Albert Einstein

Imagine completely changing the way in which people see the world. What an amazing achievement that would be. How famous you would become! That is what happened to Albert Einstein.

ALBERT EINSTEIN’S CHILDHOOD

Albert Einstein was born in Ulm, in southern Germany, on March 14, 1879. He was the eldest child of Hermann and Pauline Einstein.


When Albert was still a baby, the family moved to nearby Munich. Hermann set up an engineering business there with his brother, Jakob. Albert was an unusual child who did not start to talk until he was three years old. But he seemed fascinated by the natural world, and he loved music. He began learning to play the violin at the age of five and became a fine musician.

At school, Albert did not like the strict timetables and he found the lessons boring. His teachers thought him lazy and a dreamer.

Things did not go well for the Einstein family. Their business was failing and Albert’s parents decided to leave Germany and move to Milan in Italy. Albert left school in Munich to join them there. He was now a young man.

EINSTEIN IN SWITZERLAND

After a year in Milan, Einstein went to Switzerland to study. There he trained to teach physics and mathematics at the Swiss National Polytechnic in Zurich. Einstein did not enjoy formal studies. He missed classes, preferring to study physics on his own. He only managed to pass his exams by borrowing the notes of a classmate.

The professors at the polytechnic were not impressed. Einstein could not become a university teacher, so he worked as a tutor until 1902 when he got a job as a technical assistant in the Swiss Patent Office in Bern.

During the day, Einstein worked at the Patent Office, but in his spare time he was developing his ideas in physics. In 1905 Einstein received a doctorate from the University of Zurich. He also published three very important scientific papers.

One paper was about the movement of atoms. The second was about the nature of light. For many years, scientists thought that light was a wave. Einstein showed that it sometimes acted as a particle. Isaac Newton had suggested that light was a stream of particles in the 17th century. Now, Einstein showed that he was right, at least in some situations.

The third paper challenged the way that Newton had looked at the world. It introduced the first of Einstein’s famous theories of relativity. In his Special Theory of Relativity, Einstein started to think about space and time in a new way. He looked at things moving in relation to each other, such as a train overtaking a car. From these studies he found that there was something special about the speed of light. The speed of light (measured in a vacuum, or empty space) is always the same. And nothing can travel faster than the speed of light.

Strange things happen to objects moving close to the speed of light. If we watched a spaceship going faster and faster, until it was travelling close to the speed of light, we would see the clocks on the spaceship going slower. As the spaceship reached the speed of light, the clocks would look to us as though they had stopped!

Another idea that Einstein introduced was that energy and matter can be changed from one to the other. He wrote an equation to show how the two are connected: E = mc2. It is probably the most famous equation in the world.

These ideas were startling at the time. Very few people understood Einstein’s work. But some scientists did, and they realized its importance. The universities started to take a serious interest in this Patent Office clerk.

GERMANY AND FAME

For a few more years, Einstein continued to work at the Patent Office. He then moved into a university teaching post. He taught at Prague and Zurich, and ended up teaching in his old polytechnic. In 1913 he returned to Germany. He was made director of the Kaiser Wilhelm Institute for Physics in Berlin. He was also a professor at the University of Berlin. Einstein had left the Patent Office far behind.

He continued to work on his new view of space and time. Then in 1916 he published the General Theory of Relativity. It caused a sensation.

For over 200 years, Newton’s theory of gravity had been used to describe how things fall to Earth and how planets orbit the Sun. But it did not always give the orbits exactly. There was a particular problem with Mercury’s orbit, which did not quite fit. And there was another problem: Newton did not really explain gravity. He just said that things attract each other.

Einstein’s General Relativity showed that space and time are very closely linked. We should really think of them together, as space-time. Einstein showed how any object with mass changes the space-time around it, rather like a ball creates a curve in a rubber sheet it is sitting on. This curving of space and time is felt as gravity.

The idea seemed incredible, but it solved all the problems with the planetary orbits. And like all good theories in science, General Relativity made predictions that could be tested. If Einstein’s ideas were right, then the light of a star appearing behind the Sun would be bent by the Sun’s mass. This could only be tested during a solar eclipse, when the Sun’s dazzling disc was hidden. There was an eclipse in 1919. Across the world, people waited eagerly as Einstein’s theory was put to the test. His prediction proved to be right.

Einstein became very famous. He was surrounded by photographers and newspaper reporters, and showered with honours. In 1921 he was awarded the Nobel Prize for Physics.

WAR AND AMERICA

Einstein had strong beliefs about politics. He spoke out against Germany’s role in World War I. At that time he was a pacifist—someone who is against all war.

Later, his beliefs changed. Einstein was Jewish. He was involved in the movement (called Zionism) to create a state of Israel where Jews from all over the world could settle. Even though he was now a celebrated scientist, he was hated by those who hated all Jewish people. When Adolf Hitler and the Nazis came to power in Germany in 1933, Einstein left for the United States.

Though he had been a pacifist in World War I, Einstein believed that Hitler had to be stopped. Like others, he was worried that Hitler might be developing a powerful new kind of bomb—the atomic bomb. But in the end it was the United States that used two atomic bombs against Japan in 1945. After World War II, Einstein took part in campaigns demanding that all atomic bombs, now known as nuclear weapons, should be removed.

In the United States, Einstein joined the Institute for Advanced Study in Princeton, New Jersey. He was by now the most famous scientist in the world. He still kept working to try to find an even grander theory than his relativity—one that would bring together all the forces we know about.

There were other developments in physics. New ideas were spreading about the way tiny particles far smaller than atoms behave. The world of the very small—the quantum world—was turning out to be amazing too. But Einstein could not accept these new thoughts, although he had suggested startling ideas himself. He tried to develop his theory without them. And in this he failed.

Albert Einstein died at Princeton on April 18, 1955. His work had changed the way we understand the universe.

Charles Darwin

Charles Darwin was quiet and shy and disliked crowds. He did not want fame, but became one of the most famous scientists of all time. He suggested a theory explaining how living things gradually change, or evolve, over great periods of time. Those animals with features better matched to their surroundings are more likely to survive. These features will then be passed on to the animal’s children. Over very long periods of time, this process gradually means the animals change to suit their environment. New kinds of living things appear as older ones die out. This idea, the theory of evolution by natural selection, caused huge arguments in Darwin’s time. But it is now one of the most important ideas in all of science.

SCHOOL AND STUDIES

Charles Robert Darwin was born in Shrewsbury, Shropshire, on February 12, 1809. His family was wealthy, and his grandfather and father were well-known doctors. His mother died when Charles was eight, so his elder sisters looked after him.

Charles was not especially clever at school, but he was keen on nature and used to collect insects and worms in boxes. In 1825 he went to the University of Edinburgh to study medicine. Unfortunately, he felt sick at the sight of blood, so he moved to Cambridge University, to prepare for joining the Church. What Charles really wanted to do was to be a naturalist and study animals and plants.

OFF AROUND THE WORLD

In 1831, at the age of 22, Darwin joined the ship HMS Beagle, as the naturalist on a round-the-world scientific expedition. The expedition set off under the command of Captain Robert Fitzroy to make maps of South America’s coastline. Darwin went ashore at several places to study wildlife and collect specimens of plants, animals, rocks and fossils. He was amazed by an earthquake in Chile that raised the shoreline by over one metre. Darwin began to think about how the Earth’s surface is always changing, an idea he read in Principles of Geology (1830-1833) by British scientist Charles Lyell.

IMPORTANT ISLANDS

If the land and sea gradually changed, then Darwin wondered whether the same thing happened to animals and plants? His visit to the Galapágos Islands in the Pacific Ocean was especially important. Darwin saw how animals were very similar from one island to the next, yet slightly different. He imagined how giant tortoises, mockingbirds and finches gradually changed or evolved due to the slightly different food and other living conditions on each island.

