title: James Watt

paragraphs: James Watt (19 January 1736 19 August 1819) was a Scottish mathematician and engineer. He did not invent the first steam engine, but he did modify it to work better. There were other patented steam engines (such as the Savery and Newcomen steam engines) in use by the time Watt started his work on them. His major contribution is in developing the modern form of the steam engine. The Watt steam engine is credited for driving the Industrial Revolution of the 18th and 19th centuries. James Watt was a brilliant engineer and he also transformed the Newcomen engine.

paragraphs: Today, most people honor him by naming a unit of power, the watt, after him.

paragraphs: James Watt was born on 19 January 1736 in Greenock, Renfrewshire. His father was a shipwright, ship owner and contractor, and served as the town's chief baillie. His mother, Agnes Muirhead, came from a distinguished family and was well educated. Both were Presbyterians and strong Covenanters. Watt's grandfather, Thomas Watt, taught mathematics and was a baillie to the Baron of Cartsburn. Watt did not go to school every day. At first, he was mostly schooled at home by his mother but later he attended Greenock grammar school. He exhibited great skill with his hands and a natural ability for mathematics, although Latin and Greek failed to interest him. He also absorbed the legends and lore of the Scottish people.

paragraphs: One of Watt's many improvements was the invention of a "centrifugal governor" to regulate automatically the speed of the engine. This is most obvious on steam engines where it regulates the admission of steam into the cylinder(s). It is also found on internal combustion engines and variously fueled turbines, and in some modern striking clocks.

paragraphs: A centrifugal governor is a homeostatic device which controls the speed of an engine by regulating the amount of "intermediate substance" (steam) which drives the machine. This keeps a near constant speed whatever the load or fuel supply conditions. It uses the principle of proportional control: this means the stopping of (in this case) steam varies according to the speed of the machine.

paragraphs: On Watt's fly-ball device, as the machine speeds up, the balls fly round faster. As they fly round faster, they move out from the central post. As they move out from the central post, they close the steam supply more firmly. As they do so, the machine slows down and the balls spin more slowly, and allow more steam into the cylinders. In addition, the system has a safety release valve to allow excess steam to escape without driving the wheels. 500 Boulton & Watt engines were built by the firm between 1775 and 1800.

paragraphs: Later, this kind of feedback loop became an important tool of cybernetics.

paragraphs: Watt went into partnership with a fellow member of the Midlands Lunar Society, Matthew Boulton. The firm of Boulton & Watt designed and built steam engines, and was very important in the Industrial Revolution.

paragraphs: At first the partnership made the drawing and specifications for the engines, and supervised the work to erect it on the customer's property. They produced almost none of the parts themselves. Watt did most of his work at his home in Harper’s Hill in Birmingham, while Boulton worked at the Soho Manufactory.

paragraphs: Gradually the partners began to actually make more and more of the parts, and by 1795 they purchased a property about a mile away from the Soho manufactory, on the banks of the Birmingham Canal. There they built a new foundry for making the engines. The Soho Foundry opened in 1796 at a time when Watt’s sons, Gregory and James Jr. were heavily involved in the management of the enterprise. In 1800, the year of Watt’s retirement, the firm made a total of forty-one engines.

paragraphs: Watt retired in 1800, the same year that his fundamental patent and partnership with Boulton expired. The famous partnership was transferred to the men's sons, Matthew Robinson Boulton and James Watt Jr. Longtime firm engineer William Murdoch was soon made a partner and the firm prospered.


title: Michelangelo

paragraphs: Michelangelo di Lodovico Buonarroti Simoni (6 March 1475 – 18 February 1564), known as Michelangelo, was an Italian Renaissance painter, sculptor, architect, poet, and engineer. Along with Leonardo da Vinci, he is often called a "Renaissance Man" which means that he had great talent in many areas.

paragraphs: Michelangelo lived an extremely busy life, creating a great number of artworks. Some of Michelangelo's works are among the most famous that have ever been made. They include two very famous marble statues, "the Pieta" in Saint Peter's Basilica and "David" which once stood in a plazza in Florence but is now in the Accademia Gallery. His most famous paintings are huge frescos, the Sistine Chapel Ceiling and the "Last Judgement". His most famous work of architecture is the east end and dome of Saint Peter's Basilica.

paragraphs: A lot is known about Michelangelo's life because he left many letters, poems and journals. Because he was so famous, he became the very first artist to have his biography (story of his life) published while he was still living. His biographer, Giorgio Vasari, said that he was the greatest artist of the Renaissance. He was sometimes called "Il Divino" ("the divine one").

paragraphs: Other artists said that he had "terribilità", (his works were so grand and full of strong emotion that they were scary). Many other artists who saw his work tried to have the same emotional quality. From this idea of "terribilità" came a style of art called Mannerism.

paragraphs: Michelangelo was born on 6 March 1475 in Caprese near Arezzo, Tuscany. His father was Lodovico di Leonardo di Buonarroti di Simoni, and his mother was Francesca di Neri del Miniato di Siena. The Buonarrottis were a banking family from Florence. They claimed they were descended from the noble Countess Matilda of Canossa. Michelangelo's father had lost most of the bank’s money, so he worked for the local government in the town of Chiusi. When Michelangelo was a baby, the family moved back to Florence. As he was sickly, Michelangelo was sent to live on a small farm with a stonecutter and his wife and family. The stonecutter worked at a marble quarry owned by Michelangelo's father. Many years later Michelangelo said that the two things that had helped him to be a good artist were being born in the gentle countryside of Arezzo and being raised in a house where, along with his nurse's milk, he was given the training to use a chisel and hammer. His mother died when he was only six.

paragraphs: Michelangelo’s father then brought him back to Florence and sent him to study with a tutor, Francesco da Urbino. Michelangelo was not interested in his school lessons. He explored the great churches of the city and drew copies of the frescos that he saw there. When he was thirteen, he was apprenticed to the painter Domenico Ghirlandaio. Ghirlandaio had a large busy studio. He had rich patrons who worked for the Medici. He painted frescos in their family chapels. Michelangelo was able to learn the art of fresco painting very well, from Ghirlandaio. In a large workshop such as Ghirlandaio’s, artists would have been working in all sorts of different media, including sculpture, metalwork and painting altarpieces. Michelangelo would have learned about all these things. When Michelangelo was only fourteen, his father persuaded Ghirlandaio to pay his apprentice as an artist, which was highly unusual at the time.

paragraphs: The richest, most powerful family in Florence were the Medici. They had an academy where some of the most famous philosophers, poets, and artists met to share their ideas. The Medici family were important patrons of the arts. In 1489, Lorenzo de' Medici, the head of the family, asked Ghirlandaio to send his two best pupils to the academy. Michelangelo was one of the students chosen and he attended the academy from 1490 to 1492. He heard the teaching and discussion of Marsilio Ficino, Pico della Mirandola and Angelo Poliziano. The philosophy that they taught was called Humanism. It was based on the philosophy of the ancient Greek Plato. Michelangelo’s ideas and his art were influenced by these teachings.

paragraphs: Michelangelo and another young sculptor called Pietro Torrigiano studied sculpture under Bertoldo di Giovanni. Michelangelo had an argument with Torrigiano, who punched him on the nose so that it was badly broken and spoilt his appearance for the rest of his life. Michelangelo sculpted some reliefs (flat panels with raised figures on them). One was ‘’the Battle of the Centaurs’’ which was made for Lorenzo de Medici.

paragraphs: In 1492, Michelangelo’s patron, Lorenzo de' Medici died. This brought about a big change in Michelangelo’s life. He went back to live at his father’s house. Michelangelo asked the prior at the Church of Santo Spirito to allow him to study the anatomy of the bodies of people who had died at the church’s hospital. In 1493, as a “thank-you” gift to the prior, Michelangelo carved a large wooden Crucifix which still hangs in the church. In January 1494, there were very heavy snowfalls. Lorenzo de’ Medici’s son, Piero de Medici commissioned Michelangelo to make a snow statue. So Michelangelo began to work for the Medici again.

paragraphs: In 1494, a new leader rose up in Florence. He was a Dominican friar called Savonarola. His strong preaching caused people to burn their books, throw away their jewellery and chase the rich families out of the city. The Medici had to go. For Michelangelo, it was a good time to travel. He stayed for a while in Venice, then moved to Bologna. In Bologna he soon got work sculpting three figures for the big marble Shrine of Saint Dominic. When things calmed down in Florence, Michelangelo returned and worked for another member of the Medici family, Lorenzo di Pierfrancesco de' Medici.

paragraphs: Michelangelo made a marble statue of Cupid asleep. Lorenzo di Pierfrancesco told Michelangelo that it looked just like a real Ancient Roman statue and said that if he made it dirty and knocked a few chips off, someone would pay a lot of money for it. Lorenzo sold it to a Cardinal who discovered that it was a fraud. He thought that Michelangelo’s work was so good that he told the pope about it. The pope then invited Michelangelo to go to Rome and work for him.

paragraphs: Michelangelo arrived in Rome 25 June 1496 at the age of 21. He lived near the Church of Santa Maria di Loreto on the Gianicolo hill.

paragraphs: In 1496 he got an important “commission” (he was given a paid job) from Cardinal Raffaele Riario. The Cardinal wanted Michelangelo to make a marble statue, larger than life-size, of Bacchus, the Ancient Roman God of wine. Michelangelo worked hard at the statue. He carved Bacchus as a young man who was quite drunk and looked as if he was staggering as he raised his cup to make a toast. The cardinal did not like the drunken Bacchus and would not pay for it. A banker called Jacopo Galli bought it for his garden.

paragraphs: Michelangelo’s next important commission was from the French Ambassador who asked him to make a statue of the Virgin Mary mourning over the dead body of her son Jesus. This type of artwork, either a painting or a statue, is called by the Italian name “Pieta” (say: “Pe-ay-ta”). Michelangelo’s Pieta is the most famous Pieta that has ever been made. It is now in Saint Peter's Basilica and is visited by thousands of people every day. Giorgio Vasari wrote: "It is a miracle that a shapeless block of stone could have been carved away to make something so perfect that even nature could hardly have made it better, using real human flesh."

paragraphs: In 1499 Michelangelo returned to Florence. The priest Savonarola had made so many people angry that he had been put to death in 1498. Life in Florence started to return to normal. Many years earlier the Guild of Woolworkers had commissioned some artists to make statues of the heroes of the city. A sculptor called Agostino di Duccio had started carving a huge statue of David, the hero of the Bible story of David and Goliath. For 40 years the Guild of Woolworkers owned the huge block of marble, with the statue hardly begun. In 1501 they commissioned the young Michelangelo to carve it. It took him three years to complete.

