A Prime Minister is the head of a cabinet and the leader of the ministers in the executive branch of government in a parliamentary or semi-presidential system. A prime minister is not a head of state or chief executive officer of their respective nation, rather they are a head of government, serving under a monarch in a hybrid of aristocratic and democratic government forms. In parliamentary systems fashioned after the Westminster system, the prime minister is the presiding and actual head of government and head of the executive branch. In such systems, the head of state or the head of state's official representative holds a ceremonial position, although with reserve powers. In many systems, the prime minister selects and may dismiss other members of the cabinet, allocates posts to members within the government. In most systems, the prime minister is chairman of the cabinet. In a minority of systems, notably in semi-presidential systems of government, a prime minister is the official, appointed to manage the civil service and execute the directives of the head of state.
The prime minister is but not always, a member of the Legislature or the Lower House thereof and is expected with other ministers to ensure the passage of bills through the legislature. In some monarchies the monarch may exercise executive powers that are constitutionally vested in the crown and may be exercised without the approval of parliament; as well as being head of government, a prime minister may have other roles or posts—the Prime Minister of the United Kingdom, for example, is First Lord of the Treasury and Minister for the Civil Service. Prime ministers may take other ministerial posts. For example, during the Second World War, Winston Churchill was Minister of Defence and in the current cabinet of Israel, Benjamin Netanyahu serves as Minister of Communications, Foreign Affairs, Regional Cooperation and Interior; the term prime minister in its French form, premier ministre, is attested in 17th Century sources referring to Cardinal Richelieu after he was named to head the royal council in 1624.
The title was however informal and used alongside the informal principal ministre d'État more as a job description. After 1661, Louis XIV and his descendants refused to allow one of their ministers to be more important than the others, so the term was not in use; the term prime minister in the sense that we know it originated in the 18th century in the United Kingdom when members of parliament disparagingly used the title in reference to Sir Robert Walpole. During the whole of the 18th Century, Britain was involved in a prolonged conflict with France, periodically bursting into all-out war, Britons took outspoken pride in their "Liberty" as contrasted to the "Tyranny" of French Absolute Monarchy. Over time, the title became honorific and remains so in the 21st century; the monarchs of England and the United Kingdom had ministers in whom they placed special trust and who were regarded as the head of the government. Examples were Thomas Cromwell under Henry VIII; these ministers held a variety of formal posts, but were known as "the minister", the "chief minister", the "first minister" and the "prime minister".
The power of these ministers depended on the personal favour of the monarch. Although managing the parliament was among the necessary skills of holding high office, they did not depend on a parliamentary majority for their power. Although there was a cabinet, it was appointed by the monarch, the monarch presided over its meetings; when the monarch grew tired of a first minister, he or she could be dismissed, or worse: Cromwell was executed and Clarendon driven into exile when they lost favour. Kings sometimes divided power between two or more ministers to prevent one minister from becoming too powerful. Late in Anne's reign, for example, the Tory ministers Harley and Viscount Bolingbroke shared power. In the mid 17th century, after the English Civil War, Parliament strengthened its position relative to the monarch gained more power through the Glorious Revolution of 1688 and passage of the Bill of Rights in 1689; the monarch could no longer establish any law or impose any tax without its permission and thus the House of Commons became a part of the government.
It is at this point. A tipping point in the evolution of the prime ministership came with the death of Anne in 1714 and the accession of George I to the throne. George spoke no English, spent much of his time at his home in Hanover, had neither knowledge of, nor interest in, the details of English government. In these circumstances it was inevitable that the king's first minister would become the de facto head of the government. From 1721 this was the Whig politician Robert Walpole. Walpole chaired cabinet meetings, appointed all the other ministers, dispensed the royal patronage and packed the House of Commons with his supporters. Under Walpole, the doctrine of cabinet solidarity developed. Walpole required that no minister other than himself have private dealings with the king, that when the cabinet had agreed on a policy, all ministers must defend it in public, or resign; as a prime minister, Lord Melbourne, said, "It matters not what we say, gentlemen, so long as we all say the same thing."
Gold is a chemical element with symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.
Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.
Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.
Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. White gold alloys can be made with nickel. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese, aluminium and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.
