Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. It is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure. Bronze is an alloy containing copper, but instead of zinc it has tin. Both bronze and brass may include small proportions of a range of other elements including arsenic, phosphorus, aluminium and silicon; the distinction is historical. Modern practice in museums and archaeology avoids both terms for historical objects in favour of the all-embracing "copper alloy". Brass is used for decoration for its bright gold-like appearance, it is used in zippers. Brass is used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brass has higher malleability than zinc; the low melting point of brass and its flow characteristics make it a easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses.
The density of brass is 8.4 to 8.73 grams per cubic centimetre. Today 90% of all brass alloys are recycled; because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet. Brass scrap is transported to the foundry where it is melted and recast into billets. Billets are extruded into the desired form and size; the general softness of brass means that it can be machined without the use of cutting fluid, though there are exceptions to this. Aluminium makes brass more corrosion-resistant. Aluminium causes a beneficial hard layer of aluminium oxide to be formed on the surface, thin and self-healing. Tin has a similar effect and finds its use in seawater applications. Combinations of iron, aluminium and manganese make brass wear and tear resistant. To enhance the machinability of brass, lead is added in concentrations of around 2%. Since lead has a lower melting point than the other constituents of the brass, it tends to migrate towards the grain boundaries in the form of globules as it cools from casting.
The pattern the globules form on the surface of the brass increases the available lead surface area which in turn affects the degree of leaching. In addition, cutting operations can smear the lead globules over the surface; these effects can lead to significant lead leaching from brasses of comparatively low lead content. In October 1999 the California State Attorney General sued 13 key manufacturers and distributors over lead content. In laboratory tests, state researchers found the average brass key, new or old, exceeded the California Proposition 65 limits by an average factor of 19, assuming handling twice a day. In April 2001 manufacturers agreed to reduce lead content to 1.5%, or face a requirement to warn consumers about lead content. Keys plated with other metals are not affected by the settlement, may continue to use brass alloys with higher percentage of lead content. In California, lead-free materials must be used for "each component that comes into contact with the wetted surface of pipes and pipe fittings, plumbing fittings and fixtures."
On January 1, 2010, the maximum amount of lead in "lead-free brass" in California was reduced from 4% to 0.25% lead. The so-called dezincification resistant brasses, sometimes referred to as CR brasses, are used where there is a large corrosion risk and where normal brasses do not meet the standards. Applications with high water temperatures, chlorides present, or deviating water qualities play a role. DZR-brass is excellent in water boiler systems; this brass alloy must be produced with great care, with special attention placed on a balanced composition and proper production temperatures and parameters to avoid long-term failures. The high malleability and workability good resistance to corrosion, traditionally attributed acoustic properties of brass, have made it the usual metal of choice for construction of musical instruments whose acoustic resonators consist of long narrow tubing folded or coiled for compactness. Collectively known as brass instruments, these include the trombone, trumpet, baritone horn, tenor horn, French horn, many other "horns", many in variously-sized families, such as the saxhorns.
Other wind instruments may be constructed of brass or other metals, indeed most modern student-model flutes and piccolos are made of some variety of brass a cupronickel alloy similar to nickel silver/German silver. Clarinets low clarinets such as the contrabass and subcontrabass, are sometimes made of metal because of limited supplies of the dense, fine-grained tropical hardwoods traditionally preferred for smaller woodwinds. For the same reason, some low clarinets and contrabassoons feature a hybrid construction, with long, straight sections of wood, curved joints, and/or bell of metal; the use of metal avoids the risks of exposing wooden instruments to changes in temperature or humid
Nicaragua the Republic of Nicaragua, is the largest country in the Central American isthmus, bordered by Honduras to the northwest, the Caribbean to the east, Costa Rica to the south, the Pacific Ocean to the southwest. Managua is the country's capital and largest city and is the third-largest city in Central America, behind Tegucigalpa and Guatemala City; the multi-ethnic population of six million includes people of indigenous, European and Asian heritage. The main language is Spanish. Indigenous tribes on the Mosquito Coast speak English. Inhabited by various indigenous cultures since ancient times, the Spanish Empire conquered the region in the 16th century. Nicaragua gained independence from Spain in 1821; the Mosquito Coast followed a different historical path, with the English colonizing it in the 17th century and coming under the British rule, as well as some minor Spanish interludes in the 19th century. It became an autonomous territory of Nicaragua in 1860 and the northernmost part of it was transferred to Honduras in 1960.
