The word Bohemian was first used in Paris to mean a Gypsy because many people thought that Gypsies came from Bohemia. The word was then used in the late 19th century (1800s) for poor painters, writers, musicians and actors who often travelled to Paris from other towns and tried to earn money. Paris was a famous town for painters, writers, and musicians to gather, to learn from each other and to enjoy the life of the city. Many of them lived at Montmartre, not far from the "Moulin Rouge". One of the most famous painters to live in Montmartre was Henri Toulouse-Lautrec. He loved to paint the can-can dancers and prostitutes. He did many posters to advertise the nightclubs. The posters are now famous works of art.

In the 20th century the word "Bohemian" spread to other countries and was used to describe the lives of many different artists of different sorts. The sort of behaviour that was thought of as "Bohemian" included whether a person had a regular job, how they dressed, their political views, their religious views, their sexual behaviour and the entertainment they liked.

People who were called "Bohemians" were often very poor, because they tried to live by painting, acting or writing. It was hard to make a living. They generally wore old or second-hand clothing, and could not afford a good hair-cut. They often shared the room in the roof of a house, which was cheap, because it was cold in winter, hot in summer and often had birds living there as well. In some ways the life of a bohemian artist was difficult, but it gave people freedom to express themselves, that was often not found in more conservative society, where everyone worried about what other people thought of them, and cared a lot about things like clothes and houses. Sometimes students from richer families would come to live a "Bohemian life style", so that they could feel the same freedom to express themselves.

During the 20th century, many cities apart from Paris have areas where people have lived Bohemian lifestyles. One of the problems is that these areas often become fashionable for rich people. This soon drives away the poor artists and students, because they can no longer afford the rent.

Bohemian areas

Bohemian areas in different cities are:
 Paris- Montmartre and Montparnasse
 Istanbul- Pera (Beyoglu)
 London- Chelsea, Camden Town, and Soho
 Munich- Schwabing
 Belgrade- Skadarlija
 Madrid- Lavapiés in Madrid
 Milan- Isola and Colonne di San Lorenzo
 New York City- Greenwich Village, the East Village and Chelsea
 Massachusetts- Provincetown
 California- Carmel-by-the-Sea,
 San Francisco- the Mission District
 Chicago- Logan Square
 New Orleans- the French Quarter
 Toronto- Kensington Market
 Mexico City- Coyoacán and Condesa
 Sydney- Kings Cross and Newtown
 Tokyo - Shimokitazawa
 Vancouver- Commercial Drive

Bohemians in culture
 Bohemian people and places have very often been shown in paintings. Famous bohemian artists of Paris include Henri Toulouse-Lautrec, Vincent van Gogh and Maurice Utrillo.

 La bohème means "the Bohemian". It is the name of a famous opera written by Giacomo Puccini.
 Moulin Rouge! is a movie by Baz Lurhmann.

Related pages
 Avant-garde
 Counterculture
 Montmartre
 Moulin Rouge
 Henri Toulouse-Lautrec
 La bohème

Lifestyles

Bohemianism


A railway track or railway line is a set of two parallel rows of long pieces of steel. They are used by trains to transport people and things from one place to another. (In America, people say railroad as well as railway). Often, there is more than one set of tracks on the railway line. For example, trains go east on one track and west on the other one.

The rails are supported by cross pieces set at regular intervals (called sleepers or ties), which spread the high pressure load imposed by the train wheels into the ground. They also maintain the rails at a fixed distance apart (called the gauge). Ties are usually made from either wood or concrete. These often rest on ballast, which is a name for very small pieces of broken up rock that are packed together and keep the railway tracks in place. Tracks are often made better by ballast tampers.

The upper surfaces of the rails are inclined slightly towards each other, typically on a slope of 1/20, and the rims of the train wheels are angled in the same way ("coning"). This helps guide the vehicles of the train along the track. Each wheel also has a flange, which sticks out from one edge all the way around. This makes sure the train does not "derail" (come off the track) and helps guide the train on sharp curves.

References

Railway track


According to the WHO, a drug is a substance that can change how a living organism works. Food is usually not seen as a drug, even though some foods may have such properties. Most of the time drugs are taken to treat a disease, or other medical condition. An example for such drugs may be Aspirin or Paracetamol. These are usually given to treat fever, as well as certain infections. If such drugs are taken over a longer time, they are usually prescribed by a doctor. Other drugs are taken for fun, because of the effect they have. Some of these drugs taken for fun are better accepted by society than others. Having or taking certain drugs may be illegal, in certain countries.

Drugs that are taken to treat a disease or condition are usually called "therapeutic", drugs that are taken for fun are called "recreational" drugs.

Drugs may have other effects than those wanted. Such effects are generally known as side-effects.

Drugs act differently in different amounts. It is therefore important to take the right amount. The amount of the drug taken is called a dose. Aspirin is often prescribed against fever, or as an analgesic. One of the side-effects of Aspirin is that it makes the blood thinner. For this reason, it can also be used to prevent strokes, or heart attacks - in a much lower dose than the one used to treat fever, though.

Taking too much of a drug ("too high a dose") can cause sickness or even death.  When a doctor says how much of a drug (the right dose) to take, only that amount should be taken.  It is very important to keep taking the drug until the doctor says to stop because someone can feel better but still be sick.  When a doctor says what drug to take, how much of it, and for how long, it is called a prescription. Drugs may cause addiction. Some drugs are illegal because they are very addictive. These drugs are really expensive, too. It can also be sold illegally from drug sellers which may cause serious results

Recreational drugs
Recreational drugs can sometimes be bad for someone's health even if they make them feel good.  Alcohol can also be dangerous if the person drinking it drives a vehicle after drinking. This is called drunk driving.  Many countries make this against the law.  Common recreational drugs include:

Alcohol - In beer, wine and hard liquor
Nicotine - In cigarettes
Caffeine - In Coffee and cacao (See figure)
Cannabis - Smoked like cigarettes, or baked in something to eat, like a cake or brownie
Methamphetamine (also known as Crystal Meth) - Can be smoked, eaten, injected, or inhaled
Cocaine - can be snorted, injected or inhaled (freebasing)
Heroin - can be snorted, injected or smoked in its freebase form.

Certain recreational drugs also have uses as a therapeutic drug. Heroin can be used as an analgesic (a painkiller) and methamphetamine is used to treat narcolepsy or ADHD. Recreational drugs can be dangerous, certain countries have made it illegal to have or take them outside a medical context. Most of the time, this is because they can be addictive or that they are very dangerous when combined with other drugs. That way, Cannabis-based products are legal in the Netherlands, but illegal in many other countries.

Alcohol and Nicotine are legal almost everywhere, but there are a lot of taxes on the sale of these. In other words, they are expensive to buy. Being expensive to buy because of taxes has two benefits; one is that the taxes collected from the sale of the drugs goes into helping to pay for assistance the drug user may experience later. A smoker, for example, may develop cancer later in life and need treatment at a place that is granted a certain amount of tax money from the government to keep it operating. Another benefit to the taxing of "legal" drugs, is that the high price may stop people from beginning the habit in the first place, which will help them avoid the negative medical or addictive side effects of the drug. In some cases, not everyone is allowed to buy these drugs unless they are a minimal age to do so. The age at which someone is allowed to buy a legal drug is most often decided by the government of a country, state or province, and is usually the age where a person is considered by the law to be an "adult". Some of the most common ages this happens is at 18, 19 or 21 years of age.

Therapeutic drugs
Therapeutic drugs are also called medicinal drugs, medicine, or medication. Doctors will give therapeutic drugs to someone who is ill to make you better. You can buy these drugs at a pharmacy.  Some drugs need a prescription to be bought, other drugs do not. Drugs that do not require a prescription are called "over the counter" medications. There are lots of these drugs for different illnesses.  These include:

Aspirin - For pain
Paracetamol - For pain
Penicillin - For infections
Prozac - For depression
Diazepam - For anxiety
Antibiotics - For killing bacteria (germs)

References

Drug


A peafowl is a bird of the Phasianide family. It is a relative of the pheasant.

There are two species of peafowl: the Asiatic peafowl (Pavo) or the Congo peafowl (Afropavo congensis). The Congo peafowl is the only member of the pheasant family that originated outside Asia.

The male peafowl can have up to 150 brightly colored feathers on its tail coverts.

For centuries peafowl have been admired for their beauty and hunted for their meat. Recently peacocks have become more popular in parks and gardens.Peacocks are large, colorful pheasants (typically blue and green) known for their iridescent tails. Distinctive Tail Feathers.

Male peafowl

Appearance
The male peafowls (called peacocks) have long, colorful feathers. Female peafowls (called peahens) have shorter, brown feathers.

Habits

Eating habits
They like to eat any kind of green shoots (flowers, veggies, grass etc.) as well as wheat, cracked corn or wild game feed. They can handle freezing temperatures as long as they have a dry perch that is out of the wind and weather. Dry dog and cat chows make excellent winter feed for peafowl, who are omnivores, eating insects, small snakes, lizards, grain, as well as many varieties of greens. They are particularly fond of petunias and similar pot plants, leaving nothing but a small green circle where the stem once emerged from the soil. The birds will learn to come to a specific place at specific times of day to be fed, and a regular light feeding during summer adapts them to coming to the feeding place in winter.

Origin

The peafowl is native to southeast Asia, including India and Pakistan. They were brought to Europe long ago, and can acclimatize to colder areas.

Mating

The very long, elegant and colorful plumage of the male birds, peacocks, is grown over the winter months so that they are ready for the early spring mating season, during which each male establishes a territory. The male  calls to the females to come and admire his dance.

He displays a rustling of tail quills which hold up the fanned back plumes (= tail feathers) as he stamps and turns. The summoning call is loud, repeated, happens sometimes at night, and sounds, to some people, like a woman screaming. Often it is tri-syllabic, mi-fa-sol. Once the mating season is over, the tail feathers are naturally shed.