paragraphs: Once again Michelangelo made a statue that became world-famous. The statue shows a young man, naked in the way that statues of ancient gods were made, just pausing for a moment and looking with fierce eyes at the huge soldier Goliath that he is about to kill. The statue is 5.17 meter (17 ft) tall. It was placed in the piazza (public square) outside the Palazzo Vecchio where the town council met. After many years, the statue was put into an art gallery, the Accademia. A copy now stands in the piazza. People still go great distances to see the statue that he made.

paragraphs: In 1505 Michelangelo was invited to Rome by the newly elected Pope Julius II. Pope Julius was an old man. He wanted Michelangelo to design a grand tomb. It was to stand inside a church and have many carved figures which were to include several slaves to hold up part of the tomb and Old Testament prophets to sit in niches (openings in the walls). Michelangelo started work. He made a magnificent statue of Moses which is now in the Church of San Pietro in Vincoli (St. Peter in Chains) in Rome. Many people go to look at this statue. The slaves were only partly carved. Four of them are now in the Accademia in Florence. The rest of the great plan was unfinished.

paragraphs: The main reason that Pope Julius' tomb was not finished was that the Pope had an idea for another artwork. The Sistine Chapel near St. Peter's Basilica had its walls painted by some famous artists from Florence. The Pope decided that Michelangelo should paint the ceiling. Michelangelo did not want to. He said that he was not a painter. But the Pope bullied Michelangelo until he agreed to do it. He told the Pope that he would do it "for God" and that he would only do it if the Pope let him paint it "in his own way".

paragraphs: The chapel was long and wide. Its curved ceiling was held up by twelve fan-shaped pieces of wall called "pendentives". Pope Julius told Michelangelo to paint one of the twelve apostles of Jesus on each pendentive. Michelangelo started to do this. Then he got a different idea and scraped off the work that he had done. Instead of apostles, he painted twelve prophets. Seven of them were men from the Old Testament but the other five were women and did not come from the Bible. They were five prophets from the Classical world. Like the prophets in the Bible, they had all told people about the birth of Jesus.

paragraphs: On the middle of the ceiling, instead of painting a starry sky, Michelangelo painted scenes from the Bible telling the story of Creation and the downfall of humanity. The most famous scene is the picture of God creating Adam. The ceiling was so famous that many artists tried to copy the way that Michelangelo had arranged and painted the figures.

paragraphs: In 1513 Pope Julius II died. The next pope was Pope Leo X, a member of the Medici family. He gave Michelangelo several jobs in Florence, including designing the Medici Chapel to hold the tombs of his family members. Although not all the tombs were built, Michelangelo finished seven large statues including a "Madonna and Child". His pupils later completed the chapel.

paragraphs: In 1527, the people of Florence became angry at the Medici for acting like princes. That was not the right way for a family to act, in a city that was a republic. The people threw the Medici out, but the Medici came back with an army and took over the city. Michelangelo was so upset at the behaviour of the Medici that he left his beloved city and never went back.

paragraphs: Pope Clement VII called Michelangelo back to the Sistine Chapel to paint the wall behind the altar with a huge scene of "The Last Judgement". He worked on it from 1534 to 1541. At the centre it shows Jesus, surrounded by saints, sitting in judgement over the people of the Earth. To the left, people are rising from their graves and many are welcomed into Heaven. To the right, other people are being sent to Hell where they are dragged down by demons. It is a huge painting with many figures in it.

paragraphs: Like Adam and Eve on the ceiling, all the figures were shown naked. Some of the cardinals in the church said that it was wicked to paint saints, including the Virgin Mary, with no clothes on. They called Michelangelo "the painter of rude bits". There was a long argument about this because some people said that God had created everyone naked, so clothes would not be needed in Heaven. After Michelangelo's death another artist, Daniele da Volterra was called in to paint drapes on the figures. For the rest of his life, he was known as "the painter of pants".

paragraphs: In 1546, when Michelangelo was in his seventies, he was given one of his most important jobs. The old St. Peter's Basilica had been partly demolished and a new one designed by Bramante. But many architects had worked on it and it was still just at the beginning stages. Michelangelo was made the architect. He immediately improved the plan, had important parts made much stronger, and designed a huge dome, taller than any other domes in the world. He died before it was completed, but he left drawings and models so that the next architect, Giacomo della Porta, could finish what he had started. The dome of St. Peter's Basilica still stands as one of the greatest monuments of Christianity, and as a symbol of the city of Rome.

paragraphs: When Michelangelo died, his body was taken back to Florence and buried in the Basilica of Santa Croce (Church of the Holy Cross). On his tomb sit three mourning figures who symbolize Architecture, Painting and Sculpture.


title: Leonardo da Vinci

paragraphs: Leonardo da Vinci (15 April 1452 – 2 May 1519) was an Italian man who lived in the time of the Renaissance. He is famous for his paintings, but he was also a scientist, mathematician, engineer, inventor, anatomist, sculptor, architect, botanist, musician, and a writer.

paragraphs: Leonardo wanted to know everything about nature. He wanted to know how everything worked. He was very good at studying, designing and making all sorts of interesting things.

paragraphs: Many people think that Leonardo was one of the greatest painters of all time. Other people think that he was the most talented person ever to have lived. The art historian Helen Gardner said that no-one has ever been quite like him because he was interested in so many things that he seems to have had the mind of a giant, and yet what he was like as a person is still a mystery.

paragraphs: Leonardo was born at Vinci which is a small town near Florence, Italy. He was trained to be an artist by the sculptor and painter Verrocchio. He spent most of his life working for rich Italian noblemen. In his last years, he lived in a beautiful home given to him by the King of France.

paragraphs: Two of his pictures are among the best-known paintings in the world: the "Mona Lisa" and "The Last Supper". He did many drawings. The best-known drawing is "Vitruvian Man". Leonardo was often thinking of new inventions. He kept notebooks with notes and drawings of these ideas. Most of his inventions were never made. Some of his ideas were a helicopter, a tank, a calculator, a parachute, a robot, a telephone, evolution, and solar power.

paragraphs: Leonardo was born on 15 April 1452, in the Tuscan hill town of Vinci, in the valley of the Arno River. His grandfather, Antonio da Vinci, wrote down the details of the birth. Leonardo's parents were not married. His father was a Notary, Ser Piero da Vinci. His mother, Caterina, was a servant. She may have been a slave from the Middle East. or from China. His father later on took custody of Leonardo and his mother remarried and had 5 more children. Leonardo's full name was "Leonardo di ser Piero da Vinci", which means "Leonardo, the son of Messer (Mister) Pierdaom Vinci".

paragraphs: Leonardo spent his first five years living in a farm house with his mother. Then he lived at Vinci with his father, his father's new wife Albiera, his grandparents and uncle, Francesco. When Leonardo grew up, he only wrote down two memories from his childhood. He remembered that when he was lying outside in his cradle a large bird flew from the sky and hovered over him. Its tail feathers brushed his face. Leonardo's other important memory was how he found a cave while exploring in the mountains. He was terrified that some great monster might be hiding there. But he was also very excited and wanted to find out what was inside.

paragraphs: Leonardo started painting while he was still a boy. Giorgio Vasari wrote about Leonardo's life shortly after his death. He tells many interesting stories about how clever Leonardo was. He says that Leonardo painted a round wooden shield with a picture of snakes spitting fire. Messer Piero took his son's painting to Florence and sold it to an art dealer.

paragraphs: In 1466, when Leonardo was fourteen, his father took him to Florence, to be an apprentice to the artist Verrocchio.

paragraphs: Florence was a very exciting place for a young person who wanted to be an artist. Many famous artists had lived in Florence, starting with Cimabue and Giotto in the 1200s. Everywhere a person looked there were famous and beautiful artworks. The huge cathedral had an enormous new dome. The church of St John had doors that gleamed with gold and were said to be the most beautiful doors in the world. Another church had statues all around it by the most famous sculptors, including one by Leonardo's teacher Verrocchio.

paragraphs: If an artist was lucky, they would find a rich patron who would buy lots of their paintings. The richest family in Florence were the Medici. They had built themselves the finest palace in Florence, and liked buying paintings, statues and other beautiful things. They were also interested in the study of literature and philosophy. Many young artists hoped to get work from the Medici and their friends.

paragraphs: Verrocchio had a big workshop that was one of the busiest in Florence. Leonardo was learning to be an artist, so he had to learn drawing, painting, sculpting and model making. While he was at the workshop, he was able to learn all sorts of other useful skills: chemistry, metallurgy, metal working, plaster casting, leather working, mechanics and carpentry.

paragraphs: Leonardo was not the only young painter at Verrocchio's workshop. Many other painters were trained there, or often visited. Some of them later became famous: Ghirlandaio, Perugino and Botticelli. These artists were all just a few years older than Leonardo.

paragraphs: Giorgio Vasari tells an interesting story from this time of Leonardo's life. Verrocchio was painting a large picture of "the Baptism of Christ". He gave Leonardo the job of painting one of the angels holding Jesus' robe on the left side of the picture. Vasari said that Leonardo painted the angel so beautifully that Verrocchio put down his brush and never painted again. When the painting is examined closely it is possible to see that many other parts of the picture, such as the rocks, the brown stream and the background may have been painted by Leonardo as well. Verrocchio made a bronze statue of "David" at this time. It is believed that he used Leonardo as his model.

paragraphs: In about 1472, when he was twenty, Leonardo joined the Guild of St Luke, an organisation of artists and doctors of medicine. Even after his father set him up in his own workshop, Leonardo still enjoyed working at Verrocchio's workshop. Leonardo's earliest known work is a drawing in pen and ink of the Arno River valley. It has the date 5 August 1473. It is now in the Uffizi Gallery.

paragraphs: When Vasari writes about Leonardo, he uses words like "noble", "generous", "graceful" and "beautiful". Vasari tells us that as an adult Leonardo was a tall handsome man. He was so strong that he could bend horseshoes with his bare hands. His voice was so beautiful that it charmed everyone that heard it. Almost everyone wanted to be his friend. He loved animals, was a vegetarian and would buy birds at the market and set them free.

