Marble is a nonfoliated metamorphic rock resulting from the metamorphism of limestone, composed mostly of calcite (a crystalline form of calcium carbonate, CaCO3). It is extensively used for sculpture, as a building material, and in many other applications. The word "marble" is colloquially used to refer to many other stones that are capable of taking a high polish.
Faux marble or faux marbling is a wall painting technique that imitates the color patterns of real marble (not to be confused with paper marbling). Marble dust can be combined with cement or synthetic resins to make reconstituted or cultured marble.
Places named after the stone include Marble Arch, London; the Sea of Marmara; India's Marble Rocks; and the towns of Marble, Minnesota; Marble, Colorado; and Marble Hill, Manhattan, New York. The Elgin Marbles are marble sculptures from the Parthenon that are on display in the British Museum. They were brought to Britain by the Earl of Elgin.
Marble is a metamorphic rock resulting from regional or rarely contact metamorphism of sedimentary carbonate rocks, either limestone or dolostone, or metamorphism of older marble. This metamorphic process causes a complete recrystallization of the original rock into an interlocking mosaic of calcite, aragonite and/or dolomite crystals. The temperatures and pressures necessary to form marble usually destroy any fossils and sedimentary textures present in the original rock.
Pure white marble is the result of metamorphism of very pure limestones. The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Green coloration is often due to serpentine resulting from originally high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.
In the construction, specifically the dimension stone trade, the term "marble" is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone. For example, "Tennessee marble" is really a highly fossiliferous gray to pink to maroon Ordovician dolostone that geologists call the Holston Formation.
Thursday, March 20, 2008
Thursday, March 6, 2008
Motorcycle
A motorcycle or motorbike is a single-track, two-wheeled motor vehicle powered by an engine. Styles of motorcycles vary depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions. In many parts of the world, motorcycles are among the least expensive and most widespread forms of motorised transport.
History
The inspiration for arguably the first motorcycle was designed and built by the German inventors Gottlieb Daimler and Wilhelm Maybach in Bad Cannstatt (since 1905 a city district of Stuttgart) in 1885.The first petroleum-powered vehicle, it was essentially a motorised bicycle, although the inventors called their invention the Reitwagen ("riding car"). However, if one counts two wheels with steam propulsion as being a motorcycle, then the first one may have been American. One such machine was demonstrated at fairs and circuses in the eastern U.S. in 1867, built by Sylvester Howard Roper of Roxbury, Massachusetts.
In 1894, Hildebrand & Wolfmüller became the first motorcycle available for purchase. In the early period of motorcycle history, many producers of bicycles adapted their designs to accommodate the new internal combustion engine. As the engines became more powerful, and designs outgrew the bicycle origins, the number of motorcycle producers increased.Until the First World War, the largest motorcycle manufacturer in the world was Indian, producing over 20,000 bikes per year. By 1920, this honour went to Harley-Davidson, with their motorcycles being sold by dealers in 67 countries, until 1928 when DKW took over as the largest manufacturer.
After the Second World War, the BSA Group became the largest producer of motorcycles in the world, producing up to 75,000 bikes a year in the 1950s. The German company NSU Motorenwerke AG held the position of largest manufacturer from 1955 until the 1970s.
From the 1960s through the 1990s, small two-stroke motorcycles were popular worldwide, partly as a result of East German Walter Kaaden's engine work in the 1950s.Today, the Japanese manufacturers, Honda, Kawasaki, Suzuki, and Yamaha dominate the motorcycle industry, although Harley-Davidson still maintains a high degree of popularity in the United States. Recent years have also seen a resurgence in the popularity of several other brands sold in the U.S. market, including BMW, KTM, Triumph, Aprilia, Moto Guzzi and Ducati.
Outside of the USA, these brands have enjoyed continued and sustained success, although Triumph, for example, has been re-incarnated from its former self into a modern world-class manufacturer. In overall numbers, however, the Chinese currently manufacture and sell more motorcycles than any other country and exports are rising. The quality of these machines is asserted to be somewhat lower than their Japanese, European and American counterparts[citation needed].
Additionally, the small-capacity scooter is very popular through most of the world. The Piaggio group of Italy, for example, is one of the world's largest producers of two-wheeled vehicles. The scooter culture has, as yet, not been adopted widely in North America.