The peacock's display is a classic example of sexual selection.

Female peafowl
The female birds, peahens, are soft brown and gray with white chests and bellies and some light green on the neck, the colors blending so well with weeds and grasses that when the female is nesting on the ground, she is almost invisible.

Mothering
The hen teaches her chicks what to eat by putting her beak down at a chosen bug, grain, seed, or leaf and making a throaty "grock" sound. The chick put its beak against the mother's, follows the beak to the tip, and eats whatever it points at. The chicks can learn what to eat from a hen of another species, but, unlike baby chickens, peachicks need to be shown what to eat. Chicks hatched in a hatchery can starve to death if there is no hen to teach them what to eat.

In addition to the "eat this" sound, the female has a particular call for a missing chick, a "where are you," "hoo-hah" call, two toned, high then low, mi-do, mi-do. When a chick is missing, this call can go on for hours.

Reproduction
She lays from two to six eggs in the spring time and, once all are laid, sits on the eggs for about thirty days to hatch them, leaving the nest once or twice a day to feed and drink. Often the female will utter a shrieked "trouble" call, a quickly repeated "cuk, cuk, cuk, cuk" when she leaves the nest, to attract predators away from it.

Chicks
Once the chicks are hatched, the mother leads them away from the broken eggs, as the smell of the eggs attracts predators. They are able to flutter a little within hours, and in a few days can fly up into sheltering trees by going first to lower branches and working their way higher, preferring high, protected branches. The chicks roost on either side of the peahen, and she extends her wings to cover them during the night, thus protecting them from rain, hail, and visits from owls. They begin to grow their "crowns" when they are only a few weeks old and it takes about a year for them to reach full size, though it may take three years to reach breeding age. Both males and females are hatched with the same plumage; nine to twelve months after hatching, the males' necks begin to turn peacock blue, and their splendid plumage takes about four years to reach full size.

References

Phasianidae

Peafowl


Alejandro González Alcocer (born April 24, 1951) is a Mexican politician and lawyer, belonging to the National Action Party (PAN).

After Alcocer studied law at Universidad Nacional Autónoma de México (UNAM), he began his career in companies in the private sector, and later entered politics, where he served as Secretario del Ayuntamiento of Tijuana, and later as a federal deputy (diputado federal) in the 56th Federal Legislature. González Alcocer is the son of Manuel González Hinojosa, national head of the PAN  in the 1960s and 70s.

On October 7, 1998, he was named Substitute Governor of Baja California upon the death of governor Héctor Terán Terán.

He was elected to the Senate, representing Baja California, for the period between 2006–2012.

See also
Governor of Baja California
Baja California

External links
 The biography of Alejandro González Alcocer as Governor of Baja California

Living people
Governors of Baja California
National Action Party (Mexico) politicians
Members of the Chamber of Deputies (Mexico)
Members of the Senate of the Republic (Mexico)
Politicians from Mexico City
1951 births
21st-century Mexican politicians
National Autonomous University of Mexico alumni
20th-century Mexican politicians
20th-century Mexican lawyers

Alejandro González Alcocer


Sonata form is a way of organizing a piece of music. It has been used in several pieces since the Classical period (from the middle of the 18th century onwards). Listening to  pieces of music in sonata form will help to understand it fully and it is helpful to know something about the different keys.

Sonata form is not just used in sonatas. It can be the form for movements from symphonies, concertos, overtures etc.

In the Baroque period composers like Bach and Handel wrote pieces with dance movements such as minuets. These were in "binary form". This meant that there were two sections. The two sections were often the same length, and were separated by a double bar line which meant that each section was repeated. The music would not be in the same key all the time. The first section could modulate (change key) and then the second section would gradually modulate back again so that it sounded finished at the end.

Domenico Scarlatti wrote sonatas for harpsichord also in binary form, but long and with additional complexity. The first section would start with a theme in the main key, and then modulate to another key for contrast. The second section might be longer than the first second, starting off by modulating to remote keys before arriving back to repeat the main theme. This kind of piece is the beginning of sonata form.

Haydn, Mozart and Beethoven developed the idea of sonata form. A movement in sonata form has three sections called: "exposition", "development" and "recapitulation".
In the exposition we hear all the main material: the first tune- or group of tunes - in the main key, then a contrasting tune or tunes in a related key (normally the "dominant" i.e. the key on the 5th note of the scale of the main key, or the relative minor). Or in the case of a first section in a minor key, one might frequently hear the second subject or subjects in the relative major.
In the development section the music is developed, going into several different keys. The music here feels unstable. There is a feeling of tension. The listener wants to get back to the main key.
In the recapitulation the exposition is repeated, but it changes towards the end so that it finishes in the main key. It feels as if the tension has gone and the listener feels happy.

This way of building a piece of music was used by almost every composer from the mid 18th century onwards – well into the 20th century. It gives scope for a very dramatic piece. Of course, composers sometime use it differently. There is often a sense of development during the whole piece, not just during the so-called "development section". The first movement of Beethoven's Fifth Symphony spends all the time developing the famous idea heard at the beginning: the first four notes (short-short-short-long). Even the other three movements carry on developing this idea.

Musical forms

Sonata form


A hippie (sometimes spelled as hippy) is a label for a person of a particular counterculture that started in the United States and spread to other countries in the 1960s.

Hippies have their own opinions on drugs, sexual liberation, and women's rights.

History
The first people to be called "hippies" were young adults and teenagers in the 1960s who grew out of the beatnik movement. These people were supporters of civil rights for African-Americans in the Southern USA. They soon developed their own music scene in neighborhoods in New York City (Greenwich Village) and San Francisco (Haight-Ashbury). They were also strongly against the Vietnam War, nuclear weapons, and what they called the "Establishment" (this was a word for mainstream society). They were also against the "military-industrial complex". This phrase was taken from a warning in the farewell speech of President Dwight Eisenhower in 1961.

Many more people began to see hippies in the news after the Human Be-In (January 1967) and the 1967 "Summer of Love" were held in San Francisco. By this time, they had developed their own lifestyle that included psychedelic styles, drug use, usually some amount of travel, and much longer hair than other people. These styles quickly spread across the country, especially to college campuses where students were protesting President Lyndon Johnson's policies in Vietnam, the assassination of Dr. Martin Luther King, Jr. in 1968, and other events. They also spread to the UK, Netherlands, France, Italy, Germany, Australia, New Zealand, Pakistan and Canada, among other places.

In 1968 many more Americans turned against the war following the Tet Offensive, King was shot, and politicians began to get ready for the election for President in November. Many colleges were shut down by students, and people burned their draft cards at public rallies. A group of radical hippies called the Yippies, led by Abbie Hoffman and Jerry Rubin, led a huge protest during the 1968 Democratic Convention in Chicago, where they tried to run a pig called Pigasus as a candidate for President. The mayor responded by sending in riot police who beat people up in front of news cameras. The riot police even beat the cameramen, reporters, and other innocent people. This was shown on the news, and many programs and television stations began to feel more sympathetic to the hippies for a while. This made hippie lifestyle much more mainstream through the early seventies.

In 1969, Richard Nixon succeeded Johnson as President, and protests continued — not just against the war, but against the court trials and hearings of the Yippie leaders who became known as "the Chicago Seven" (originally "Chicago Eight"). Also in that year, a huge rock concert was held in Bethel, New York — the three day Woodstock Festival. At this festival, 500,000 hippies and music fans heard some of the most famous singers and groups of the time. The people there also did things like nude swimming, mud-sliding, rain-dancing and mass tribal chants. They did this to show their freedom to the world.

Late that year, a murderer named Charles Manson who posed as a hippie killed several people. Because some people blamed hippies for this, the term began to fall a little out of fashion in 1970, even if the fashions themselves did not. A new type of hard rock called heavy metal was developing out of one style of hippie music. A band called Led Zeppelin took the number one spot for most popular band of the year in 1970, which had been held by the Beatles for eight years. Also that year, when students at Kent State University in Ohio were protesting Nixon's spread of bombing to Laos, the National Guard shot at them, and four were killed. This had a chilling effect on the hippies and the whole country, but the peace movement continued. In 1973, the draft was ended, and the war ended soon after that. US public attention turned to the Watergate scandal. After this, hippies never again had the attention they once did, though the lifestyle continued, especially in other countries. In the mid-seventies, trends like punks and disco were also spreading, causing the hippie image to fade in the media.

References

Social issues
Lifestyles
Sexual revolution
Subculture

Hippie


Light rail transit (LRT) is a form of passenger urban rail transit characterized by a combination of tram and rapid transit features. While its rolling stock is similar to a traditional tram, it operates at a higher capacity and speed, and often on an exclusive right-of-way. In many cities, light rail transit systems more closely resemble, and are therefore indistinguishable from, traditional underground or at-grade subways and heavy-rail metros.

There is no standard definition, but in the United States (where the terminology was devised in the 1970s from the engineering term light railway), light rail operates primarily along exclusive rights-of-way and uses either individual tramcars or multiple units coupled to form a train that is lower capacity and lower speed than a long heavy-rail passenger train or rapid transit system.

A few light rail networks tend to have characteristics closer to rapid transit or even commuter rail; some of these heavier rapid transit-like systems are referred to as light metros. Other light rail networks are tram-like and partially operate on streets.

History

The world's first electric tram line operated in Sestroretsk near Saint Petersburg, Russia, invented and tested by Fyodor Pirotsky in 1880. The second line was the Gross-Lichterfelde tramway in Lichterfelde near Berlin in Germany, which opened in 1881. It was built by Werner von Siemens who contacted Pirotsky. This was the world's first commercially successful electric tram. It initially drew current from the rails, with overhead wire being installed in 1883. The first interurban to emerge in the United States was the Newark and Granville Street Railway in Ohio, which opened in 1889.