The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric
Provenance is the chronology of the ownership, custody or location of a historical object. The term was mostly used in relation to works of art but is now used in similar senses in a wide range of fields, including archaeology, archives, printed books and science and computing; the primary purpose of tracing the provenance of an object or entity is to provide contextual and circumstantial evidence for its original production or discovery, by establishing, as far as practicable, its history the sequences of its formal ownership and places of storage. The practice has a particular value in helping authenticate objects. Comparative techniques, expert opinions and the results of scientific tests may be used to these ends, but establishing provenance is a matter of documentation; the term dates to the 1780s in English. Provenance is conceptually comparable to the legal term chain of custody. In archaeology and paleontology, the derived term provenience is used with a related but particular meaning, to refer to the location where an artifact or other ancient item was found.
Provenance covers an object's complete documented history. An artifact may thus have both a provenance; the provenance of works of fine art and antiquities is of great importance to their owner. There are a number of reasons why painting provenance is important, which also apply to other types of fine art. A good provenance increases the value of a painting, establishing provenance may help confirm the date and for portraits, the subject of a painting, it may confirm. The provenance of paintings can help resolve ownership disputes. For example, provenance between 1933 and 1945 can determine whether a painting was looted by the Nazis. Many galleries are putting a great deal of effort into researching the provenance of paintings in their collections for which there is no firm provenance during that period. Documented evidence of provenance for an object can help to establish that it has not been altered and is not a forgery, a reproduction, stolen or looted art. Provenance helps assign the work to a known artist, a documented history can be of use in helping to prove ownership.
An example of a detailed provenance is given in the Arnolfini portrait. The quality of provenance of an important work of art can make a considerable difference to its selling price in the market; the provenance of a work of art may vary in length, depending on context or the amount, known, from a single name to an entry in a scholarly catalogue some thousands of words long. An expert certification can mean the difference between an object having no value and being worth a fortune. Certifications themselves may be open to question. Jacques van Meegeren forged the work of his father Han van Meegeren. Jacques sometimes produced a certificate with his forgeries stating that a work was created by his father. John Drewe was able to pass off as genuine paintings, a large number of forgeries that would have been recognised as such by scientific examination, he established an impressive provenance and because of this galleries and dealers accepted the paintings as genuine. He created this false provenance by forging letters and other documents, including false entries in earlier exhibition catalogues.
Sometimes provenance can be as simple as a photograph of the item with its original owner. Simple yet definitive documentation such as that can increase its value by an order of magnitude, but only if the owner was of high renown. Many items that were sold at auction have gone far past their estimates because of a photograph showing that item with a famous person; some examples include antiques owned by politicians, artists, etc. The objective of provenance research is to produce a complete list of owners from when the painting was commissioned or in the artist's studio through to the present time. In practice, there are to be gaps in the list and documents that are missing or lost; the documented provenance should list when the painting has been part of an exhibition and a bibliography of when it has been discussed in print. Where the research is proceeding backwards, to discover the previous provenance of a painting whose current ownership and location is known, it is important to record the physical details of the painting – style, signature, dimensions, etc.
The titles of paintings and the attribution to a particular artist may change over time. The size of the work and its description can be used to identify earlier references to the painting; the back of a painting can contain significant provenance information. There may be exhibition marks, dealer stamps, gallery labels and other indications of previous ownership. There may be shipping labels. In the BBC TV programme Fake or Fortune? the provenance of the painting Bords de la Seine à Argenteuil was investigated using a gallery sticker and shipping label on the back. Early provenance can sometimes be indicated by a cartellino added to the front of a painting. However, these can fade or be painted over. Auction records are an important resource to assist i
Pembroke College, Cambridge
Pembroke College is a constituent college of the University of Cambridge, England. The college is the third-oldest college of the university and has over seven hundred students and fellows. Physically, it is one of the university's larger colleges, with buildings from every century since its founding, as well as extensive gardens, its members are termed "Valencians". Pembroke has selective admissions rate and a level of academic performance among the highest of all the Cambridge colleges. Pembroke is home to the first chapel designed by Sir Christopher Wren and is one of the six Cambridge colleges to have educated a British prime minister, in Pembroke's case William Pitt the Younger; the college library, with a Victorian neo-gothic clock tower, is endowed with an original copy of the first encyclopaedia to contain printed diagrams. The college's current master is Baron Smith of Finsbury. Marie de St Pol, Countess of Pembroke founded Cambridge. On Christmas Eve 1347, Edward III granted Marie de St Pol, widow of the Earl of Pembroke, the licence for the foundation of a new educational establishment in the young university at Cambridge.
