Small swing bridges as found over canals may be pivoted only at one end, opening as would a gate, but require substantial underground structure to support the pivot. In its closed position, a bridge carrying a road or railway over a river or canal, for example. When a water vessel needs to pass the bridge, road traffic is stopped, as this type requires no counterweights, the complete weight is significantly reduced as compared to other moveable bridges. Where sufficient channel is available to have individual traffic directions on each side, the central support is often mounted upon a berm along the axis of the watercourse, intended to protect the bridge from watercraft collisions when it is opened. This artificial island forms an excellent construction area for building the movable span as the construction will not impede channel traffic, for a symmetrical bridge, the central pier forms a hazard to navigation. Asymmetrical bridges may place the pivot near one side of the channel, where a wide channel is not available, a large portion of the bridge may be over an area that would be easily spanned by other means. A wide channel will be reduced by the pivot and foundation.
If struck from the water near the edge of the span, buna River Bridge, in Shkodra, Albania. Puente de la Mujer, an asymmetrical cable-stayed span, the Sale Swing Bridge, Victoria, Australia. Dunalley Bridge, Tasmania Still in use, Belize City Swing Bridge, Belize City, Belize. Oldest such bridge in Central America and one of the few manually operated swing bridge in world still in operation, the longest swing bridge span is 340 metres, by the El Ferdan Railway Bridge across the Suez Canal. Le pont tournant rue Dieu, across the Canal Saint-Martin in Paris, is a location in the 1938 film Hôtel du Nord. Kalpaka Tilts, Liepāja, connecting the city with the former Russian/Soviet port Karosta, the Abtsewoudsebrug in Delft, close to the Technische Universiteit Delft, is a bridge of this type. 52°0′5. 71″N 4°21′50. 10″E Theres another one on the channel between Ghent and Terneuzen at Sas Van Gent, many inner cities have swing bridges, since these require less street space than other types of bridges.
Kopu Bridge, Waihou River, near Thames, New Zealand A swing bridge at the Gatun Locks provides the only road passage over the Atlantic side of the Panama Canal and this is a small bridge that swings out from each side. Another larger swing bridge at the Miraflores Locks is on the Pacific side but is used, having been supplanted by the Bridge of the Americas. Crosskeys Bridge - carries the A17 road over the River Nene in Lincolnshire Folkestone Harbour railway station - railway bridge on the branch line, goole railway swing bridge Glasson Dock swing bridge Hawarden Railway Bridge - rail. Many are manually operated, carrying only farm tracks, but a significant number carry road traffic and are mechanised for boater operation, manchester Ship Canal at Latchford, Stockton Heath and Lower Walton in Warrington, and slightly further west at Moore
Dun is a generic term for an ancient or medieval fort. It is mainly used in the British Isles to describe a kind of hillfort, the term comes from Irish dún or Scottish Gaelic dùn, and is cognate with Old Welsh din comes. In some areas duns were built on any suitable crag or hillock, particularly south of the Firth of Clyde, there are many duns on the west coast of Ireland and they feature in Irish mythology. For example, the tale of the Táin Bó Flidhais features Dún Chiortáin, duns seem to have arrived with the Celts in about the 7th century BC. Early duns had near vertical ramparts made of stone and timber, vitrified forts are the remains of duns that have been set on fire and where stones have been partly melted. Use of duns continued in some parts into the Middle Ages, duns are similar to brochs, but are smaller and probably would not have been capable of supporting a very tall structure. Good examples of this kind of dun can be found in the Outer Hebrides of Scotland and it is ultimately cognate to English town
A gatehouse, in architectural terminology, is a building enclosing or accompanying a gateway for a castle, manor house, town or similar buildings of importance. Gatehouses made their first appearance in the early antiquity when it became necessary to protect the entrance to a castle or town. Over time, they evolved into very complicated structures with many lines of defence, strongly fortified gatehouses would normally include a drawbridge, one or more portcullises, arrow loops and possibly even murder-holes where stones would be dropped on attackers. In some castles, the gatehouse was so strongly fortified it took on the function of a keep, examples of such gate keeps can be found at Bodiam Castle and Beaumaris Castle. In the late Middle Ages, some of these arrow loops might have converted into gun loops. Sometimes gatehouses formed part of fortifications, perhaps defending the passage of a bridge across a river or a moat. York has four important gatehouses, known as Bars, in its city walls, the French term for gatehouse is logis-porche.