Since its independence, Nicaragua has undergone periods of political unrest, dictatorship and fiscal crisis, leading to the Nicaraguan Revolution of the 1960s and 1970s and the Contra War of the 1980s. The mixture of cultural traditions has generated substantial diversity in folklore, cuisine and literature the latter given the literary contributions of Nicaraguan poets and writers, such as Rubén Darío. Known as the "land of lakes and volcanoes", Nicaragua is home to the second-largest rainforest of the Americas; the country has set a goal of 90% renewable energy by the year 2020. The biological diversity, warm tropical climate and active volcanoes make Nicaragua an popular tourist destination. There are two prevailing theories on; the first is that the name was coined by Spanish colonists based on the name Nicarao, the chieftain or cacique of a powerful indigenous tribe encountered by the Spanish conquistador Gil González Dávila during his entry into southwestern Nicaragua in 1522. This theory holds that the name Nicaragua was formed from Nicarao and agua, to reference the fact that there are two large lakes and several other bodies of water within the country.
However, as of 2002, it was determined that the cacique's real name was Macuilmiquiztli, which meant "Five Deaths" in the Nahuatl language, rather than Nicarao. The second theory is that the country's name comes from any of the following Nahuatl words: nic-anahuac, which meant "Anahuac reached this far", or "the Nahuas came this far", or "those who come from Anahuac came this far". Paleo-Americans first inhabited what is now known as Nicaragua as far back as 12,000 BCE. In pre-Columbian times, Nicaragua's indigenous people were part of the Intermediate Area, between the Mesoamerican and Andean cultural regions, within the influence of the Isthmo-Colombian area. Nicaragua's central region and its Caribbean coast were inhabited by Macro-Chibchan language ethnic groups, they had coalesced in Central America and migrated to present-day northern Colombia and nearby areas. They lived a life based on hunting and gathering, as well as fishing, performing slash-and-burn agriculture. At the end of the 15th century, western Nicaragua was inhabited by several different indigenous peoples related by culture to the Mesoamerican civilizations of the Aztec and Maya, by language to the Mesoamerican Linguistic Area.
The Chorotegas were Mangue language ethnic groups who had arrived in Nicaragua from what is now the Mexican state of Chiapas sometime around 800 CE. The Pipil-Nicarao people were a branch of Nahuas who spoke the Nahuat dialect, like the Chorotegas, they too had come from Chiapas to Nicaragua in 1200 CE. Prior to that, the Pipil-Nicaraos had been associated with the Toltec civilization. Both the Chorotegas and the Pipil-Nicaraos were from Mexico's Cholula valley, had migrated southward. Additionally, there were trade-related colonies in Nicaragua, set up by the Aztecs starting in the 14th century. In 1502, on his fourth voyage, Christopher Columbus became the first European known to have reached what is now Nicaragua as he sailed southeast toward the Isthmus of Panama. Columbus explored the Mosquito Coast on the Atlantic side of Nicaragua but did not encounter any indigenous people. 20 years the Spaniards returned to Nicaragua, this time to its southwestern part. The first attempt to conquer Nicaragua was by the conquistador Gil González Dávila, who had arrived in Panama in January 1520.
