System of measurement
A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have been important and defined for the purposes of science and commerce. Systems of measurement in use include the International System of Units, the modern form of the metric system, the imperial system, United States customary units; the French Revolution gave rise to the metric system, this has spread around the world, replacing most customary units of measure. In most systems, length and time are base quantities. Science developments showed that either electric charge or electric current could be added to extend the set of base quantities by which many other metrological units could be defined. Other quantities, such as power and speed, are derived from the base set: for example, speed is distance per unit time. A wide range of units was used for the same type of quantity: in different contexts, length was measured in inches, yards, rods, furlongs, nautical miles, leagues, with conversion factors which were not powers of ten.
Such arrangements were satisfactory in their own contexts. The preference for a more universal and consistent system only spread with the growth of science. Changing a measurement system has substantial financial and cultural costs which must be offset against the advantages to be obtained from using a more rational system; however pressure built up, including from scientists and engineers for conversion to a more rational, internationally consistent, basis of measurement. In antiquity, systems of measurement were defined locally: the different units might be defined independently according to the length of a king's thumb or the size of his foot, the length of stride, the length of arm, or maybe the weight of water in a keg of specific size itself defined in hands and knuckles; the unifying characteristic is. Cubits and strides gave way to "customary units" to meet the needs of merchants and scientists. In the metric system and other recent systems, a single basic unit is used for each base quantity.
Secondary units are derived from the basic units by multiplying by powers of ten, i.e. by moving the decimal point. Thus the basic metric unit of length is the metre. Metrication is complete or nearly complete in all countries. US customary units are used in the United States and to some degree in Liberia. Traditional Burmese units of measurement are used in Burma. U. S. units are used in limited contexts in Canada due to the large volume of trade. A number of other jurisdictions have laws mandating or permitting other systems of measurement in some or all contexts, such as the United Kingdom – whose road signage legislation, for instance, only allows distance signs displaying imperial units – or Hong Kong. In the United States, metric units are used universally in science in the military, in industry, but customary units predominate in household use. At retail stores, the liter is a used unit for volume on bottles of beverages, milligrams, rather than grains, are used for medications; some other standard non-SI units are still in international use, such as nautical miles and knots in aviation and shipping.
Metric systems of units have evolved since the adoption of the first well-defined system in France in 1795. During this evolution the use of these systems has spread throughout the world, first to non-English-speaking countries, to English speaking countries. Multiples and submultiples of metric units are related by powers of ten and their names are formed with prefixes; this relationship is compatible with the decimal system of numbers and it contributes to the convenience of metric units. In the early metric system there were the metre for length and the gram for mass; the other units of length and mass, all units of area and derived units such as density were derived from these two base units. Mesures usuelles were a system of measurement introduced as a compromise between the metric system and traditional measurements, it was used in France from 1812 to 1839. A number of variations on the metric system have been in use; these include gravitational systems, the centimetre–gram–second systems useful in science, the metre–tonne–second system once used in the USSR and the metre–kilogram–second system.
The current international standard metric system is the International System of Units It is an mks system based on the metre and second as well as the kelvin, ampere and mole. The SI includes two classes of units which are agreed internationally; the first of these classes includes the seven SI base units for length, time, electric current, luminous intensity and amount of substance. The second class consists of the SI derived units; these derived. All other quantities are expressed in terms of SI derived units. Both imperial units and US customary units derive from earlier English units. Imperial units were used in the former British Empire and
The United Kingdom the United Kingdom of Great Britain and Northern Ireland, sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world; the Irish Sea lies between Great Ireland. With an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world, it is the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017. The UK is constitutional monarchy; the current monarch is Queen Elizabeth II, who has reigned since 1952, making her the longest-serving current head of state.
The United Kingdom's capital and largest city is London, a global city and financial centre with an urban area population of 10.3 million. Other major urban areas in the UK include Greater Manchester, the West Midlands and West Yorkshire conurbations, Greater Glasgow and the Liverpool Built-up Area; the United Kingdom consists of four constituent countries: England, Scotland and Northern Ireland. Their capitals are London, Edinburgh and Belfast, respectively. Apart from England, the countries have their own devolved governments, each with varying powers, but such power is delegated by the Parliament of the United Kingdom, which may enact laws unilaterally altering or abolishing devolution; the nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the UK, being Crown dependencies with the British Government responsible for defence and international representation. The medieval conquest and subsequent annexation of Wales by the Kingdom of England, followed by the union between England and Scotland in 1707 to form the Kingdom of Great Britain, the union in 1801 of Great Britain with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland.
Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain and Northern Ireland. There are fourteen British Overseas Territories, the remnants of the British Empire which, at its height in the 1920s, encompassed a quarter of the world's land mass and was the largest empire in history. British influence can be observed in the language and political systems of many of its former colonies; the United Kingdom is a developed country and has the world's fifth-largest economy by nominal GDP and ninth-largest economy by purchasing power parity. It has a high-income economy and has a high Human Development Index rating, ranking 14th in the world, it was the world's first industrialised country and the world's foremost power during the 19th and early 20th centuries. The UK remains a great power, with considerable economic, military and political influence internationally, it is sixth in military expenditure in the world. It has been a permanent member of the United Nations Security Council since its first session in 1946.
It has been a leading member state of the European Union and its predecessor, the European Economic Community, since 1973. The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the G20, NATO, the Organisation for Economic Co-operation and Development and the World Trade Organization; the 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain". The term "United Kingdom" has been used as a description for the former kingdom of Great Britain, although its official name from 1707 to 1800 was "Great Britain"; the Acts of Union 1800 united the kingdom of Great Britain and the kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland. Following the partition of Ireland and the independence of the Irish Free State in 1922, which left Northern Ireland as the only part of the island of Ireland within the United Kingdom, the name was changed to the "United Kingdom of Great Britain and Northern Ireland".
Although the United Kingdom is a sovereign country, Scotland and Northern Ireland are widely referred to as countries. The UK Prime Minister's website has used the phrase "countries within a country" to describe the United Kingdom; some statistical summaries, such as those for the twelve NUTS 1 regions of the United Kingdom refer to Scotland and Northern Ireland as "regions". Northern Ireland is referred to as a "province". With regard to Northern Ireland, the descriptive name used "can be controversial, with the choice revealing one's political preferences"; the term "Great Britain" conventionally refers to the island of Great Britain, or politically to England and Wales in combination. However, it is sometimes used as a loose synonym for the United Kingdom as a whole; the term "Britain" is used both as a synonym for Great Britain, as a synonym for the United Kingdom. Usage is mixed, with the BBC preferring to use Britain as shorthand only for Great Britain and the UK Government, while accepting that both terms refer to the United K
Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, ductile unreactive, silverish-white transition metal, its name is derived from the Spanish term platino, meaning "little silver". Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements, it has six occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of 5 μg/kg, it occurs in some nickel and copper ores along with some native deposits in South Africa, which accounts for 80% of the world production. Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, given its important uses, it is valuable and is a major precious metal commodity. Platinum is one of the least reactive metals, it has remarkable resistance to corrosion at high temperatures, is therefore considered a noble metal. Platinum is found chemically uncombined as native platinum; because it occurs in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts.
It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, jewelry. Being a heavy metal, it leads to health problems upon exposure to its salts. Compounds containing platinum, such as cisplatin and carboplatin, are applied in chemotherapy against certain types of cancer; as of 2018, the value of platinum is $833.00 per ounce. Pure platinum is a lustrous and malleable, silver-white metal. Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold; the metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. Platinum does oxidize, forming PtO2, at 500 °C, it reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride.
It is attacked by chlorine, bromine and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia, to form chloroplatinic acid, H2PtCl6, its physical characteristics and chemical stability make it useful for industrial applications. Its resistance to wear and tarnish is well suited to use in fine jewellery; the most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are less common, are stabilized by metal bonding in bimetallic species; as is expected, tetracoordinate platinum compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is unreactive, it dissolves in hot aqua regia to give aqueous chloroplatinic acid: Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2OAs a soft acid, platinum has a great affinity for sulfur, such as on dimethyl sulfoxide. In 2007, Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum.