Social aspects,Subcultures
Around the world, motorcycles have historically been associated with subcultures. Some of these subcultures have been loose-knit social groups such as the cafe racers of 1950s Britain, and the Mods and Rockers of the 1960s. A few are believed to be criminal gangs.
Social motorcyclist organisations are popular and are sometimes organised geographically, focus on individual makes, or even specific models. Example motorcycle clubs include: American Motorcyclist Association, Harley Owners Group, Moto Guzzi National Owners Club, Gold Wing Road Riders (GWRRA), and BMW MOA.
Many motorcycle organisations raise money for charities through organised events and rides. Some organisations hold large international motorcycle rallies in different parts of the world that are attended by many thousands of riders.
Some other motorcycle organisations exist only for the direct benefit of others. Bikers Against Child Abuse (BACA) is one example. BACA assigns members to individual children to help them through difficult situations, or even stay with the child if the child is alone or frightened.In recent decades, motorcyclists have formed political lobbying organisations in order to influence legislators to introduce motorcycle-friendly legislation. One of the oldest such organisations, the British Motorcycle Action Group, was founded in 1973 specifically in response to helmet compulsion, introduced without public consultation.In addition, the British Motorcyclists Federation (BMF), originally founded in 1960 as a reaction to the public perception of motorcyclists as leather-jacketed hooligans, has itself moved into political lobbying.
Likewise, the U.S. has ABATE, which, like most such organisations, also works to improve motorcycle safety, as well as running the usual charity fund-raising events and rallies, often for motorcycle-related political interests. Some other lobbying organisations are listed in Category:Motorcyclists organizations.
Mobility
While the reasons for people choosing to ride motorcycles are many and varied, those reasons are increasingly practical, with riders opting for a powered two-wheeler as a cost-efficient alternative to infrequent and expensive public transport systems, or as a means of avoiding or reducing the effects of urban congestion.In places where it is permitted, lane splitting, also known as filtering, allows motorcycles to use the space between vehicles to move through stationary or slow traffic.
In the UK, motorcycles are exempt from the £8 per day London congestion charge other vehicles must pay to enter the city during the day. Motorcycles are also exempt from toll charges at some river crossings, such as the Severn Bridge, Dartford Crossing, and Mersey Tunnels. Some cities, such as Bristol, allow motorcycles to use bus lanes and provide dedicated free parking. In the United States, those states that have high-occupancy vehicle lanes also allow for motorcycle travel in them. Other countries have similar policies.
In many cultures motorcycles are the primary means of motorised transport. According to the Taiwanese government, for example, "the number of automobiles per ten thousand population is around 2,500, and the number of motorcycles is about 5,000."
Safety
Motorcycles have a higher rate of fatal accidents than automobiles. United States Department of Transportation data for 2005 from the Fatality Analysis Reporting System show that for passenger cars, 18.62 fatal crashes occur per 100,000 registered vehicles. For motorcycles this figure is higher at 75.19 per 100,000 registered vehicles – four times higher than for cars.The same data show that 1.56 fatalities occur per 100 million vehicle miles travelled for passenger cars, whereas for motorcycles the figure is 43.47 – 28 times higher than for cars. Furthermore for motorcycles the accident rates have increased significantly since the end of the 1990s, while the rates have dropped for passenger cars.
The two major causes of motorcycle accidents in the United States are: motorists pulling out or turning in front of motorcyclists and violating their rights-of-way and motorcyclists running wide through turns. The former is sometimes called a SMIDSY, an acronym formed from the motorists' common response of "Sorry mate, I didn't see you". The latter is more common when motorcyclists mix drinking with riding.Motorcyclists can anticipate avoid these crashes with proper training, increasing their conspicuousness to other traffic, and separating alcohol and riding.The United Kingdom has a number of organisations which are dedicated to improving motorcycle safety by providing advanced rider training over and above what is necessary to pass the basic motorcycle test. These include the Institute of Advanced Motorists (IAM) and the Royal Society for the Prevention of Accidents (RoSPA). Along with increased personal safety, riders with these advanced qualifications often benefit from reduced insurance costs.