BACK AT HOME

The Beagle returned after five years and Darwin set to work in London, studying all the specimens that he had collected. His book of the voyage, Journal of Researches (1839), sold very well. Darwin read An Essay on the Principle of Population (1798) by Thomas Robert Malthus. Malthus showed how humans and other living things produced far more offspring than could survive. Darwin realized that there must be reasons why some offspring lived but others died. Perhaps nature chose, or selected, the survivors? In the 1840s he developed this idea, but kept it private. It would offend many people who believed in the Bible and that animals and plants, created by God, were unchanging.

AN INSTANT BEST-SELLER

In 1839 Charles Darwin married Emma Wedgwood and moved to Down House in Downe, Kent. They had ten children, but three died when they were babies. Darwin began to suffer long illnesses, perhaps due to a disease caught in South America. In 1858 he received a letter from Alfred Russel Wallace, a naturalist travelling in Malaysia. Wallace described ideas on evolution very similar to Darwin’s own. Darwin was persuaded to give a talk on the topic in London, to the Linnean Society, and to finish his own book. This he did in 1859. On the Origin of Species by Means of Natural Selection sold out on its first day, and has been a best-seller ever since.

A HUGE ARGUMENT

As Darwin had expected, his book caused a storm of arguments. Many people saw that the idea of evolution could be applied to humans, and made fun of the idea that we are related to apes. Darwin was very upset by this. Many others soon saw the scientific sense in Darwin’s work. In particular, he was supported by Thomas Henry Huxley, who became known as ”Darwin’s Bulldog”.

A QUIET LIFE

In his later life Darwin stayed at home, quietly studying nature. He wrote several more books on breeding new garden plants, animal pets and how earthworms are “nature’s gardeners” and enrich the soil. In 1871 he tackled human evolution from apes, in The Descent of Man. Gradually, he was given many honours and awards, including a fellowship of the Royal Society. When he died on April 19, 1882, he was a world-famous scientist and was buried with great ceremony in London’s Westminster Abbey.

Did you know?

• Charles Darwin left medical school because he was squeamish and did not like dissection or surgery.
• In 2000, Charles Darwin's picture replaced that of Charles Dickens on the Bank of England's new £10 notes.
• After leaving medical school, Charles Darwin went to Cambridge University to study theology. However, he spent a lot of time collecting beetles instead of studying.

John Dalton

In the early 19th century John Dalton, a British schoolteacher and chemist, was fascinated by the patchwork puzzle of chemical elements. His understanding of atoms and how they combined to form different elements led to a revolution in scientific thought and helped create the modern world.

JOHN’S EARLY LIFE

John Dalton was born on September 6, 1766, in the village of Eaglesfield, in Cumberland (now Cumbria). His parents belonged to the fundamentalist Christian movement known as the Quakers and he was educated at the Quaker village school. Young John was so good at his studies that when he was 12 he became a teacher there. In 1781 he became a teaching assistant at the Quaker school in Kendal, and four years later became joint principal with his brother. While there he came under the influence of the wealthy, blind scientist John Gough, who taught him mathematics, meteorology and botany.

In 1793, Dalton was appointed professor of mathematics and natural philosophy at New College, Manchester. This college was established by followers of the Presbyterian Church movement. Before this, only members of the Church of England could attend university. In 1800 he became secretary of the Manchester Literary and Philosophical Society. It was at this time that Dalton became interested in chemistry, and in how the various chemical elements combine with one another to form chemical compounds.

DALTON’S DISCOVERIES

In 1803, Dalton suggested that the tiniest particles of a chemical element are atoms of that element. This had been suspected by many thinkers since the time of the Ancient Greeks, but Dalton was the first to use science to show that it could be true. He realized that atoms of different chemical elements join together in fixed numbers based on their weights to make chemical compounds. This achievement was known as his atomic theory.

At first, some scientists did not agree with his atomic theory, but by the end of the 19th century lots of evidence showed that he was largely right. Dalton also believed that atoms could not be divided up, but we now know that this is not true. There is a whole world of particles, such as electrons, smaller than atoms. This did not matter at the time though. Dalton had shown the world that atoms are the basic building blocks of the objects we see around us and that all our chemistry is about atoms.

FURTHER SCIENTIFIC RESEARCH

Dalton’s later work concentrated on atomic weights. He was the first scientist to understand that chemical elements could be classified according to their atomic weights. He realized the importance of atomic weights after studying how gases dissolved in water. He concluded that their mixing depended on the weight of the individual atoms of the gases. He devised a system of chemical symbols and formulae and drew up a table of the atomic weights of all the elements then known.

His theory of atomic weights contained errors. At first, he had not realized that atoms group together to form molecules. In 1811 this idea was shown by Italian physicist Amedeo Avogadro to be true. But Dalton’s general idea was right, and a precise value could then be given to the mass of each atom.

His studies of the Earth’s atmosphere contributed a great deal to meteorology. He was the first person to confirm that rain is caused by a drop in temperature and not a change in atmospheric pressure, as previously thought. He also studied aurora, the dancing “lights” seen at the north and south poles, as well as the Earth’s magnetism and wind system. His studies of gases led to Dalton’s Law, which states that the total pressure of a mixture of gases equals the sum of each of the pressures of the gases in the mixture. This was a very important law in chemistry.

Dalton also became the first scientist to describe the medical condition known as colour blindness. This is a defect of vision affecting the ability to distinguish between colours. He had the condition (and so did his brother), and the first of his many readings to the Manchester Literary and Philosophical Society in 1794 was devoted to it.

MODEST MAN OF SCIENCE

Dalton’s ideas brought him great fame and changed the study and use of science everywhere. He gave many scientific lectures throughout Britain. In 1817 he became president of the Manchester Literary and Philosophical Society, a post that he held until his death. The French Académie des Sciences elected him as one of their eight foreign associates in 1830. He also helped found the British Association for the Advancement of Science in 1831.

In private he lived a simple and quiet life as a Quaker. He had few friends and never married. He was deeply dedicated to the search for answers to scientific problems.

Following a stroke in 1837, Dalton became an invalid. He died in Manchester on July 27, 1844, and was given a funeral by the city that was attended by 40,000 mourners. Since 1884 there has been a statue to him in the entrance to Manchester Town Hall.

Galileo Galilei

Galileo Galilei was one of the first modern scientists, and made exciting discoveries about stars and planets using his telescope. He also found out about how things move as they fall to Earth. He was important because of the way he did his work. He observed carefully how things behaved and took notes. He then set up experiments to test his theories.

Galileo knew how to focus on what really mattered in a problem. And he did not just use words to describe how things move. He used mathematics. That meant he could say things very precisely.

Galileo was an important figure in the Scientific Revolution. This brought a new way of thinking to Europe in the 16th and 17th centuries.

GALILEO’S EARLY LIFE

Galileo was born near Pisa, in Italy, in 1564. He lived in Italy all his life. His father was a music teacher. When he was a child, Galileo studied in a monastery. He liked the quiet way of life there and wanted to become a monk. But his father sent him to the University of Pisa to study medicine. Galileo did not find medicine interesting and preferred mathematics. He eventually gave up his medical studies and taught mathematics instead. Soon, important mathematicians started to take notice of him. He became a professor of mathematics and taught at the universities of Pisa and Padua. His work made him famous. The powerful Grand Duke of Tuscany, Cosimo de’ Medici, made him his court mathematician.

GALILEO’S FIRST EXPERIMENTS

In Galileo’s time, people’s ideas about the world came mainly from the famous Greek philosopher Aristotle. Aristotle had said that heavy objects fall more quickly than light ones. Galileo found that Aristotle was wrong. He showed that if you drop a light object and a heavy object from the same height, they will speed up at the same rate and reach the ground at the same time. This was a surprise. It went against Aristotle’s ideas and common sense. But Galileo’s experiments showed that it was true.