This could be a large, complex structure that served both as a gateway and lodging or it could have composed of a gateway through an enclosing wall. A very large gatehouse might be called a châtelet, at the end of the Middle Ages, many gatehouses in England and France were converted into beautiful, grand entrance structures to manor houses or estates. Many of them became a separate feature free-standing or attached to the manor or mansion only by an enclosing wall, by this time the gatehouse had lost its defensive purpose and had become more of a monumental structure designed to harmonise with the manor or mansion. On the continent of Europe, there are examples of surviving gatehouses in France, Austria. Bargate, in Hampshire is a gatehouse in the city centre of Southampton. Constructed in 1180 as part of the Southampton town walls Ightham Mote, Durham Castle, in Durham has an 11th-century gatehouse that is now used as accommodation for students attending University College, Durham. Layer Marney Tower, the apotheosis of the Tudor gatehouse, stokesay Castle, a 13th-century fortified manor house in Shropshire has a Jacobean half-timbered gatehouse.
Stanway House, Gloucestershire, where the gatehouse measures 44 ft. by 22 ft. and has three storeys, westwood House, which has a frontage of 54 ft. with two storeys. Burton Agnes Hall, East Riding of Yorkshire, which has three storeys and is flanked by octagonal towers at the angles. Hylton Castle, Sunderland, although it is an actual castle, château de Châteaubriant, two gatehouses, one for the lower bailey, one for the upper ward. Château de Suscinio, a large 15th-century gatehouse in the style, Morbihan
A city gate is a gate which is, or was, set within a city wall. City gates were built to provide a point of controlled access to and departure from a walled city for people, goods. The city gate was used to display diverse kinds of public information such as announcements and toll schedules, standards of local measures. City gates, in one form or another, can be found across the world in cities dating back to ancient times to around the 19th century. Many cities would close their gates after a certain curfew each night, for example a bigger one like Prague or a smaller one like Flensburg, in the north of Germany. With increased stability and freedom, many walled cities removed such fortifications as city gates, although many still survive, many surviving gates have been heavily restored, rebuilt or new ones created to add to the appearance of a city, such as Bab Bou Jalous in Fes. With increased levels of traffic, city gates have come under threat in the past for impeding the flow of traffic, ireland, St.
Laurences Gate, 13th Century, in Drogheda, Co
A vertical-lift bridge or just lift bridge is a type of movable bridge in which a span rises vertically while remaining parallel with the deck. The vertical lift offers several benefits over other movable bridges such as the bascule, generally speaking they cost less to build for longer moveable spans. The counterweights in a lift are only required to be equal to the weight of the deck. As a result, heavier materials can be used in the deck, although most vertical-lift bridges use towers, each equipped with counterweights, some use hydraulic jacks located below the deck. An example is the 52-foot span bridge at St Paul Avenue in Milwaukee, another design used balance beams to lift the deck, with pivoting bascules located on the top of the lift towers. An example of this kind was built at La Salle in Illinois, the biggest disadvantage to the vertical-lift bridge is the height restriction for vessels passing under it. This is a result of the deck remaining suspended above the passageway, Ryde Bridge – road – Ryde, New South Wales – opened 1935, now permanently lowered Hexham Bridge – road – Hexham, New South Wales – opened 1952.
In addition, there are Bridges 13,17 and 18 on the Welland Recreational Waterway, these bridges have not been operational since 1973. Bridges 13 and 18 have had their counterweights removed while the machinery for Bridge 17 has been dismantled, in addition, Bridge 18 no longer possesses its towers, they were removed for ease of maintenance. Burlington Canal Lift Bridge, over the Burlington Canal, information is available from Built 1962. Second Narrows Bridge Vancouver, BC over Burrard Inlet, Okanagan Lake Bridge in Kelowna, BC across Okanagan Lake – replaced in 2008. Shippagan Bridge Shippagan, NB over Shippagan Bay, sir Ambrose Shea Bridge, Placentia, NL. Pont Gustave-Flaubert – crossing the Seine at Rouen, this bridge is the highest vertical-lift bridge in Europe. It is 670 m long, with a span of 116 metres, a striking design feature, the two road sections are mounted outside the central towers. The bridge was designed by François Gillard and Aymeric Zublena and opened to traffic on 25 September 2008.