paragraphs: Very little is known about Leonardo's life and work between 1472 and 1481. He was probably busy in Florence. In 1478, he had an important commission to paint an altarpiece for the Monks of San Donato a Scopeto. The painting was to be the "Adoration of the Magi" ("The Three Wise Men"). The painting was never finished because Leonardo was sent away to Milan.

paragraphs: Leonardo was a very talented musician. In 1482, he made a silver lyre (a musical instrument) in the shape of a horse's head. At that time there was a new ruler in the city of Milan, in the north of Italy. Duke Ludovico il Moro was making other rulers nervous. Lorenzo Medici sent Leonardo to Milan as an ambassador. Lorenzo de' Medici wanted Leonardo to give Ludovico the lyre as a present from him. Leonardo wrote a letter to the Duke of Milan, telling him about all the clever and useful things that he could do, like making war machines. He wrote in the letter that he could "also paint". Leonardo did not know at the time that it was for painting that he would be mostly remembered. Leonardo stayed in Milan and worked for the Duke between 1482 and 1499. Part of his work was to design festivals and carnival processions. In Leonardo's note books are drawings of theatre costumes, amazing helmets and scenes that might be for the theatre.

paragraphs: Leonardo, like most other well-known artists of his time, had servants, young students and older assistants in his workshop. One of his young students was a boy whose name was Gian Giacomo Caprotti da Oreno. He was a handsome boy with beautiful long golden curls. He looked perfect as an artist's model for an angel. But he was such a difficult and dishonest boy that Leonardo called him "Salai" or "Salaino" which means "the little devil". Leonardo wrote in his notebook that Salai was very greedy, that he was a liar and that he had stolen things from the house at least five times. Salai stayed in Leonardo's household for thirty years as a pupil and a servant.

paragraphs: Leonardo's most important work for Duke Ludovico was to make a huge statue of the previous ruler, Francesco Sforza, on horseback. He started with the horse. After studying horses and drawing designs, he made a huge horse of clay. It was called the "Gran Cavallo". It was going to be cast in bronze. It was going to be the biggest bronze horse that had been made for more than a thousand years. Unfortunately, the bronze horse was never made. In 1494, Ludovico gave the bronze to be made into cannons because the French army was invading Milan. The huge clay horse was still standing when the French army invaded again in 1499. This time it was used for target practice and was completely destroyed.

paragraphs: While Leonardo was working for Duke Ludovico, he had two important painting commissions. One was to do an oil painting to go in a big altarpiece for the Confraternity of the Immaculate Conception. Leonardo did the painting twice. He left one with the monks in Milan, and took the other painting to France where it is now in the Louvre Museum. The paintings are both called "the Virgin of the Rocks". They show a scene of the Virgin Mary and the child Jesus in a rocky mysterious landscape. Mary and Jesus are meeting with John the Baptist. There is a story (which is not in the Bible but is part of Christian tradition) about how the baby John and the baby Jesus met on the road to Egypt. In this scene John is praying and the baby Jesus raises his hand to bless John. The paintings have a strange eerie light with soft deep shadows. In the background is a lake and mountains in the mist. No painting like this had ever been done before.

paragraphs: Leonardo's other important painting in Milan is even more famous. It is the "Last Supper". The painting shows the last meal shared by Jesus with his disciples, before his capture and death. Leonardo chose to paint the moment when Jesus has said "one of you will betray me". Leonardo tells the story of the surprise and upset that this caused to the twelve followers of Jesus. He tells the story through the actions and faces of the people in the painting. Some of them are talking, some of them have stood up, some are raising their hands in horror.

paragraphs: The novelist Matteo Bandello saw Leonardo at work. Bandello wrote that on some days he would paint from morning till night without stopping to eat. Then for three or four days he would not paint at all. He would often just stand and look at the painting. Vasari said that the prior of the convent was very annoyed. He asked Ludovico to tell Leonardo to work faster. Vasari said that Leonardo was worried because he did not think that he could paint the face of Jesus well enough. Leonardo told the Duke that he might use the face of the prior as his model for Judas, the traitor.

paragraphs: When it was finished, everyone that saw it said that the painting was a masterpiece. But Leonardo had not used proper fresco for the painting. He had used tempera over gesso, which is not usually used for wall painting. Soon the painting started to grow mold and flake off the wall. In a hundred years it was "completely ruined".

paragraphs: Even though in some places the paint has fallen right off the wall, the painting is so popular that it is printed and copied more that any other religious painting in the world.

paragraphs: In 1499, Ludovico il Moro was overthrown. Leonardo left Milan with his servant Salai and a friend, Luca Pacioli, who was a mathematician. They went to Venice. Leonardo worked as a military architect and engineer. Because Venice is a city on many islands, Leonardo tried to think of ways to defend the city from a naval attack.

paragraphs: In 1500, Leonardo went back to Florence, taking his "household" of servants and apprentices with him. The monks from the monastery of "The Holy Annunciation" gave Leonardo a home and a large workshop. In 2005, some buildings which were used by the Department of Military Geography were being restored. The restorers discovered that part of the building was Leonardo's studio.

paragraphs: Leonardo started work on a new painting. He drew a large "cartoon". (This means a drawing that is a plan for the painting.) The cartoon showed the Virgin Mary sitting on the knee of her mother, St Anne. Mary holds the baby Jesus in her arms. Jesus stretches out his hands to his young cousin John the Baptist. Vasari says that everyone was so amazed by the beautiful drawing that "men and women, young and old" came in large groups to see it "as if they were attending a great festival". The drawing is now in the National Gallery, London. Even though it is old and faded and is kept in a dark room, people go to the gallery to sit in front of it every day. Like many of Leonardo's projects, the painting was never done.

paragraphs: In 1502 and 1503, Leonardo worked for Cesare Borgia, a powerful noble who was the son of Pope Alexander VI. Leonardo travelled around Italy with Borgia, as a military architect and engineer. Late in 1503, Leonardo returned to Florence. He rejoined the Guild of St Luke.

paragraphs: He was given a very important commission. The Signoria (Town Council) of the City of Florence wanted two large frescos painted on the walls of the most important room of the Signoria Palace. Michelangelo was to paint "The Battle of Cascina" and Leonardo was to paint "The Battle of Anghiari". Leonardo began the project by studying and drawing the faces of angry men and fighting horses. These drawings can still be seen in his notebooks. But unfortunately, this was to be another failure for Leonardo. When he painted the picture on the wall, instead of using fresco, he mixed the paints with oil. The paint would not dry. Leonardo lit some fires to dry it, and the painting melted. Peter Paul Rubens drew a copy of the middle part. After a time, the town council covered it up and got somebody else to paint the wall. Michelangelo did not finish his painting either, because the Pope called him to Rome.

paragraphs: In about 1503 Leonardo began painting the portrait of a woman known as "Mona Lisa", the most famous portrait that has ever been painted. He continued working on it for many years. It is a small picture, painted in oil on a wooden panel. It shows the face, upper body and hands of a woman. She is very plainly dressed. For a portrait, a woman would usually put on her best clothes and jewellery. Mona Lisa has a dark dress and a fine black veil over her head. Leonardo often left symbols in his paintings that give clues about the person. The unusual thing about this picture is the smile. The smile is the clue to her name: Mona Lisa Giacondo. Giacondo means "the joking one". (Mona is short for Madonna which means "My Lady".)

paragraphs: The reason why the painting is so famous is that it seems to be full of mystery. Mona Lisa's eyes look out at the viewer. But no-one can guess what she is thinking. Her eyes and her mouth seem to be smiling. This is very unusual in a portrait painting. Most people in portraits look very serious. It is hard to tell what Mona Lisa's exact expression is. When a person wants to read another person's feelings, they look at the corners of their mouth and eyes. But Leonardo has painted soft shadows in the corners of Mona Lisa's mouth and eyes, to disguise her expression. The soft shadows are also found on the sides of her face, her neck and hands. The way that Leonardo uses shadow is called "sfumato" (which is an Italian word for "smoke"). Vasari said that the picture was so beautifully painted that every other artist who looked at it thought that they could never paint so well.

paragraphs: In 1506, Leonardo went back to Milan with his pupils, and lived in his own house in Porta Orientale. Some of the pupils became painters: Bernardino Luini, Giovanni Antonio Boltraffio and Marco D'Oggione. D'Oggione made several copies of the "Last Supper". Luini made a copy of "the Virgin of the Rocks". Boltraffio (and the others) painted many Madonna and Child pictures which can still be seen in art galleries and churches. One of pupils was a young nobleman called Count Francesco Melzi. Melzi never became a very good painter, but he loved Leonardo and stayed with him until the day he died.

paragraphs: In September 1513 Leonardo went to Rome and lived there until 1516. He lived in the Vatican. The three greatest painters of the High Renaissance, Leonardo, Michelangelo and Raphael were all working in Rome at the same time. Even though their names are often said together as if they were friends, they were not. Leonardo at this time was in his sixties, Michelangelo was middle-aged. He was not friendly to either Leonardo or Raphael. Raphael was a very clever young painter who learnt a lot by looking at the pictures painted by Leonardo and Michelangelo. But neither of them was ever his teacher.

paragraphs: In October 1515, King Francis I of France captured Milan. On December 19, there was a meeting of Francis I and Pope Leo X, in Bologna. Leonardo went to the meeting with Pope Leo.

paragraphs: Leonardo made an amazing toy to entertain King Francis. It was a life-sized mechanical lion that could walk. It had doors in its chest which opened, and a bunch of lilies came out. Lilies were the royal symbol of the French Kings.

paragraphs: In 1516, Francis I invited Leonardo to go to France with him. He gave Leonardo a beautiful house called "Clos Lucé" (sometimes called "Cloux"). It is near the king's palace, Chateau Amboise. Leonardo spent the last three years of his life at Clos Lucé, with his faithful friend and apprentice, Count Melzi. The king gave Leonardo a pension of 10,000 scudi. One of the last paintings that Leonardo did was a picture of "John the Baptist". His model was Salai, with his beautiful long curling hair.

paragraphs: When Leonardo was dying, he asked for a priest to come, so that he could make his confession and receive Holy Communion.

paragraphs: Leonardo died at Clos Lucé, on May 2, 1519. King Francis had become a close friend. Vasari says that the King held Leonardo's head in his arms as he died. In his will, he asked that sixty beggars should follow his casket in procession. He was buried in the Chapel of the Chateau Amboise.