Galileo also looked at pendulums. He found that they take the same time to complete a swing, however far they swing.

WHAT DID GALILEO DISCOVER?

In 1609, Galileo heard of an amazing Dutch spyglass that could make faraway things seem close at hand. He was fascinated. Soon he was making his own telescopes. They were much better than the early Dutch ones. Then one day he turned his telescope to the night sky. What he saw astonished him. Galileo found that the Moon had mountains, valleys and craters. He discovered that Jupiter had four little stars of its own going round it (he was seeing Jupiter’s four biggest moons). He found that the pale glow of the Milky Way was in fact the light of many thousands of faint stars. He watched sunspots. And he saw that the planet Venus showed phases, appearing as waxing and waning crescents just like the Moon.

These discoveries did not fit in with people’s ideas about the universe. Aristotle had taught that the heavenly bodies were smooth and perfect spheres. Yet the Moon clearly was not like that.

Aristotle and the Greek astronomer Ptolemy had believed the Sun and planets went round the Earth. In 1543 a book by Nicolaus Copernicus, a Polish astronomer, suggested that the Earth and planets went round the Sun instead. By Galileo’s time, many people thought it was true that the planets went round the Sun, but they still believed the Sun went round the Earth. Galileo could see that his work supported Copernicus. But Copernican theory went against the teaching of the Catholic Church. The Bible said that the Earth did not move, and was at the centre of the universe.

GALILEO AND THE CHURCH

In Galileo’s day, people could be tried and even killed as heretics if they wrote books that went against the Church’s teaching. The Inquisition was responsible for trying heretics. Galileo hoped he would be safe because the Pope liked his work. So he wrote a book showing that he believed that Copernican theory was probably true. But the book was banned and Galileo was tried by the Inquisition. He was forced to say he had been wrong, and was sentenced to life imprisonment, although he was allowed to live at home. He carried on working on moving objects, and wrote his most important book in these last years. Galileo died in Arcetri, near Florence, in 1642.


Galileo’s trial became famous. He had not wanted to go against the Church. He was a religious man. But he felt that people should accept what science had shown to be true when they interpreted the Bible. He thought you should not believe it blindly word for word.

Galileo only had simple telescopes. And not all of his arguments were correct. But now we have plenty of evidence that the Earth is just another planet going round the Sun. We have even found planets orbiting other stars.

Did you know?

• When Galileo left the University of Pisa in 1585 he did so without having passed his degree, although it had been medicine that he was studying and not the astronomy or physics that he would later be acclaimed for.
• In 1992 the Roman Catholic Church officially apologized for condemning Galileo to life imprisonment for going against their teachings in claiming that the Earth revolved around the Sun and not the other way round. After almost five centuries the Church had finally admitted that it was wrong and that Galileo was right.
• Legend has it that Galileo dropped two objects from the Leaning Tower of Pisa to show that if you drop a light object and a heavy object from the same height, they will speed up at the same rate and reach the ground at the same time. This story was first told by his last pupil and first biographer, Vincenzo Viviani, although many believe that at best it is more probably an exaggerated version of an actual event.

Leonardo da Vinci

Leonardo da Vinci is one of the greatest artists who has ever lived. He is also among the greatest scientists. He experimented with unusual ways to mix paint and use colours. He created new painting techniques and original ways to compose pictures. He studied everything he saw—from living things to machines, using his incredible drawing skills to record them in detail. Then he used his observations to think up plans for inventions that were not built until hundreds of years later, such as a telescope, a tank and a helicopter!

LEONARDO’S CHILDHOOD

Leonardo was born on April 15, 1452, in the small town of Vinci, near Florence, in Italy. (His name means in Italian, “Leonardo of Vinci”.) His father was a wealthy Florentine official who did not marry his mother, a simple peasant woman.
Leonardo was brought up by his mother’s family in the beautiful Tuscan countryside. As a small boy, he spent hours exploring the woods, fields and streams. He loved to watch insects, animals and birds, and to examine different plants and flowers, then make sketches of them. His restless curiosity, interest in nature and keen eye for observation shaped the whole course of his life.

LEONARDO BECOMES A CRAFTSMAN

At the age of about 12, Leonardo went to live with his father in Florence. The great city was then a bustling centre for training master artists and for brilliant students of literature and science. Leonardo was sent to school to learn reading, writing and maths, and he became a fine musician. However, he showed such a talent for drawing that he was taken on as an apprentice by one of the leading artists in the city, Andrea del Verrocchio.

In Verrocchio’s workshop, Leonardo began to learn how to mix different types of paint, make brushes and prepare canvases for painting. He studied the art of fresco (painting using watercolours on wet plaster) and learnt how to sculpt. Artists in those days knew many other skills. Wealthy people paid Verrocchio to create bronze church bells, musical instruments and furniture, to make compasses for ships and to cast objects in gold and silver.

Leonardo studied all the crafts in the workshop, and became fascinated by the variety of tools and machines used there. He examined how each of the pieces of technical equipment worked and made careful drawings of them. Leonardo carried a sketchpad with him at all times, so he could make accurate drawings of anything around Florence that interested him. He began to think about how everyday machines worked, such as the waterwheels that turned millstones to grind corn. And he studied the specialist machines being used on an enormous construction site where the city cathedral was being built.

AN ARTIST IN FLORENCE

By 1472, Leonardo had finished his apprenticeship with Verrocchio. However, he stayed working in the great craftsman’s workshop as his assistant. Verrocchio thought the 21-year-old was so skilled that he allowed Leonardo to help with a masterpiece he was working on called The Baptism of Christ. Leonardo painted an angel kneeling in the left of the picture, and some of the background. He used delicate colours to show feelings on the angel’s face, and tried a new idea for painting haziness in the landscape to try to show distance. In those days, artists could only paint flat pictures; they did not know how to show perspective.
By 1478, Leonardo had set up a workshop of his own. Two of his first paintings were gentle, touching portraits of Mary with baby Jesus, called Madonnas. Between 1480 and 1481 he also created a lovely, small painting called the Annunciation, showing the Bible story of how Mary was once visited by an angel. Leonardo brilliantly captured the meeting of the human and the spiritual worlds by setting the figures in a deep, misty, magical landscape, with exquisitely detailed, lifelike wildflowers and plants around the angel’s feet.

Many wealthy people in Florence began to ask Leonardo to create works of art for them—in particular the ruler of the city himself, the great Lorenzo de’ Medici. Strangely, Leonardo never carried out work on one big order, which was for a painting in the chapel of a palace, the Palazzo Vecchio. He also left several other works unfinished. One of these was a portrait of St Jerome. Another was an order from a monastery for his first large-scale painting, The Adoration of the Magi, showing the visit of the Three Wise Men to baby Jesus. Perhaps Leonardo did not finish the paintings because he was engrossed with other work he was doing in private. Leonardo was not only still studying and sketching machines, such as pumps and army equipment. He was also planning new machines of his own.

WORK AT THE COURT OF MILAN

In 1482, Lorenzo de’ Medici sent Leonardo on an important mission. He asked him to take a silver musical instrument called a lute as a peace offering to the warlike ruler of Milan, Duke Lodovico Sforza. Leonardo wrote a daring personal letter to deliver to the duke at the same time. In it, he described the amazing ideas he had for incredible new machines, which would be perfect for the Duke’s army. These included armoured vehicles, moveable bridges and original designs for catapults, cannons and other weapons. At the end of the letter, Leonardo added that he also happened to be a skilled painter, sculptor and musician. He offered to create a bronze horse statue to honour the Duke’s father.

