International Bureau of Weights and Measures

The International Bureau of Weights and Measures is the English name of the Bureau international des poids et mesures (BIPM, often written in English Bureau International des Poids et Mesures), a standards organization, one of the three organizations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention). Note that the abbreviation IBWM does not exist. It is based at th ...

Read more here: » International Bureau of Weights and Measures: Encyclopedia - International Bureau of Weights and Measures

The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures (CGPM, never GCWM). It is one of the three organizations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention) of 1875. It meets in Paris every four to six years. In 2002 the CGPM represented 51 member states and ten further associ ...

Including:

• General Conference on Weights and Measures - CGPM Meetings

Read more here: » General Conference on Weights and Measures: Encyclopedia - General Conference on Weights and Measures

Metrology is variously described as the science of measurement; the science of accuracy and precision; the history of measures; the history of measurement and other definitions. It is a field of study which has been highly politicized and nationalized with sharp even severe rhetoric as the field progressed. Metrology, as defined by the International Organization of Legal Metrology (OIML) in its 2000 publication International Vocabulary of Terms in Legal Metrology [1], is the "Science of Measurement." Legal metr ...

Including:

• Metrology - Introduction
• Metrology - Historical development
• Metrology - Mechanisms of metrology

Read more here: » Metrology: Encyclopedia - Metrology

IEEE 1541 recommends: a set of units to refer to quantities used in digital electronics and computing: bit (symbol b), a binary digit; byte (symbol B), a set of adjacent bits (usually, but not necessarily, eight) operated on as a group; octet (symbol o), an eight-bit byte; a set of prefixes to indicate binary multiples of the aforesaid units: kibi- (symbol Ki), 210 = 1,024; mebi- (symbol ...

See also:

IEEE 1541, IEEE 1541 - Recommendations, IEEE 1541 - Acceptance

Read more here: » IEEE 1541: Encyclopedia II - IEEE 1541 - Recommendations

There are three main exceptions to the metrication trend: the UK, the U.S., and global air and sea transport industry. Contrary to popular belief, the U.S. and the UK do not use a common system (see English unit, Imperial unit and U.S. customary units for details). With the exception of the length, with the yard standardised at exactly 0.9144 m by an international conference in 1958, most other units differ in value in the U.S. and UK. A gallon of liquid, for example, is 3.8 l in the U.S. but 4.5 l in the UK. The U.S. also has ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Exceptions

There are three main exceptions to the metrication trend: the UK, the USA, and global air and sea transport industry. Contrary to popular belief, the USA and the UK do not use a common system (see English unit, Imperial unit and U.S. customary units for details). With the exception of the length, with the yard standardised at exactly 0.9144 m by an international conference in 1958, most other units differ in value in the USA and UK. A gallon of liquid, for example, is 3.8 l in the USA but 4.5 l in the UK. The USA also have ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Exceptions

Metrology was originally a study of historical measurement examining ancient, beginning of history documents from Assyria, Egypt, Greece and Roman origin. Early metrologists asserted that early cultures used a system of measurement in commerce that created a foundation for the study of scientific measurement. The studies by John Greaves (1602-1652) and Eduard Bernard (1638-1697) assert that a basic unit of measurement was used between cultures of the time based on the foot or cubit and that the basic measure of length cubed and filled with rainwa ...

See also:

Metrology, Metrology - Introduction, Metrology - Historical development, Metrology - Mechanisms of metrology

Read more here: » Metrology: Encyclopedia II - Metrology - Historical development

A platinum family metal, iridium is white, resembling platinum, but with a slight yellowish cast. Due to its extreme hardness and brittle properties, iridium is difficult to machine, form, or work. Iridium is the most corrosion-resistant metal known. Iridium cannot be attacked by any acids or by aqua regia, but it can be attacked by molten salts, such as NaCl and NaCN. The measured density of this element is only slightly lower than that of osmium, which is therefore often listed as the heaviest element known. However, calculations of ...

See also:

Iridium, Iridium - Notable characteristics, Iridium - Applications, Iridium - History, Iridium - Occurrence, Iridium - Isotopes, Iridium - Precautions

Read more here: » Iridium: Encyclopedia II - Iridium - Notable characteristics

Interestingly, considering it was the birthplace of the metric system, France experienced a particularly rough journey to metrication. The traditional French measuring system was chaotic, with size of units differing in each small town, and often even within towns. Lyon had two different values of pound in general use, one of 14 ounces, and another of 15 ounces, the latter only being used for measuring silk. The revolutionary government, which had ordered the creation of the metric system, first attempted a quick conversion, legalisin ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Opposition

Despite the presence of the standard, the new binary prefixes have difficulty in gaining acceptance. Common refutations are that SI prefixes for binary multiples have been used for years for computer-related quantities and that major operating systems and applications still use SI prefixes for binary multiples. Nevertheless, manufacturers of storage devices, such as hard disks and DVDs, are used to decimal multiples to express capacities, and decimal multiples are used for transmission rates as well. This is common cause of confusion among users that see those amounts reported inconsistently, especially as capacities become bigger and ...

