 27 March 1819, two months before Victoria was born. Victoria's father died in January 1820. A week her grandfather died and was succeeded by his eldest son as George IV. Victoria was third in line to the throne after York and Clarence. Clarence's second daughter was Princess Elizabeth of Clarence who lived for twelve weeks from 10 December 1820 to 4 March 1821 and, while Elizabeth lived, Victoria was fourth in line; the Duke of York died in 1827. When George IV died in 1830, he was succeeded by his next surviving brother, Clarence, as William IV, Victoria became heir presumptive; the Regency Act 1830 made special provision for Victoria's mother to act as regent in case William died while Victoria was still a minor. King William distrusted the Duchess's capacity to be regent, in 1836 he declared in her presence that he wanted to live until Victoria's 18th birthday, so that a regency could be avoided. Victoria described her childhood as "rather melancholy".
Her mother was protective, Victoria was raised isolated from other children under the so-called "Kensington System", an elaborate set of rules and protocols devised by the Duchess and her ambitious and domineering comptroller, Sir John Conroy, rumoured to be the Duchess's lover. The system prevented the princess from meeting people whom her mother and Conroy deemed undesirable, was designed to render her weak and dependent upon them; the Duchess avoided the court because she was scandalised by the presence of King William's illegitimate children. Victoria shared a bedroom with her mother every night, studied with private tutors to a regular timetable, spent her play-hours with her dolls and her King Charles Spaniel, Dash, her lessons included French, German and Latin, but she spoke only English at home. In 1830, the Duchess of Kent and Conroy took Victoria across the centre of England to visit the Malvern Hills, stopping at towns and great country houses along the way. Similar journeys to oth
Whitchurch is a market town in northern Shropshire, England. It lies 2 miles east of the Welsh border, 20 miles north of the county town of Shrewsbury, 20 miles south of Chester, 15 miles east of Wrexham. At the 2011 Census, the population of the town was 9,781. Whitchurch is the oldest continuously inhabited town in Shropshire, it is twinned with France. Although there is no written history of early times, there is evidence from various discovered artifacts that people lived in this area about 3,000 BC. Flakes of flint from the Neolithic era were found in nearby Dearnford Farm. A settlement founded by the Romans about AD 52–70 called Mediolanum, it stood on a major Roman road between Chester and Wroxeter, it was listed on the Antonine Itinerary but is not the Mediolanum of Ptolemy's Geography, in central Wales. Local Roman artefacts can be seen at the Whitchurch Heritage Centre. In 1066, Whitchurch was called Westune for its location on the western edge of Shropshire, bordering the north Welsh Marches.
Before the Norman conquest of England, the area had been held by Harold Godwinson. After the conquest, Whitchurch's location on the marches would require the Lords of Whitchurch to engage in military activity. There was a castle at Whitchurch built by the same Earl of Surrey, which would predate the birth of Ralph; the Domesday Book estimates that the property was worth £10 annually, having been worth £8 in the reign of Edward the Confessor. By the time it was recorded in Doomsday Book, Whitchurch was held by William de Warenne, 1st Earl of Surrey, Roger de Montgomery, it was part of the hundred of Hodnet. The surrounding hamlets became townships and Dodtune is now integrated into Whitchurch as Dodington; the first church was built on the hill in AD 912. After the Norman Conquest a motte and bailey castle and a new white Grinshill stone church were built. Westune became Album Monasterium; the name Whitchurch is from the Middle English for "White Church", referring to a church constructed of white stone in the Norman period.
The area was known as Album Monasterium and Blancminster, the Warennes of Whitchurch were surnamed de Albo Monasterio in contemporary writings. It is supposed that the church was built by 1st Earl of Surrey. In 1377 the Whitchurch estates passed to the Talbot family, it was sold by the Talbots to Thomas Egerton, from whom it passed to the earls of Bridgwater and to Earl Brownlow. The town was granted market status in the 14th Century; the replacement third church collapsed in July 1711 and the present Queen Anne parish church of St Alkmund was constructed to take its place. It was consecrated in 1713. William fitz Ranulf is the earliest individual of the Warenne family recorded as the Lord of Whitchurch, first appearing in the Shropshire Pipe Roll of 1176. In 1859, Robert Eyton considered it that Ralph, son of William de Warenne, 2nd Earl of Surrey, was the father of William and that he first held that title. However, other theories have been put forward. During the reign of Henry I in the 12th century, Whitchurch was in the North Division of Bradford Hundred which by the 1820s was referred to as North Bradford Hundred.