Postwar
Many original tram and streetcar systems in the United Kingdom, United States, and elsewhere were decommissioned starting in the 1950s as subsidies for the car increased. Britain abandoned its tram systems, except for Blackpool, with the closure of Glasgow Corporation Tramways (one of the largest in Europe) in 1962.

Revival
Although some traditional trolley or tram systems continued to exist in San Francisco and elsewhere the term "light rail" has come to mean a different type of rail system as modern light rail technology has primarily post-WWII West German origins. An attempt by Boeing Vertol to introduce a new American light rail vehicle in the 1970s was proven to have been a technical failure by the following decade. After World War II, the Germans retained many of their streetcar networks and evolved them into model light rail systems (Stadtbahnen). With the exception of Hamburg, all large and most medium-sized German cities maintain light rail networks.

The basic concepts of light rail were put forward by H. Dean Quinby in 1962 in an article in Traffic Quarterly called "Major Urban Corridor Facilities: A New Concept". Quinby distinguished this new concept in rail transportation from historic streetcar or tram systems as:
 having the capacity to carry more passengers
 appearing like a train, with more than one car connected
 having more doors to facilitate full utilization of the space
 faster and quieter in operation

The term light rail transit was introduced in North America in 1972 to describe this new concept of rail transportation. Prior to that time the abbreviation "LRT" was used for "Light Rapid Transit" and "Light Rail Rapid Transit".

The first of the new light rail systems in North America began operation in 1978 when the Canadian city of Edmonton, Alberta, adopted the German Siemens-Duewag U2 system, followed three years later by CTrain Calgary, Alberta, and San Diego, California. The concept proved popular, and there are now at least 30 light rail systems in the United States and over 40 in North America.

Britain began replacing its run-down local railways with light rail in the 1980s, starting with the Tyne and Wear Metro and followed by the Docklands Light Railway (DLR) in London. The historic term light railway was used because it dated from the British Light Railways Act 1896, although the technology used in the DLR system was at the high end of what Americans considered to be light rail. The trend to light rail in the United Kingdom was firmly established with the success of the Manchester Metrolink system, which opened in 1992.

Definition

The term light rail was coined in 1972 by the U.S. Urban Mass Transportation Administration (UMTA; the precursor to the Federal Transit Administration) to describe new streetcar transformations that were taking place in Europe and the United States. In Germany, the term Stadtbahn (to be distinguished from S-Bahn, which stands for Stadtschnellbahn) was used to describe the concept, and many in UMTA wanted to adopt the direct translation, which is city rail (the Norwegian term, by bane, means the same). However, UMTA finally adopted the term light rail instead. Light in this context is used in the sense of "intended for light loads and fast movement", rather than referring to physical weight. The infrastructure investment is also usually lighter than would be found for a heavy rail system.

The Transportation Research Board (Transportation Systems Center) defined "light rail" in 1977 as "a mode of urban transportation utilizing predominantly reserved but not necessarily grade-separated rights-of-way. Electrically propelled rail vehicles operate singly or in trains. LRT provides a wide range of passenger capabilities and performance characteristics at moderate costs."

The American Public Transportation Association (APTA), in its Glossary of Transit Terminology, defines light rail as:
...a mode of transit service (also called streetcar, tramway, or trolley) operating passenger rail cars singly (or in short, usually two-car or three-car, trains) on fixed rails in the right-of-way that is often separated from other traffic for part or much of the way. Light rail vehicles are typically driven electrically with power being drawn from an overhead electric line via a trolley [pole] or a pantograph; driven by an operator onboard the vehicle; and may have either high platform loading or low-level boarding using steps."
However, some diesel-powered transit is designated light rail, such as the O-Train Trillium Line in Ottawa, Ontario, Canada, the River Line in New Jersey, United States, and the Sprinter in California, United States, which use diesel multiple unit (DMU) cars.

Light rail is similar to the British English term light railway, long-used to distinguish railway operations carried out under a less rigorous set of regulations using lighter equipment at lower speeds from mainline railways. Light rail is a generic international English phrase for types of rail systems using modern streetcars/trams, which means more or less the same thing throughout the English-speaking world.

People movers and personal rapid transit are even "lighter", at least in terms of capacity. Monorail is a separate technology that has been more successful in specialized services than in a commuter transit role.

British English versus American English
The use of the generic term light rail avoids some serious incompatibilities between British and American English. The word tram, for instance, is generally used in the UK and many former British colonies to refer to what is known in North America as a streetcar, but in North America tram can instead refer to an aerial tramway, or, in the case of the Disney amusement parks, even a land train. (The usual British term for an aerial tramway is cable car, which in the US usually refers to a ground-level car pulled along by subterranean cables.) The word trolley is often used as a synonym for streetcar in the United States but is usually taken to mean a cart, particularly a shopping cart, in the UK and elsewhere. Many North American transportation planners reserve streetcar for traditional vehicles that operate exclusively in mixed traffic on city streets, while they use light rail to refer to more modern vehicles operating mostly in exclusive rights of way, since they may operate both side-by-side targeted at different passenger groups.

The difference between British English and American English terminology arose in the late 19th century when Americans adopted the term "street railway", rather than "tramway", with the vehicles being called "streetcars" rather than "trams". Some have suggested that the Americans' preference for the term "street railway" at that time was influenced by German emigrants to the United States (who were more numerous than British immigrants in the industrialized Northeast), as it is the same as the German term for the mode, Straßenbahn (meaning "street railway"). A further difference arose because, while Britain abandoned all of its trams except Blackpool after World War II, eight major North American cities (Toronto, Boston, Philadelphia, San Francisco, Pittsburgh, Newark, Cleveland, and New Orleans) continued to operate large streetcar systems. When these cities upgraded to new technology, they called it light rail to differentiate it from their existing streetcars since some continued to operate both the old and new systems. Since the 1980s, Portland, Oregon, has built all three types of system: a high-capacity light rail system in dedicated lanes and rights-of-way, a low-capacity streetcar system integrated with street traffic, and an aerial tram system.

The opposite phrase heavy rail, used for higher-capacity, higher-speed systems, also avoids some incompatibilities in terminology between British and American English, for instance in comparing the London Underground and the New York City Subway. Conventional rail technologies including high-speed, freight, commuter, and rapid transit urban transit systems are considered "heavy rail". The main difference between light rail and heavy rail rapid transit is the ability for a light rail vehicle to operate in mixed traffic if the routing requires it.

Types

Due to varying definitions, it is hard to distinguish between what is called light rail, and other forms of urban and commuter rail. A system described as a light rail in one city may be considered to be a streetcar or tram system in another. Conversely, some lines that are called "light rail" are very similar to rapid transit; in recent years, new terms such as light metro have been used to describe these medium-capacity systems. Some "light rail" systems, such as Sprinter, bear little similarity to urban rail, and could alternatively be classified as commuter rail or even inter-city rail. In the United States, "light rail" has become a catch-all term to describe a wide variety of passenger rail systems.

There is a significant difference in cost between these different classes of light rail transit. Tram-like systems are often less expensive than metro-like systems by a factor of two or more.

Lower capacity
The most difficult distinction to draw is that between light rail and streetcar or tram systems. There is a significant amount of overlap between the technologies, many of the same vehicles can be used for either, and it is common to classify streetcars or trams as a subcategory of light rail rather than as a distinct type of transportation. The two general versions are:
 The traditional type, where tracks and trains run along the streets and share space with road traffic. Stops tend to be very frequent, but little effort is made to set up special stations. Because space is shared, the tracks are usually visually unobtrusive.
 A more modern variation, where the trains tend to run along with their own right-of-way, separated from road traffic. Stops are generally less frequent, and the vehicles are often boarded from a platform. Tracks are highly visible, and in some cases, significant effort is expended to keep traffic away through the use of special signaling, level crossings with gate arms, or even a complete separation (semi-metro) with non-level crossings.

Higher capacity

At the highest degree of separation, it can be difficult to draw the line between light rail and metros. The London Docklands Light Railway would likely not be considered as "light rail" were it not for the contrast between it and the rapid transit London Underground. In Europe and Asia, the term light rail is increasingly used to describe any rapid transit system with a fairly low frequency or short trains compared to heavier mass rapid systems such as the London Underground or Singapore's Mass Rapid Transit. However, upon closer inspection, these systems are better classified as light metro or people movers. For instance, Line 1 and Line 3 in Manila are often referred to as "light rail", despite being fully segregated, mostly elevated railways. This phenomenon is quite common in East Asian cities, where elevated metro lines in Shanghai, Wuhan, and Dalian in China; and Jakarta, Greater Jakarta and Palembang in Indonesia are called light rail lines. In North America, such systems are not usually considered light rail.

Mixed systems

Many systems have mixed characteristics. Indeed, with proper engineering, a rail line could run along a street, then go underground, and then run along an elevated viaduct. For example, the Los Angeles Metro Rail's A Line "light rail" has sections that could alternatively be described as a tramway, a light metro, and, in a narrow sense, rapid transit. This is especially common in the United States, where there is not a popularly perceived distinction between these different types of urban rail systems. The development of technology for low-floor and catenary-free trams facilitates the construction of such mixed systems with only short and shallow underground sections below critical intersections as the required clearance height can be reduced significantly compared to conventional light rail vehicles.

It is even possible to have high-floor rapid transit cars run along a street, like a tram; this is known as street running.

Speed and stop frequency

In some areas, "light rail" may also refer to any rail line with frequent low speeds or many stops in a short distance. This inherits the old definition of light railway in the UK. Hong Kong's Light Rail is an example of this, although it is also called "light rail" because it is a lower-scale system than the rest of the MTR. Sprinter in the San Diego area uses DMUs and is targeted towards a commuter rail audience; however, because of the large number of stops along the line, it is called the light rail.