See also:

IEEE 1541, IEEE 1541 - Recommendations, IEEE 1541 - Acceptance

Read more here: » IEEE 1541: Encyclopedia II - IEEE 1541 - Acceptance

Confusion over units during the process of metrication can sometimes lead to accidents. One of the most famous examples is the Gimli Glider, a Boeing 767 that ran out of fuel in Canada in 1983 due, in large part, to confusion at Air Canada during Canada's metrication. While not strictly an example of national metrication, the use of two different systems was the contributing factor in the loss of the Mars Climate Orbiter in 1998. NASA specified metric units in the contract. NASA and other organisations worked in metric units but one s ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Accidents and incidents

There are three common routes that nations take in converting from traditional measurement systems to the metric system. The first is a quick, so called "Big-bang" route which was used by India in the early 1960s and several other developing nations since then. The second two routes are both variations on the slower phase-in route that tends to be favoured by industrial nations. The first, "Big-bang", route is to simultaneously outlaw the use of pre-metric measurement, metricise and reissue all government publications and laws, and ch ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Conversion process

Iridium was discovered in 1803 by Smithson Tennant in London, England along with osmium in the dark-colored residue of dissolving crude platinum in aqua regia (a mixture of hydrochloric and nitric acid). The element was named after the Latin word for rainbow (iris; iridium means "of rainbows") because many of its salts are strongly colored. An alloy of 90% platinum and 10% iridium was used in 1889 to construct the standard metre bar and kilogram mass, kept by the International Bureau of Weights and Measures near Paris. T ...

See also:

Iridium, Iridium - Notable characteristics, Iridium - Applications, Iridium - History, Iridium - Occurrence, Iridium - Isotopes, Iridium - Precautions

Read more here: » Iridium: Encyclopedia II - Iridium - History

The principal use of iridium is as a hardening agent in platinum alloys. Other uses: For making crucibles and devices that require high temperatures. Electrical contacts (notable example: Pt/Ir sparkplugs). Osmium/iridium alloys are used for tipping fountain pen nibs and for compass bearings. Iridium is used as a catalyst for carbonylation of methanol to produce acetic acid At one time iridium, as an alloy with platinum, was used in bushing the vents of heavy ordnance and, in a finely powdered condition (iridi ...

See also:

Iridium, Iridium - Notable characteristics, Iridium - Applications, Iridium - History, Iridium - Occurrence, Iridium - Isotopes, Iridium - Precautions

Read more here: » Iridium: Encyclopedia II - Iridium - Applications

Iridium is found uncombined in nature with platinum and other platinum group metals in alluvial deposits. Naturally occurring iridium alloys include osmiridium and iridiosmium, both of which are mixtures of iridium and osmium. It is recovered commercially as a by-product from nickel mining and processing. Iridium is rare on Earth, but relatively common in meteorites. ...

See also:

Iridium, Iridium - Notable characteristics, Iridium - Applications, Iridium - History, Iridium - Occurrence, Iridium - Isotopes, Iridium - Precautions

Read more here: » Iridium: Encyclopedia II - Iridium - Occurrence

Medieval trade was organized on a city-by-city basis by guilds, which set local laws on weights and measures. For example, the ell or elle was a unit of length commonly used in Europe, but its value varied from 40.2 cm in one part of Germany to 70 cm in The Netherlands to 94.5 cm in Edinburgh. A survey of Switzerland in 1838 revealed that the foot had 37 different regional variations, the ell had 68, there were 83 different measures for dry grain and 70 for fluids, and 63 different measures for "dea ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Before the metric system

Scientists, chiefly in France, had been advocating and discussing a decimal system of measurement based on natural units at least since 1640, but the first official adoption of such a system was after the French Revolution of 1789. The creators of the metric system tried to choose units that were non-arbitrary and practical, merging well with the revolution's official ideology of "pure reason". The original system started with the metre as the unit of distance, the gram as the unit of mass, and the second as the unit of ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Système International SI

The metric system, developed in France around the turn of the 19th century, was quickly taken up by Europe's scientists before spreading to traders and industrialists and finally to the common people. France's neighbour the Kingdom of the Netherlands (present The Netherlands, Belgium, and Luxembourg), changed in 1820. Spain and its former American colonies changed in the 1850s and 1860s. Italy and Germany went metric after their respective unifications in 1861 and 1871, followed shortly by Portugal, Norway, Sweden and Austria-Hungary. By 1900, 39 countries in Europe and Lat ...

See also:

Metrication, Metrication - Before the metric system, Metrication - Système International SI, Metrication - Conversion process, Metrication - Adoption, Metrication - Exceptions, Metrication - United Kingdom, Metrication - United States, Metrication - Liberia and Myanmar, Metrication - Air and sea transport, Metrication - Accidents and incidents, Metrication - Opposition

Read more here: » Metrication: Encyclopedia II - Metrication - Adoption