In 1522, González Dávila ventured into the area that became known as the Rivas Department of Nicaragua. It was there that he encountered an indigenous Nahua tribe led by a chieftain named Macuilmiquiztli, whose name has sometimes been erroneously referred to as "Nicarao" or "Nicaragua". At the time, the tribe's capital city was called Quauhcapolca. González Dávila had brought along two indigenous interpreters, taught the Spanish language, thus he was able to have a discourse with Macuilmiquiztli. After exploring and gathering gold in the fertile western valleys, González Dávila and his men were attacked and driven off by the Chorotega, led by the chieftain Diriangen; the Spanish attempted to convert the tribes to Christianity. The first Spanish permanent settlements were founded in 1524; that year, the conquistador
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals; this led to early human use in several regions, from c. 8000 BC. Thousands of years it was the first metal to be smelted from sulfide ores, c. 5000 BC, the first metal to be cast into a shape in a mold, c. 4000 BC and the first metal to be purposefully alloyed with another metal, tin, to create bronze, c. 3500 BC. In the Roman era, copper was principally mined on Cyprus, the origin of the name of the metal, from aes сyprium corrupted to сuprum, from which the words derived and copper, first used around 1530.
The encountered compounds are copper salts, which impart blue or green colors to such minerals as azurite and turquoise, have been used and as pigments. Copper used in buildings for roofing, oxidizes to form a green verdigris. Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as bacteriostatic agents and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the iron-complexed hemoglobin in fish and other vertebrates. In humans, copper is found in the liver and bone; the adult body contains between 2.1 mg of copper per kilogram of body weight. Copper and gold are in group 11 of the periodic table; the filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through metallic bonds.
Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are weak. This observation explains the low high ductility of single crystals of copper. At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form, which has greater strength than monocrystalline forms; the softness of copper explains its high electrical conductivity and high thermal conductivity, second highest among pure metals at room temperature. This is because the resistivity to electron transport in metals at room temperature originates from scattering of electrons on thermal vibrations of the lattice, which are weak in a soft metal; the maximum permissible current density of copper in open air is 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively. Copper is one of a few metallic elements with a natural color other than silver.
Pure copper acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light; as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. Copper does not react with water, but it does react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the rust that forms on iron in moist air, protects the underlying metal from further corrosion. A green layer of verdigris can be seen on old copper structures, such as the roofing of many older buildings and the Statue of Liberty. Copper tarnishes when exposed to some sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising 69% of occurring copper. The other isotopes are radioactive, with the most stable being 67Cu with a half-life of 61.83 hours.
Seven metastable isotopes have been characterized. Isotopes with a mass number above 64 decay by β−, whereas those with a mass number below 64 decay by β+. 64Cu, which has a half-life of 12.7 hours, decays both ways.62Cu and 64Cu have significant applications. 62Cu is used in 62Cu-PTSM as a radioactive tracer for positron emission tomography. Copper is produced in massive stars and is present in the Earth's crust in a proportion of about 50 parts per million. In nature, copper occurs in a variety of minerals, including native copper, copper sulfides such as chalcopyrite, digenite and chalcocite, copper sulfosalts such as tetrahedite-tennantite, enargite, copper carbonates such as azurite and malachite, as copper or copper oxides such as cuprite and tenorite, respectively; the largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US. Native copper is a polycrystal
Fortress of the Immaculate Conception
The Fortress of the Immaculate Conception, is a fortification located on the southern bank of the San Juan River, in the village of El Castillo in southern Nicaragua. The fortress is situated 6 kilometers from the border with Costa Rica, at the Raudal del Diablo rapids of the San Juan River, it was completed in 1675 as part of a series of fortifications along the San Juan River, to defend against pirate attacks upon the city of Granada. The settlement of El Castillo and its fortress continued to be strategically important to the Captaincy General of Guatemala until the late 18th century. An important historic landmark of Nicaragua, the fortress is on a list of sites as an initial stage in achieving World Heritage Site status with the United Nations Educational and Cultural Organization. Gil González Dávila was a Spanish conquistador and the first European to arrive in present-day Nicaragua. After discovering the "freshwater sea" on January 21, 1522, he speculated that it discharged into the Caribbean Sea.