The Duke was highly impressed and invited Leonardo to work for him as an engineer and painter. Leonardo set up a studio with pupils and assistants helping him on many different projects. From 1483 to 1485 he worked on two versions of a wonderful picture called The Virgin of the Rocks. Then he was asked to paint a massive fresco on the wall of a dining room in a monastery. For the next two years, Leonardo created a masterpiece called The Last Supper, which showed the final meal Jesus Christ shared with his close followers.

However, much of Leonardo’s time was taken up with scientific studies. He was employed on the duke’s many war campaigns, advising on new ideas for weapons and building defences. He also produced models for the building of a magnificent dome for Milan cathedral, drew up plans for other great buildings, and designed theatre sets and costumes. He studied how humans and animals moved, explored possibilities for inventing flying machines, and thought deeply about the moon, stars and planets. He also became firm friends with a mathematician called Luca Pacioli, who was working on the relationship between distances. Leonardo made a series of drawings to illustrate Pacioli’s ideas, and studied how he could use mathematical rules to create paintings that looked solid, deep and lifelike.

FOUR YEARS IN FLORENCE

Leonardo stayed in Milan for 18 years. Then at the end of 1499, French soldiers attacked the city and conquered it. The 48-year-old artist returned to Florence once more. Not long afterwards Florence was caught up in its own war against the city of Pisa. In 1502, Duke Cesare Borgia asked Leonardo to become his chief architect and engineer. He worked hard, designing and building forts. He also drew up plans to cut off Pisa’s water supply and force the city to surrender. His brilliant ideas involved changing the direction of a river and also building canals, but these were not carried out.

Leonardo saw horrors during the war, which inspired him to plan an enormous painting called the Battle of Anghiari for the great hall of the Palazzo Vecchio. However, he only got as far as making detailed sketches and a full-size drawing. Instead, Leonardo turned to studying the flight of birds and experimenting further with his designs for flying machines. He also painted several famous portraits. The only one that still survives is a captivating picture of a woman with a mysterious smile, called the Mona Lisa. It is probably the most famous painting in all the world today.

LEONARDO’S LATER YEARS

In 1506, Leonardo returned to Milan, at the request of the French governor there. The King of France himself, Louis XII, was living in Milan at the time, and just a year later he appointed Leonardo to be his court painter. However, Leonardo continued to devote lots of time to engineering projects and scientific investigations, such as examining fossils to work out what they were.

After the governor of Milan died, Leonardo went to Rome in 1514 to work for the brother of the pope. Although he completed one magnificent painting, a portrait of St John the Baptist, he spent most of his time studying and experimenting. By examining animal parts from a butcher’s shop, he produced brilliant models of how the heart works. He tried making giant, rounded mirrors because he wanted to see the moon and stars close-up. And by studying he plants he discovered that the same patterns exist in many natural things.

Shortly after the pope’s brother died, in 1516, Leonardo went to live and work in France. He was 64 years old. King Francis I gave Leonardo the title of “First painter, architect and mechanic of the king”, and set him up in a house near his own palace in Amboise. He paid Leonardo well and left him to do as he pleased, visiting him now and again to enjoy fascinating conversations. Leonardo began the huge job of sorting out all the scientific papers he had produced during his lifetime. He died before he was able to finish, on May 2, 1519.

Did you know ?

• Leonardo never finished the horse statue he offered to make for the Duke of Milan. He got as far as creating an enormous clay model, but when the French armies invaded the city, they destroyed it by using it for archery practice!
• When Leonardo wrote in his notebooks, he wrote backwards (from right to left) using 'mirror writing'. No one is sure why. Some people think that he wanted to make it hard for others to read his studies and steal his ideas. Other people think that it was just easier for him, because he was left-handed. Whatever the reason, when Leonardo wrote documents for other people to read, he wrote in the usual way.
• In Leonardo's day, very few people grew up left-handed like him. Everyone was very supersitious and many believed that the left side of the body was evil and unlucky. Children who showed signs of being left-handed were usually forced to using their right hand instead. Leonardo was also a vegetarian, which was equally unusual in those times.
• Leonardo was buried in the palace church at Amboise in France. However, the building was destroyed three hundred years later, during the French Revolution, so his grave can no longer be found.

Michael Faraday

Whenever you turn on a light, listen to a CD or watch the television, you will probably not think about it, but you are doing something that owes a great deal to the life and work of the English scientist Michael Faraday.

In the 19th century he worked on electricity and magnetism. His work helped others understand the science of electricity and magnetism. This eventually led to the development of everyday conveniences and luxuries that we take for granted today. Faraday was one of the greatest and most important scientists in history.

WHAT WAS HIS EARLY LIFE LIKE?

Michael Faraday was born in Newington Butts, Surrey, on September 22, 1791. His father was a blacksmith. The Faradays were a deeply religious family and belonged to a small sect of Christianity called the Sandemanians. Michael was committed to this sect for the whole of his life. In 1821 he married a fellow Sandemanian, Sarah Barnard, and was later both a deacon and an elder in the Church.

A DEVELOPING INTEREST IN SCIENCE

Michael attended a day school in London before being apprenticed as a bookbinder between 1805 and 1812. During his apprenticeship he developed a great love of reading. He also developed an interest in science after attending various scientific lectures, especially meetings of the City Philosophical Society in Fleet Street. In 1812 he attended the Royal Institution to hear the final four lectures of the great English chemist Sir Humphry Davy. He made detailed notes of the lectures and sent them to Davy asking for a job. The following year, Davy appointed Faraday as his assistant at the Royal Institution.

Between 1813 and 1815 he and Davy toured many of the great chemistry laboratories of Europe. Back at the Royal Institution, Faraday continued working on chemistry and helped Davy invent the miner’s safety lamp. By the age of 30 Faraday had become a very senior person at the Royal Institution and was becoming increasingly interested in physics.

WHAT DID FARADAY DISCOVER?

Faraday believed that there was a relationship between electricity and magnetism. In 1819 the Danish physicist Hans Christian Oersted discovered the idea of electromagnetism. He found that a wire carrying an electric current deflects a magnetic needle at right angles to the wire. This showed that an electric current can create a magnetic field. In 1821 Faraday began experimenting with electromagnetism. He demonstrated how electrical energy can be converted into mechanical energy—and thus invented the world’s first electric motor.

Another great idea came in 1831. Oersted had earlier shown that an electric current can create a magnetic field, but Faraday now discovered that a magnetic field could be used to create an electric current. This was known as “electromagnetic induction”. He showed it by moving coils of copper wire inside a magnetic field, causing an electric current to flow in the wire. The discovery helped him to create the world’s first electric dynamo—a machine that converts mechanical energy into electrical energy.

With his inventions of both the electric motor and the electric dynamo, Faraday showed that electricity could be produced and controlled by man. As we know now, one day it would be used to provide the power for our homes, factories, hospitals, streets and much more.

MORE SCIENCE

Faraday also investigated an area of science known as electrochemistry, which deals with the relationship between electric currents and chemical reactions. In 1834 he established the basic laws of electrolysis when he discovered that acids, bases and salts are electrolytes. This means that when acids, bases and salts are dissolved in water they produce a liquid solution that contains charged particles or ions that can conduct an electric current. Faraday also developed a liquid version of the gas chlorine and identified the gas called benzene. He also invented the words anode, cathode, electrode and ion. As well as all this he made great contributions to the studies of light and gravity.

In 1826 Faraday started the Royal Institution Christmas lectures for children. These continue today and have been televised each year since 1966. Faraday delivered many lectures himself and became one of the most popular scientific speakers of the day. In 1833 he became professor of chemistry at the Royal Institution.

Faraday also worked for the British government. From 1830 until 1851 he was professor of chemistry at the Royal Military Academy, Woolwich. There he worked on improving explosives. Between 1836 and 1865 he was scientific adviser to Trinity House, which meant that he oversaw the programme to electrify all the lighthouses around the British Isles. The government was very pleased with Faraday’s work and granted him a generous pension, although he refused the offer of a knighthood.