Platinum has six occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, 198Pt. The most abundant of these is 195 Pt, it is the only stable isotope with a non-zero spin. 190Pt is the least abundant at only 0.01%. Of the occurring isotopes, only 190Pt is unstable, though it decays with a half-life of 6.5×1011 years, causing an activity of 15 Bq/kg of natural platinum. 198 Pt can undergo alpha decay. Platinum has 31 synthetic isotopes ranging in atomic mass from 166 to 204, making the total number of known isotopes 39; the least stable of these is 166Pt, with a half-life of 300 µs, whereas the most stable is 193Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta alpha decay. 188Pt, 191Pt, 193Pt decay by electron capture. 190Pt and 198Pt are predicted to have energetically favorable double beta decay paths. Platinum is an rare metal, occurring at a concentration of only 0.005 ppm in Earth's crust. It is sometimes mistaken for silver. Platinum is found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly.
Most the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals. Another large alluvial deposit is in the Ural Mountains, it is still mined. In nickel and copper deposits, platinum-group metals occur as sulfides, tellurides and arsenides, as end alloys with nickel or copper. Platinum arsenide, sperrylite, is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, about 17,000 kg was mined between 1927 and 1975; the mine ceased operations in 1990. The rare sulfide minera
The Hefner lamp, or in German Hefnerkerze, is a flame lamp used in photometry that burns amyl acetate. The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with a luminous intensity unit of the Hefnerkerze; the lamp was specified as having an 8 mm diameter wick. The Hefner lamp provided the German and Scandinavian standard for luminosity during the late nineteenth and early twentieth centuries; the unit of light intensity was defined as that produced by the lamp burning amyl acetate with a 40 mm flame height. The light unit was known as the Hefnereinheit. In 1897 it was adopted by the Association of German Electrical Engineers under the name Hefnerkerze. Germany moved to using the New Candle from 1 July 1942 and the candela from 1948; the HK unit is still used as a measure of the intensity of kerosene pressure lamps in Germany. 1 Hefnerkerze is about 0.920 candela. Candlepower List of obsolete units of measurement "Lichtstärke und Lichteinheit".
Archived from the original on 2008-04-19
A standards organization, standards body, standards developing organization, or standards setting organization is an organization whose primary activities are developing, promulgating, amending, interpreting, or otherwise producing technical standards that are intended to address the needs of a group of affected adopters. Most standards are voluntary in the sense that they are offered for adoption by people or industry without being mandated in law; some standards become mandatory when they are adopted by regulators as legal requirements in particular domains. The term formal standard refers to a specification, approved by a standards setting organization; the term de jure standard refers to a standard mandated by legal requirements or refers to any formal standard. In contrast, the term de facto standard refers to a specification that has achieved widespread use and acceptance – without being approved by any standards organization. Examples of de facto standards that were not approved by any standards organizations include the Hayes command set developed by Hayes, Apple's TrueType font design and the PCL protocol used by Hewlett-Packard in the computer printers they produced.
The term standards organization is not used to refer to the individual parties participating within the standards developing organization in the capacity of founders, stakeholders, members or contributors, who themselves may function as the standards organizations. The implementation of standards in industry and commerce became important with the onset of the Industrial Revolution and the need for high-precision machine tools and interchangeable parts. Henry Maudslay developed the first industrially practical screw-cutting lathe in 1800, which allowed for the standardisation of screw thread sizes for the first time. Maudslay's work, as well as the contributions of other engineers, accomplished a modest amount of industry standardization. Joseph Whitworth's screw thread measurements were adopted as the first national standard by companies around the country in 1841, it came to be known as the British Standard Whitworth, was adopted in other countries. By the end of the 19th century differences in standards between companies was making trade difficult and strained.
For instance, an iron and steel dealer recorded his displeasure in The Times: "Architects and engineers specify such unnecessarily diverse types of sectional material or given work that anything like economical and continuous manufacture becomes impossible. In this country no two professional men are agreed upon the size and weight of a girder to employ for given work"; the Engineering Standards Committee was established in London in 1901 as the world's first national standards body. It subsequently extended its standardization work and became the British Engineering Standards Association in 1918, adopting the name British Standards Institution in 1931 after receiving its Royal Charter in 1929; the national standards were adopted universally throughout the country, enabled the markets to act more rationally and efficiently, with an increased level of cooperation. After the First World War, similar national bodies were established in other countries; the Deutsches Institut für Normung was set up in Germany in 1917, followed by its counterparts, the American National Standard Institute and the French Commission Permanente de Standardisation, both in 1918.