Reference speed from major light rail systems, including station stop time, is shown below.

However, low top speed is not always a differentiating characteristic between light rail and other systems. For example, the Siemens S70 LRVs used in the Houston METRORail and other North American LRT systems have a top speed of  depending on the system, while the trains on the all-underground Montreal Metro can only reach a top speed of . Los Angeles Metro light rail vehicles have higher top and average speeds than Montreal Metro or New York City Subway trains. The main difference is that Montreal Metro and New York City Subway trains carry far more passengers than any North American LRT system, and the trains have faster acceleration, making station-to-station times relatively short in their densely populated urban areas. Most light rail systems serve less densely populated cities and suburbs where passenger traffic is not high, but low cost combined with high top speed may be important to compete with automobiles.

System-wide considerations
Many light rail systems—even fairly old ones—have a combination of both on- and off-road sections. In some countries (especially in Europe), only the latter is described as light rail. In those places, trams running on mixed rights-of-way are not regarded as a light rail but considered distinctly as streetcars or trams. However, the requirement for saying that a rail line is "separated" can be quite low—sometimes just with concrete "buttons" to discourage automobile drivers from getting onto the tracks. Some systems such as Seattle's Link had on-road mixed sections but were closed to regular road traffic, with light rail vehicles and traditional buses both operating along a common right-of-way (however, Link converted to full separation in 2019).

Some systems, such as the AirTrain JFK in New York City, the DLR in London, and Kelana Jaya Line in Kuala Lumpur, have dispensed with the need for an operator. The Vancouver SkyTrain was an early adopter of driverless vehicles, while the Toronto Scarborough rapid transit operated the same trains as Vancouver, but used drivers. In most discussions and comparisons, these specialized systems are generally not considered light rail but as light metro systems.

Track gauge
Historically, the track gauge has had considerable variations, with narrow gauge common in many early systems. However, most light rail systems are now standard gauge. Older standard-gauge vehicles could not negotiate sharp turns as easily as narrow-gauge ones, but modern light rail systems achieve tighter turning radii by using articulated cars. An important advantage of the standard gauge is that standard railway maintenance equipment can be used on it, rather than custom-built machinery. Using standard gauges also allows light rail vehicles to be conveniently moved around using the same tracks as freight railways. Additionally, wider gauges provide more floor clearance on low-floor trams that have constricted pedestrian areas at the wheels, which is especially important for wheelchair access, as narrower gauges can make it challenging or impossible to pass the tram's wheels. Furthermore, standard-gauge rolling stock can be switched between networks either temporarily or permanently, and both newly built and used standard-gauge rolling stock tends to be cheaper to buy, as more companies offer such vehicles.

Capacity

Efficiency

Energy efficiency for light rail may be 120 passenger miles per gallon of fuel (or equivalent), but variation is great, depending on circumstances.

Comparison with high capacity roads
One line of light rail (requires 7.6 m, 25' right of way) has a theoretical capacity of up to 8 times more than one 3.7 m (12 foot) lane on a freeway, excluding busses, during peak times. Roads have ultimate capacity limits that can be determined by traffic engineering, and usually experience a chaotic breakdown inflow and a dramatic drop in speed (a traffic jam) if they exceed about 2,000 vehicles per hour per lane (each car roughly two seconds behind another). Since most people who drive to work or on business trips do so alone, studies show that the average car occupancy on many roads carrying commuters is only about 1.5 people per car during the high-demand rush hour periods of the day.
This combination of factors limits roads carrying only automobile commuters to a maximum observed capacity of about 3,000 passengers per hour per lane. The problem can be mitigated by introducing high-occupancy vehicle (HOV) lanes and ride-sharing programs, but in most cases, policymakers have chosen to add more lanes to the roads, despite a small risk that in unfavorable situations an extension of the road network might lead to increased travel times (Downs–Thomson paradox, Braess paradox).

By contrast, light rail vehicles can travel in multi-car trains carrying a theoretical ridership up to 20,000 passengers per hour in much narrower rights-of-way, not much more than two car lanes wide for a double track system. They can often be run through existing city streets and parks, or placed in the medians of roads. If run in streets, trains are usually limited by city block lengths to about four 180-passenger vehicles (720 passengers). Operating on two-minute headways using traffic signal progression, a well-designed two-track system can handle up to 30 trains per hour per track, achieving peak rates of over 20,000 passengers per hour in each direction. More advanced systems with separate rights-of-way using moving block signaling can exceed 25,000 passengers per hour per track.

Practical considerations
Most light rail systems in the United States are limited by demand rather than capacity (by and large, most American LRT systems carry fewer than 4,000 persons per hour per direction), but Boston's and San Francisco's light rail lines carry 9,600 and 13,100 passengers per hour per track during rush hour. Elsewhere in North America, the Calgary C-Train and Monterrey Metro have higher light rail ridership than Boston or San Francisco. Systems outside North America often have much higher passenger volumes. The Manila Light Rail Transit System is one of the highest capacity ones, having been upgraded in a series of expansions to handle 40,000 passengers per hour per direction, and having carried as many as 582,989 passengers in a single day on its Line 1. It achieves this volume by running four-car trains with a capacity of up to 1,350 passengers each at a frequency of up to 30 trains per hour. However, the Manila light rail system has full grade separation and as a result, has many of the operating characteristics of a metro system rather than a light rail system. A capacity of 1,350 passengers per train is more similar to the heavy rail than light rail.

Bus rapid transit (BRT) is an alternative to LRT and many planning studies undertake a comparison of each mode when considering appropriate investments in transit corridor development. BRT systems can exhibit a more diverse range of design characteristics than LRT, depending on the demand and constraints that exist, and BRT using dedicated lanes can have a theoretical capacity of over 30,000 passengers per hour per direction (for example, the Guangzhou Bus Rapid Transit system operates up to 350 buses per hour per direction). For the effective operation of a bus or BRT system, buses must have priority at traffic lights and have their dedicated lanes, especially as bus frequencies exceed 30 buses per hour per direction. The higher theoretical of BRT relates to the ability of buses to travel closer to each other than rail vehicles and their ability to overtake each other at designated locations allowing express services to bypass those that have stopped at stations. However, to achieve capacities this high, BRT station footprints need to be significantly larger than a typical LRT station. In terms of cost of operation, each bus vehicle requires a single driver, whereas a light rail train may have three to four cars of much larger capacity in one train under the control of one driver, or no driver at all in fully automated systems, increasing the labor costs of BRT systems compared to LRT systems. BRT systems are also usually less fuel-efficient as they use non-electrified vehicles.

The peak passenger capacity per lane per hour depends on which types of vehicles are allowed on the roads. Typically roadways have 1,900 passenger cars per lane per hour (pcplph). If only cars are allowed, the capacity will be less and will not increase when the traffic volume increases.

When there is a bus driving on this route, the capacity of the lane will be higher and will increase when the traffic level increases. And because the capacity of a light rail system is higher than that of a bus, there will be even more capacity when there is a combination of cars and light rail. Table 3 shows an example of peak passenger capacity.

Safety
An analysis of data from the 505-page National Transportation Statistics report published by the US Department of Transportation shows that light rail fatalities are higher than all other forms of transportation except motorcycle travel (31.5 fatalities per 100 million miles).

However, the National Transportation Statistics report published by the US Department of Transportation states that:Caution must be exercised in comparing fatalities across modes because significantly different definitions are used. In particular, Rail and Transit fatalities include incident-related (as distinct from accident-related) fatalities, such as fatalities from falls in transit stations or railroad employee fatalities from a fire in a workshed. Equivalent fatalities for the Air and Highway modes (fatalities at airports not caused by moving aircraft or fatalities from accidents in automobile repair shops) are not counted toward the totals for these modes. Thus, fatalities not necessarily directly related to in-service transportation are counted for the transit and rail modes, potentially overstating the risk for these modes.

Construction and operation costs

The cost of light rail construction varies widely, largely depending on the amount of tunneling and elevated structures required. A survey of North American light rail projects shows that costs of most LRT systems range from $15 million to over $100 million per mile. Seattle's new light rail system is by far the most expensive in the US, at $179 million per mile, since it includes extensive tunneling in poor soil conditions, elevated sections, and stations as deep as  below ground level. This results in costs more typical of subways or rapid transit systems than light rail. At the other end of the scale, four systems (Baltimore, Maryland; Camden, New Jersey; Sacramento, California; and Salt Lake City, Utah) incurred construction costs of less than $20 million per mile. Over the US as a whole, excluding Seattle, new light rail construction costs average about $35 million per mile.

By comparison, a freeway lane expansion typically costs $1.0 million to $8.5 million per lane mile for two directions, with an average of $2.3 million. However, freeways are frequently built in suburbs or rural areas, whereas light rail tends to be concentrated in urban areas, where right of way and property acquisition is expensive. Similarly, the most expensive US highway expansion project was the "Big Dig" in Boston, Massachusetts, which cost $200 million per lane mile for a total cost of $14.6 billion. A light rail track can carry up to 20,000 people per hour as compared with 2,000–2,200 vehicles per hour for one freeway lane. For example, in Boston and San Francisco, light rail lines carry 9,600 and 13,100 passengers per hour, respectively, in the peak direction during rush hour.

Combining highway expansion with LRT construction can save costs by doing both highway improvements and rail construction at the same time. As an example, Denver's Transportation Expansion Project rebuilt interstate highways 25 and 225 and added a light rail expansion for a total cost of $1.67 billion over five years. The cost of  of highway improvements and  of double-track light rail worked out to $19.3 million per highway lane-mile and $27.6 million per LRT track-mile. The project came in under budget and 22 months ahead of schedule.