Francisco Hernández de Córdoba was another Spanish conquistador who founded the city of Granada on the shore of Lake Nicaragua on December 8, 1524. Under orders from Hernández de Córdoba, an expedition that included Hernando de Soto, Ruy Díaz and Sebastián de Belalcázar explored Lake Nicaragua, they succeeded in locating a waterway running eastwards towards the Caribbean Sea, but reported it to be not navigable. Martin Estete, a citizen of Granada discovered the outlet of Lake Nicaragua in 1528 and named it the Río San Juan. Estete was unable to navigate past the rapids however. In 1529, Diego Machuca became the first man to reach the Caribbean Sea from Lake Nicaragua. After circumnavigating the lake in a group of boats and his team entered the San Juan River. From here, Machuca led a group of 200 men. Machuca named the rapids after himself, named the port at the mouth of the river San Juan de las Perlas. By the late 17th century, the success of the city of Granada had made it a victim of pirate attacks, the first of, in 1670 by the pirate Gallardino.
In response to this and other pirate attacks, the Spanish colonial authorities constructed the Fortress of the Immaculate Conception as a means to protect the citizens of Granada from future attacks. Captain General Fernando Francisco de Escobedo, at that time Governor of Yucatán, visited the area from January — February 1673. Escobedo was accompanied by Martín de Andújar Cantos, a military engineer, responsible for selection of the site. Escobedo and Andújar Cantos arrived at San Juan del Norte travelled upstream along the San Juan River and into Lake Nicaragua. Upon their return to Granada, they set about planning the construction of definitive fortifications along the San Juan River, they decided to build the fortress at the Raudal del Diablo, atop the ruins of the previous Fuerte de Santa Cruz, which dated from the time of King Philip III of Spain. Construction of the fortress named Fortaleza de la Limpia Pura e Inmaculada Concepción, was begun on March 10, 1673 and completed in 1675. Despite the construction of the fortress, buccaneer William Dampier plundered the city and set it on fire on April 8, 1685.
On the morning of July 26, 1762, a combined British and Miskito Sambu expeditionary force laid siege to the fortress in what would be called the Battle for the Río San Juan de Nicaragua. The attacking force consisted of two thousand men and more than fifty boats, while the soldiers at the fortress numbered only around a hundred; the garrison commander, Lieutenant Colonel Don José de Herrera y Sotomayor, had died unexpectedly on July 15, only 11 days earlier. Inspired by acts of heroism displayed by Herrera's 19-year-old daughter Rafaela, pro tempore garrison commander Lieutenant Juan de Aguilar y Santa Cruz led the defenders to victory in a battle that lasted six days; the British lifted their siege and retreated on August 3, 1762. After Spain entered the American Revolutionary War in 1779, Major General John Dalling, the British governor and commander-in-chief of Jamaica, proposed a second expedition to Nicaragua; the goal was to sail up the San Juan River to Lake Nicaragua and capture the town of Granada, which would cut Spanish America in half as well as provide potential access to the Pacific Ocean.
During this expedition, which took place in 1780 and became known as the San Juan Expedition, Colonel John Polson and Captain Horatio Nelson led a British attack against the fortress. At the time, the Spanish garrison consisted of 228 men under the command of Juan de Ayssa; the expeditionary force succeeded in capturing the fortress on April 29, 1780, despite the fact that it consisted of only 200 men. The 22-year-old Nelson, in command of HMS Hinchinbrook, was responsible for leading his men through dense jungle to attack the fortress from a hill in the rear; the British captured the fortress and occupied it for nine months abandoning it in January 1781. The hill is named Lomas de Nelson to this day; the Fortress of the Immaculate Conception is a historic landmark of Nicaragua, which houses a museum and l
José Santos Zelaya
José Santos Zelaya López was the President of Nicaragua from 25 July 1893 to 21 December 1909. He was a son of José María Zelaya Irigoyen, born in Nicaragua, his mistress Juana López Ramírez, his father José María was married to Rosario Fernández. Zelaya was of Nicaragua's Liberal party and enacted a number of progressive programs, including improved public education and established steam ship lines, he enacted constitutional rights that provided for equal rights, property guarantees, habeas corpus, compulsory vote, compulsory education, the protection of arts and industry, minority representation, the separation of state powers. However, his desire for national sovereignty led him to policies contrary to colonialist interests. In 1894, he took control of the Mosquito Coast by military force. Indeed, Nicaragua had always claimed the Caribbean Coast, but "Zambos" pirates and part of the Misquito Indians, together with the military support of the British Marines, tried to create a colonial British settlement.