In the 18th Century many of the earlier timber-framed buildings were refaced in the more fashionable brick. New elegant Georgian houses were built in Dodington; as dairy farming became more profitable Whitchurch developed as a centre for Cheshire cheese production. Cheese fairs were held on every third Wednesday. Cheese and other goods could be transported to wider markets when the Whitchurch Arm of Thomas Telford's Llangollen Canal was opened in 1811; the railway station was opened in 1858 on the first railway line in North Shropshire, running from Crewe to Shrewsbury. On 23 November 1981, an F1/T2 tornado passed through Whitchurch as part of the record-breaking nationwide tornado outbreak on that day; the Whitchurch tornado was the longest-lived tornado of the entire outbreak, having first touched down 35 miles away in the south Shropshire village of Norbury. After passing through Whitchurch, the tornado dissipated. Whitchurch has its own town council, responsible for street lights and the civic centre, located in the centre of the town.
The council organises various events throughout the year including the Christmas Lights. The town is part of Shropshire Council, the local authority for Shropshire, it is a unitary authority, having the powers of a non-metropolitan county and district council combined. The residents of Whitchurch elect three councillors to this council; the town is located within the North Shropshire parliamentary constituency. This constituency is rural with the main urban centres being Oswestry, Market Drayton and Whitchurch, it has been in existence since 1832 although it was abolished in 1885 but re-established in 1983. The residents of the constituency elect one MP who since 1997 has been Owen Paterson, a Conservative. There are over 100 listed buildings in Whitchurch, including the churches detailed in the religion section lower down. In the picture to the left is the street named Bargates. At the top on the left is St Alkmund's Church; this is followed by the former almhouses by Samuel Higginson. This is followed by the former girls' school founded by Jane Higginson and the old Whitchurch Grammar School, founded in 1548.
The grammar school building dates from 1708 (Grade II listed
Opal is a hydrated amorphous form of silica. Because of its amorphous character, it is classed as a mineraloid, unlike crystalline forms of silica, which are classed as minerals, it is deposited at a low temperature and may occur in the fissures of any kind of rock, being most found with limonite, rhyolite and basalt. Opal is the national gemstone of Australia. There are two broad classes of opal: common. Precious opal displays play-of-color, common opal does not. Play-of-color is defined as "a pseudochromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to diffract light. Depending on the conditions in which it formed, opal may be transparent, translucent or opaque and the background color may be white, black or nearly any color of the visual spectrum. Black opal is considered to be the rarest, whereas white and green are the most common. Precious opal shows a variable interplay of internal colors, though it is a mineraloid, it has an internal structure.
At microscopic scales, precious opal is composed of silica spheres some 150 to 300 nm in diameter in a hexagonal or cubic close-packed lattice. It was shown by J. V. Sanders in the mid-1960s that these ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal; the regularity of the sizes and the packing of these spheres determines the quality of precious opal. Where the distance between the packed planes of spheres is around half the wavelength of a component of visible light, the light of that wavelength may be subject to diffraction from the grating created by the stacked planes; the colors that are observed are determined by the spacing between the planes and the orientation of planes with respect to the incident light. The process can be described by Bragg's law of diffraction. Visible light cannot pass through large thicknesses of the opal; this is the basis of the optical band gap in a photonic crystal.