The Hall of Valence Mary, as it was known, was thus founded to house a body of students and fellows. The statutes were notable in that they both gave preference to students born in France who had studied elsewhere in England, that they required students to report fellow students if they indulged in excessive drinking or visited disreputable houses; the college was renamed Pembroke Hall, became Pembroke College in 1856. Marie was involved with College affairs in the thirty years up to her death in 1377, she seems to have been something of a disciplinarian: the original Foundation documents had strict penalties for drunkenness and lechery, required that all students’ debts were settled within two weeks of the end of term, gave strict limits on numbers at graduation parties. In 2015, the college received a bequest of £34 million from the estate of American inventor and Pembroke alumnus Ray Dolby, thought to be the largest single donation to a college in the history of Cambridge University; the first buildings comprised a single court containing all the component parts of a college – chapel, hall and buttery, master's lodgings, students' rooms – and the statutes provided for a manciple, a cook, a barber and a laundress.
Both the founding of the college and the building of the city's first college Chapel required the grant of a papal bull. The original court was the university's smallest at only 95 feet by 55 feet, but was enlarged to its current size in the nineteenth century by demolishing the south range; the college's gatehouse is the oldest in Cambridge. The original Chapel now forms the Old Library and has a striking seventeenth-century plaster ceiling, designed by Henry Doogood, showing birds flying overhead. Around the Civil War, one of Pembroke's fellows and Chaplain to the future Charles I, Matthew Wren, was imprisoned by Oliver Cromwell. On his release after eighteen years, he fulfilled a promise by hiring his nephew Christopher Wren to build a great Chapel in his former college; the resulting Chapel was consecrated on St Matthew's Day, 1665, the eastern end was extended by George Gilbert Scott in 1880, when it was consecrated on the Feast of the Annunciation. An increase in membership over the last 150 years saw a corresponding increase in building activity.
The Hall was rebuilt in 1875–6 to designs by Alfred Waterhouse after he had declared the medieval Hall unsafe. As well as the Hall, Waterhouse designed a new range of rooms, Red Buildings, in French Renaissance style, designed a new Master's Lodge on the site of Paschal Yard, pulled down the old Lodge and the south range of Old Court to open a vista to the Chapel, designed a new Library in the continental Gothic style; the construction of the new library was undertaken by Kett. Waterhouse was dismissed as architect in 1878 and succeeded by George Gilbert Scott, after extending the Chapel, provided additional accommodation with the construction of New Court in 1881, with letters on a series of shields along the string course above the first floor spelling out the text from Psalm 127:1, "Nisi Dominus aedificat domum…". Building work continued into the 20th century with W. D. Caröe as architect, he added Pitt Building between Ivy Court and Waterhouse's Lodge, extended New Court with the construction of O staircase on the other side of the Lodge.
He linked his two buildings with an arched stone screen, Caröe Bridge, along Pembroke Street in a late Baroque style, the principal function of, to act as a bridge by which undergraduates might cross the Master's forecourt at first-floor level from Pitt Building to New Court without leaving the College or trespassing in what was the Fellows' Garden. In 1926, as the Fellows had become disenchanted with Waterhouse's Hall, Maurice Webb was brought in to remove the open roof, put in a flat ceiling and add two storeys of sets above; the wall between the Hall and the Fellows' Parlour was taken down, the latter made into a High Table dais. A new Senior Parlour was created on the ground floor of Hitcham Building; the remodelling work was completed in 1949 when Murray Easton replaced the Gothic tracery of the windows with a simpler design in the style of the medieval Hall. In 1933 Maurice Webb built a new Master's Lodge in the south-east corner of the College gardens
South African National Museum of Military History
The South African National War Museum in Johannesburg was opened by Prime Minister Jan Smuts on 29 August 1947 to preserve the history of South Africa's involvement in the Second World War. In 1975, the museum was renamed the South African National Museum of Military History and its function changed to include all conflicts that South Africa has been involved in. In 1999 it was amalgamated with the Pretoria-based Transvaal Museum and National Cultural History Museum to form the NFI. In April 2010 Ditsong was renamed Ditsong Museums of South Africa and the SANMMH was renamed the Ditsong National Museum of Military History. In the grounds of the museum is a large memorial designed by Sir Edwin Lutyens. On 30 November 1910 Prince Arthur, Duke of Connaught and Strathearn laid a commemorative stone at the memorial. Called the Rand Regiments Memorial and dedicated to British soldiers that lost their lives during the Second Boer War, it was rededicated on 10 October 1999 to all people who died during the Second Boer War and renamed the Boer War Memorial.