LRT cost efficiency improves dramatically as ridership increases, as can be seen from the numbers above: the same rail line, with similar capital and operating costs, is far more efficient if it is carrying 20,000 people per hour than if it is carrying 2,400. The Calgary, Alberta, C-Train used many common light rail techniques to keep costs low, including minimizing underground and elevated trackage, sharing transit malls with buses, leasing rights-of-way from freight railroads, and combining LRT construction with freeway expansion. As a result, Calgary ranks toward the less expensive end of the scale with capital costs of around $24 million per mile.

However, Calgary's LRT ridership is much higher than any comparable US light rail system, at 300,000 passengers per weekday, and as a result, its capital efficiency is also much higher. Its capital costs were one-third those of the San Diego Trolley, a comparably sized US system built at the same time, while by 2009 its ridership was approximately three times as high. Thus, Calgary's capital cost per passenger was much lower than that of San Diego. Its operating cost per passenger was also much lower because of its higher ridership. A typical C-Train vehicle costs only  per hour to operate, and since it averages 600 passengers per operating hour, Calgary Transit estimates that its LRT operating costs are only 27 cents per ride, versus $1.50 per ride on its buses.

Compared to buses, costs can be lower due to lower labor costs per passenger mile, higher ridership (observations show that light rail attracts more ridership than a comparable bus service) and faster average speed (reducing the number of vehicles needed for the same service frequency). While light rail vehicles are more expensive to buy, they have a longer useful life than buses, sometimes making for lower life-cycle costs.

Health impact

Integration with bicycles
Light rail lines have various policies on bicycles. Some fleets restrict bicycles on trains during peak hours. Some light rail systems, such as the St. Louis MetroLink, allow bicycles on the trains, but only in the rear sections of cars. Some light rail lines, like San Francisco's, allow only folding bicycles on board. In some systems, dedicated bike parking is available at select stations and others are integrated with local bike share systems.

Variations

Trams operating on mainline railways

Around Karlsruhe, Kassel, and Saarbrücken in Germany, dual-voltage light rail trains partly use mainline railroad tracks, sharing these tracks with heavy rail trains. In the Netherlands, this concept was first applied on the RijnGouweLijn. This allows commuters to ride directly into the city center, rather than taking a mainline train only as far as a central station and then having to change to a tram. In France, similar tram-trains are planned for Paris, Mulhouse, and Strasbourg; further projects exist. In some cases, tram trains use previously abandoned or lightly used heavy rail lines in addition to or instead of still in use mainline tracks.

Some of the issues involved in such schemes are:
 compatibility of the safety systems
 power supply of the track to the power used by the vehicles (frequently different voltages, rarely third rail vs overhead wires)
 width of the vehicles to the position of the platforms
 height of the platforms

There is a history of what would now be considered light rail vehicles operating on heavy rail rapid transit tracks in the US, especially in the case of interurban streetcars. Notable examples are Lehigh Valley Transit trains running on the Philadelphia and Western Railroad high-speed third rail line (now the Norristown High-Speed Line). Such arrangements are almost impossible now, due to the Federal Railroad Administration refusing (for crash safety reasons) to allow non-FRA compliant railcars (i.e., subway and light rail vehicles) to run on the same tracks at the same times as compliant railcars, which includes locomotives and standard railroad passenger and freight equipment. Notable exceptions in the US are the NJ Transit River Line from Camden to Trenton and Austin's Capital MetroRail, which have received exemptions to the provision that light rail operations occur only during daytime hours and Conrail freight service only at night, with several hours separating one operation from the other. The O-Train Trillium Line in Ottawa also has freight service at certain hours.

Ground-level power supply for trams

When electric streetcars were introduced in the late 19th century, conduit current collection was one of the first ways of supplying power, but it proved to be much more expensive, complicated, and trouble-prone than overhead wires. When electric street railways became ubiquitous, conduit power was used in those cities that did not permit overhead wires. In Europe, it was used in London, Paris, Berlin, Marseille, Budapest, and Prague. In the United States, it was used in parts of New York City and Washington, D.C. Third rail technology was investigated for use on the Gold Coast of Australia for the G:link light rail, though power from overhead lines was ultimately utilized for that system.

In the French city of Bordeaux, the tramway network is powered by a third rail in the city center, where the tracks are not always segregated from pedestrians and cars. The third rail (actually two closely spaced rails) is placed in the middle of the track and divided into eight-metre sections, each of which is powered only while it is completely covered by a tram. This minimizes the risk of a person or animal coming into contact with a live rail. In outer areas, the trams switch to conventional overhead wires. The Bordeaux power system costs about three times as much as a conventional overhead wire system and took 24 months to achieve acceptable levels of reliability, requiring the replacement of all the main cables and power supplies. Operating and maintenance costs of the innovative power system still remain high. However, despite numerous service outages, the system was a success with the public, gaining up to 190,000 passengers per day.

Comparison to other rail transit modes
With its mix of right-of-way types and train control technologies, LRT offers the widest range of latitude of any rail system in the design, engineering, and operating practices. The challenge in designing light rail systems is to realize the potential of LRT to provide fast, comfortable service while avoiding the tendency to overdesign that results in excessive capital costs beyond what is necessary to meet the public's needs.

Typical rolling stock
The BART railcar in the following chart is not generally considered to be a "light rail" vehicle (it is a heavy rail vehicle), and is only included for comparison purposes.

Train operation

An important factor crucial to LRT is the train operator. Unlike rail rapid transit, which can travel unattended under automatic train operation (ATO), safe, high-quality LRT operation relies on a human operator as a key element. The reason that the operator is so important is that the train tracks often share the streets with automobiles, other vehicles, and pedestrians. If trains were fully automated on roads, nobody would be there to stop the train if a car pulled in front of it. Light rail trains are very sturdily built for passenger safety, and to reduce damage from impacts with cars.

Floor height

The latest generation of LRVs has the advantage of partially or fully low-floor design, with the floor of the vehicles only  above the top of the rail, a feature not found in either rapid rail transit vehicles or streetcars. This allows them to load passengers, including those in wheelchairs or strollers, directly from low-rise platforms that are little more than raised sidewalks. This satisfies requirements to provide access to disabled passengers without using expensive and delay-inducing wheelchair lifts, while also making boarding faster and easier for other passengers.

Power sources
Overhead lines supply electricity to the vast majority of light rail systems. This avoids the danger of passengers stepping on an electrified third rail. The Docklands Light Railway uses an inverted third rail for its electrical power, which allows the electrified rail to be covered and the power drawn from the underside. Trams in Bordeaux, France, use a special third-rail configuration where the power is only switched on beneath the trams, making it safe on city streets. Several systems in Europe and a few recently opened systems in North America use diesel-powered trains.

Tram and other light rail transit systems worldwide

Around the world, there are many extant tram and streetcar systems. Some date from the beginning of the 20th century or earlier such as Toronto streetcar system, but many of the original tram and streetcar systems were closed down in the mid-20th century, except for many Eastern European countries. Even though many systems closed down over the years, there are still several tram systems that have been operating much as they did when they were first built over a century ago. Some cities (such as Los Angeles and Jersey City) that once closed down their streetcar networks are now restoring, or have already rebuilt, at least some of their former streetcar/tram systems. Most light rail services are currently committed to articulated vehicles like modern LRVs, i.e. trams, except for large underground metro or rapid transit systems.

Several UK cities have substantial light rail networks including the Nottingham Express Transit, Sheffield Supertram, Manchester Metrolink.

A smaller network between Birmingham and The Black Country (West Midlands Metro), with plans to add 6 new lines and extend out to Stourbridge, Birmingham Airport & Walsall. Edinburgh Trams is also a single line route, currently looking to add other lines.

See also

 Capa vehicle
 General Motors streetcar conspiracy
 H-Bahn
 Light rail in North America
 List of modern tramway and light rail systems in the United Kingdom
 List of rail transit systems in the United States
 List of town tramway systems (all-time lists)
 List of tram and light rail transit systems(operational systems only)
 Medium-capacity rail transport system
 Passenger rail terminology
 Railway electrification system
 Premetro
 Rubber-tyred trams
 Streetcars in North America
 Tram and light rail transit systems

References

External links

 Light Rail Transit Committee of the Transportation Research Board (US)
 Light Rail Transit Association (UK-based, international organization)
 Light Rail Now! (US) A pro-light rail web site opposing less common transportation systems.
 "This Is Light Rail Transit" (PDF) brochure by the American Public Transportation Association (APTA) (2000; updated 2003)

Sustainable urban planning
Tram transport

Light rail


A musical synthesizer is an instrument that uses electricity to make musical sounds. They are the main instrument for making electronic music. Many synthesizers have a keyboard like that of a piano. When playing a piano keyboard, sounds are made by hitting soft hammers against strings pulled very tight. When playing a synthesizer keyboard, sounds are made by turning electrical oscillators on and off. Since "synthesizer" is such a big word, the word is usually shortened to "synth".

How synthesizers work

An oscillator is something that "vibrates", or repeats the same pattern. The pendulum of a clock, for example, is a very slow oscillator. A piano string "oscillates" when struck by a hammer.

Electric oscillators might be made using transistors. They turn electricity into electrical patterns, or signals, that repeat over and over. When different keys are pressed, different notes are heard. This is done by making the signal from the oscillator repeat at different rates.

The signal can be boosted in strength and sent straight to a loudspeaker. But the sound of a simple signal can be boring after a while. Sounds can be made more interesting in many ways.

For example
 Signals are often shaped by changing how fast they get loud and then soft again. This method, called "ADSR", helps synthesizers to sound more like older instruments — pianos, trumpets, flutes, and so on.
 The signals from several different oscillators may be combined. This helps to make a richer sound.
 The signal can then be sent to one or more filters. Filters are used to take away parts of the signal. For example, they might make the signal sound "brighter" or "duller", "soft" or "harsh".
 Many synthesizers use special oscillators called "LFOs". For example, an LFO might control how loud and soft the signal is, or control the pitch of the signal. An LFO might even control the actions of the filters.