The notion that opals are photonic crystals for visible light was expressed in 1995 by Vasily Astratov's group. In addition, microfractures may be filled with secondary silica and form thin lamellae inside the opal during solidification; the term opalescence is used to describe this unique and beautiful phenomenon, which in gemology is termed play of color. In gemology, opalescence is applied to the hazy-milky-turbid sheen of common or potch opal which does not show a play of color. Opalescence is a form of adularescence. For gemstone use, most opal is cut and polished to form a cabochon. "Solid" opal refers to polished stones consisting wholly of precious opal. Opals too thin to produce a "solid" may be combined with other materials to form attractive gems. An opal doublet consists of a thin layer of precious opal, backed by a layer of dark-colored material, most ironstone, dark or black common opal, onyx, or obsidian; the darker backing emphasizes the play of color, results in a more attractive display than a lighter potch.
An opal triplet is similar to a doublet, but has a third layer, a domed cap of clear quartz or plastic on the top. The cap acts as a protective layer for the opal; the top layer acts as a magnifier, to emphasize the play of color of the opal beneath, of lower quality. Triplet opals therefore have a more artificial appearance, are not classed as precious opal. Jewelry applications of precious opal can be somewhat limited by opal's sensitivity to heat due to its high water content and predisposition to scratching. Combined with modern techniques of polishing, doublet opal produces a similar effect to black or boulder opal at a fraction of the price. Doublet opal has the added benefit of having genuine opal as the top visible and touchable layer, unlike triplet opals. Besides the gemstone varieties that show a play of color, the other kinds of common opal include the milk opal, milky bluish to greenish. Common opal displays a hazy-milky-turbid sheen from within the stone. In gemology, this optical effect is defined as opalescence, a form of adularescence.
Fire opal is a transparent with warm body colors of yellow to orange to red. Although it does not show any play of color a stone will exhibit bright green flashes; the most famous source of fire opals is the state of Querétaro in Mexico. Fire opals that do not show play of color are sometimes referred to as jelly opals. Mexican opals are sometimes cut in their rhyolitic host material if it is hard enough to allow cutting and polishing; this type of Mexican opal is referred to as a Cantera opal. A type of opal from Mexico, referred to as Mexican water opal, is a colorless opal which exhibits either a bluish or golden internal sheen. Girasol opal is a term sometimes mistakenly and improperly used to refer to fire opals, as well as a type of transparent to semitransparent type milky quartz from Madagascar which displays an asterism, or star effect, when cut properly
Isle of Man
The Isle of Man, sometimes referred to as Mann, is a self-governing British Crown dependency in the Irish Sea between Great Britain and Ireland. The head of state is Queen Elizabeth II, who holds the title of Lord of Mann and is represented by a lieutenant governor. Defence is the responsibility of the United Kingdom; the island has been inhabited since before 6500 BC. Gaelic cultural influence began in the 5th century AD, the Manx language, a branch of the Gaelic languages, emerged. In 627, Edwin of Northumbria conquered the Isle of Man along with most of Mercia. In the 9th century, Norsemen established the Kingdom of the Isles. Magnus III, King of Norway, was King of Mann and the Isles between 1099 and 1103. In 1266, the island became part of Scotland after being ruled by Norway. After a period of alternating rule by the kings of Scotland and England, the island came under the feudal lordship of the English Crown in 1399; the lordship revested into the British Crown in 1765, but the island never became part of the 18th-century Kingdom of Great Britain or its successors the United Kingdom of Great Britain and Ireland and the present-day United Kingdom.
It retained its internal self-government. In 1881, the Isle of Man parliament, became the first national legislative body in the world to give women the right to vote in a general election, although this excluded married women. In 2016, the Isle of Man was awarded biosphere reserve status by UNESCO. Insurance and online gambling generate 17% of GNP each, followed by information and communications technology and banking with 9% each. Internationally, the Isle of Man is best known for the Isle of Man TT competition; the Manx name of the Isle of Man is Ellan Vannin: ellan is a Manx word meaning "island". The short form used in English, Mann, is derived from the Manx Mannin, though sometimes the name is written as Man; the earliest recorded Manx form of the name is Mana. The Old Irish form of the name is Mano. Old Welsh records named it as Manaw reflected in Manaw Gododdin, the name for an ancient district in north Britain along the lower Firth of Forth; the oldest known reference to the island calls it Mona, in Latin.