Faraday had become very famous. His portrait was often painted and he was one of the most photographed men in the country. In 1858 Queen Victoria and Prince Albert gave him a home for free at Hampton Court Palace. It was there that he died on August 25, 1867.

Faraday’s work greatly advanced our understanding of science and made it of practical use to us all. He helped change the world.

Isaac Newton

On Christmas Day, 1642, a boy was born in the manor house of Woolsthorpe, near Grantham, in Lincolnshire. He was born prematurely and was tiny, but he survived to become one of the greatest scientists the world has ever known.

NEWTON’S CHILDHOOD

Isaac Newton was named after his father, a farmer who had died a few months before Isaac was born. When Isaac was two years old, his mother Hannah married again. Isaac was brought up at Woolsthorpe by his grandmother. He did not like his mother’s remarriage and hated his stepfather, the Reverend Barnabus Smith.

His mother had three children by her second husband. When Isaac was 11, his stepfather died, and his mother, stepbrothers and sisters moved to live with him and his grandmother.

Isaac was sent to the Free Grammar School in Grantham. It was 8 kilometres from home, and he stayed with a family in the town. Isaac’s school reports were not very good and his mother thought he might be better off managing the farm. But Isaac did not get on too well with that either. Luckily, an uncle noticed his cleverness and love of learning. He persuaded Isaac’s mother to send him back to school. He also encouraged Isaac to go to university.

NEWTON GOES TO UNIVERSITY

In 1661 Newton entered Trinity College, at the University of Cambridge. He studied law, but he had a lot of freedom in his studies and he became interested in mathematics and astronomy. He read about the work of the astronomers Nicolaus Copernicus and Johannes Kepler, and worked through many mathematics books by himself. His mind was buzzing with ideas.

In 1665 the university was closed because of the Great Plague, which swept through southern England, killing thousands. Newton went home and for a year worked on mathematics and physics and developed his theory of gravity. This was probably the most creative time in his life.

NEWTON BECOMES A SCIENTIST

Back at the University of Cambridge, people began to recognize his ability. In 1669, at the age of just 27, he became a professor of mathematics there. For nearly 20 years, as well as giving lectures, Isaac Newton worked on his ideas in mathematics and physics. Many scientists admired his work. One was Edmond Halley, an important astronomer. Halley encouraged Newton to write up his work and publish it.

Newton needed the encouragement. He was a shy man, but could become angry if his work was criticized. He held long-lasting grudges. He did not publish his work for years because he was afraid it might be attacked.

In 1671 Newton was made a Fellow of the Royal Society—a society in London that only very important scientists are invited to join. He had been experimenting with light and told the Royal Society about his discoveries. Another important scientist belonging to the society, called Robert Hooke, did not agree with his ideas. Nor did the Dutch scientist Christiaan Huygens. Newton and Hooke became enemies, though they were polite in public.

In 1687 his friend Halley published Newton’s most famous work. It was written in Latin. It was called Philosophiae Naturalis Principia Mathematica, or Mathematical Principles of Natural Philosophy (science was called “natural philosophy” in those days). It is usually known as the Principia.

In this work, Newton described his theories about liquids and gases, and presented his theory of gravity. It was widely admired. But Hooke said that Newton had taken some of his ideas. Newton and Hooke continued their quarrel for years. Newton waited until Hooke died in 1703 before publishing his work on light.

Newton’s work on mathematics involved him in another argument. During the year he spent at home because of the plague, he had started to work on the mathematics of things that change. We now call this branch of mathematics calculus. Another famous scientist, Gottfried Leibniz, had come up with the same ideas a little later than Newton. They argued about who invented calculus first. The argument lasted until Leibniz died in 1716, and even after that.

All this anger and resentment led Newton to a nervous breakdown in 1678, and another in 1693. He turned away from people and shut himself away for long periods. Newton was deeply religious. Alongside his work in science, he pored over the Bible. He thought there were deep meanings hidden in its words. He was also fascinated by alchemy—the attempt to change different substances into gold.

MASTER OF THE MINT

Newton joined the Royal Mint in London in 1696. The Royal Mint makes the coins used as money. Three years later he became Master of the Mint and a rich man, but he never married, and he lived simply.

Newton was now 57 years old. For the rest of his life he was in charge of the Royal Mint. He also kept up his argument with Leibniz. In 1703 Newton became president of the Royal Society. Two years later he was knighted Sir Isaac Newton by Queen Anne.
Isaac Newton died in London on March 20, 1727, at the age of 85. He was the first scientist to be buried in Westminster Abbey.

WHAT WERE NEWTON’S ACHIEVEMENTS?

Isaac Newton is most famous for his theory of gravity. The story goes that he was sitting in the garden one day when he saw an apple fall from a tree. He wondered why it did not just float in the air instead of falling.

He realized that the force that made the apple fall to the ground was the same as the force that kept the Moon going round the Earth. He was able to describe the orbits of all the planets using this force—the force of gravity. But there were problems with his theory too. One basic problem was that Newton never really explained gravity. He just said that any two masses pull each other.
The problems were only solved many years later, in the 20th century, when Albert Einstein worked out his Theory of General Relativity. But Newton’s theory was good at describing the way objects fall and how planets orbit the Sun. We still use it for many things.

Newton also showed that white light is a mixture of all the colours of the rainbow. He used a prism to split white light into its separate colours. He made many other studies of light. Newton believed that light is a stream of particles. Other scientists agreed with Christiaan Huygens that light must be a wave. Now we know that Newton was not wrong—light acts as both a particle and a wave.
Newton’s interest in light came from his efforts to make a good telescope. He invented a reflecting telescope, which used mirrors instead of lenses, in 1668. We call them Newtonian telescopes.

He also invented the mathematical method of calculus. Though Leibniz invented the same method, Newton had thought of it earlier. We now use calculus as a basic tool in many problems in science and mathematics.

Newton’s Principia is often described as the greatest scientific work ever written. It seems hard to believe that one person could achieve so much. Newton could be difficult, and sometimes unpleasant, but he devoted his life to searching for truth and he knew that there was a great deal more to learn. He wrote:

“To myself, I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.”

Did you know?

• In addition to being a great scientist, Isaac Newton was also a Member of Parliament. He tried to prevent King James II from turning the universities into Catholic institutions and was elected Member of Parliament for the University of Cambridge in 1689 to make sure that this did not happen.
• Isaac Newton was a deeply religious man and he devoted a great deal of his time to investigating religion. In fact he owned more books on that subject than he did on science. He also sought to find evidence in the Bible for much of the mythology of Ancient Greece.
• Some people today have accused Isaac Newton of trying to destroy the reputation of the scientist Robert Hooke, with whom he had lots of arguments. Although no real evidence supports this, many believe that some of Newton's great scientific ideas were actually those of Hooke.

Thomas Edison

One of the most remarkable and creative people ever to have lived was an American inventor and scientist called Thomas Edison. In the late 19th and early 20th centuries he created hundreds of inventions that greatly changed everyday life—and his influence is still felt today. Without Thomas Edison we may never have had lights in our home, or the opportunity to buy music from shops or to visit a cinema to see the latest blockbuster. It is hard to imagine life without these things.

EARLY LIFE

Thomas Alva Edison was born in Milan, Ohio, on February 11, 1847. He attended school for only three months. As an 11-year-old boy he worked in the family market garden, delivering produce on a pony and trap. His main interest at this time was science, and he had a great thirst for technical knowledge. In his spare time he experimented with printing presses and with electrical and mechanical equipment. When he was 12, in order to buy books and chemical apparatus to continue his studies, he began selling newspapers and country produce on the Grand Trunk Railway. He even had a laboratory in a compartment on the train. In 1862 he began publishing the Grand Trunk Herald, a weekly newspaper that he produced on board the train.