By the mid to late 19th century, efforts were being made to standardize electrical measurement. An important figure was R. E. B. Crompton, who became concerned by the large range of different standards and systems used by electrical engineering companies and scientists in the early 20th century. Many companies had entered the market in the 1890s and all chose their own settings for voltage, frequency and the symbols used on circuit diagrams. Adjacent buildings would have incompatible electrical systems because they had been fitted out by different companies. Crompton could see the lack of efficiency in this system and began to consider proposals for an international standard for electric engineering. In 1904, Crompton represented Britain at the Louisiana Purchase Exposition in St. Louis, Missouri, as part of a delegation by the Institute of Electrical Engineers, he presented a paper on standardisation, so well received that he was asked to look into the formation of a commission to oversee the process.
By 1906 his work was complete and he drew up a permanent constitution for the first international standards organization, the International Electrotechnical Commission. The body held its first meeting that year with representatives from 14 countries. In honour of his contribution to electrical standardisation, Lord Kelvin was elected as the body's first President; the International Federation of the National Standardizing Associations was founded in 1926 with a broader remit to enhance international cooperation for all technical standards and specifications. The body was suspended in 1942 during World War II. After the war, ISA was approached by the formed United Nations Standards Coordinating Committee with a proposal to form a new global standards body. In October 1946, ISA and UNSCC delegates from 25 countries met in London and agreed to join forces to create the new International Organization for Standardization. Standards organizations can b
Colza oil or colza is a non-drying oil obtained from the seeds of rapeseed. Colza is extensively cultivated in France, the United States, the Netherlands and Poland. In France the extraction of the oil is an important industry. In commerce, colza is a traditional rapeseed oil, to which they are closely allied in both source and properties, it is a comparatively nonodoriferous oil of a yellow colour, having a specific gravity varying between 0.912 and 0.920. The cake left. Colza oil is extensively used as a lubricant for machinery. Colza oil was used extensively in European domestic lighting before the advent of coal gas or kerosene, it was the preferred oil for train pot lamps, was used for lighting railway coaches in the United Kingdom before gas lighting, electric lighting, were adopted. Burned in a Carcel lamp, it was part of the definition of the French standard measure for illumination, the carcel, for most of the nineteenth century. In lighthouses, for example in early Canada, colza oil was used before the introduction of mineral oil.
The colza oil was used with the Argand burner. Colza was burned to a limited extent in the Confederacy during the American Civil War. Colza oil was used in Gombault's Caustic Balsam, a popular horse and human liniment at the turn of the 20th century. Among the more unusual applications of colza oil is the calming of choppy seas, where the oil modifies the surface tension of the water and smooths the surface. For this purpose, colza oil was carried in ship's lifeboats. Rescue and recovery operations have been made far less risky in this way. More colza has been cultivated in Europe as an ingredient for biodiesel fuels, is the primary source of biodiesel in Germany. Toxic oil syndrome Canola oil, a low erucic acid rapeseed oil This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed.. "Colza Oil". Encyclopædia Britannica. 6. Cambridge University Press. P. 748
National Physical Laboratory (United Kingdom)
The National Physical Laboratory is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, England. It comes under the management of the Department for Business and Industrial Strategy; the National Physical Laboratory was established in 1900 at Bushy House "to bring scientific knowledge to bear upon our everyday industrial and commercial life". It grew to fill a large selection of buildings on the Teddington site. NPL procured a large state-of-the-art laboratory under a Private Finance Initiative contract in 1998; the construction, being undertaken by John Laing, the maintenance of this new building, being undertaken by Serco, was transferred back to the DTI in 2004 after the private sector companies involved made losses of over £100m. The laboratory was run by the UK government, with members of staff being part of the civil service. Administration of the NPL was contracted out in 1995 under a Government Owned Contractor Operated model, with Serco winning the bid and all staff transferred to their employ.