Latin references have Mevania or Mænavia, Eubonia or Eumonia by Irish writers. It is found in the Sagas of Icelanders as Mön; the name is cognate with the Welsh name of the island of Anglesey, Ynys Môn derived from a Celtic word for'mountain', from a Proto-Celtic *moniyos. The name was at least secondarily associated with that of Manannán mac Lir in Irish mythology. In the earliest Irish mythological texts, Manannán is a king of the otherworld, but the 9th-century Sanas Cormaic identifies a euhemerised Manannán as "a famous merchant who resided in, gave name to, the Isle of Man". A Manannán is recorded as the first king of Mann in a Manx poem; the island was cut off from the surrounding islands around 8000 BC, but was colonised by sea some time before 6500 BC. The first residents were fishermen. Examples of their tools are kept at the Manx Museum; the Neolithic Period marked the beginning of farming, megalithic monuments began to appear, such as Cashtal yn Ard near Maughold, King Orry's Grave at Laxey, Meayll Circle near Cregneash, Ballaharra Stones at St John's.
There were the local Ronaldsway and Bann cultures. During the Bronze Age, burial mounds became smaller. Bodies were put in stone-lined graves with ornamental containers; the Bronze Age burial mounds created long-lasting markers around the countryside. The ancient Romans knew of the island and called it Insula Manavia although it is uncertain whether they conquered the island. Around the 5th century AD, large-scale migration from Ireland precipitated a process of Gaelicisation evidenced by Ogham inscriptions, giving rise to the Manx language, a Goidelic language related to Irish and Scottish Gaelic. Vikings arrived at the end of the 8th century, they introduced many land divisions that still exist. In 1266 King Magnus VI of Norway ceded the islands to Scotland in the Treaty of Perth. In 1290 King Edward I of England sent Walter de Huntercombe to take possession of Mann, it remained in English hands until 1313, when Robert Bruce took it after besieging Castle Rushen for five weeks. A confused period followed when Mann was sometimes under English rule and sometimes Scottish, until 1346, when the Battle of Neville's Cross decided the long struggle between England and Scotland in England's favour.
English rule was delegated to a series of magnates. The Tynwald passed laws concerning the government of the island in all respects and had control over its finances, but was subject to the approval of the Lord of Mann. In 1866, the Isle of Man obtained limited home rule, with democratic elections to the House of Keys, but an appointed Legislative Council. Since democratic government has been extended; the Isle of Man has designated more than 250 historic sites as registered buildings. The Isle of Man is located in the middle of t
Clock towers are a specific type of building which houses a turret clock and has one or more clock faces on the upper exterior walls. Many clock towers are freestanding structures but they can adjoin or be located on top of another building. Clock towers are a common sight in many parts of the world with some being iconic buildings. One example is the Elizabeth Tower in London. There are many structures which may have clocks or clock faces attached to them and some structures have had clocks added to an existing structure. According to the Council on Tall Buildings and Urban Habitat a building is defined as a building if at least fifty percent of its height is made up of floor plates containing habitable floor area. Structures that do not meet this criterion, are defined as towers. A clock tower fits this definition of a tower and therefore can be defined as any tower built with one or more clock faces and that can be either freestanding or part of a church or municipal building such as a town hall.
Not all clocks on buildings therefore make the building into a clock tower. The mechanism inside the tower is known as a turret clock, it marks the hour by sounding large bells or chimes, sometimes playing simple musical phrases or tunes. Although clock towers are today admired for their aesthetics, they once served an important purpose. Before the middle of the twentieth century, most people did not have watches, prior to the 18th century home clocks were rare; the first clocks didn't have faces, but were striking clocks, which sounded bells to call the surrounding community to work or to prayer. They were therefore placed in towers. Clock towers were placed near the centres of towns and were the tallest structures there; as clock towers became more common, the designers realized that a dial on the outside of the tower would allow the townspeople to read the time whenever they wanted. The use of clock towers dates back to the antiquity; the earliest clock tower was the Tower of the Winds in Athens.