paragraphs: Leonardo had never married and had no children of his own. In his will, he left his money, his books and most of his paintings to Count Melzi. Leonardo also remembered his other pupil Salai and his servant Battista di Vilussis, who each received half of Leonardo's vineyards near Milan. Leonardo's left to his serving woman a black cloak with a fur edge. Salai was the owner of Leonardo's most famous oil painting, the "Mona Lisa". He still owned it a few years later when he died, after fighting in a duel.

paragraphs: King Francis said: "There had never been another man born in the world who knew as much as Leonardo, not so much about painting, sculpture and architecture, as that he was a very great philosopher."

paragraphs: Leonardo did not paint very many pictures. But he drew hundreds of quick sketches, plans, maps and detailed drawings. This is the way that he recorded all the interesting things that he saw, studied and thought about.

paragraphs: Some of Leonardo's drawings are "studies" for paintings. In these drawings Leonardo planned the things he was going to paint. Some studies are plans for whole paintings. One of these paintings is the large beautiful drawing of the Madonna and Child with St Anne and St John the Baptist that is now in the National Gallery, London.

paragraphs: Many of the studies show "details" that Leonardo wanted to get just right. One study shows a very detailed perspective drawing of the ruined buildings in the background of the painting of the Magi. Other studies show hands, faces, drapery, plants, horses and babies.

paragraphs: The earliest drawing by Leonardo that has a date on it, is a "Landscape of the Arno Valley", 1473, which shows the river, the mountains, Montelupo Castle and the farmlands beyond it in great detail.

paragraphs: Leonardo studied things all his life. He did not go to university to study. He studied by looking at things in the world around him. He looked at things to see how they were made and how they worked. He drew the things that he saw and the discoveries that he made into his notebooks, and made notes about them. Many of his notebooks are now in museums. There are 13,000 pages of notes and drawings. Many of these are scientific studies.

paragraphs: Leonardo's notebooks are hard to read because he wrote backwards in "mirror writing". Some people think that perhaps he was trying to keep his work secret. This is not true. Leonardo wrote (and sometimes drew) with his left hand. In those days pens were made from a quill (a large feather) that was cut with a pen-knife on the end. It is hard for a left-handed person to write with a quill in the ordinary way, but quite easy to write backwards.

paragraphs: It is likely that Leonardo planned to publish the studies in his notebooks. He organized many pages carefully, with one study taking up the front and back of each page. There is a page with drawings and writing about the human heart and a page about the womb and the fetus. One page shows drawings of the muscles of a shoulder and another page shows how an arm works.

paragraphs: The notebooks were not published in Leonardo's lifetime. After he died, they were divided between different people who had known him. They are nearly all in museums or libraries such as Windsor Castle, the Louvre, and the British Library. The Biblioteca Ambrosiana (a library) in Milan has the twelve-volume "Codex Atlanticus".

paragraphs: Some of the things that Leonardo studied are:

paragraphs: Many of the drawings and notes in Leonardo's notebooks are designs, plans and inventions.

paragraphs: Some of the things that Leonardo designed are:


title: Platinum

paragraphs: Platinum is a soft, heavy, white metal. It is a precious metal . It usually costs more than gold.

paragraphs: In chemistry, platinum is element number 78, and its atoms have an atomic weight of 195 a.m.u.. The symbol for platinum is Pt, from Spanish "platina" meaning "little silver".

paragraphs: Platinum is very malleable and ductile, which means it can be hammered into thin sheets and it can be pulled into wire. Platinum is very stable. Acids do not affect platinum.

paragraphs: The most common use of Platinum is in a vehicle's catalytic converter.


title: Mineral

paragraphs: Minerals are substances that are formed naturally in the Earth. Rocks are made of minerals.

paragraphs: Minerals are usually solid, inorganic, have a crystal structure, and form naturally by geological processes.

paragraphs: The study of minerals is called mineralogy.

paragraphs: A mineral can be made of single chemical element or more usually a compound. There are over 4,000 types of known minerals. Two common minerals are quartz and feldspar.

paragraphs: Alternatively, a mineral is one listed as such by the International Mineralogical Association.

paragraphs: Minerals are different from rocks. A mineral is a chemical compound with a given composition and a defined crystal structure. A rock is a mixture of one or several minerals, in varying proportions.

paragraphs: A rock has only two of the characteristics minerals have–it is a solid and it forms naturally. A rock usually contains two or more types of minerals. Two samples of the same type of rock may have different kinds of minerals in them. Minerals are always made up of the same materials in nearly the same proportions. A ruby is a mineral. Therefore, a ruby found in India has similar makeup as a ruby found in Australia.

paragraphs: Minerals are formed by natural processes. A few substances with the same chemical composition as minerals can be produced by living creatures as part of their shells or bones. The shells of molluscs are composed of either calcite or aragonite, or both.

paragraphs: Traditionally, chemicals produced by living things are not considered minerals. However, it is difficult to see why an organic substance should not be called a mineral if its chemical nature "and" its crystalline structure is identical with its inorganic twin. This issue is now under debate: see Railsback part II.

paragraphs: Minerals form in many ways. The mineral halite, which is used as table salt, forms when water evaporates in a hot, shallow part of the ocean, leaving behind the salt it contained. Many types of minerals are made when molten rock, or magma cools and turns into a solid. Talc, a mineral that can be used to make baby powder, forms deep in Earth as high pressure and temperature causes changes in solid rock.

paragraphs: The extraordinary thing is, that most minerals owe their formation to life, or at least to the Great Oxygenation Event. "Sturdy minerals rather than fragile organic remains may provide the most robust and lasting signs of biology".

paragraphs: A mineral is a solid—that is, it has a definite volume and a rough shape. Volume refers to the amount of space an object takes up. For example, a golf ball has a smaller volume than a baseball, and a baseball has a smaller volume than a basketball.

paragraphs: A substance that is a liquid or a gas is not a mineral. However, in some cases its solid form is a mineral. For instance, liquid water is not a mineral, but ice is.

paragraphs: The particles of ice that make up frost have smooth, flat surfaces. These flat surfaces form because of the arrangement of atoms in the ice, which is a mineral. Such an internal arrangement is a characteristic of minerals. It is the structure of a crystal, a solid in which the atoms are arranged in an orderly, repeating three-dimensional pattern.

paragraphs: Each mineral has its own type of crystal structure. In some cases, two minerals have the same chemical composition but different crystal structures. For example, both diamond and graphite consist of just one element—carbon. But the arrangements of the carbon atoms in these two minerals are not the same, so they have different crystal structures and very different properties. Diamonds are extremely hard and have a brilliant sparkle. Graphite is soft, gray, and dull.

paragraphs: In nature, a perfect crystal is rare. Most crystals have imperfect shapes because their growth was limited by other crystals forming next to them.

paragraphs: Each mineral has a definite chemical makeup: it consists of a specific combination of atoms of certain elements. An element is a substance that contains only one type of atom.

paragraphs: Scientists can classify minerals into groups on the basis of their chemical makeup. Though there are thousands of different minerals, only about 30 are common in Earth's crust. These 30 minerals make up most rocks in the crust. For that reason, they are called rock-forming minerals.

paragraphs: People use minerals for many everyday purposes. Every time people turn on a microwave oven or a TV, minerals are being used. The copper in the wires that carry electricity to the machine is made from a mineral. Table salt or halite, is another mineral that people use in their everyday life.


title: Craft

paragraphs: Craft or handicraft is about making things with one's own hands and skills. The different types of crafts can be put in groups according to the material being used. In the Middle Ages the most common materials were metal, wood or clay.

paragraphs: A Craftsman is a person who has the knowledge and skills of a craft. When they have a lot of experience they may be called a "master craftsman". If they are young people learning a craft they are called an "apprentice".


title: Kim Jong-il

paragraphs: Kim Jong-il, birth name Yuri Irsenovich Kim (according to the Soviet Union's records) (, 16 February 1941 – 17 December 2011) was the Supreme Leader of Democratic People's Republic of Korea (North Korea) from the time of his father's death in 1994 until his own death in 2011. He was the son of Kim Il-Sŏng. Official North Korean propaganda said that Jong-il was born on Mount Paektu (a holy mountain in Korea); but most historians think that he was born near Chabarowsk in the Soviet Union. The North Korean laws made him permanent ruler of North Korea for life. He was sometimes referred to as the "Dear Leader", but this was not an official title. His official title was "Chairman of the National Defense Commission of North Korea", "Supreme Commander of the Korean People's Army" and "General Secretary of the Workers' Party of Korea". Many people in North Korea were imprisoned or killed for speaking out against the Kim regime. Almost everyone in North Korea wore a small pin with a picture of Kim Jŏng-Il or Kim Il-Sŏng on it.

paragraphs: The North Korean government told people of his death through the state media on 19 December 2011. It was said that he had died two days earlier of "physical and mental over-work".

paragraphs: Jong-il was born Yuri Irsenovich Kim on 16 February 1941.

paragraphs: Jong-il was a Stalinist. He believed in the North Korean Communist philosophy of Juche (self-reliance). He was afraid to travel on aeroplanes and traveled only on trains. He was well known for his love of movies and luxury goods, especially caviar and Hennessey brand cognac, even though North Korea was one of the poorest countries in the world. Former United States Secretary of State Madeleine Albright once gave Jong-il a present of a basketball signed by Michael Jordan when he visited North Korea because Jong-il was a fan of the National Basketball Association and of Michael Jordan.

paragraphs: On the morning of 17 December 2011, at the age of 69 or 70, Jong-il died of a heart attack while traveling. His funeral was held on 28 December, and as a result, Kim Jong-un was then elected as the new leader of North Korea. On 13 April 2012, Kim Jong-il was made Eternal Chairman of the National Defence Commission and Eternal General Secretary of the Workers Party of Korea.


title: Silver

paragraphs: Silver (symbol Ag) is a chemical element. In chemistry, silver is element 47, a transition metal. It has an atomic weight of 107.86 a.m.u. Its symbol is Ag, from the Latin word for silver, "argentum".

paragraphs: Silver is a soft metal. It is also a precious metal. When it is used in money or in jewellery, it is often mixed with gold or some other metal to make it harder. It is bluish-white. It reflects light very well. It is a very good conductor of electricity. It is considered a precious metal. Silver is very malleable, and ductile, which means it can be pulled into wire or hammered into thin sheets. Silver is one of the only words in the English language that does not rhyme with any other word. Silver coins and bars can be bought and sold at coin shops around the world.