This is similar to the cases of Belize and Guatemala, except that Belize has been an independent nation since 1981. Zelaya's fortitude paid off, the United Kingdom, which did not wish to go to war over this distant land of the Empire, recognized Nicaraguan sovereignty over the area; the strategic value of this land led to the name "Vía del Tránsito". Both the United Kingdom and the USA wanted the control of this route, which connected the Caribbean Sea to the Pacific Coast across the San Juan River and Lake Nicaragua. At this point, the Panama Canal did not exist, the USA was rising as a new continental power. Cornelius Vanderbilt became the owner of the steamboats in the San Juan River, but he was expropriated by William Walker. José Santos Zelaya was reelected president in 1902 and again in 1906; the possibility of building a canal across the isthmus of Central America had been the topic of serious discussion since the 1820s, Nicaragua was long a favored location. When the United States shifted its interests to Panama, Zelaya negotiated with Germany and Japan in an unsuccessful effort to have a canal constructed in his state.
Fearful that president Zelaya might generate an alternative foreign alignment in the region, the U. S. labeled him a tyrant in opposition to U. S. planned hegemony. José Zelaya had the project of reuniting the Federal Republic of Central America, with, he hoped, himself as national president. With this aim in mind, he gave aid to liberal federalist factions in other Central American nations; this threatened to create a full scale Central American war which would endanger the United States Panamanian canal and give European nations, such as Germany, an excuse to intervene to protect the collection of their bank's payments in the region or if failing that demand a land concession. The Zelaya administration had growing friction with the United States government, for example while the French government had inquired to the U. S. whether a loan to Nicaragua would be deemed unfriendly, the U. S. Secretary of State required the loan to be conditional on U. S. relations. After the loan was pending on the Paris stock exchange, the U.
S. further isolated Nicaragua by claiming any money Zelaya would receive "would be without doubt spent to purchase munitions to oppress his neighbors" and in "hostility to peace and progress in Central America." The US State Department demanded that all investments in Central America would need be approved by the U. S. as a means to protect U. S. interests and to overthrow president Zelaya according to a French minister. The U. S. started giving financing aid to his Conservative and Liberal opponents in Nicaragua who broke out in open rebellion in October 1909, led by Liberal General Juan J. Estrada. Nicaragua sent its forces into Costa Rica to suppress Estrada's pro U. S. destabilizing forces, but U. S. officials deemed the incursion as an affront to Estrada's aims and attempted to coerce Costa Rica into acting first against Nicaragua, but Foreign Minister Ricardo Fernández Guardia assured Calvo that Costa Rica was determined "not to enter such dangerous actions as those proposed by Washington."
It "considered the joint action proposed contrary to the Washington treaty and desired to maintain a neutral attitude." Costa Rican officials considered the United States a more serious threat to Central American peace and harmony than Zelaya's Nicaragua. Costa Rica Foreign Minister Fernández Guardia insisted, "We do not understand here what interests can the Washington government have that Costa Rica assumes a resolutely aggressive position against Nicaragua, with the danger of compromising the observation of the...conventions of December 20, 1907.... It is in Central America's interest that U. S. action with respect to Nicaragua should assume the character of an international conflict and in no sense the character of an intervention tolerated and less solicited or supported by the other signatory republics of the Washington Treaty. So Costa Rica the fact that came itself from a kind of small civil Counter-Revolution in 1889 against Liberal-Military regime, never was an accomplice of USA Imperialist Policy against Nicaragua in those times.
On the contrary, some Liberals from Costa Rica exiled in Nicaragua during Zelaya's regime. Liberals returned to the Government in Costa Rica with the polemic President Ascensión Esquivel Ibarra
The dollar or peso sign is a symbol used to indicate the units of various currencies around the world, including the peso and the US dollar. The symbol can interchangeably have two vertical strokes. In common usage, the sign appears to the left of the amount specified, as in $1. A common hypothesis holds that the sign derives from the symbolic representation of the Pillars of Hercules; this representation can have either a banner separately around each pillar, or, as in the Spanish coat of arms, a banner curling between them. In 1492, Ferdinand II of Aragon adopted the symbol of the Pillars of Hercules and added the Latin warning Non plus ultra meaning "nothing further beyond", indicating "this is the end of the world", but when Christopher Columbus came to America, the legend was changed to Plus ultra, meaning "further beyond". The Pillars of Hercules wrapped in a banner thus became a symbol of the New World; the link between this symbol and the dollar sign is more seen in Spanish coins of the period, which show two pillars, each with a separate banner, rather than one banner spanning both pillars.