Under this regime, overhead costs halved, third party revenues grew by 16% per annum, the number of peer-reviewed research papers published doubled. It was decided in 2012 to change the operating model for NPL from 2014 onward to include academic partners and to establish a postgraduate teaching institute on site; the date of the changeover was postponed for up to a year. The candidates for lead academic partner were the Universities of Edinburgh, Southampton and Surrey with an alliance of the Universities of Strathclyde and Surrey chosen as preferred partners. In January 2013 funding for a new £25m Advanced Metrology Laboratory was announced that will be built on the footprint of an existing unused building; the operation of the laboratory transferred back to the Department for Business and Skills ownership on 1 January 2015. The National Physical Laboratory is involved with new developments in metrology, such as researching metrology for, standardising, nanotechnology, it is based at the Teddington site, but has a site in Huddersfield for dimensional metrology and an underwater acoustics facility at Wraysbury Reservoir.
Notable researchers at NPL Researchers who have worked at NPL include: D. W. Dye who did important work in developing the technology of quartz clocks; the inventor Sir Barnes Wallis did early development work there on the "Bouncing Bomb" used in the "Dam Busters" wartime raids. H. J. Gough, one of the pioneers of research into metal fatigue, worked at NPL for 19 years from 1914 to 1938. Sydney Goldstein and Sir James Lighthill worked in NPL's aerodynamics division during World War II researching boundary layer theory and supersonic aerodynamics respectively. Dr Clifford Hodge worked there and was engaged in research on semiconductors. Others who have spent time at NPL include Robert Watson-Watt considered the inventor of radar, Oswald Kubaschewski, the father of computational materials thermodynamics and the numerical analyst James Wilkinson. NPL research has contributed to physical science, materials science and bioscience. Applications have been found in ship design, aircraft development, computer networking and global positioning.
The first accurate atomic clock, a caesium standard based on a certain transition of the caesium-133 atom, was built by Louis Essen and Jack Parry in 1955 at NPL. Calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale ephemeris time; this led to the internationally agreed definition of the latest SI second being based on atomic time. NPL has undertaken computer research since the mid-1940s. From 1945, Alan Turing led the design of the Automatic Computing Engine computer; the ACE project was floundered, leading to Turing's departure. Donald Davies took the project over and concentrated on delivering the less ambitious Pilot ACE computer, which first worked in May 1950. Among those who worked on the project was American computer pioneer Harry Huskey. A commercial spin-off, DEUCE was manufactured by English Electric Computers and became one of the best-selling machines of the 1950s. Beginning in the mid-1960s, Donald Davies and his team at the NPL pioneered packet switching, now the dominant basis for data communications in computer networks worldwide.
Davies designed and proposed a national data network based on packet switching in his 1965 Proposal for the Development of a National Communications Service for On-line Data Processing. Subsequently, the NPL team developed the concept into a local area network which operated from 1969 to 1986, carried out work to analyse and simulate the performance of packet switching networks, their research and practice influenced the ARPANET in the United States, the forerunner of the Internet, other researchers in the UK and Europe. Directors of NPL Directors of NPL include a number of notable individuals. Sir Richard Tetley Glazebrook, 1900–1919 Sir Joseph Ernest Petavel, 1919–1936 Sir Frank Edward Smith, 1936–1937 Lawrence Bragg, 1937–1938 Sir Charles Galton Darwin, 1938–1949 Sir Edward Victor Appleton, 1941 Sir Edward Crisp Bullard, 1948–1955 Dr Reginald Leslie Smith-Rose, 1955–1956 Sir Gordon Brims Black McIvor Sutherland, 1956–1964 Dr John Vernon Dunworth, 1964–1977 Dr Paul Dean, 1977–1990 Dr Peter Clapham, 1990–1995Managing Directors Dr John Rae, 1995–2000 Dr Bob McGuiness, 2000–2005 Steve McQuillan, 2005–2008 Dr Martyn Sené, 2008–2009, 2015 Dr Brian Bowsher, 2009–2015Chief Executive Officers Dr Peter Thompson, 2015–presentN