paragraphs: It is not reactive. It does not dissolve in most acids. Nitric acid dissolves it, though, to make silver nitrate. It does react with strong oxidizing agents like potassium dichromate or potassium permanganate. It does not corrode easily. It only corrodes when there is hydrogen sulfide in the air. Then, it forms a black coating known as tarnish.

paragraphs: Silver exists in two main oxidation states: +1 and +2. The +1 is much more common. A few compounds exist in the +2 oxidation state, but they are very strong oxidizing agents. Silver compounds can be brown, black, yellow, gray, or colorless. Silver compounds are disinfectants.

paragraphs: Silver(I) compounds are oxidizing agents. They are more common. Most of them are very expensive.

paragraphs: Silver(II) compounds are powerful oxidizing agents and rare.

paragraphs: Silver can be found as a native metal. Silver can be found with copper, lead, or gold in rocks. The rocks are found mostly in Canada, Mexico, Peru, and the United States. Peru produces the most silver. Silver is also in chemical compounds. Acanthite is a silver ore that is a silver compound.

paragraphs: Silver is extracted from the earth in several ways. It is normally extracted using electrolysis.

paragraphs: Silver has been used for many thousands of years by people all over the world, for jewellery, as money, and many other things. It is called a white metal even though it looks grey. The word silver is also used to talk about this color or shade of grey. Silver is also used for utensils. It may be used to fill teeth in dentistry as an amalgam. Silver is used as a catalyst.

paragraphs: Silver compounds are disinfectants. It can kill bacteria and has other useful properties. It is used in the silver oxide battery. They are also used in photographic film. They can also be used to reduce odors in clothes. Some silver compounds are used in creams that help burns heal.

paragraphs: Silver has been around for thousands of years. It was normally considered second to gold in value. Romans used silver as money. The symbol Ag is from the Latin name for silver, "argentum". Silver was also used to prevent infections and decay.

paragraphs: Silver is not a large danger to humans. Silver compounds are toxic. They make the skin turn blue. Some can be carcinogens. Colloidal silver, a common homeopathic remedy, is not toxic in normal amounts, but it does not do much.

paragraphs: Silver, because it is depleting, is actually more valuable than gold. The silver saved up in the world is running out very quickly because more of it has been used each year than the amount mined in each year since 1990. Companies that use silver have benefited from speculators who sell promises to deliver silver that does not exist, keeping prices artificially low. This is called naked short selling. The amount owed is more than all the silver in the world. The price of silver could go very high when the stored silver runs out and investors start asking for their metal back, instead of taking more I.O.U.'s.

paragraphs: Silver is 18 US dollars per troy ounce as of June 2010.

paragraphs: Silver increased to 28 US dollars per troy ounce as of December 2010.


title: Pope

paragraphs: The Pope is the head of the Catholic Church. His official title is the Bishop of Rome. Politically, he is also the head of state of the Vatican City. The current Pope is Pope Francis.

paragraphs: Popes are elected by Cardinals of the Catholic Church. Once they are elected they hold the position until they die or resign. Usually they do not resign, though; Pope Benedict XVI is the only Pope to resign in the last 500 years. A newly elected Pope chooses a regnal name. Everyone is told this new name when the Habemus Papam is read out. The current pope (Francis) was called Jorge Bergoglio before he became a pope.

paragraphs: The name "Pope" comes from the Greek word "pappas", meaning "father". Catholics believe that when making statements "ex cathedra", that is official statements teaching about faith and morals, the Pope is "infallible" - which means God will not allow his followers to be misled by allowing their leader to make a wrong statement. Only two of any Pope's statements have been "ex cathedra".

paragraphs: Popes today travel to many countries around the world preaching. The Pope is the only person in the world who both leads the church and government. Like other bishops he wears a big hat called a mitre and holds a staff called a crosier.

paragraphs: Some recent Popes, and the time they were Pope:

paragraphs: During parts of the Middle Ages, the French kings had a lot of influence in Europe. For this reason, seven popes (and two anti-popes) lived in Avignon, rather than Rome. The Avignon Papacy was from 1309 to 1377. During that time, the popes were known for their greed and corruption. These popes were allies of France; the enemies of France were also their enemies.

paragraphs: The Bishops of Rome who lived in Avignon were:

paragraphs: Two antipopes were based in Avignon as well:

paragraphs: Antipopes were people that were elected by small groups who did not like the official choice.

paragraphs: Catherine of Siena convinced pope Gregory XI to move back to Rome. Unfortunately, he died shortly after moving. The cardinals then elected Urban VI to be the next pope. The French cardinals did not recognise this election as legitimate. They declared the papal see as vacant; which led to the Western Schism. The schism lasted until the Council of Constance in 1417. During this time, there was a pope in Rome, an Antipope in Avignon, and for some time, a second antipope. Each of the three was recognised as legitimate pope by different European powers. This led to a big split in the church as a whole. The council elected Pope Martin V as a new pope, recognised by all parties.


title: San Andreas Fault

paragraphs: The San Andreas Fault is a right-moving ('dextral') strike-slip fault. It marks the boundary between the North American Plate on the east and the Pacific Plate on the west. The fault was the cause of the 1906 San Francisco earthquake. It first appeared about 20 million years ago.

paragraphs: The San Andreas Fault is a zone several miles wide with multiple strands. The main active strand runs both on and off-shore between Cape Mendocino and the Sea of Cortez. From Cape Mendocino, it runs offshore to Tomales Bay. Then it goes southward through Bolinas Lagoon, just west of the San Francisco Peninsula, to come onshore again at Daly City, through the hills of the Peninsula. Crystal Springs reservoir is formed by the fault itself.

paragraphs: In the Santa Cruz mountains, it bends slightly eastward. This is the site of the 1989 Loma Prieta Earthquake. The fault continues south through the historic mission at San Juan Bautista and through the town of Hollister (where active creep can be seen to offset sidewalks and even houses). The Transverse Ranges north of Santa Barbara are formed by compression. Strands of the fault snake under the Los Angeles Basin. From there it connects into the active spreading under the Sea of Cortez.

paragraphs: The San Andreas fault was discovered by Andrew Lawson in 1895, who climbed into the faulted serpentinite well where the south tower of the Golden Gate Bridge was being poured. In spite of the extreme deformation of the serpentinite, Lawson declared the bridge perfectly safe. The events of the 1906 San Francisco earthquake would seem to support his conclusion: the ruptured strand was not the one he observed in the footprint of the bridge.


title: Void (astronomy)

paragraphs: In astronomy, voids are the empty spaces between filaments. Both filaments and Voids are one of the largest-scale structures in the Universe. There are no or few galaxies in voids. Most voids have a diameter of 11 to 150 Mpc.

paragraphs: Especially large voids are the empty spaces without many superclusters.

paragraphs: These voids are sometimes called supervoids.

paragraphs: A 1994 official counting (""The structure of the Universe traced by rich clusters of galaxies."", see References) lists a total of 27 supervoids with a distance of up to 740 Mpc. Some of supervoids chosen from the list are given below.


title: Computer mouse

paragraphs: A computer mouse is an input device that is used with a computer. Moving a mouse along a flat surface can move the cursor to different items on the screen. Items can be moved or selected by pressing the mouse buttons (called clicking). Today's mice have two buttons, the left button and right button, with a scroll wheel in between the two. Today, many computer mice use wireless technology and have no wire.

paragraphs: There are many types of mouse. Optical mouse, wireless mouse, mechanical mouse, trackball mouse. A computer mouse is a handheld hardware input device that controls a cursor in a GUI and can move and select text, icons, files, and folders. For desktop computers, the mouse is placed on a flat surface such as a mouse pad or a desk and is placed in front of your computer. The picture to the right is an example of a desktop computer mouse with two buttons and a wheel. The mouse was originally known as the X-Y position Indicator for a display system and was invented by Douglas Engelbart in 1963 while working at Xerox PARC. However, due to Alto's lack of success, the first widely used application of the mouse was with the Apple Lisa computer.

paragraphs: Today this device is on virtually every computer. The primary function is to move the mouse pointer on the screen. The mouse pointer can be used for many actions on the computer. Clicking or double clicking an icon, folder, or other object will open a document or execute the program. Users can also move an icon, folder, or other object by clicking a mouse button and dragging the object with the mouse pointer. Pointing to an item on the screen means moving your mouse so the pointer appears to be touching the item. When you point to something, a small box often appears that describes the item.

paragraphs: In 1964 Douglas Engelbart (1925-2013), a researcher at Stanford Research Institute, wanted to find a way to make using computers easier. In those days, computers were large and expensive. Using them was very hard because everything had to be typed in on a keyboard. This command line interface is still used by some people, such as programmers, to get things done faster.

paragraphs: After studying and designing for a long time, Engelbart succeeded in inventing an input device which he named 'XY index'. At first, it needed two hands to use, but it was changed so that only one hand was needed to use it. This model was more like the mouse that we use today, but was made up of a big ball that the user had to roll in different directions to move the cursor.

paragraphs: The computer mouse began to be widely used when Xerox Palo Alto Research introduced a GUI in 1981, where the mouse was used to click things on the screen. This was also the case with the Macintosh operating system from Apple of Apple Inc when it came out in 1984, as well as Microsoft Windows. Windows became popular over the years, so over time computer mice became used with many computers.

paragraphs: In 1991, the company Logitech invented the wireless mouse. Unlike a normal mouse, wireless mice were connected by radio signals. Newer wireless mice use Bluetooth or WiFi to connect wireless mice to computers.

paragraphs: On most computers, the user can move the mouse to move the cursor in the same direction. To choose something that is on the screen, the user can move the cursor to it and "click" the left mouse button. The right button is used to open menus that are different depending on where the cursor is. The other mouse buttons can do different things, depending on the software. Most mice have two buttons to click.

paragraphs: Most mice also have the "scroll wheel"—a small wheel found between the two main mouse buttons. The user can move the wheel back and forth to "scroll" through things like a website or folder. "Scrolling" means moving the words or pictures up or down on the screen, so another part of the page comes into view. The wheel can also be pressed, to click it like another button.

paragraphs: A mouse can also be connected to and used the same way with a laptop computer, but unlike a desktop computer, one does not have to be connected to use the laptop. This is because along with the keyboard, laptops have a built-in input device called a trackpad which does the same thing as a mouse. Similarly, tablet computers have a touchscreen as an input device, but some, like the Microsoft Surface and those that use Android, also work with mice.