It is named after the author Gustave Flaubert who was born in Rouen, the central lift span is 117m long and can be lifted vertically up to 53m to let tall ships pass underneath. The bridge is 575m long with the lift span weighing around 2,600 tonnes. Its width varies from 32 to 45m and it will be used by cars, cyclists and it can handle 43,000 vehicles a day and will reduce traffic congestion in Bordeaux
Alnwick Castle is a castle and stately home in Alnwick in the English county of Northumberland. It is the seat of the Duke of Northumberland, built following the Norman conquest and it is a Grade I listed building and as of 2012 received over 800,000 visitors per year. Alnwick Castle guards a road crossing the River Aln. Yves de Vescy, Baron of Alnwick, Beatrix de Vesci, daughter of Yves de Vescy married Eustace Fitz John, Constable of Chestershire and Knaresborough. By his marriage to Beatrix de Vesci he gained the Baronies of Malton, the castle was first mentioned in 1136 when it was captured by King David I of Scotland. At this point it was described as very strong and it was besieged in 1172 and again in 1174 by William the Lion, King of Scotland and William was captured outside the walls during the Battle of Alnwick. Eustace de Vesci, lord of Alnwick, was accused of plotting with Robert Fitzwalter against King John in 1212, in response, John ordered the demolition of Alnwick Castle and Baynards Castle, his instructions were not carried out at Alnwick.
When the Vescy family became extinct, Alnwick Castle and the manor were bequeathed to Antony Bek the Bishop of Durham. The Percy family benefited from Englands wars with Scotland, through his military accomplishments Henry Percy, 1st Baron Percy, in 1309 he purchased the barony of Alnwick from Bek, and it has been owned by the Percy family, the Earls and Dukes of Northumberland since. The stone castle Henry Percy bought was a modest affair, though he did not live to see its completion, the building programme turned Alnwick into a major fortress along the Anglo-Scottish border. His son, called Henry, continued the building, the Abbots Tower, the Middle Gateway and the Constables Tower survive from this period. The work at Alnwick Castle balanced military requirements with the familys residential needs, in 1345 the Percys acquired Warkworth Castle, in Northumberland. Though Alnwick was considered prestigious, Warkworth became the familys preferred residence. The Percy family were lords in northern England.
Henry Percy, 1st Earl of Northumberland, rebelled against King Richard II, the earl rebelled against King Henry IV and after defeating the earl in the Battle of Shrewsbury, the king chased him north to Alnwick. The castle surrendered under the threat of bombardment in 1403, during the Wars of the Roses, castles were infrequently engaged in battle and conflict was generally based around combat in the field. It was held against King Edward until its surrender in mid-September 1461 after the Battle of Towton, re-captured by Sir William Tailboys, during the winter it was surrendered by him to Hastings, Sir John Howard and Sir Ralph Grey of Heton in late July 1462. Grey was appointed captain but surrendered after a siege in the early autumn. King Edward responded with vigour and when the Earl of Warwick arrived in November Queen Margaret and her French advisor and they organised a mainly Scots relief force which, under George Douglas, 4th Earl of Angus and de Brézé, set out on 22 November
The word derives from the Old French word machecol, mentioned in Medieval Latin as machecollum, probably from Old French machier crush and col neck. Machicolate is only recorded in the 18th century in English, but a verb machicollāre is attested in Anglo-Latin, the Spanish word denoting this structure, matacán, is similarly composed from matar canes meaning roughly killing dogs, the latter being a reference to infidels. The design of a machicoulis, commonly known as drop box, in Arab fortifications they are usually found on defensive walls. The original Arab design was small, and similar to the domestic wooden balcony known as Mashrabiya. However, different from the balcony, for defense purposes it prominently features a wide opening at the bottom. The opening allows the dropping of hot water or oil and other material intended to harm to the enemy below. The feature of a closed balcony allows to cover while making use. A hoarding is a structure made of wood, usually temporarily constructed in the event of a siege.