In this example the right-hand pillar resembles the dollar sign, additionally directly relates to the use of money. The symbol was adopted by Charles V and was part of his coat of arms representing Spain's American possessions; the symbol was stamped on coins minted in gold and silver. The coin known as Spanish dollar, was the first global currency used in the world since the Spanish Empire was the first global empire; these coins, depicting the pillars over two hemispheres and a small "S"-shaped ribbon around each, were spread throughout America and Asia. According to this, traders wrote signs that, instead of saying "Spanish dollar", had this symbol made by hand, this in turn evolved into a simple S with two vertical bars; when the United States gained their independence from Great Britain, they created the US dollar, but in its early decades they continued to use the Spanish dollar, more trusted in all markets. The United States after independence, was still using the pound sterling as currency.
This is attested in state legislation of the early 1780s, referring to pounds and pence, which predated the U. S. Constitution and federal legislation. Given the origin of this theory – related to Spanish colonisation of the Americas – it is that the cifrão or peso signs share the same origin, that the double stroke usage is a stylistic variant, rather than a distinct character; the sign is first attested in Spanish American, Canadian and other British business correspondence in the 1770s, referring to the Spanish American peso known as "Spanish dollar" or "piece of eight" in North America, which provided the model for the currency that the United States adopted in 1792 and the larger coins of the new Spanish American republics such as the Mexican peso, Peruvian eight-real and Bolivian eight-sol coins. This explanation holds that the sign evolved out of the Spanish and Spanish American scribal abbreviation "pˢ" for pesos. A study of late eighteenth- and early nineteenth-century manuscripts shows that the s came to be written over the p, developing into a close equivalent to the "$" mark.
A variation, though less plausible, of this hypothesis derives the sign from a combination of the Greek character "psi" and "S". There are a number of other hypotheses about the origin of the symbol, some with a measure of academic acceptance, others the symbolic equivalent of false etymologies. Among the various hypotheses, the simplest one is that the barred S is a typo modified 8, from its obvious link with the pieces of eight, the popular name of the Spanish dollar; the added bar should be the same used to distinguish a letter dedicated to a currency value, like £. Kingdom of Sicily deniers minted by Manfred of Hohenstaufen in the Kingdom of Sicily between 1258 and 1266 had what can be construed as an early dollar symbol; these coins were circulated outside Europe due to the Crusades, including the Crusade that targeted Tunis. Several alternative hypotheses relate to the dollar sign drawn with two vertical lines. A dollar sign with two vertical lines could have started off as a monogram of'USA', used on money bags issued by the United States Mint.
The letters U and S superimposed resemble the historical double-stroke dollar sign: the bottom of the'U' disappears into the bottom curve of the'S', leaving two vertical lines. It is postulated in the papers of Dr. James Alton James, a professor of history at Northwestern University from 1897 to 1935, that the symbol with two strokes was an adapted design of the patriot Robert Morris in 1778. Robert Morris was such a zealous patriot – known as the "Financier of the Revolution in the West" – that James came to believe that this hypothesis is viable. A similar idea claims that the letters U and S would stand for unit of silver, referencing pieces of eight again, but, unlikely since one would expect it to be in Spanish instead. Another hypothesis is. According to Ovason, on one type of thaler one side showed a crucifix while the other showed a serpent hanging from a cross, the letters NU near the serpent's head, on the other side of the cross the number 21; this refers to the Bible, Chapter 21.