title: Metallurgy

paragraphs: Metallurgy is the study of metals. Alloys (mixtures of metals) are also studied. People who study or work with metals are called "metallurgists".

paragraphs: Ores are rocks that have a chemical compound of a metal with oxygen, called an oxide. Separating the oxygen from the metal is called smelting. This is done with chemistry or electricity, usually at very high temperatures. This is the first step in metallurgy. A rock containing enough metal to be profitable is called "ore".

paragraphs: Another part of metallurgy is making parts from metals. These parts must be made so they will not break when they are used. Metallurgists work to make the metal good when they are used. Sometimes the metal must be strong. Other times it must be tough (not easily broken). The metallurgist must follow directions when making the part to know what metal to use. Steel has a low cost, but rusts. Choosing a good metal is sometimes hard.

paragraphs: A metal starts as a block, called an ingot. Metallurgists must know how to make a metal part from an ingot. Parts are made from ingots different ways. When a big hammer is used, it is called forging. To make thin metals, a metal is put between two rolls and moved, called rolling.

paragraphs: Making metal hot makes it easier to change the shape of a metal part. For this reason, most metal parts are made using hot metal. This is hot work.

paragraphs: Two metal parts can be put together with much heat. This is called welding. Iron is easy to weld.

paragraphs: Metallurgists use many tools to know what to do to the metal. The most useful is the microscope. The microscope gives much information about the way the metal moves. Metals are sometimes pulled until they break. This is the tension test. Some useful information can be gotten from this test.


title: Fixed-wing aircraft

paragraphs: A fixed-wing aircraft is a kind of aircraft. An aircraft is a machine that can fly, but is heavier than air. Fixed-wing aircraft are sometimes called airplanes, aeroplanes or sometimes just "planes". All fixed-wing aircraft have wings that use forward airspeed to generate lift. Gliders are fixed-wing aircraft that do not have engines.

paragraphs: A steam-powered unmanned fixed-wing aircraft, that weighed , was built by John Stringfellow, in Chard, Somerset, England in 1848. It could fly by itself without needing to be dropped from high up. There were gliders before this, but they had to fly by being pushed off a building or hill.

paragraphs: The first man who flew (took off, steered, and landed) a motor-powered aircraft was Orville Wright in 1903 in Kitty Hawk, North Carolina, USA.

paragraphs: Today, fixed-wing aircraft fly between many cities all over the world, carrying people and cargo. Big cities usually have an international airport, where large fixed-wing aircraft can land and take off safely. Some large cities like New York City and London have more than one airport. Two major makers of fixed-wing aircraft are Airbus and Boeing.

paragraphs: Advances in technology have made fixed-wing aircraft more efficient. Things like winglets and more efficient turbofans have helped to do this.

paragraphs: Most fixed-wing aircraft have certain parts in common.

paragraphs: Fixed-wing aircraft have long been used as airliners for moving passengers from place to place. Cargo aircraft carry cargo across seas and long distances, and passenger aircraft also carry some cargo.

paragraphs: The first aircraft for war bombing was used in Libya in 1911 by Italy against the Ottoman Empire. Some fixed-wing aircraft are used by air forces to defend countries. These may be fighter aircraft, using guns or missiles for combat with other aircraft. They may be bombers, dropping bombs on ground targets.

paragraphs: Fixed-wing aircraft allow people to travel longer distances, and faster than ships or trains. Aircraft can fly from New York to London in about 7 hours. It would take one week or more on a ship. Militaries use airplanes to carry their soldiers quickly from place to place.

paragraphs: Airplanes are also used by the military to see many things on the ground easily. This is called surveillance or reconnaissance. Often, fixed-wing aircraft will take photographs as well, which can be used for military planning later.

paragraphs: Statistics show that riding in a plane is safer than driving in a car.


title: Aircraft

paragraphs: An aircraft is a flying machine. There are many different kinds of aircraft.

paragraphs: Some aircraft keep in the sky by moving air over their wings. Examples are aeroplanes, helicopters, and gliders. Some aircraft keep in the sky by floating. Examples are balloons and airships.

paragraphs: Most aircraft use engine power. Examples are aeroplanes, helicopter, and airships. Gliders and balloons use no power. A few aircraft use muscle power.

paragraphs: Big aeroplanes for transporting people are called "airliners". Airliners are the quickest way to travel. Airliners can fly over mountains and bad weather. Airliners have complex technology to make them fly quickly, safely and for less money.

paragraphs: A few fighter aircraft can fly at 3,200 km/h (2,000 mph).

paragraphs: The person who drives an aircraft is called the pilot.

paragraphs: The smallest aircraft is a nano-aircraft.

paragraphs: These are the largest aircrafts. They are:


title: Victoria, British Columbia

paragraphs: Victoria is the capital city of the province of British Columbia, Canada. It is named after Queen Victoria. Over 350,000 people live in the Victoria area. Many people work for the government or in tourism. It is warmer than other Canadian cities in the winter, so many Canadians move there when they retire.

paragraphs: Victoria is on Vancouver Island. Most people travel there by boat (ferry) from Vancouver, or from Washington State. Victoria has three ferry docks and an airport, Victoria International Airport.

paragraphs: Victoria has one of the mildest climates in Canada, with gardens blooming year-round.

paragraphs: Some tourist attractions are the Butchart Gardens and the Royal British Columbia Museum. Some of the best-known buildings are the government buildings and the Empress Hotel, and both are by the Inner Harbour.

paragraphs: The first people to live in the area were the Coast Salish native people. People from England built Fort Victoria in 1843. Victoria became a city in 1862.

paragraphs: 18,000 students study at the University of Victoria. Other people study at Camosun College, Royal Roads University, University Canada West, Victoria College of Art, and the Canadian College of Performing Arts. Students from all over the world study at Pearson College, near Victoria.

paragraphs: The Canadian navy has ships in a part of the city called Esquimalt.

paragraphs: Some of the parks include Beacon Hill Park, East Sooke Park, Mount Work Park, and Mount Douglas Park.

paragraphs: There are many flowers in Victoria; it is called the "city of gardens." It is a lot drier than places nearby, and has little snow.

paragraphs: Some well-known people from Victoria are:

paragraphs: The Victoria area is made up of 13 parts. Four of them make up Greater Victoria:

paragraphs: Three of them make up the Saanich Peninsula:

paragraphs: The others make up the Western Communities:


title: Suez Canal

paragraphs: The Suez Canal (Arabic: قناة السويس, "Qanā al-Suways", French: "Le Canal de Suez") is a canal in Egypt. It lies west of the Sinai Peninsula. The canal is 163 km long (101 miles) and, at its narrowest point, 300 m wide (984 ft). It runs between Port Said ("Būr Sa'īd") on the Mediterranean Sea, and Suez ("al-Suways") on the Red Sea. It was built by a French company. The canal was started in 1859 and finished in 1869.

paragraphs: The canal allows ships to travel between Europe and Asia without having to go the way around Africa. This saves time and fuel. It was built for Europeans to go to and from the Indian Ocean.

paragraphs: In 1859, the Suez Canal was built by Ferdinand de Lesseps of the Universal Suez Ship Canal Company, and took 10 years to build. The first ship passed through the canal 17 November, 1869; Giuseppe Verdi wrote the famous opera Aida for this ceremony.

paragraphs: The canal made it possible to easily transport goods across the world. The canal also allowed Europeans to travel to East Africa, and this area was soon controlled by European powers. The British tried to stop it, fearing that it would increase French power in the Indian Ocean. Later, they bought shares in the company.

paragraphs: The success of the Suez Canal encouraged the French to try to build the Panama Canal. But they did not finish it. The Panama Canal was finished later.

paragraphs: The canal was a central point during the Six Day War in 1967. A UN peacekeeping force has been stationed in the Sinai Peninsula since 1974, to avoid more wars. The canal reopened in 1975.

paragraphs: About 15,000 ships pass through the canal each year, which is about 14% of world shipping. Each ship takes up to 16 hours to cross the canal. In 2015 a central part of the canal was expanded so more ships can go through and go faster.


title: Canal

paragraphs: A canal is a waterway made by humans. For many centuries, canals have been built as a way of transporting heavy goods in barges or boats. Canals usually connect lakes, rivers, or oceans. The Panama Canal is a famous canal that connects the Atlantic Ocean with the Pacific Ocean. Many canals are reinforced with clay or concrete on the sides.

paragraphs: Other canals are used for irrigation or hydropower.


title: Mars (mythology)

paragraphs: Mars is the god of war in Roman mythology. Mars is the son of Juno and Jupiter. Mars is the father of Romulus and Remus. The planet Mars and the month March are named after him. He was the god of war, murder, and bloodshed. His Greek name is Ares.


title: Cessna

paragraphs: Cessna is a company that makes airplanes. They are in Wichita, Kansas in the United States. They make small aircraft that can hold 2 to 4 people.


title: Clothing

paragraphs: Clothing is an item or fabric, usually sewn together to cover part of the human body. Humans are the only animals which wear clothing, and all people do wear suitable clothing.

paragraphs: The torso (body) can be covered by shirts, arms by sleeves, legs by pants or skirts, hands by gloves, feet by footwear, and head by headgear or masks. In cold climates, people also wear heavy, thick coats such as trenchcoats.

paragraphs: Clothing protects the human body from the hot sun and high temperatures in warm tropical countries. Clothing such as thick wool coats and boots keeps the human body warm in very cold temperatures (such as in the arctic). To some extent, clothing protects people from damage to their body.

paragraphs: Clothing is also worn for decoration, as a fashion (clothing). People from different cultures wear different clothing, and have different beliefs and customs about what type of clothing should be worn.

paragraphs: For many people, clothing is a status symbol. It helps people project an image. Often, clothing is a form of self-expression. Adults in different social or work situations present different views of themselves by the clothes they wear. Young people have an entirely different form of dress to express their personalities. Often people will simply follow popular fashion styles so that they will fit in. Clothing is far more than just a means to protect our bodies.

paragraphs: There is no easy way to be sure when clothing was first developed, because it was prehistoric and clothing is perishable. Some information comes from studying lice. The body louse lives in clothing, and diverged from head lice about 107,000 years ago. This suggests that clothing existed at that time. Another theory is that modern humans are the only survivors of several species of primates who may have worn clothes, and that clothing may have been used as long ago as 650 thousand years ago. Other louse-based estimates put the introduction of clothing at around 42,000–72,000 BC.