By combining many of these methods, synths can now sound very much like older instruments. For one example, special synths called "drum synths" are used just to make the sounds a drummer might make. Synths can also make many new sounds never heard before.

In the early 2000s, computers got fast enough so "software synths" could be made. These are computer programs designed to look and work like a synth. They tend to be less expensive, so more can be used. Most of these programs can be downloaded for free, however this may be illegal.

There are special tools available to play synths. For example, a thing called a "wind controller" lets players of wind instruments use their special skills. But there is still a need for more ways to control synths to make them more expressive.

Other websites
 Sonic State describing 3000 models of Synthesizers
 Analog & Digital Synthesizers museum  - Synthesizers database, resources, user reviews, pictures
 Vintage Synth Explorer - facts and photos of hundreds of old and new synths
 The history of Electronic Music
 120 years of Electronic Music

Electronic musical instruments
Audio technology

Synthesizer


A graph is a picture designed to express words, particularly the connection between two or more quantities. You can see a graph on the right.

A simple graph usually shows the relationship between two numbers or measurements in the form of a grid. If this is a rectangular graph using Cartesian coordinate system, the two measurements will be arranged into two different lines at right angle to one another. One of these lines will be going up (the vertical axis). The other one will be going right (the horizontal axis). These lines (or axes, the plural of axis) meet at their ends in the lower left corner of the graph.

Both of these axes have tick marks along their lengths. You can think of each axis as a ruler drawn on paper. So each measurement is indicated by the length of the associated tick mark along the particular axis.

A graph is a kind of chart or diagram. However, a chart or a diagram may not relate one quantity to other quantities. Flowcharts and tree diagrams are charts or diagrams that are not graphs.

How to draw a simple graph

Let's say you wanted to make a graph showing your height as you were growing up. You might show your height in centimeters on the vertical axis and your age in years on the horizontal axis.

For example, say you were 60 centimeters tall at age 1, 85 centimeters tall at age 2 and 95 centimeters tall at age 3. You would draw an imaginary straight line passing through the 50 centimeters height mark on the vertical axis. Then you would draw a second imaginary line passing through the age of 1 year on the horizontal axis. At the place where the two imaginary lines meet (called their intersection), you would then draw a dot. Really, the imaginary lines are usually replaced by graph paper (see below). The drawing of this intersection is called "plotting the point 50 centimeters for year 1".

You would then plot 85 centimeters for year 2 and 95 centimeters for year 3. If you had more heights for more years, you would plot years 4, 5 and so forth. When you had enough points on your graph, you could draw a line through each of the plotted points, making your graph a line graph. For example, the line graph at the upper right shows the unemployment rate (as a percent) on the vertical axis and the year (from 1950 to 2005) on the horizontal axis.

Let's say you wanted a single graph showing both your height and your brother's height. This could be expressed as two sets of plotted points: one for you and one for your brother. You could use different colors to tell your plot from your brother's. Or you might plot the Gross Domestic Product (in billions of dollars) as a second line against the same years on the unemployment graph above. This would show you the relationship between GDP and unemployment.

Uses of graphs

Graphs make information easier to see. This is especially true when two or more sets of numbers are related in some way.

For example, the unemployment rates graph at the beginning of this article could be expressed in the form of a table. Like this:

But a long string of numbers makes it difficult to see the underlying meaning. It is much simpler to understand when the table is expressed in the form of a graph. In particular, it is easier to see the relationships between the two sets of data. For example, by looking at the graph you can see at a glance that unemployment was relatively low in the late sixties but relatively high in the early eighties.

Scientists and engineers use graphs so that they can get a better understanding of the broad meaning and importance of their data. Salesmen and businessmen often use graphs to add importance to their points in a sales or business presentation. Graphs with many plotted points may be created on a computer rather than being drawn by hand.

Mathematicians use graphs that "plot themselves", without taking measurements. For example, the formula x = y says that the value of x will always be equal to the value of y. If you plot this formula as a graph, with x as the horizontal axis and y as the vertical axis, you will get a graph that looks like a straight line angled at precisely 45 degrees. The use of these graphs forms a branch of mathematics called analytic geometry.

Graph paper

Usually, graphs are created on specially designed paper called graph paper. This paper has evenly drawn horizontal and vertical lines on it. On the right is an example of a sheet of graph paper.

Different types of graphs require different forms of graph paper. What we have been talking about in the article above is the commonest form of graphs and graph paper. It is known as rectangular or Cartesian graphs. However the evenly drawn vertical and horizontal lines on the paper are not the graph itself but are part of the graph paper. The graph is the set of plotted points, along with its axes.

There are various types of graphs (and graph paper) other than Cartesian. These include: bar graphs, pie graphs, polar graphs, scatter graphs, three-dimensional graphs, logarithmic graphs and many others.

Mathematics
Statistics
Graphics

pt:Função#Gráficos de função

Graph


The Cainozoic (Cenozoic) is the current geological era. It began 66 million years ago and continues today. Before it was the Mesozoic.

During the Cainozoic the continents moved into their present positions. The climate started warm, but cooling continued steadily. Finally ice ages occurred.

The word Cainozoic is derived from Greek kainos = "new", and zoe = "life". 'Cainozoic' may be spelled 'Cenozoic'. It has three periods, and the periods are split into stages.

 Cainozoic
 Palaeogene
 Palaeocene
 Eocene
 Oligocene
 Neogene
 Miocene
 Pliocene
 Quaternary
 Pleistocene
 Holocene

Previously, what is now the Cainozoic was divided into two periods, the Tertiary and the Quaternary. The Tertiary corresponded to the Palaeogene+Neogene. Now, the term 'Tertiary' is not used. Officially, it is 'deprecated'.

Biota
On land, the Cainozoic is the era of mammals, and of birds and flowering plants. Grassland became a major habitat. Aquatic mammals took over the roles of predatory reptiles like the mosasaurs and plesiosaurs. As a result, the ecological landscape of the Cainozoic has become quite different from the Mesozoic.

References

Cainozoic


A code is a way of changing information into something else.  Sometimes this is done as a way of keeping a message secret. This is called encryption or cryptography.
One source gives this explanation: a code is "a word, number or some other symbol used to represent a word, phrase or syllable in plaintext". It is one of the earliest forms of cryptography. Contrast code with cypher, in which the individual letters are encrypted (changed).

Sometimes it is done as an easier way of sending a message.  For example, when people on two different boats want to send a message, they may be too far away to shout, but they can send messages with a flag code.  Another code that people use is called Morse code, which changes letters to dots and dashes, like this:

  SOS:   ···−−−···

Computers use codes, by changing letters into 1's and 0's. This method was invented for punched tape. Now the usual alphanumeric code is ASCII.

Some people write codes as a kind of game.  They think it is fun to make ciphers, and fun to break them.  Breaking a code means taking it apart to understand how it works, and then you can understand messages that are written in that code. Cryptanalysis is also serious business. Nations and other organizations have been breaking each other's ciphers for many centuries.

The algorithm (code) for making a message secret is called the encryption algorithm.  To change a secret message back a decryption algorithm is needed.

References

Related pages
Character encoding

Cryptography
Human communication

Code


In Computer science, client-server is a software architecture model consisting of two parts, client systems and server systems, both communicating over a computer network or on the same computer. A client-server application is a distributed system made up of both client and server software. Client server application provide a better way to share the workload. The client process always initiates a connection to the server, while the server process always waits for requests from any client.

When both the client process and server process are running on the same computer, this is called a single seat setup.

P2P
Another type of related software architecture is known as peer-to-peer, because each host or application instance can simultaneously act as both a client and a server (unlike centralized servers of the client-server model) and because each has equivalent responsibilities and status. Peer-to-peer architectures are often abbreviated using the acronym P2P.

Both client-server and P2P architectures are in wide usage today.

Client-server relationship
The client-server relationship describes the relation between the client and how it makes a service request to the server, and how the server can accept these requests, process them, and return the requested information to the client. The interaction between client and server is often described using sequence diagrams. Sequence diagrams are standardized in the Unified Modeling Language.

Two-tier
The basic type of client-server software architecture employs only two types of hosts: clients and servers. This type of architecture is sometimes referred to as two-tier. The two-tier architecture means that the client acts as one tier and server process acts as the other tier.

Network computing
The client-server software architecture has become one of the basic models of network computing. Many types of applications have been written using the client-server model. Standard networked functions such as E-mail exchange, web access and database access, are based on the client-server model. For example, a web browser is a client program at the user computer that may access information at any web server in the world.

Clients characteristics
 Always initiates requests to servers.
 Waits for replies.
 Receives replies.
 Usually connects to a small number of servers at one time.
 Usually interacts directly with end-users using any user interface such as graphical user interface.

Server characteristics
 Always wait for a request from one of the clients.
 Serves clients' requests then replies to the clients with the requested data.
 A server may communicate with other servers in order to serve a client request.
 If additional information is required to process a request (or security is implemented), a server may request additional data (passwords) from a client before processing a request.
 End users typically do not interact directly with a server, but use a client.

Advantages
 In most cases, a client-server architecture enables the worsening of roles and responsibilities of a computing system to be distributed among several independent computers that are known to each other only through a network, so one of advantages of this model is greater ease of maintenance. For example, it is possible to replace, repair, upgrade, or even relocate a server while its clients remain both unaware and unaffected by that change. This independence from change is also referred to as encapsulation.
 All the data is stored on the servers, which generally have better security controls than most clients. Servers can better control access and resources, to guarantee that only those clients with the appropriate permissions may access and change data.
 Since data storage is centralized, updates to that data are much easier to administrators than what would be possible under a P2P architecture. Under a P2P architecture, data updates may need to be distributed and applied to each "peer" in the network, which is both time-consuming and error-prone, as there can be thousands or even millions of peers.
 Many advanced client-server technologies are already available which were designed to ensure security, user friendly interfaces, and ease of use.
 It works with multiple different clients of different specifications.