Advantages of machicolations over wooden hoardings include the strength and fire resistance of stone. Machicolations were more common in French castles than English, where they were restricted to the gateway. One of the first examples of machicolation that still exists in northern France is Château de Farcheville built in 1291 outside Paris, similar to a machicolation is a smaller version which opens as a balcony, generally from a tower rather than a larger structure. Machicolations were a feature in many towers and rural buildings in Malta until the 18th century. Buildings with machicolations include Cavalier Tower, Gauci Tower, the Captains Tower, machicolation was used for decorative effect with spaces between the corbels but without the openings, and subsequently became a characteristic of many non-military buildings. Bretèche Arrow slit Hoarding Murder hole Media related to Machicolations at Wikimedia Commons Glossary of Medieval Art and Architecture, machicolation
A trunnion is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannon, they are an important military development, alternatively, a trunnion is a shaft that positions and supports a tilting plate. This is a misnomer, as in reality it is a cradle for the true trunnion, in mechanical engineering, it is one part of a rotating joint where a shaft is inserted into a full or partial cylinder. In a cannon, the trunnions are two projections cast just forward of the center of mass of the cannon and fixed to a two-wheeled movable gun carriage. As they allowed the muzzle to be raised and lowered easily, with the creation of larger and more powerful siege guns in the early 15th century, a new way of mounting them had to be specially designed. Stouter gun carriages were created with reinforced wheels, guns would be up to eight feet in length and shoot iron projectiles weighing from twenty-five to fifty pounds. These wrought iron balls when discharged were comparable in range and accuracy with stone-firing bombards, trunnions were mounted near the center of mass to allow the barrel to be elevated to any desired angle, without having to dismount it from the carriage upon which it rested.
Some guns had a set of trunnions placed several feet back from the first pair. The gun would recoil causing the carriage to move backwards several feet and it became easier to rapidly transport these large siege guns, maneuver them from transportation mode to firing position, and they could go wherever a team of men or horses could pull them. Due to its capabilities, the French- and Burgundy-designed siege gun, equipped with its trunnions, king Charles VIII and the French army used this new gun in the 1494 invasion of Italy. Although deemed masters of war and artillery at that time, Italians had not anticipated the innovations in French siege weaponry. Prior to this, field guns were huge, large-caliber bombards, superguns that. Cities that had proudly withstood sieges for up to seven years fell swiftly with the advent of new weapons. Defensive tactics and fortifications had to be altered since these new weapons could be transported so speedily and these towers would be deemed trace Italienne.
Whoever could afford these new weapons had the advantage over their neighbors and smaller sovereignties. Smaller states, such as the principalities of Italy, began to conglomerate, preexisting stronger entities, such as France or the Habsburg emperors, were able to expand their territories and maintain tighter control. With the threat of their land and castles being seized, the nobility began to pay their taxes, on firearms, the barrel is sometimes mounted in a trunnion, which in turn is mounted to the receiver. This usage is common for tubular or pressed metal frame guns, such as the AK-47, PPSh-41, Uzi and others
A broch is an Iron Age drystone hollow-walled structure of a type found only in Scotland. Brochs belong to the classification complex atlantic roundhouse devised by Scottish archaeologists in the 1980s and their origin is a matter of some controversy. The theory that they were defensive military structures is not accepted by modern archaeologists. Although most stand alone in the landscape, some examples exist of brochs surrounded by clusters of smaller dwellings, the word broch is derived from Lowland Scots brough, meaning fort. In the mid-19th century Scottish antiquaries called brochs burgs, after Old Norse borg, place names in Scandinavian Scotland such as Burgawater and Burgan show that Old Norse borg is the older word used for these structures in the north. Brochs are often referred to as duns in the west, antiquaries began to use the spelling broch in the 1870s. A precise definition for the word has proved elusive, brochs are the most spectacular of a complex class of roundhouse buildings found throughout Atlantic Scotland.