Motorcycle Safety Education is offered throughout the United States by a number of organisations ranging from state agencies to non-profit organisations to corporations. The courses, designed by the Motorcycle Safety Foundation (MSF), include a Basic Rider Course, an Intermediate Rider Course and an Advanced Rider Course.
In the UK and some Australian jurisdictions, such as New South Wales, the Australian Capital Territory and the Northern Territory, it is compulsory to undertake a rider training course before being issued a Learners Licence.
In Canada, motorcycle rider training is compulsory in Quebec and Manitoba only, but all provinces and territories have Graduated Licensing programs which place restrictions on new drivers until they have gained experience. Eligibility for a full motorcycle license or endorsement for completing a Motorcycle Safety course varies from province to province. The Canada Safety Council (CSC), a non-profit safety organisation, offers the Gearing Up program across Canada and is endorsed by the Motorcycle and Moped Industry Council.Training course graduates may qualify for reduced insurance premiums.
History
The inspiration for arguably the first motorcycle was designed and built by the German inventors Gottlieb Daimler and Wilhelm Maybach in Bad Cannstatt (since 1905 a city district of Stuttgart) in 1885.The first petroleum-powered vehicle, it was essentially a motorised bicycle, although the inventors called their invention the Reitwagen ("riding car"). However, if one counts two wheels with steam propulsion as being a motorcycle, then the first one may have been American. One such machine was demonstrated at fairs and circuses in the eastern U.S. in 1867, built by Sylvester Howard Roper of Roxbury, Massachusetts.
In 1894, Hildebrand & Wolfmüller became the first motorcycle available for purchase. In the early period of motorcycle history, many producers of bicycles adapted their designs to accommodate the new internal combustion engine. As the engines became more powerful, and designs outgrew the bicycle origins, the number of motorcycle producers increased.Until the First World War, the largest motorcycle manufacturer in the world was Indian, producing over 20,000 bikes per year. By 1920, this honour went to Harley-Davidson, with their motorcycles being sold by dealers in 67 countries, until 1928 when DKW took over as the largest manufacturer.
After the Second World War, the BSA Group became the largest producer of motorcycles in the world, producing up to 75,000 bikes a year in the 1950s. The German company NSU Motorenwerke AG held the position of largest manufacturer from 1955 until the 1970s.
From the 1960s through the 1990s, small two-stroke motorcycles were popular worldwide, partly as a result of East German Walter Kaaden's engine work in the 1950s.Today, the Japanese manufacturers, Honda, Kawasaki, Suzuki, and Yamaha dominate the motorcycle industry, although Harley-Davidson still maintains a high degree of popularity in the United States. Recent years have also seen a resurgence in the popularity of several other brands sold in the U.S. market, including BMW, KTM, Triumph, Aprilia, Moto Guzzi and Ducati.
Outside of the USA, these brands have enjoyed continued and sustained success, although Triumph, for example, has been re-incarnated from its former self into a modern world-class manufacturer. In overall numbers, however, the Chinese currently manufacture and sell more motorcycles than any other country and exports are rising. The quality of these machines is asserted to be somewhat lower than their Japanese, European and American counterparts[citation needed].
Additionally, the small-capacity scooter is very popular through most of the world. The Piaggio group of Italy, for example, is one of the world's largest producers of two-wheeled vehicles. The scooter culture has, as yet, not been adopted widely in North America.
Social aspects,Subcultures
Around the world, motorcycles have historically been associated with subcultures. Some of these subcultures have been loose-knit social groups such as the cafe racers of 1950s Britain, and the Mods and Rockers of the 1960s. A few are believed to be criminal gangs.
Social motorcyclist organisations are popular and are sometimes organised geographically, focus on individual makes, or even specific models. Example motorcycle clubs include: American Motorcyclist Association, Harley Owners Group, Moto Guzzi National Owners Club, Gold Wing Road Riders (GWRRA), and BMW MOA.
Many motorcycle organisations raise money for charities through organised events and rides. Some organisations hold large international motorcycle rallies in different parts of the world that are attended by many thousands of riders.