Disadvantages
 Networks traffic blocking is one of the problems related to the client-server model. As the number of simultaneous client requests to a given server increases, the server can become overloaded. Contrast that to a P2P network, where its bandwidth actually increases as more nodes are added, since the P2P network's overall bandwidth can be roughly computed as the sum of the bandwidths of every node in that network.
 Comparing client-server model to the Peer to Peer model, if one server fail, clients' requests cannot be served but in case of P2P networks, servers are usually distributed among many nodes. Even if one or more nodes fail, for example if a node failed to download a file the remaining nodes should still have the data needed to complete the download.

Examples
Specific types of servers include: web servers, FTP servers, database servers, E-mail servers, file servers, print servers. Most web services are also types of servers.
Computer science
File sharing

Client-server


The cor anglais, or English horn, is a double reed instrument in the woodwind family.  It is very similar to an oboe, but as it is longer than an oboe it plays lower notes.

The lowest note of an oboe is B flat (just below Middle C).  The lowest note of a cor anglais is an E natural, a diminished fifth (five notes of a scale, minus a semitone) lower than the oboe's lowest note.

The cor anglais is a transposing instrument pitched in F.  This means that the music sounds a fifth lower than written.  This has the advantage that the cor anglais player uses fingering as if he were playing an oboe, but it will sound a fifth lower.

The bell (the bit at the end of the instrument) is shaped like a pear.  This gives it a less nasal sound (the sound of the cor anglais is less as if played through the nose).  The reed is not fixed to a piece of cork like the oboe reed but it is put straight onto the short piece of metal (called a "bocal") at the top of the instrument.

Etymology
The word "cor anglais" is a French word which literally means "English horn", but the cor anglais is neither English nor a horn. No one is sure how it got its name, but many people think it is because the bocal at the top is curved (the French word for curved, "anglé" is pronounced like the word for English "anglais").

Repertoire
Many oboists can play the cor anglais as well, just as flautists can play the piccolo (if they play both instruments in the same concert this is called doubling).

There are few solo pieces for the instrument, but mostly it is used for solo melodies in slow pieces for orchestra because it can sound very expressive.

Some famous examples of cor anglais solos can be found in:

Alfred Reed's Russian Christmas Music (1944)
Antonín Dvořák's Symphony No. 9 (1893), the New World Symphony (Largo)
Joaquín Rodrigo's Concierto de Aranjuez (1939) (2nd movement)
Hector Berlioz's Symphonie fantastique (third movement) (1830)
Alexander Borodin's Eine Steppenskizze aus Mittelasien

Double reed instruments

Cor anglais


The Great Proletarian Cultural Revolution (Simplified Chinese: 无产阶级文化大革命, Traditional Chinese: 無產階級文化大革命, Pinyin: Wúchǎn Jiējí Wénhuà Dà Gémìng, literally: Proletarian Cultural Great Revolution); shortened in Chinese as  or , also known simply as the Cultural Revolution, was a time of large cultural change in China, started by Mao Zedong, Chairman of the Communist Party of China.  It happened from 1966 to 1976.

The start of the Cultural Revolution followed the failure of the Great Leap Forward. Mao tried to remove capitalists from the Communist Party of China, the party in charge of China. To get rid of the capitalists, he started the Socialist Education Movement. It started in 1962 and ended in 1965. At the same time, a redoing of the school system made sure that students were able to also work in factories and communes. Mao slowly started to regain power in 1965, supported by Lin Biao, Jiang Qing, and Chen Boda.

The Communist Party was split between Mao's partners and Deng Xiaoping's partners. Deng Xiaoping was a rival of Mao.  Mao then tried to get support from young people in China by creating the book Quotations from Chairman Mao Zedong (also known as the Little Red Book), a collection of Mao's sayings. The Red Guard was also made popular. They were a group of young people in China that went around teaching Mao's sayings. They also beat people who disagreed with Mao and destroyed homes and museums. There were many fights breaking out, and China faced anarchy. During the revolution, several important people in China were forced to leave. These people included Liu Shaoqi, President of China, and Deng Xiaoping, the secretary-general of the Communist Party of China.

The Cultural Revolution began to slow down in 1967, and ended in 1969. The Ninth National Party Congress was a meeting where the end of the Cultural Revolution was announced.

Effects

The Cultural Revolution caused a lot of problems in China. Production in factories was lowered because of the workers' political activities. It was also lowered because the people put in charge of the factories did not know how to run them.  Transportation was made worse because a lot of trains were being used to take Red Guards around the country.  Many scientists and engineers were put in jail or sent to work on the farms, which meant that their knowledge was lost.  Because of these changes, the industrial output of China was reduced by 14 percent.

The education of many Chinese people was also cut short. The education system was more disrupted in the cities than in the countryside.  Universities and many schools were closed. A program called the "sent-down youth" program also disrupted education. In that program, children were sent from the cities to the countryside.

Related pages
Great Leap Forward

References

History of China

Cultural Revolution


Subspecies is a classification (taxonomy) in biology. It is directly below species. When looking at the Latin name, subspecies are indicated by the third name. Subspecies can mix with each other; animals or plants from different subspecies can have offspring together (This is usually not the case with animals from different species).

When looking at subspecies, they can also be told apart sufficiently by looking at the appearance or DNA of an animal or plant.

Very often, there are populations that are between two subspecies; this is because evolution is a continuous process. Subspecies can often be recognised by subsp or ssp (before the third part of the name) especially in botany.

Examples of subspecies are:
The dog (Canis lupus familiaris) and the dingo (Canis lupus dingo) are both subspecies of the wolf (Canis lupus)
The domestic cat (Felis silvestris catus) is a subspecies of the wildcat (Felis silvestris)

Nominate subspecies
In zoology, when a species is split into subspecies, the first described population is known as the "nominate subspecies", and it repeats the same name as the species. For example, the "Daboia russelii russelii" (known as the Indian Russell's Viper) is a nominate subspecies of the species "Daboia russelii" (known as the Russell's Viper).

Taxonomy

Subspecies


Carl Edward Sagan (November 9, 1934 - December 20, 1996) was an American astronomer. He was very interested in what life on other planets would be like, which is known as SETI (search for extraterrestrial intelligence).

Sagan was a science communicator, which meant he taught people about science. He felt like the general public was losing interest in science, so he wrote many books and appeared on television to make it popular again. He mostly talked about planetary science and topics related to space. One of his most famous works includes. Cosmos: A Personal Voyage. Cosmos was a television series about many different scientific topics, which Sagan co-wrote and narrated. It made him very famous outside the world of science.

Sagan supported the scientific method and scientific skepticism.

Education and work

Carl Sagan was born in Brooklyn, New York City. Carl's family was Jewish. His father, Samuel Sagan, was an immigrant from the Russian Empire. Samuel was born in 1905 in a city called Kamianets-Podilskyi. The Russian Empire no longer exists, so today Kamianets-Podilskyi is in Ukraine. Samuel made clothes for a living. Carl's mother, Rachel Molly Gruber, was a housewife. Carl had a sister named Carol, who became a social worker. Carl was named after his grandmother, Chaiya (Clara).

Sagan attended the University of Chicago earning two degrees in physics. He followed with a doctorate in astronomy in 1960 and taught at Harvard University until 1968, when he moved to Cornell University.

Sagan became a teacher and director at Cornell in 1971. He helped many unmanned spacecraft to explore outer space. He thought of the idea of putting a message on spacecraft which could be understood by any life from another planet that might find it. The first message sent into space was a large gold-plated label on the space probe Pioneer 10. He continued to make the messages better. The last message he helped with was the Voyager Golden Record that was sent out with the Voyager space probes.

Scientific achievements

He was well known as a writer who warned of the dangers of nuclear winter. He helped people learn about the atmosphere of Venus, seasonal changes on Mars, and Saturn's moon Titan. He showed that the atmosphere of Venus is very hot and dense. He also said that global warming was a growing, man-made danger like the natural development of Venus into a hot and dangerous planet with greenhouse gases. He suggested that the seasonal changes on Mars were due to dust storms.

Sagan was among the first to guess that Titan and Jupiter's moon Europa might have oceans or lakes, which means that life could be there. Europa's underground ocean was later confirmed by the spacecraft Galileo.

Sagan thought the search for life on other planets was a good idea. He said scientists should listen with large radio telescopes for signals from other planets. He thought sending probes to other planets was a good idea. Sagan was editor Icarus (a magazine about space exploration) for 12 years. He helped start the Planetary Society and was a member of the SETI Institute Board of Trustees.

Social concerns

Sagan also believed that the Drake equation suggested that many kinds of intelligent life could form, but that the lack of evidence (the Fermi paradox) suggests that intelligent beings destroy themselves rather quickly. This made him keen to talk about ways that humanity could destroy itself, in the hope of avoiding such destruction.

Under the name "Mr. X," Sagan wrote about pot smoking in the 1971 book Reconsidering Marijuana. Lester Grinspoon (the book's editor), told this to Keay Davidson, Sagan's biographer. Sagan said that marijuana helped him write some of his books.

Making science popular

Sagan was very good at helping people to understand the cosmos. He gave the 1977/1978 Christmas Lectures for Young People at the Royal Institution. He wrote (with Ann Druyan, who became his third wife) and made the very popular thirteen-part PBS television series Cosmos; he also wrote books to help science become more popular (The Dragons of Eden, which won a Pulitzer Prize, Broca's Brain, etc.) and a novel, Contact, that was a best-seller and was made into a film starring Jodie Foster in 1997. The film won the 1998 Hugo Award.