Researcher Euan MacKie has proposed a smaller total for Scotland of 104. The origin of brochs is a subject of continuing research and this view contrasted, for example, with that of Sir Lindsay Scott, who argued, following Childe, for a wholesale migration into Atlantic Scotland of people from southwest England. Meanwhile, the increasing number – albeit still pitifully few – of radiocarbon dates for the use of brochs still suggests that most of the towers were built in the 1st centuries BC. A few may be earlier, notably the one proposed for Old Scatness Broch in Shetland, Caithness and the Northern Isles have the densest concentrations, but there are a great many examples in the west of Scotland and the Hebrides. Although mainly concentrated in the northern Highlands and the Islands, a few occur in the Borders, on the west coast of Dumfries and Galloway. In a c.1560 sketch there appears to be a broch by the next to Annan Castle in Dumfries. This small group of southern brochs has never been satisfactorily explained, the original interpretation of brochs, favoured by nineteenth century antiquarians, was that they were defensive structures, places of refuge for the community and their livestock.
They were sometimes regarded as the work of Danes or Picts, from the 1930s to the 1960s, archaeologists like V. Gordon Childe and John Hamilton regarded them as castles where local landowners held sway over a subject population. The castle theory fell from favour among Scottish archaeologists in the 1980s, once again, there is a lack of archaeological proof for this reconstruction, and the sheer number of brochs, sometimes in places with a lack of good land, makes it problematic. Brochs close groupings and profusion in many areas may indeed suggest that they had a defensive or even offensive function. Often they are at key strategic points, in Shetland they sometimes cluster on each side of narrow stretches of water, the broch of Mousa, for instance, is directly opposite another at Burraland in Sandwick
A defensive wall is a fortification used to protect a city, town or other settlement from potential aggressors. In ancient to modern times, they were used to enclose settlements, beyond their defensive utility, many walls had important symbolic functions – representing the status and independence of the communities they embraced. Existing ancient walls are almost always masonry structures, although brick, depending on the topography of the area surrounding the city or the settlement the wall is intended to protect, elements of the terrain may be incorporated in order to make the wall more effective. Walls may only be crossed by entering the city gate and are often supplemented with towers. Simpler defensive walls of earth or stone, thrown up around hillforts, early castles, from very early history to modern times, walls have been a near necessity for every city. Uruk in ancient Sumer is one of the worlds oldest known walled cities, before that, the city of Jericho in what is now the West Bank had a wall surrounding it as early as the 8th millennium BC.
The Assyrians deployed large labour forces to build new palaces, some settlements in the Indus Valley Civilization were fortified. By about 3500 B. C. hundreds of small farming villages dotted the Indus floodplain, many of these settlements had fortifications and planned streets. Mundigak in present-day south-east Afghanistan has defensive walls and square bastions of sun dried bricks, babylon was one of the most famous cities of the ancient world, especially as a result of the building program of Nebuchadnezzar, who expanded the walls and built the Ishtar Gate. Exceptions were few — notably, ancient Sparta and ancient Rome did not have walls for a long time, these fortifications were simple constructions of wood and earth, which were replaced by mixed constructions of stones piled on top of each other without mortar. In Central Europe, the Celts built large fortified settlements which the Romans called oppida, the fortifications were continuously expanded and improved. In ancient Greece, large stone walls had been built in Mycenaean Greece, in classical era Greece, the city of Athens built a long set of parallel stone walls called the Long Walls that reached their guarded seaport at Piraeus.
Large tempered earth walls were built in ancient China since the Shang Dynasty, although stone walls were built in China during the Warring States, mass conversion to stone architecture did not begin in earnest until the Tang Dynasty. The large walls of Pingyao serve as one example, the famous walls of the Forbidden City in Beijing were established in the early 15th century by the Yongle Emperor. The Romans fortified their cities with massive, mortar-bound stone walls, the most famous of these are the largely extant Aurelian Walls of Rome and the Theodosian Walls of Constantinople, together with partial remains elsewhere. These are mostly city gates, like the Porta Nigra in Trier or Newport Arch in Lincoln, apart from these, the early Middle Ages saw the creation of some towns built around castles. These cities were only protected by simple stone walls and more usually by a combination of both walls and ditches. From the 12th century AD hundreds of settlements of all sizes were founded all across Europe and these cities are easy to recognise due to their regular layout and large market spaces