In its interior, there was a water clock, driven by water coming down from the Acropolis. In Song China, an astronomical clock tower was designed by Su Song and erected at Kaifeng in 1088, featuring a liquid escapement mechanism. In England, a clock was put up in a clock tower, the medieval precursor to Big Ben, at Westminster, in 1288; the oldest surviving turret clock part of a clock tower in Europe is the Salisbury cathedral clock, completed in 1306. Al-Jazari constructed an elaborate clock and described it in his Book of Knowledge of Ingenious Mechanical Devices in 1206, it was about 3.3 metres high, had multiple functions alongside timekeeping. It included a display of the zodiac and the solar and lunar paths, a pointer in the shape of the crescent moon which travelled across the top of a gateway, moved by a hidden cart and causing automatic doors to open, each revealing a mannequin, every hour, it was possible to re-program the length of day and night daily in order to account for the changing lengths of day and night throughout the year, it featured five robotic musicians who automatically play music when moved by levers operated by a hidden camshaft attached to a water wheel.
Other components of the castle clock included a main reservoir with a float, a float chamber and flow regulator and valve trough, two pulleys, crescent disc displaying the zodiac, two falcon automata dropping balls into vases. Line synchronous tower clocks were introduced in the United States in the 1920s; some clock towers have become famous landmarks. Prominent examples include Elizabeth Tower built in 1859, which houses the Great Bell in London, the tower of Philadelphia City Hall, the Rajabai Tower in Mumbai, the Spasskaya Tower of the Moscow Kremlin, the Torre dell'Orologio in the Piazza San Marco in Venice and the Zytglogge clock tower in the Old City of Bern, Switzerland; the tallest freestanding clock tower in the world is the Joseph Chamberlain Memorial Clock Tower at the University of Birmingham in Birmingham, United Kingdom. The tower stands at 100 metres tall and was completed in 1908; the clock tower of Philadelphia City Hall was part of the tallest building in the world from 1894, when the tower was topped out and the building occupied, until 1908.
Taller buildings have had clock faces added to their existing structure such as the Palace of Culture and Science in Warsaw, with a clock added in 2000. The building has a roof height of 187.68 m, an antenna height of 237 m. The NTT Docomo Yoyogi Building in Tokyo, with a clock added in 2002, has a roof height of 240 m, an antenna height of 272 m; the Abraj Al Bait, a hotel complex in Mecca constructed in 2012, has the largest and highest clock face on a building in the world, with its Makkah Royal Clock Tower having an occupied height of 494.4 m, a tip height of 601 m. The tower has four clock faces. List of clock towers Bell tower Minaret Street clock Thirteenth stroke of the clock Towerclocks.org - Tower clocks database Railway Station Clock Towers Architecture of time
William Henry Kitto was Captain of the Foxdale Mines, vice-chairman of the Isle of Man Steam Packet Company, a director of the Isle of Man Railway and a Justice of the Peace who became a Member of the House of Keys for the constituency of Glenfaba in 1902. William Henry Kitto was born in Perranzabuloe, near Perranporth, Cornwall in 1855, his father named William Kitto, was a mine engineer who had worked in the Cornish mining industry before moving with his family to the Isle of Man to take a position with the Isle of Man Mining Company as manager of the Foxdale Mines. Following his schooling the younger Kitto followed him into the profession. Kitto joined the Isle of Man Mining Company, serving as under-manager to his father until 1890 when his father was appointed to take charge of the Cape Copper Company's property at Namaqualand, South Africa. Kitto succeeded his father as manager of the mines at Foxdale, Isle of Man, the position being referred to as the Mine Captain. William Kitto remained with the Isle of Man Mining Company until the closure of the Foxdale Mines in 1911.
Said to have been respected within the mining industry, he is noted for his display of extraordinary courage during the Snaefell Mine Disaster in 1897 when he was instrumental in the recovery operation. Kitto was a director of the Isle of Man Steam Packet Company, being vice-chairman at the time of his death in addition to which he served as a director of the Isle of Man Railway Company. In 1901 he was appointed a Justice of the Peace, a position which he held until his death, by which time he was recognised as the oldest magistrate on the Isle of Man. William Kitto was elected as a Member of the House of Keys for the constituency of Glenfaba in 1902, succeeding John Joughin. Said to have been liberal in his political beliefs, he held the position until 1919 when he declined re-nomination. Kitto was twice married. On 23 March 1876 he married Susan of Cheshire, his first wife predeceased him in 1914. He married Isabel Goldsmith in 1928. In 1908, in the company of Alex Hill, a fellow magistrate and a manager with the Isle of Man Bank, Kitto undertook a trip around the world.