A similar symbol, constructed by superposition of "S" and "I" or "J", was used to denote German Joachimsthaler. It was known in the English-speaking world by the 17th century, appearing in 1
A central bank, reserve bank, or monetary authority is the institution that manages the currency, money supply, interest rates of a state or formal monetary union, oversees their commercial banking system. In contrast to a commercial bank, a central bank possesses a monopoly on increasing the monetary base in the state, generally controls the printing/coining of the national currency, which serves as the state's legal tender. A central bank acts as a lender of last resort to the banking sector during times of financial crisis. Most central banks have supervisory and regulatory powers to ensure the solvency of member institutions, to prevent bank runs, to discourage reckless or fraudulent behavior by member banks. Central banks in most developed nations are institutionally independent from political interference. Still, limited control by the executive and legislative bodies exists. Functions of a central bank may include: implementing monetary policies. Setting the official interest rate – used to manage both inflation and the country's exchange rate – and ensuring that this rate takes effect via a variety of policy mechanisms controlling the nation's entire money supply the Government's banker and the bankers' bank managing the country's foreign exchange and gold reserves and the Government bonds regulating and supervising the banking industry Central banks implement a country's chosen monetary policy.
At the most basic level, monetary policy involves establishing what form of currency the country may have, whether a fiat currency, gold-backed currency, currency board or a currency union. When a country has its own national currency, this involves the issue of some form of standardized currency, a form of promissory note: a promise to exchange the note for "money" under certain circumstances; this was a promise to exchange the money for precious metals in some fixed amount. Now, when many currencies are fiat money, the "promise to pay" consists of the promise to accept that currency to pay for taxes. A central bank may use another country's currency either directly in a currency union, or indirectly on a currency board. In the latter case, exemplified by the Bulgarian National Bank, Hong Kong and Latvia, the local currency is backed at a fixed rate by the central bank's holdings of a foreign currency. Similar to commercial banks, central banks incur liabilities. Central banks create money by issuing interest-free currency notes and selling them to the public in exchange for interest-bearing assets such as government bonds.
When a central bank wishes to purchase more bonds than their respective national governments make available, they may purchase private bonds or assets denominated in foreign currencies. The European Central Bank remits its interest income to the central banks of the member countries of the European Union; the US Federal Reserve remits all its profits to the U. S. Treasury; this income, derived from the power to issue currency, is referred to as seigniorage, belongs to the national government. The state-sanctioned power to create currency is called the Right of Issuance. Throughout history there have been disagreements over this power, since whoever controls the creation of currency controls the seigniorage income; the expression "monetary policy" may refer more narrowly to the interest-rate targets and other active measures undertaken by the monetary authority. Frictional unemployment is the time period between jobs when a worker is searching for, or transitioning from one job to another. Unemployment beyond frictional unemployment is classified as unintended unemployment.
For example, structural unemployment is a form of unemployment resulting from a mismatch between demand in the labour market and the skills and locations of the workers seeking employment. Macroeconomic policy aims to reduce unintended unemployment. Keynes labeled any jobs that would be created by a rise in wage-goods as involuntary unemployment: Men are involuntarily unemployed if, in the event of a small rise in the price of wage-goods to the money-wage, both the aggregate supply of labour willing to work for the current money-wage and the aggregate demand for it at that wage would be greater than the existing volume of employment.—John Maynard Keynes, The General Theory of Employment and Money p11 Inflation is defined either as the devaluation of a currency or equivalently the rise of prices relative to a currency. Since inflation lowers real wages, Keynesians view inflation as the solution to involuntary unemployment. However, "unanticipated" inflation leads to lender losses as the real interest rate will be lower than expected.
Thus, Keynesian monetary policy aims for a steady rate of inflation. A publication from the Austrian School, The Case Against the Fed, argues that the efforts of the central banks to control inflation have been counterproductive. Economic growth can be enhanced by investment such as more or better machinery. A low interest rate implies that firms can borrow money to invest in their capital stock and pay less interest for it. Lowering the interest is therefore considered to encourage economic growth and is used to alleviate times of low economic growth. On the other hand, raising the interest rate is used in times of high economic growth as a contra-cyclical device to keep the economy from overheating and avoid market bubbles. Further goals of monetary policy are stability of interest rates, of the financial market, of the foreign exchange market. Goals cannot be separated fr