FIRST INVENTIONS

At 16 he saved the life of a railway station official's child and was rewarded by being taught telegraphy, which he soon mastered. He moved about from one station to another, working as a telegraph operator for the Grand Trunk Railway, and within a year he was working for the Western Union Telegraph Company. The railway brought him into contact with engines and electricity, and he soon made his first important invention: a telegraphic repeating instrument that enabled messages to be transmitted automatically over a second line without the presence of an operator.

Edison moved to Boston, Massachusetts, and devoted all his spare time to research. In 1868 he gained his first official patent for an invention. It was for an electric vote recorder, for use in the American government’s House of Representatives. It was never used, probably because it was not practical enough. He then invented the Edison Universal Printer. It was the world's first really practical tape printing machine, and was used in stock exchanges and news agencies all over the world.

In 1874 he devised a system of quadruplex telegraphy. This was an automatic telegraph system that made itpossible to transmit several messages on one line simultaneously. For this and the sale of other telegraphic appliances, the Western Union Telegraph Company paid Edison US$40,000. It was a huge sum of money and in 1876 Edison built his own laboratory. He could now afford to invent full time, and he began taking out patents year after year.

MUSIC, LIGHTS AND FILM

Edison's next important invention was the carbon telephone transmitter. This played a vital role in the development of the telephone, which had recently been patented by the American inventor Alexander Graham Bell.

In 1877 Edison invented the phonograph, which was the world's first machine for both recording and playing back sound—it was the equivalent of the CD of today. His phonograph had a tinfoil-covered rotating cylinder onto which mechanically recorded sounds were made by converting vibrations of air into a groove that was engraved on it. He later improved on this with the gramophone, where the sound was impressed onto a disc instead of a cylinder. The gramophone had a diamond needle and other improved features.

Two years later he showed the world his incandescent electric light bulb, which was probably his most important creation. It had taken more research and experimentation to perfect than any of his previous inventions. It was a great success. Now Edison had to create an electrical generating system. He knew that huge electric dynamos would be needed to generate the necessary electric current to power the millions of light bulbs that would illuminate America's towns and cities. In 1882 he developed and installed the world's first large central electric-power station, located in New York. In the future his direct electric current system was bettered by an alternating-current system developed by fellow American inventors Nikola Tesla and George Westinghouse. Soon the major cities of the world were adopting Edison's ideas to power and light their homes, streets, shops and factories.

In 1888 Edison invented the kinetoscope, an early film projector. It was the first machine to produce 'cinema' films, and did so by showing a rapid succession of individual images. By synchronizing his gramophone and kinetoscope, he produced, in 1913, the first sound film. His other later discoveries include the mimeograph (a duplicating machine), the microtasimeter (a machine to detect tiny changes in temperature), a wireless telegraphic method for communicating with moving trains, and the nickel-iron storage battery, which was the result of many thousands of experiments and is very important in heavy industry. His later work consisted mainly of improving and perfecting previous inventions.

A REMARKABLE LIFE

Edison’s great achievements were recognized throughout the world and he was awarded many medals and prizes. In 1878 he was appointed Chevalier of the Légion d'honneur of France and in 1889 was made Commander of the Légion d'honneur. In 1892 he was awarded the Albert Medal of the Royal Society of Arts of Great Britain. During World War I he worked for the United States government, and in 1928 he received the Congressional Gold Medal “for development and application of inventions that have revolutionized civilization in the last century”.

Thomas Edison died in West Orange on October 18, 1931. Many people have made great contributions to life, but few have made as great a contribution as Thomas Edison in shaping modern society.

Did you know?

• In 1882, Edison took out an astonishing 107 patents on new inventions. That is more than one every three days.
• In one of the most famous quotes in history, Edison once said: 'Genius is 1 per cent inspiration and 99 per cent perspiration.' He truly believed in the importance of hard work above all else.
• Sound was first recorded by Thomas Edison in 1877. The first reproduced phrase, 'hello', was actually recorded on a telephone repeater, but Edison invented the more sophisticated phonograph the same year.
• Thomas Edison is known as the inventor of the light bulb, but it is not widely known that he used to sit in a dark cupboard to think up all his best ideas and inventions.
• Edison's home and laboratory in West Orange, New Jersey, where he lived from 1887 until his death, were established as the Edison National Historic Site in 1955.

Nicolaus Copernicus

Can you imagine knowing that you are right about something very important and that the rest of the world is wrong but will not listen? This is exactly what happened to the Polish astronomer Nicolaus Copernicus. In the 16th century he discovered that the Earth and planets revolved around the Sun. It challenged what people had believed for more than 1,000 years.

NICOLAUS’S EARLY LIFE

Nicolaus Copernicus was born on February 19, 1473, in Thorn (now Toruń), Poland. His family were wealthy merchants and town officials. His uncle, Bishop Łukasz Watzenrode, supported him in his education. Nicolaus started at the University of Kraków in 1491 and studied the liberal arts for four years without receiving a degree. In 1497 he became a Church administrator at the cathedral at Frauenberg (now Frombork). In the same year he went to Italy to continue his education—like many Polish men of his high social class. He studied law at the University of Bologna between 1497 and 1501, and then studied medicine at the University of Padua between 1501 and 1503.

AN INTEREST IN ASTRONOMY

Copernicus’s interest in astronomy began while at Bologna, where he lived at the home of a mathematics professor, Domenico Maria de Novara. Together they observed the occultation (the eclipse by the Moon) of the star Aldebaran on March 9, 1497. Domenico Maria was critical of the accuracy of the work of the 2nd-century astronomer Ptolemy. Ptolemy said that the Sun and planets revolved around a unmoving Earth. This idea was generally accepted as true and was strongly supported by the Roman Catholic Church, which was very powerful. Copernicus became more and more unhappy with this view because the evidence of planetary motion did not seem to support it. He began developing his view that the Earth and other planets revolved around a point in space near the Sun. This view would be known as the “heliocentric theory of planetary motion”.

THE SEARCH FOR THE TRUTH

In 1503 Copernicus returned to Poland to take up his administrative duties as canon with the Church. He lived in his uncle's bishopric palace in Lidzbark Warmiński until 1510. The job gave him lifelong financial security and involved no priestly duties. This allowed him the time he needed to study astronomy.

Sometime between 1507 and 1515 he completed a short astronomical essay called De Hypothesibus Motuum Coelestium a se Constitutis Commentariolus (known as the Commentariolus). It was not published until the 19th century. In it he laid down the principles of his new heliocentric astronomy.

After moving back to Frauenberg in 1512, he began his major work called De Revolutionibus Orbium Coelestium (On the Revolutions of the Celestial Spheres), which brought together all of his astronomical ideas. The book was finished in 1530, but was not published for many years as Copernicus feared criticism from the scientific and religious communities. It was finally printed by a Lutheran printer in Nuremberg, Germany (Lutherans were opposed to the ideas of the Roman Catholic Church). Soon after, on May 24, 1543, Copernicus died at Frauenberg.

REVOLUTIONARY IDEAS

Copernicus's major ideas were that the Earth rotates once a day on its axis (wobbling like a top as it rotates) and revolves once a year around the Sun. Also, the planets encircle the Sun.

This view solved many issues. It explained the apparent daily and yearly motion of the Sun and the stars, and why Mercury and Venus never move more than a certain distance from the Sun (that is because they are closest to the Sun). It also explained the apparent retrograde motion of Mars, Jupiter and Saturn. This last problem, in which the motion of these three planets through the sky appears from time to time to halt and then to proceed in the opposite direction, had puzzled astronomers since ancient times.