The museum is divided into a number of areas The Main Courtyard A memorial erected in honour of fallen members of the airborne forces of 44 Parachute Regiment, 44 Parachute Brigade and the South African Special Forces A memorial honouring members of 61 Mechanised Battalion Group Various field guns such as the 8.8 cm Flak 37 gun, QF 1-pounder pom-pom guns, Pak 38 Anti-Tank guns, etc. The GP Capt. "Sailor" Malan Hall withMesserschmitt Bf 109 Messerschmitt Me 262 Focke-Wulf Fw 190 The GE Brink Hall withHawker Hurricane Royal Aircraft Factory S. E.5 Supermarine Spitfire Messerschmitt Bf 109 de Havilland Mosquito Hawker Hartebeest A Battle of Britain exhibit Artifacts from the Royal Air Force Artifacts from South Africa's involvement in various world conflicts, such as the Korean War and the two World Wars A large medal collection from various veterans of the armed forces, such as General Jan Smuts and General George Brink Anglo Boer War exhibits An exhibit honouring members of the Native Military Corps, Indian Service Corps and the Cape Corps An exhibit detailing major events in South African History between the Boer Wars and the 1994 South African general elections.
Events covered include the political divisions in the country during the first and second world wars, the Rand Rebellion, the sabotage campaign of the Ossewabrandwag during the Second World War and South Africa's involvement in the Angolan Civil War. Dan Pienaar Gun ParkVarious guns from around the world such as the British Ordnance QF 18-pounder and the BL 6-inch Gun Mk XIX and the German 7.7 cm FK 96 field gun. The FB Adler Hall with Sexton self Propelled gun M4 Sherman tank M3 Stuart tank A large amount of Artillery pieces such as the Ordnance QF 20 pounder and the BL 5.5-inch Medium Gun Exhibits detailing South Africa's involvement in World War Two, including artefacts from various countries such as uniforms, helmets, etc. Anglo-Zulu War exhibits South African Border War exhibit A small South African Navy exhibit A large collection of uniforms, ceremonial swords, infantry swords, cavalry swords and daggers A large variety of small arms from around the world, such as the Bren light machine gun, the M1 Garand, Mauser rifles, Lee–Enfield rifles, the Maxim gun, the MG 42, the Thompson submachine gun, the Winchester Model 1876, the AK-47, the Vektor R4 Rifle R1 Rifle, various other muskets and machine guns.
Outdoor exhibitsA small 32 Battalion indoor exhibit Molch one man submarine QF 4 inch Mk XVI naval gun turret from a South African Navy Loch-class frigate Aircraft such as the Blackburn Buccaneer S Mk 50, the Douglas C-47 ‘Dakota’, the Dassault Mirage III and the Impala MkII South African/British armoured vehicles such as the Comet tank, the Centurion tank, the Crusader tank and the Churchill tank Captured Angolan/Cuban/Soviet vehicles such as the T-34/85 tank, the T-54/55 tank and the PT-76 amphibious tank Captured Italian/German vehicles such as the Carro Veloce CV-35 tank and the Sd. Kfz. 251 half-track A large collection of heavy Artillery featuring the G5 howitzer and the G6 howitzer Lt Gen AML Masondo Library building withA Library with literature concerning South Africa's Military History Armoured Vehicles such as the Alvis Saracen, Ford Lynx, Ratel-20, Daimler Ferret, M9A1 Half-track, Universal Carrier, several different models of the Marmon-Herrington and Eland Mk7 armoured cars, etc.