After Cosmos, Sagan was linked with the catchphrase "billions and billions", which he never used in the television series (but he often used the word "billions"). He wrote Pale Blue Dot: A Vision of the Human Future in Space, which was chosen as a notable book of 1995 by The New York Times.

Not all scientists agreed with him. Although they all liked the way he made science popular, some were afraid that people would think that his personal opinions might be confused with real science. What he said about the Kuwait oil well fires during the first Gulf War were shown later to be wrong.

Later in his life, Sagan's books showed his skeptical, naturalistic view of the world. In his book The Demon-Haunted World, Sagan gave a list of mistakes he had made as an example of how science is self-correcting. The compilation Billions and Billions: Thoughts on Life and Death at the End of the Millennium, published after Sagan's death, contains essays written by Sagan, such as his views on abortion, and Ann Druyan's account of his death as a non-believer.

Legacy

After a long and difficult fight with myelodysplasia, Sagan died of pneumonia at the age of 62, on December 20, 1996, at the Fred Hutchinson Cancer Research Center in Seattle, Washington. Sagan was very important, because he made science popular, and changed the way science was organized, and because he defended humanism, and argued against seeing things from only one point of view.

The landing site of the unmanned Mars Pathfinder spacecraft was renamed the Carl Sagan Memorial Station in honor of Dr. Sagan on July 5, 1997. Asteroid 2709 Sagan is also named in his honor.

The 1997 movie Contact (see above), based on Sagan's novel of the same name, and finished after his death, ends with the dedication "For Carl."

Awards and medals

 Apollo Achievement Award - National Aeronautics and Space Administration
 Chicken Little Honorable Mention - 1991 - National Anxiety Center
 Distinguished Public Service - National Aeronautics and Space Administration
 Emmy - Outstanding individual achievement - 1981 - PBS series Cosmos
 Emmy - Outstanding Informational Series - 1981 - PBS series Cosmos
 Exceptional Scientific Achievement Medal - National Aeronautics and Space Administration
 Helen Caldicott Leadership Award - Women's Action for Nuclear Disarmament
 Homer Award - 1997 - Contact
 Hugo Award - 1998 - Contact
 Hugo Award - 1981 - Cosmos
 Hugo Award - 1997 - The Demon-Haunted World
 In Praise of Reason Award - 1987 - Committee for the Scientific Investigation of Claims of the Paranormal
 Isaac Asimov Award - 1994 - Committee for the Scientific Investigation of Claims of the Paranormal
 John F. Kennedy Astronautics Award - American Astronautical Society
 John W. Campbell Memorial Award - 1974 - The Cosmic Connection
 Konstantin Tsiolkovsky Medal - Soviet Cosmonauts Federation
 Locus Poll Award 1986 - Contact
 Lowell Thomas Award - Explorers Club - 75th Anniversary
 Masursky Award - American Astronomical Society
 Peabody - 1980 - PBS series Cosmos
 Public Welfare Medal - 1994 - National Academy of Sciences
 Pulitzer Prize for Literature - 1978 - The Dragons of Eden
 SF Chronicle Award - 1998 - Contact
 Carl Sagan Memorial Award - Named in his honor

Related books and media

 Sagan, Carl and Jonathon Norton Leonard and editors of Life, Planets. Time, Inc., 1966
 Sagan, Carl and I.S. Shklovskii, Intelligent Life in the Universe. Random House, 1966
 Sagan, Carl, Communicaton with Extraterrestrial Intelligence. MIT Press, 1973
 Sagan, Carl, et al. Mars and the Mind of Man. Harper & Row, 1973
 Sagan, Carl, Other Worlds. Bantam Books, 1975
 Sagan, Carl, et al. Murmurs of Earth: The Voyager Interstellar Record. Random House, 1977
 Sagan, Carl et al. The Nuclear Winter: The World After Nuclear War. Sidgwick & Jackson, 1985
 Sagan, Carl and James Randi, The Faith Healers. Prometheus Books, May 1989, , 318 pgs
 Sagan, Carl and Richard Turco, A Path Where No Man Thought: Nuclear Winter and the End of the Arms Race. Random House, 1990
 Sagan, Carl, The Dragons of Eden: Speculations on the Evolution of Human Intelligence. Ballantine Books, December 1989, , 288 pgs
 Sagan, Carl, Broca's Brain: Reflections on the Romance of Science. Ballantine Books, October 1993, , 416 pgs
 Sagan, Carl and Ann Druyan, Shadows of Forgotten Ancestors: A Search for Who We Are. Ballantine Books, October 1993, , 528 pgs
 Sagan, Carl and Ann Druyan, Comet. Ballantine Books, February 1997, , 496 pgs
 Sagan, Carl, Contact. Doubleday Books, August 1997, , 352 pgs
 Sagan, Carl, Pale Blue Dot: A Vision of the Human Future in Space. Ballantine Books, September 1997, , 384 pgs
 Sagan, Carl and Ann Druyan, Billions & Billions: Thoughts on Life and Death at the Brink of the Millennium. Ballantine Books, June 1998, , 320 pgs
 Sagan, Carl, The Demon-Haunted World: Science As a Candle in the Dark. Ballantine Books, March 1997, , 480 pgs
 Sagan, Carl and Jerome Agel, Cosmic Connection: An Extraterrestrial Perspective. Cambridge University Press, January 15, 2000, , 301 pgs
 Sagan, Carl, Cosmos. Random House, May 7, 2002, , 384 pgs
 Zemeckis, Robert, Contact. Warner Studios, 1997, ASIN 0790736330 IMDB
 Davidson, Keay, Carl Sagan: A Life. John Wiley & Sons, August 31, 2000, , 560 pgs

Other websites

 In Memory of Carl Sagan. Tributes by Tom McDonough, James Randi and Michael Shermer, and a selection of quotes from Sagan's works, published in Skeptic, Vol. 4, no. 4, 1996, pp. 10–17.
 CarlSagan.Com. Homepage of Cosmos Studios, which sells the Cosmos series on DVD and VHS video tape.
 Carl Sagan, Cornell astronomer, dies today (Dec. 20) in Seattle. Cornell University press release on Sagan's death.
 Even in Death, Carl Sagan's Influence Is Still Cosmic by William J. Broad, The New York Times, November 30, 1998. Describes Sagan's legacy for space science.
 Astronomy Picture of the Day: Carl Sagan. December 26, 1996.
 Contact: A Eulogy to Carl Sagan, by Dr. Ray Bohlin, president of Probe Ministries. Dr. Bohlin suggests that the movie Contact can serve as a fitting eulogy for Carl Sagan. Sagan's scientific approach to the question, "was the universe created?" is critically analyzed by Bohlin from his Christian perspective.
 The Untold Truth about Carl Sagan Grunge.com

References

1934 births
1996 deaths
Agnostics
American astronomers
Deaths from pneumonia
Infectious disease deaths in the United States
Jewish American scientists
Jewish American writers
Pulitzer Prize winners
Scientists from New York (state)
Writers from New York City
Emmy Award winners

Carl Sagan


John of Gaunt (John Plantagenet, 1st Duke of Lancaster, 1st Duke of Aquitaine, 6 March 1340 – 3 February 1399) was a member of the House of Plantagenet, who ruled England for over 300 years. Gaunt was the third surviving son of Edward III and Philippa of Hainault. He was the father of Henry IV.

Gaunt was a younger brother of Edward, the Black Prince. He had great influence over the English throne during the childhood of his nephew, Richard II, and during the ensuing periods of political strife. He is not thought to have been an opponent of the king.

John of Gaunt's legitimate male heirs, the Lancasters, included Kings Henry IV, Henry V, and Henry VI. His other legitimate children included, by his first wife Blanche, his daughters  Philippa of Portugal and Elizabeth, Duchess of Exeter; and by his second wife Constance, his daughter Queen Catherine of Castile.

John fathered five children outside marriage, one early in life by a lady-in-waiting to his mother, and four by Katherine Swynford, Gaunt's long-term mistress and third wife. These were surnamed Beaufort (after a former French possession of the Duke). The Beaufort children, three sons and a daughter, were legitimised by royal and papal decrees after John and Katherine married in 1396. Their half-brother Henry IV added a later proviso that they were barred from inheriting the throne.

Descendants of this marriage included Henry Beaufort, Bishop of Winchester and eventually cardinal; Joan Beaufort, Countess of Westmorland, grandmother of Kings Edward IV and Richard III; John Beaufort, 1st Earl of Somerset, the great-grandfather of King Henry VII; and Joan Beaufort, Queen of Scots, from whom are descended, beginning in 1437, all subsequent sovereigns of Scotland, and successively, from 1603 on, the sovereigns of England, of Great Britain and Ireland, and of the United Kingdom to the present day. The three succeeding houses of English sovereigns from 1399 — the Houses of Lancaster, York and Tudor — were descended from John through Henry Bolingbroke, Joan Beaufort and John Beaufort, respectively.

Lancaster's eldest son and heir, Henry Bolingbroke, Duke of Hereford, was exiled for ten years by King Richard II in 1398 as resolution to a dispute between Hereford and Thomas de Mowbray, Duke of Norfolk.

When John of Gaunt died in 1399, his estates and titles were declared forfeit to the crown as King Richard II named Hereford a traitor and commuted his sentence to exile for life.  Henry Bolingbroke returned from exile to reclaim his inheritance and depose Richard. Bolingbroke then reigned as King Henry IV of England (1399–1413), the first of the descendants of John of Gaunt to hold the throne of England.

Due to some generous land grants, John was not only one of the richest men in his era, but also one of the wealthiest men to have ever lived. Taking into account inflation rates, John was worth a modern equivalent of $110 billion, making him the sixteenth richest man in history.

References

House of Plantagenet
English Dukes
Knights of the Garter
1399 deaths
1340 births
People from Ghent

John of Gaunt