The planets could now be placed in their correct positions in terms of distance from the Sun. This was because the greater the time a planet takes to make one circuit around the Sun, the greater the radius of its orbit and its distance from the Sun.
Copernicus did not get everything right. His ideas that the stars are in fixed positions in a sphere at the edge of the Solar System and that the planets had circular and not elliptical (oval-shaped) orbits we now know are wrong.

COPERNICUS’S GREAT INFLUENCE

Copernicus’s ideas were new and revolutionary, and the idea of a moving Earth was difficult for most 16th-century scholars to accept. For many years after his death his ideas were either ignored or rejected. The powerful Roman Catholic Church was particularly hostile—especially to the suggestion that the Earth was no longer the centre of the universe.

One of the first people to openly support Copernicus’s ideas was the German astronomer Johannes Kepler. In the early 17th century, Kepler made precise astronomical studies of the motions of the planets that provided clear scientific evidence to prove Copernicus’s heliocentric view of planetary motion was correct. Kepler’s work was later used by both the Italian scientist Galileo Galilei and the English scientist Isaac Newton. These two men were part of a movement that would later be known as the Scientific Revolution. By the late 17th century the Copernican system was the most widely accepted picture of the universe. Nowadays, we know it to be true.

It is clear that much of what we know today about our world and its place in the universe began with Nicolaus Copernicus.

Did you know?

• The university in Nicolaus Copernicus's home town of Torun, in central Poland, is now named after him.
• Nicolaus Copernicus was not the only famous student of the University of Kraków. Pope John Paul II also studied there.
• Copernicus's first book had nothing to do with astronomy. It was a Latin translation of letters on morals by a 7th-century Byzantine writer, Theophylactus of Simocatta.
• All of Copernicus's astronomical observations were undertaken without the use of a telescope. The telescope was invented in the Netherlands in about 1608, which was 65 years after Copernicus had died.

Joseph Priestley

In the 18th century the great British scientist Joseph Priestley helped found the science of chemistry, and discovered several important gases. He was also one of the first people in history to understand the importance of conducting experiments.

A RELIGIOUS BACKGROUND

Joseph was born on March 13, 1733, in Fieldhead, Yorkshire. His father was a Calvinist minister, and his mother died when he was seven. He was brought up by his equally religious aunt, but because he was a sickly child he received little education. Both Joseph’s parents and his aunt had wanted him to become a religious minister in the Dissenting Church, which was made up of various churches that had separated from the Church of England. He seemed destined for this life when he entered the Dissenting Academy at Daventry, Northamptonshire, at the age of 19. Joseph questioned much of the religious teaching there, but he later served at ministries at Needham Market in Suffolk from 1755 to 1758, and at Nantwich in Cheshire from 1758 to 1761. Later he became a teacher at the Warrington Academy in Lancashire, where he helped to create practical courses for students planning to enter industry and commerce, and not the Church. He was ordained a minister in the Dissenting Church in 1762.

Joseph Priestley had not been educated in science but he had always shown an interest in the subject, and throughout his years in the Church this interest grew.

SCIENCE IN THE 18TH CENTURY

This period in history was known as the Age of Enlightenment. There was a growing interest in science, but little had been discovered. For hundreds of years before this time, many people had attempted to discover more about chemical compounds and reactions, but they were hardly scientists or chemists as we now think of them. They were known as “alchemists” and they studied alchemy, which was a combination of science, art and magic. Alchemists believed that the world was made up of four “elements” known as earth, air, fire and water, and that these four contained something called phlogiston, a substance produced during a process known as combustion, or burning. Priestley also believed in phlogiston and wanted to know more about it.

In the mid-1760s Priestley began attending a series of lectures being given in London by some of the greatest names in science. In 1766 the American statesman and scientist Benjamin Franklin encouraged Priestley to conduct experiments in the new science of electricity. The following year, Priestley wrote a history of electricity, and also discovered that charcoal can conduct electricity. In 1767 he became a minister at Leeds in Yorkshire, and began research on gases. His innovative experimental work resulted in his election to the French Academy of Sciences in 1772. He was also employed as a librarian and literary companion to William Petty Fitzmaurice, 2nd Earl of Shelburne. This arrangement allowed Joseph the time and money to be able to continue with his experiments.

PRIESTLEY’S DISCOVERIES

On August 1, 1774, Priestley was heating red mercury oxide when he obtained a colourless gas in which a candle would burn with a “remarkably vigorous flame”. Priestley had discovered the gas oxygen. He realized that this gas was a component of ordinary air and he then attempted to investigate its role in combustion and in respiration (breathing). He discovered that plants produce oxygen.

Priestley believed in the phlogiston theory and called the new gas “dephlogisticated air”. He had not completely understood the future importance of his discovery. Nor had he realized that oxygen was a separate chemical element. His discovery was still a great breakthrough though, and he had begun the revolution that established modern chemistry. However, it was French chemist Antoine Lavoisier who became the first person to isolate and name the element as oxygen a few years later. Lavoisier also correctly described its role in combustion and respiration. Priestley disagreed with Lavoisier’s view throughout his life and continued to believe in phlogiston.

Later, Priestley isolated and described the properties of several other gases, including ammonia, nitrous oxide, sulphur dioxide and carbon monoxide.

POLITICS, SCIENCE AND RELIGION

In 1780, Priestley fell out with the Earl of Shelburne because of religious and political differences, and he became a minister in Birmingham. Priestley was becoming very radical in his religious thinking and was now turning towards Unitarianism, which rejected most of the basic doctrines of Christianity. His book, History of the Corruptions of Christianity (1782), was considered so dangerous that it was officially burned in 1785. Because of his open support of the French Revolution, and his belief in religious and political freedom, his house and laboratory were destroyed by a mob in 1791. He left Birmingham and went to live in London where he believed he would be safe.

In 1794 Joseph emigrated to the United States, which had only recently achieved independence and freedom from Britain in the American War of Independence. While there he freely pursued his religious, political and scientific writing for the remainder of his life.

Priestley died in Northumberland, Pennsylvania, on February 6, 1804.

Did you know?

• In olden times pencil errors were rubbed out using balls of moist bread. It was Joseph Priestley who discovered that rubber can be used to erase pencil marks.

• Priestley was a member of the Lunar Society, the 18th-century group of thinkers and inventors that met at each other's homes in or near Birmingham at the time of a full moon. Its members contributed to the progress of the Industrial Revolution and the Enlightenment through discussion, correspondence, mutual support, observation and experiment.

• The Swedish chemist Carl Wilhelm Scheele may have discovered oxygen in 1773, a year before Joseph Priestley, but he did not make his work known in time to be credited with its discovery.

• In 1772, while living next door to a brewery, Joseph invented soda water. It is used as the basis for the soft drinks industry.

• Priestley discovered eight different gases in his life, more than any other scientist in history has done.

Antoine Lavoisier

In the 18th century the discoveries of the French scientist Antoine Lavoisier were so important that today he is thought of as being the founder of modern chemistry. He was one of the greatest scientists in history.

ANTOINE’S EARLY LIFE

Antoine was born on August 26, 1743, in Paris. His father was a prosperous lawyer, but when Antoine was five his mother died and he was looked after by an unmarried aunt. Although interested in science as a child, while at school he mainly studied Ancient Greece and Rome, as well as literature. There were few jobs in science, and so when Antoine left school he became a lawyer, qualifying in 1764. He also worked for the French government, helping to make improvements in both farming and taxation. This changed in May 1768 when Antoine won a prize for an essay on street lighting in Paris. He was also elected as a junior member of the Academy of Sciences, the most important scientific institution in France.