More artefacts of World War I and World War II South African Air Force Museum South African Naval Museum Military history of South Africa Official website Google Maps view with overlay of images from Commons
Sheffield is a city and metropolitan borough in South Yorkshire, England. Part of the West Riding of Yorkshire, its name derives from the River Sheaf, which runs through the city. With some of its southern suburbs annexed from Derbyshire, the city has grown from its industrial roots to encompass a wider economic base; the population of the City of Sheffield is 577,800 and it is one of the eight largest regional English cities that make up the Core Cities Group. Sheffield is the third-largest English district by population; the metropolitan population of Sheffield is 1,569,000. The city is in the eastern foothills of the Pennines, the valleys of the River Don and its four tributaries, the Loxley, the Porter Brook, the Rivelin and the Sheaf. Sixty-one per cent of Sheffield's entire area is green space, a third of the city lies within the Peak District national park. There are more than 250 parks and gardens in the city, estimated to contain around 4.5 million trees. Sheffield played a crucial role in the Industrial Revolution, with many significant inventions and technologies developed in the city.
In the 19th century, the city saw a huge expansion of its traditional cutlery trade, when stainless steel and crucible steel were developed locally, fuelling an tenfold increase in the population. Sheffield received its municipal charter in 1843, becoming the City of Sheffield in 1893. International competition in iron and steel caused a decline in these industries in the 1970s and 1980s, coinciding with the collapse of coal mining in the area; the 21st century has seen extensive redevelopment in Sheffield, along with other British cities. Sheffield's gross value added has increased by 60% since 1997, standing at £9.2 billion in 2007. The economy has experienced steady growth averaging around 5% annually, greater than that of the broader region of Yorkshire and the Humber; the city has a long sporting heritage, is home to the world's oldest football club, Sheffield F. C. Games between the two professional clubs, Sheffield United and Sheffield Wednesday, are known as the Steel City derby; the city is home to the World Snooker Championship and the Sheffield Steelers, the UK's first professional ice hockey team.
The area now occupied by the City of Sheffield is believed to have been inhabited since at least the late Upper Paleolithic, about 12,800 years ago. The earliest evidence of human occupation in the Sheffield area was found at Creswell Crags to the east of the city. In the Iron Age the area became the southernmost territory of the Pennine tribe called the Brigantes, it is this tribe who are thought to have constructed several hill forts around Sheffield. Following the departure of the Romans, the Sheffield area may have been the southern part of the Brittonic kingdom of Elmet, with the rivers Sheaf and Don forming part of the boundary between this kingdom and the kingdom of Mercia. Anglian settlers pushed west from the kingdom of Deira. A Britonnic presence within the Sheffield area is evidenced by two settlements called Wales and Waleswood close to Sheffield; the settlements that grew and merged to form Sheffield, date from the second half of the first millennium, are of Anglo-Saxon and Danish origin.
In Anglo-Saxon times, the Sheffield area straddled the border between the kingdoms of Mercia and Northumbria. The Anglo-Saxon Chronicle reports that Eanred of Northumbria submitted to Egbert of Wessex at the hamlet of Dore in 829, a key event in the unification of the kingdom of England under the House of Wessex. After the Norman conquest of England, Sheffield Castle was built to protect the local settlements, a small town developed, the nucleus of the modern city. By 1296, a market had been established at what is now known as Castle Square, Sheffield subsequently grew into a small market town. In the 14th century, Sheffield was noted for the production of knives, as mentioned in Geoffrey Chaucer's The Canterbury Tales, by the early 1600s it had become the main centre of cutlery manufacture in England outside London, overseen by the Company of Cutlers in Hallamshire. From 1570 to 1584, Queen of Scots, was imprisoned in Sheffield Castle and Sheffield Manor. During the 1740s, a form of the crucible steel process was discovered that allowed the manufacture of a better quality of steel than had been possible.
In about the same period, a technique was developed for fusing a thin sheet of silver onto a copper ingot to produce silver plating, which became known as Sheffield plate. These innovations spurred Sheffield's growth as an industrial town, but the loss of some important export markets led to a recession in the late 18th and early 19th century; the resulting poor conditions culminated in a cholera epidemic that killed 402 people in 1832. The population of the town grew throughout the 19th century; the Sheffield and Rotherham railway was constructed in 1838. The town was incorporated as a borough in 1842, was granted a city charter in 1893; the influx of people led to demand for better water supplies, a number of new reservoirs were constructed on the outskirts of the town. The collapse of the dam wall of one of these reservoirs in 1864 resulted in the Great Sheffield Flood, which killed 270 people and devastated large parts of the town; the growing population led to the construction of many back-to-back dwellings that, along with severe pollution from the factories, inspired George Orwell in 1937 to write: "Sheffield, I suppose, could justly claim to be called the ugliest town in the Old World".