Captain Kitto was involved in the Freemasons movement, being the senior member of the St Maughold Lodge, Isle of Man. On 4 March 1930, in the capacity of a director of the Isle of Man Steam Packet Company, Capt. Kitto attended the launch of the company's new steamer, the Lady of Mann at Barrow-in-Furness, he presided at a dinner on the eve of the launch. Upon his return to the Isle of Man, Captain Kitto suffered a stroke and died at his home, Union Mills, on the evening of 26 March; the funeral was on Saturday 29 March, his body was interred at St. Paul's Churchyard, Foxdale
Concrete Portland cement concrete, is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens over time—most a lime-based cement binder, such as Portland cement, but sometimes with other hydraulic cements, such as a calcium aluminate cement. It is distinguished from other, non-cementitious types of concrete all binding some form of aggregate together, including asphalt concrete with a bitumen binder, used for road surfaces, polymer concretes that use polymers as a binder; when aggregate is mixed together with dry Portland cement and water, the mixture forms a fluid slurry, poured and molded into shape. The cement reacts chemically with the water and other ingredients to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. Additives are included in the mixture to improve the physical properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials embedded to provide tensile strength, yielding reinforced concrete.
Famous concrete structures include the Panama Canal and the Roman Pantheon. The earliest large-scale users of concrete technology were the ancient Romans, concrete was used in the Roman Empire; the Colosseum in Rome was built of concrete, the concrete dome of the Pantheon is the world's largest unreinforced concrete dome. Today, large concrete structures are made with reinforced concrete. After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century. Worldwide, concrete has overtaken steel in tonnage of material used; the word concrete comes from the Latin word "concretus", the perfect passive participle of "concrescere", from "con-" and "crescere". Small-scale production of concrete-like materials was pioneered by the Nabatean traders who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan from the 4th century BC, they discovered the advantages of hydraulic lime, with some self-cementing properties, by 700 BC.
They built kilns to supply mortar for the construction of rubble-wall houses, concrete floors, underground waterproof cisterns. They kept the cisterns secret; some of these structures survive to this day. In the Ancient Egyptian and Roman eras, builders discovered that adding volcanic ash to the mix allowed it to set underwater. German archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, which dates to 1400–1200 BC. Lime mortars were used in Greece and Cyprus in 800 BC; the Assyrian Jerwan Aqueduct made use of waterproof concrete. Concrete was used for construction in many ancient structures; the Romans used concrete extensively from 300 BC to a span of more than seven hundred years. During the Roman Empire, Roman concrete was made from quicklime, pozzolana and an aggregate of pumice, its widespread use in many Roman structures, a key event in the history of architecture termed the Roman Architectural Revolution, freed Roman construction from the restrictions of stone and brick materials.
It enabled revolutionary new designs in terms of both structural dimension. Concrete, as the Romans knew it, was a revolutionary material. Laid in the shape of arches and domes, it hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete. However, due to the absence of reinforcement, its tensile strength was far lower than modern reinforced concrete, its mode of application was different: Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice consisted of rubble. Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon the strength of the concrete bonding to resist tension.
The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic rock and ash, whereby crystallization of strätlingite and the coalescence of calcium–aluminum-silicate–hydrate cementing binder helped give the concrete a greater degree of fracture resistance in seismically active environments. Roman concrete is more resistant to erosion by seawater than modern concrete; the widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon. After the Roman Empire, the use of burned lime and pozzolana was reduced until the technique was all but forgotten between 500 and the 14th century. From the 14th century to the mid-18th century, the use of cement returned; the Canal du Midi was built using concrete in 1670.
The greatest step forward in the modern use