Some other motorcycle organisations exist only for the direct benefit of others. Bikers Against Child Abuse (BACA) is one example. BACA assigns members to individual children to help them through difficult situations, or even stay with the child if the child is alone or frightened.In recent decades, motorcyclists have formed political lobbying organisations in order to influence legislators to introduce motorcycle-friendly legislation. One of the oldest such organisations, the British Motorcycle Action Group, was founded in 1973 specifically in response to helmet compulsion, introduced without public consultation.In addition, the British Motorcyclists Federation (BMF), originally founded in 1960 as a reaction to the public perception of motorcyclists as leather-jacketed hooligans, has itself moved into political lobbying.
Likewise, the U.S. has ABATE, which, like most such organisations, also works to improve motorcycle safety, as well as running the usual charity fund-raising events and rallies, often for motorcycle-related political interests. Some other lobbying organisations are listed in Category:Motorcyclists organizations.
Mobility
While the reasons for people choosing to ride motorcycles are many and varied, those reasons are increasingly practical, with riders opting for a powered two-wheeler as a cost-efficient alternative to infrequent and expensive public transport systems, or as a means of avoiding or reducing the effects of urban congestion.In places where it is permitted, lane splitting, also known as filtering, allows motorcycles to use the space between vehicles to move through stationary or slow traffic.
In the UK, motorcycles are exempt from the £8 per day London congestion charge other vehicles must pay to enter the city during the day. Motorcycles are also exempt from toll charges at some river crossings, such as the Severn Bridge, Dartford Crossing, and Mersey Tunnels. Some cities, such as Bristol, allow motorcycles to use bus lanes and provide dedicated free parking. In the United States, those states that have high-occupancy vehicle lanes also allow for motorcycle travel in them. Other countries have similar policies.
In many cultures motorcycles are the primary means of motorised transport. According to the Taiwanese government, for example, "the number of automobiles per ten thousand population is around 2,500, and the number of motorcycles is about 5,000."
Safety
Motorcycles have a higher rate of fatal accidents than automobiles. United States Department of Transportation data for 2005 from the Fatality Analysis Reporting System show that for passenger cars, 18.62 fatal crashes occur per 100,000 registered vehicles. For motorcycles this figure is higher at 75.19 per 100,000 registered vehicles – four times higher than for cars.The same data show that 1.56 fatalities occur per 100 million vehicle miles travelled for passenger cars, whereas for motorcycles the figure is 43.47 – 28 times higher than for cars. Furthermore for motorcycles the accident rates have increased significantly since the end of the 1990s, while the rates have dropped for passenger cars.
The two major causes of motorcycle accidents in the United States are: motorists pulling out or turning in front of motorcyclists and violating their rights-of-way and motorcyclists running wide through turns. The former is sometimes called a SMIDSY, an acronym formed from the motorists' common response of "Sorry mate, I didn't see you". The latter is more common when motorcyclists mix drinking with riding.Motorcyclists can anticipate avoid these crashes with proper training, increasing their conspicuousness to other traffic, and separating alcohol and riding.The United Kingdom has a number of organisations which are dedicated to improving motorcycle safety by providing advanced rider training over and above what is necessary to pass the basic motorcycle test. These include the Institute of Advanced Motorists (IAM) and the Royal Society for the Prevention of Accidents (RoSPA). Along with increased personal safety, riders with these advanced qualifications often benefit from reduced insurance costs.
Motorcycle Safety Education is offered throughout the United States by a number of organisations ranging from state agencies to non-profit organisations to corporations. The courses, designed by the Motorcycle Safety Foundation (MSF), include a Basic Rider Course, an Intermediate Rider Course and an Advanced Rider Course.
In the UK and some Australian jurisdictions, such as New South Wales, the Australian Capital Territory and the Northern Territory, it is compulsory to undertake a rider training course before being issued a Learners Licence.
In Canada, motorcycle rider training is compulsory in Quebec and Manitoba only, but all provinces and territories have Graduated Licensing programs which place restrictions on new drivers until they have gained experience. Eligibility for a full motorcycle license or endorsement for completing a Motorcycle Safety course varies from province to province. The Canada Safety Council (CSC), a non-profit safety organisation, offers the Gearing Up program across Canada and is endorsed by the Motorcycle and Moped Industry Council.Training course graduates may qualify for reduced insurance premiums.
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