The Great Depression hit the city in the 1930s, but as international tensions increased and the Second
Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio in the metal. In modern manufacturing, other chemicals may be used on other types of material; as a method of printmaking, it is, along with engraving, the most important technique for old master prints, remains in wide use today. In a number of modern variants such as microfabrication etching and photochemical milling it is a crucial technique in much modern technology, including circuit boards. In traditional pure etching, a metal plate is covered with a waxy ground, resistant to acid; the artist scratches off the ground with a pointed etching needle where he or she wants a line to appear in the finished piece, so exposing the bare metal. The échoppe, a tool with a slanted oval section, is used for "swelling" lines; the plate is dipped in a bath of acid, technically called the mordant or etchant, or has acid washed over it. The acid "bites" into the metal where it is exposed, leaving behind lines sunk into the plate.
The remaining ground is cleaned off the plate. The plate is inked all over, the ink wiped off the surface, leaving only the ink in the etched lines; the plate is put through a high-pressure printing press together with a sheet of paper. The paper picks up the ink from the etched lines; the process can be repeated many times. The work on the plate can be added to by repeating the whole process. Etching has been combined with other intaglio techniques such as engraving or aquatint. Etching by goldsmiths and other metal-workers in order to decorate metal items such as guns, armour and plates has been known in Europe since the Middle Ages at least, may go back to antiquity; the elaborate decoration of armour, in Germany at least, was an art imported from Italy around the end of the 15th century—little earlier than the birth of etching as a printmaking technique. Printmakers from the German-speaking lands and Central Europe perfected the art and transmitted their skills over the Alps and across Europe.
The process as applied to printmaking is believed to have been invented by Daniel Hopfer of Augsburg, Germany. Hopfer was a craftsman who decorated armour in this way, applied the method to printmaking, using iron plates. Apart from his prints, there are two proven examples of his work on armour: a shield from 1536 now in the Real Armeria of Madrid and a sword in the Germanisches Nationalmuseum of Nuremberg. An Augsburg horse armour in the German Historical Museum, dating to between 1512 and 1515, is decorated with motifs from Hopfer's etchings and woodcuts, but this is no evidence that Hopfer himself worked on it, as his decorative prints were produced as patterns for other craftsmen in various media; the oldest dated etching is by Albrecht Dürer in 1515, although he returned to engraving after six etchings instead of developing the craft. The switch to copper plates was made in Italy, thereafter etching soon came to challenge engraving as the most popular medium for artists in printmaking.
Its great advantage was that, unlike engraving where the difficult technique for using the burin requires special skill in metalworking, the basic technique for creating the image on the plate in etching is easy to learn for an artist trained in drawing. On the other hand, the handling of the ground and acid need skill and experience, are not without health and safety risks, as well as the risk of a ruined plate. Prior to 1100 AD, the New World Hohokam independently utilized the technique of acid etching in marine shell designs. Jacques Callot from Nancy in Lorraine made important technical advances in etching technique, he developed the échoppe, a type of etching-needle with a slanting oval section at the end, which enabled etchers to create a swelling line, as engravers were able to do. Callot appears to have been responsible for an improved, recipe for the etching ground, using lute-makers' varnish rather than a wax-based formula; this enabled lines to be more bitten, prolonging the life of the plate in printing, greatly reducing the risk of "foul-biting", where acid gets through the ground to the plate where it is not intended to, producing spots or blotches on the image.
The risk of foul-biting had always been at the back of an etcher's mind, preventing too much time on a single plate that risked being ruined in the biting process. Now etchers could do the detailed work, the monopoly of engravers, Callot made full use of the new possibilities. Callot made more extensive and sophisticated use of multiple "stoppings-out" than previous etchers had done; this is the technique of letting the acid bite over the whole plate stopping-out those parts of the work which the artist wishes to keep light in tone by covering them with ground before bathing the plate in acid again. He achieved unprecedented subtlety in effects of distance and light and shade by careful control of this process. Most of his prints were small—up to about six inches or 15 cm on their longest dimension, but packed with detail. One of his followers, the Parisian Abraham Bosse, spread Callot's innovations all over Europe with the first published manual of etching, translated into Italian, Dutch and English.