paragraphs: A cloak made of the fur of squirrels, from a cave in Italy, has been dated to 23.000 years BP, and is possibly among the oldest items of clothing.

paragraphs: People often decorate their bodies with makeup or perfume, and they also cut or change the hair on their heads and faces. They might also go in for body modification: tattoos, scarifications, and body piercings. But makeup and tattoos are not kinds of clothing.

paragraphs: Things that are carried and not worn, like wallets, purses, canes, and umbrellas, are called accessories, but they are not kinds of clothing, either. Jewelry and eyeglasses are also accessories that are put on the body. Nail polish is also put on the fingertips and can be interpreted as makeup.


title: Shoe

paragraphs: A shoe is a type of footwear. It is an item of clothing. Shoes come in pairs, with one shoe for each foot.

paragraphs: There are many different types of shoes. Athletic shoes, for example, are to make running, walking or jogging easier by making the weight of the shoe lighter and the sole of the shoe softer. Leather shoes are formal shoes. They are worn for business and ceremonial functions. They are also worn for fashion. Slippers are a kind of indoor shoe. They are often worn when it is cold. Rubber boots are used on rainy days. The shoes with a high heel which women wear are called high heels.

paragraphs: People usually wear shoes in public. They are worn for hygiene, style, and comfort.


title: Footwear

paragraphs: Footwear is an item of clothing made by humans that covers and protects the foot, including the soles of the feet. Footwear allows people to walk on rough surfaces such as gravel roads without hurting their feet. Some types of footwear such as boots help to keep people's feet dry, or help to keep people's feet warm in cold weather.

paragraphs: People in many countries make their own footwear by hand, using simple tools. A simple pair of sandals can be made by hand cutting a foot-shaped sole out of a thick, flexible material such as rubber. Next, straps of fabric, rope or leather can be added with a needle and thread. A simple pair of boots can be made by hand by using animal hide with fur, and sewing it with strong thread.

paragraphs: Many people wear footwear that is made in a factory. The machines in shoe factories and boot factories can make footwear much more quickly than people who are making footwear by hand with a needle and thread.


title: Café

paragraphs: A café is a type of restaurant which typically serves coffee and tea, in addition to light refreshments such as baked goods or snacks. The term "café" comes from the French word meaning "coffee".

paragraphs: A café setting is known as a casual social environment where you can find people reading newspapers and magazines, playing board games, studying or chatting with others about current events. It is known also regarded as a place where information can be exchanged.

paragraphs: A café is sometimes called a coffeehouse or a coffee shop or tea shop in English, a café in French and a bar in Italian. (Cafe or café is the common spelling used in English, French, Spanish, et al. however the word is spelled "caffè" in Italian.) It shares some characteristics of a bar and some characteristics of a restaurant given its selection of foods and beverages served, but is distinct from a cafeteria which is a type of restaurant where customers can choose from many dishes displayed on a serving line. In some countries, cafés are designed to more closely resemble restaurants whereby offering a range of hot meals and possibly licensed to serve alcohol. Most British cafés however, do not sell alcohol likely due to the prominent pub culture.

paragraphs: In the Netherlands, cannabis-selling cafés face an uncertain future under a planned new law banning smoking in public places. The cafés, which attract millions of tourists each year, allow customers to buy marijuana over the counter and openly smoke it. The acronym CAFE, Cannabis and Fine Edibles is used in Canada to represent the largest retail chain in the Country, post-legalization.

paragraphs: A new type of café, known as the Internet café, was introduced in the 1990s and went hand in hand with the rising prevalence of computers in society. Computers and Internet access in a contemporary atmosphere created a youthful, modern public space compared to existing locales including traditional bars and old-fashioned diners. Nowadays, many cafés offer public wireless Internet or even have computers, telephones, and newspapers for customer use. Further integrating internet usage to the café atmosphere, some stores like Starbucks allow you to order directly from your smartphone, tablet, or other devices through their free store app or websites online.

paragraphs: More recently alongside the growing popularity of geek and gaming culture, gaming cafés have also begun to open in cities worldwide. These cafés offer a library of board games and tabletop games, from childhood classics such as Monopoly to indie games, for customers to play at their leisure for a nominal fee.


title: Jazz

paragraphs: Jazz is a type of music which was invented in the United States. Jazz music combines African-American music with European music. Jazz first became popular in the 1910s. It is still a popular music to play and hear because of the different styles.

paragraphs: Some common jazz instruments include the saxophone, trumpet, piano, double bass, and drums.

paragraphs: It is difficult to give an exact definition for "jazz". A singer Nina Simone said, "Jazz is not just music, it is a way of life, it is a way of being, a way of thinking". But when we talk about jazz as music, one important part of jazz is improvisation (improv), which means the person playing is making music up as they go along. If a jazz band is playing a song, the song may have several solos where one player will improvise while the rest of the band, except for the rhythm section (such as the piano, bass, or drums), does not play. Most jazz is very rhythmic, which is called "swing," and uses "blue" notes. Blue notes is referred as a musical term in blues.

paragraphs: Jazz began in the United States in the early 20th century. Jazz music was first based on the music of African slaves who were forced to work in the plantations of the southern United States. This included call and response songs, spirituals, chants and blue notes. These characteristics are what developed blues, a sad song that slaves sung during their labor. These influences were indirect, through earlier musical forms such as ragtime.

paragraphs: Jazz also has musical styles from European music, as well as the brass and stringed instruments and (sometimes) the use of musical notation.

paragraphs: There have been different types of jazz through time. New Orleans jazz began in the early 1910s. Dixieland jazz was also popular. In the 1930s, there was swing jazz, which was also called big band jazz. In the 1940s, bebop became a major type of jazz, with fast songs and complex harmony.

paragraphs: Large jazz bands, which are called big bands, were also popular in the 1940s. Big bands usually have 5 saxophone players, 4 or 5 trumpet players, 4 trombone players, a piano player or guitar player, an acoustic bass player, a drummer, and sometimes a singer.

paragraphs: In the 1950s, there was hard bop jazz. In the 1960s, there was modern jazz and free jazz. In the 1970s, jazz fusion began to blend jazz music with rock music. Some jazz is still played with the same improv methods as it did at its beginning, except with modern electronic instruments.

paragraphs: April 30 is an "International Jazz Day". Each year jazz concerts and educational events take place around the world. This is the day to increase understanding to jazz. The United Nations Education and Science Organization (UNESCO) also take part in this event. People celebrate the day, because they believe the history of jazz has something to do with peace, freedom and equality.


title: Coffee

paragraphs: Coffee is a plant (Coffea) and the name of the drink that is made from this plant. The coffee plant is a bush or tree that can grow up to ten meters (about 32 feet) high, but is usually cut shorter. Coffee plants originally grew in Africa, and now also grow in South America, Central America and Southeast Asia. They are an important crop for the economies of many countries.

paragraphs: The first branded coffee to be sold commercially to the public was Nes Café in 1879.

paragraphs: The drink is made from the seeds of the coffee plant, called coffee beans. Coffee is usually served hot, and is a popular drink in many countries. Coffee contains a chemical called caffeine, a mild drug that keeps people awake.

paragraphs: To make a drink from coffee beans, the beans must first be specially prepared by drying the beans and then roasting. The beans are dried a short time after they are picked. This preserves them and makes them ready to be packed or roasted. Before the beans are made into a drink, they must be roasted or ground (crushed into tiny pieces in a coffee mill). When the ground coffee is placed into boiling water, the flavour and dark brown colour of the beans goes into the water. Making coffee is called brewing coffee. There are several different ways that coffee can be brewed.

paragraphs: There are two main types of coffee plants. The "Coffea Arabica", the most common. Most of the world's coffee is made from Arabica beans, and the "Coffea Robusta", which is easier to grow in places where Arabica will not grow.

paragraphs: Robusta is cheaper and has more caffeine than Arabica and it is used in many commercial coffee products. But Robusta tastes bitter and acidic, so people only drink it with other things. Better quality Robustas are in some espresso blends.

paragraphs: In the past, people gave names to new Arabica coffees from the port they came from. The two oldest Arabica coffees are "Mocha" and "Java". Today, names are more specific. They tell us the country, region, and sometimes even the property where they come from.

paragraphs: Some sorts of coffee taste better if the beans are "aged". This means that after they are picked, the beans are dried and then kept from three to eight years. This "aging" gives the coffee a less acidic taste. Coffee that has been aged is often mixed or "blended" with other coffee that is not aged.

paragraphs: "Roasting" is one of the important stages in making coffee beans into coffee. When a coffee bean is roasted, it grows nearly two times bigger and changes from green to yellow to brown.

paragraphs: The length of time that the coffee beans are roasted makes the coffee taste different. Some types of coffee, such as Mocha and Java, are roasted for a short time. It is easy to tell from the flavour where the coffee is from. When coffee is roasted for a long time, it is harder to tell the different types apart. Green coffee beans can be bought and roasted at home in the oven.

paragraphs: Before the coffee is made into a drink, it is "ground" in a small grinding machine called a "coffee mill". The coffee mill breaks the beans into very small pieces. Coffee is turned into a drink in several different ways. For some ways of making coffee, such as "espresso" it is best to have the coffee ground into fine powder but for other types of coffee-making, such as "filtered coffee", the coffee is in larger pieces to stop it going through the filter. Finely ground coffee makes a stronger taste.

paragraphs: Coffee is made into a drink by putting the coffee into boiling water. This is called "brewing" coffee.

paragraphs: There are many ways to brew coffee. Four of the most popular are:

paragraphs: "Instant coffee" is a very quick way to make a cup of coffee to drink. It is made in a factory and sold in jars or packets. First, strong coffee is made using ground coffee and boiling water. Then, the coffee grounds are filtered out. The coffee liquid is dried out until nothing is left except granules (little crunchy pieces), or fine powder. This is then put into jars or packets. As soon as a spoonful of "instant coffee" is added to boiling water, it dissolves in the water to make coffee to drink. The taste can be very different from fresh coffee. Part of the reason for the different taste is that "Robusta" coffee beans are usually used for making instant coffee. Robusta coffee beans do not cost as much as "Arabica".

paragraphs: The United States buys the most coffee; Germany is next. People in Finland drink the most coffee for each person. In Canada, the United States and Europe, some restaurants sell mainly coffee; they are referred to as "cafés" or "coffeehouses". Cafés often sell food, but the type of food is different from one country to another.

paragraphs: In some countries, for example, those in northern Europe, people like having coffee parties. At these parties, people have coffee and cake.

paragraphs: In many countries, people drink coffee at work; in the United States and England, for example, people drink it in the morning. In other countries, such as Mexico, people drink it in the evening to help them stay awake.

paragraphs: Coffee contains the drug caffeine. Caffeine is a mild stimulant which helps to keep people awake. Caffeine, like many drugs, can be addictive and can cause health problems.

paragraphs: Some studies have looked at the health risks of coffee. In February 2003, there was a study in Denmark of 18,478 women to find out if coffee had an effect on pregnancy and birth. It was found that if a woman drank between four and seven cups of coffee a day, it did not seem to make a big change to the number of babies that were born dead, (stillborn). But the women in the study who drank eight or more cups of coffee a day had three times as much chance of having a stillborn baby.

paragraphs: For this, and other reasons, some people drink coffee substitutes or decaffeinated coffee instead.

paragraphs: The BMJ quotes a study that concluded that there are health benefits for drinking up to four coffee cups per day. However, drinking coffee is not recommended for pregnant women and for women who are in danger of fractured bones. According to the BMJ not everyone agrees with these findings


title: Beef

paragraphs: Beef is a type of meat that comes from cows. There are different types of beef. Beef is popular in the United States.


title: Hyaena

paragraphs: Hyaenas (sometimes 'Hyena') are mammals. They are the family Hyaenidae, in the order Carnivora. They live in Africa, and in west and south Asia. In the past they had a much wider distribution. Now there are two subfamilies with four species.

paragraphs: With only four species, it is the fourth-smallest family in the Carnivora, and one of the smallest in the class Mammalia. Despite their low diversity, hyenas are unique and vital components to most African and some Asian ecosystems.

paragraphs: Hyaena walk much like bears because their front legs are longer than their back. Hyaenas are known to have one of the world's strongest bites. Its function is to crush bone.

paragraphs: Hyaenas look much like canids, but they are actually in the Feliformia, with cats and mongooses. Although related to felines and viverrids, their life style is similar to canids. Convergent evolution has taken place. Both hyaenas and canids are non-climbing, running hunters which catch prey with their teeth rather than claws. Both eat food quickly and may store it. Their calloused feet have large, blunt, nonretractable nails, good for running and making sharp turns. However, the hyaenas' grooming, scent marking, defecating habits, mating, and parental behaviour are similar to the behaviour of other feliforms. Hyenas are matriarchal. This means that females dominate and males are inferior.

paragraphs: Hyaenas were long said to be cowardly scavengers, but they kill as much as 95% of the food they eat (especially spotted hyaenas). They can drive off leopards or lionesses from their kills. Hyenas are mostly nocturnal animals, but may leave their lairs in the early morning. Except for the very social spotted hyaena, hyenas are generally not gregarious animals, though they may live in family groups and come together at kills.

paragraphs: Hyaenas are intelligent creatures. They work together well and are cooperative. They have strategic hunting methods and work to steal and protect it from other predators. Hyaenas main targets are zebra and wildebeest. Their main rival is the lion. Whether hyaenas do or do not chase lions off their kills is mostly a matter of numbers.


title: Table salt

paragraphs: Table salt is a mineral composed mainly of sodium chloride (NaCl). This is a chemical compound, one of many salts. Salt in its natural form as a crystalline mineral is known as rock salt or halite.

paragraphs: When salt (sodium chloride) is mixed with water, the salt dissolves into the water, creating a saline solution. Salt is present in vast quantities in seawater, where it is the main mineral constituent. The open ocean has about of solids per litre, a salinity of 3.5%.

paragraphs: Salt can be made by either evaporation or can be mined. To get sea salt, man-made holes are built then filled with sea water. The water evaporates and leaves salt behind.


title: Silk

paragraphs: Silk is a natural fibre made by the silk worm cocoon. Silk fibres are very strong and are often used to make cloth. The Chinese invented silk in 3000 B.C. and traded it across the world through the Silk Road because it was very valuable and costly .

paragraphs: The cloth from silk can be made into rugs, bedding, or can be used to write or paint on. In the past, silk was used to make parachutes. The practice of growing silkworms for silk production is called "sericulture".

paragraphs: Most spiders make a natural fibre of their own that is also called silk.

paragraphs: Silk that is made by the silk worm is made up of two main proteins, sericin and fibroin.

paragraphs: Fibroin is the structural center of the silk and gives it its strength. It is made up of amino acids, which make the fibers strong and hard to break. The tensile strength is there because of hydrogen bonds. When silk is stretched, there is a strong force on these many bonds, so they do not break.

paragraphs: Serecin is the sticky material which surrounds the fibroin and gives it protection from the outside. Silk is resistant to most mineral acids, except for sulfuric acid, which dissolves it. Perspiration gives the


title: The Beatles

paragraphs: The Beatles were an English rock band, started in Liverpool, England in 1960. The members of the band were John Lennon, Paul McCartney, George Harrison, and Ringo Starr. Most people say they are the most successful and influential band in the history of popular music. The group were a main part of the creation of 1960s counterculture. They began as a skiffle and beat band and were influenced by 1950s American rock and roll. They later used parts of classical music and Indian music.

paragraphs: Their main songwriters were Lennon and McCartney. Before The Beatles became popular, they played in clubs in Liverpool and Hamburg over three years between 1960 and 1963, with Stuart Sutcliffe playing bass. They went through many drummers, including Pete Best, before finally asking Ringo Starr to join in 1962. Sutcliffe also quit, meaning Paul McCartney started playing the bass instead. Brian Epstein was their manager and George Martin produced most of their music. Their first single was "Love Me Do", in late 1962. It was a hit and they became popular in the United Kingdom. As they became more popular, the press called the popularity "Beatlemania".

paragraphs: By 1964, the Beatles were worldwide stars and led the "British Invasion" of the United States. They brought out some of the best-selling albums of the 1960s, with twelve studio albums. They broke-up in 1970. John Lennon was later murdered in New York City in 1980 and George Harrison died of lung cancer in 2001. McCartney and Starr still make music.

paragraphs: Starting in 1956, John Lennon and several of his friends played in a British band called the Quarrymen. Over the next few years, the members of the band changed, and by 1960, the band was called the Beatles. They did not have their first hit until 1962. In February 1963 their song, "Please Please Me", reached the number 1 position on the British charts. This was the first of a record 15 British number 1 singles. They first came to the United States in 1964. They were met at the airport by thousands of screaming American teenagers. The Beatles were so popular that they were attacked by screaming fans everywhere they went around the world. The effect they had on their fans was known as 'Beatlemania'. The Beatles made their first live American television appearance on The Ed Sullivan Show on 9 February 1964. About 74 million viewers — about half of the American population — watched the group perform on the show. Beatles songs soon filled the top 5 places on the American top 40 chart - a record that has never been matched.

paragraphs: After the Beatles became so popular in the United States, other British bands, such as The Rolling Stones, The Animals, The Kinks and Gerry and the Pacemakers had songs become hits there as well. So many British bands became popular after the Beatles' success that this time became known in America as the "British Invasion".

paragraphs: Towards the mid 1960s, The Beatles became bolder with their style of music. This largely started in 1965, with the release of the album "Rubber Soul", and hit a peak in 1967 with the release of "Sgt. Pepper's Lonely Hearts Club Band", which was named as the greatest album of all time by Rolling Stone Magazine. They were also named the most influential artists of all time by Rolling Stone magazine, because their music, clothing style, and attitudes shaped much of what was popular among young people in the 1960s.

paragraphs: The Beatles became so popular that no regular concert venue was big enough for their concerts. This led to them playing the first ever stadium rock concert at Shea Stadium in America, to around 50,000 people. The Beatles stopped touring and playing live music in 1966 because they were sick of audiences screaming so loudly that their music could not be heard. They were also tired of the pressures of touring. Among other things, they were so popular that thousands of people would gather outside the hotels they stayed in day and night meaning that they could never leave their rooms unless they were playing a concert.

paragraphs: The Beatles broke up in 1970 because of the pressures of fame and each member becoming more independent both in their personal lives and musically. In 1973 the two-disc sets "1962-1966" (the "Red Album") and "1967-1970" "(the "Blue Album") were released. These were both re-released on CD in 1993.

paragraphs: The band was still very popular all over the world after they broke up. According to the "Guinness Book of World Records", they are the highest-selling recording artists ever. They have sold more than one billion records, including albums and singles. Their music is still important and still influences many musicians. Musicians today perform cover versions of Beatles songs, and people everywhere still listen to their music. Their song 'Yesterday' has been recorded by more artists than any other song. It is also the song that has been played the most on radio ever.

paragraphs: The Beatles made thirteen albums and twenty-six singles together. They also started their own record label, Apple Records. They made two movies, "A Hard Day's Night" and "Help!", where they appeared as actors. Later they made "Magical Mystery Tour", a television special. "Yellow Submarine" was a cartoon movie based on their music. "Let It Be" showed them working on a new album.

paragraphs: After the Beatles broke up in 1969, all four members started their own solo careers.

paragraphs: John Lennon became a famous peace activist in the late 1960s and early 1970s. He wrote successful songs including "Give Peace a Chance", "Imagine", and "Happy Xmas (War Is Over)". John Lennon was murdered on December 8, 1980 outside his home in New York. Part of Central Park in New York and an airport in Liverpool are named in his honor.

paragraphs: The other three Beatles got together in the 1990s to make two new records. They used demo recordings of two John Lennon songs and added their own new parts. Producer Jeff Lynne helped them so all four members could appear on the songs. The songs were "Free as a Bird" and "Real Love". Both were top 5 hits in the UK in 1995 and 1996.

paragraphs: Paul McCartney started the band "Wings" with his wife Linda. In 1977 his song, "Mull of Kintyre", became the biggest selling single in British history. It sold even more copies than the Beatles' singles. Paul McCartney was knighted in 1997.

paragraphs: George Harrison and Ringo Starr had early success as solo artists but were less successful later on. George formed the group "the Traveling Wilburys" in the 80s with other rock legends Bob Dylan, Roy Orbison, Tom Petty, and Jeff Lynne. George Harrison died of cancer on November 29, 2001. Ringo still tours the world with his "All Starr Band" and was knighted in 2018.

paragraphs: The Beatles made 13 very successful albums during their active years from 1960-1970. Listed below are the albums made during their career.