SCIENCE IN THE 18TH CENTURY

This period in history was known as the Age of Enlightenment. There was a growing interest in science, but little had been discovered. Before this time, many people had attempted to discover more about chemical compounds and reactions, but they were hardly scientists or chemists as we now think of them. They were known as “alchemists”. Alchemy was a combination of science, art and magic, and had been practised for hundreds of years. Alchemists and many others agreed with the work of the Ancient Greek philosopher Aristotle that the world was made up of four “elements” known as earth, air, fire and water. Many believed that these four “elements” contained something called phlogiston, a substance released during a process known as combustion (burning).

WHAT DID LAVOISIER DISCOVER?

Lavoisier built on the work already done in the 1770s by the English scientists Henry Cavendish and Joseph Priestley. He became the first person to isolate and name the element oxygen, which is the most common element on Earth. He also discovered that air contains 21 per cent oxygen and 78 per cent nitrogen (plus 1 per cent of other gases), and he later gave the element hydrogen its name.

Lavoisier was determined to find out the truth about phlogiston and combustion. In a series of brilliant experiments, he showed that combustion was due to the combination of a combustible substance (such as carbon) with oxygen, and that this forms gases of the substance known as oxides (such as carbon dioxide). Lavoisier had proven that there was no such thing as phlogiston.

In 1784, Lavoisier and fellow French scientist Pierre Simon Laplace analysed the breath of a guinea pig to show that respiration (breathing) involved breathing in oxygen and breathing out carbon dioxide.

After further experiments, he became the first to understand that mercury and nitrogen were chemical elements, and he also realized that water was not a single element but a compound of oxygen and hydrogen. Lavoisier also worked for the government as Commissioner of the Royal Gunpowder Administration. While living in the arsenal (a weapons store) in Paris, he and his wife improved the quality of the army’s gunpowder.

FURTHER DISCOVERIES

Lavoisier developed the law of conservation of mass or matter, which states that in a chemical reaction the total mass or matter of the compounds remains constant. This is a very important law of chemistry.

In 1787, Lavoisier worked with three French colleagues—Guyton de Morveau, Claude Louis Berthollet and Antoine François de Fourcroy—to produce the textbook called Méthode de Nomenclature Chimique (Method of Chemical Nomenclature). This introduced the system of chemical names that we use today. Two years later, in Traité Élémentaire de Chimie (Elementary Treatise on Chemistry), he began to list all the known chemical elements that were now the building blocks of the new science called chemistry. Along with other chemists, he also helped launch the first ever chemistry journal, which he called Annales de Chimie (Annals of Chemistry).

A TRAGIC END

In 1789 the French Revolution began. Although Lavoisier was at first supportive of its aims of overthrowing the monarchy, he was later imprisoned, together with unpopular tax collectors. On May 8, 1794, Lavoisier was tried, condemned and executed by guillotine.

Lavoisier was the greatest French scientist of his age. His work and vigorous experimentation had created a revolution in chemistry, and it was now a science in its own right.

James Watt

James Watt was a Scottish inventor who made great improvements to the design of the steam engine in the late 18th and early 19th centuries. Before James Watt’s time, industry was based on horsepower, wind-power and water-power. His work made it possible to use steam engines in factories, and helped to drive Britain's Industrial Revolution.

JAMES’S EARLY LIFE

James Watt was born on January 19, 1736, at Greenock, in south-western Scotland, where his father James was a merchant and shipowner. He was not a good student as a child, but at the age of 13 he began to show great ability in mathematics and was interested in scientific instruments for surveying and navigation. In 1755 he went to London and became an apprentice to an instrument-maker called John Morgan.

In 1756, Watt returned to Scotland. A year later he established a business in Glasgow making precision machine equipment such as quadrants, scales, telescopes, compasses and some scientific apparatus for the university. He later branched out into making musical instruments such as flutes, organs, violins and guitars.

Between 1766 and 1774 Watt practised as a civil engineer. He undertook surveys of several canals in Scotland, including the Forth and Clyde Canal, linking the River Forth to the River Clyde via Loch Lomond, and the Caledonian Canal, through the GreatGlen from Inverness to Fort William. He designed bridges and advised on improvements to harbours and waterwheels . He also visited many factories, which would later help him when he began selling his steam engines to mills.

WATT’S FIRST STEAM ENGINE

In 1763, Watt was asked to repair a Newcomen steam engine that belonged to the University of Glasgow. The Newcomen engine was designed between 1705 and 1725 by the English engineer and inventor Thomas Newcomen. It was a simple steam engine for pumping water, mainly from coal mines to prevent flooding. Watt realized that the engine wasted energy. By 1765 he had introduced a variety of modifications to it. These included a separate cooling chamber for the steam, which allowed the working cylinder to be kept permanently hot, thus making the engine much more efficient. This single, great new idea, which he patented in 1769, meant that the steam engine could now be made practical for large-scale industrial use.

Watt continued his experiments on steam, but it took a few years before he could afford to make and sell his new engine. In 1774 he moved to Birmingham and began a famous partnership with Matthew Boulton, a manufacturer who had become interested in Watt’s work. In the years to 1800, 164 pumping and 24 blowing engines were constructed by Watt and Boulton.

FURTHER ACHIEVEMENTS

Between 1781 and 1784, Watt developed the rotative steam engine, which proved to be even more important than his original steam engine. While his earlier engine, with its up-and-down pumping action, was suited to draining mines, the rotative engine could be used to power several types of machinery. The rotative engine had three major innovations. By 1800, 308 rotative engines had been built.

CHANGING THE WORLD

The rotative engine was the first reliable source of power for the manufacturing industry in Britain, and was used to drive corn mills, iron forge hammers and textile mills. Later it would be used in the development of the coal industry, and in iron and steel manufacturing in particular. It meant that the Industrial Revolution could expand more quickly than it had done so far, making Britain the most powerful industrial nation on Earth.

In 1795 both Watt and Boulton handed over most of their business to their sons, who established the Soho Foundry at Birmingham. James died at his home at Heathfield, Birmingham, on August 25, 1819. He was one of the most important and influential people in the history of Britain and his work changed the world forever.

Marie Curie

Marie Curie was probably the greatest woman scientist in history. In the late 19th and early 20th centuries her discoveries in a new area of science known as radioactivity made her famous throughout the world. She would pay a high price for her success.

MARIE’S EARLY LIFE

Marie Curie was born Maria Sklodowska on November 7, 1867, in Warsaw, Poland, which was then part of the Russian Empire. Her father was a mathematics and physics teacher. Marie was interested in science as a child, winning a gold medal at school for her studies. She found the lack of opportunities for a Polish woman in a Russian-dominated land very frustrating. After working as a governess in Warsaw, she moved to Paris when she was 24 to continue her studies. She studied physics and mathematics at the famous Sorbonne university. In 1894 she met Pierre Curie, who was also a physicist, and in the following year they married. Together they began a great partnership of scientific discovery.

DISCOVERING RADIUM

In 1895 the scientific world was in a state of intense excitement. German scientist Wilhelm Roentgen had just discovered a new form of radiation, which he called X-rays. The very next year, French scientist Antoine Henri Becquerel discovered that the chemical element uranium emitted another new radiation.

Marie was interested in whether other elements emitted this new radiation. She began working on a naturally occurring black substance called pitchblende, from which uranium is produced. In 1898 she discovered that pitchblende produced very strong emissions of radiation, and she called these emissions “radioactive”. Marie realized that this radioactivity was so strong that it had to be due to the presence of one or more elements in the pitchblende and not just the uranium. After a huge effort, she and Pierre collected tiny amounts of two new elements that were causing the radioactivity: she named them polonium and radium.

Many scientists were not so sure about these discoveries and wanted to see more. In a shed in the grounds of the physics school where they worked, Marie and Pierre spent four years collecting 0.1 gram of pure radium and so proved to the world that they were right.

GREAT SCIENTIST

The world soon recognized their achievement, and Marie and Pierre, together with Becquerel, were awarded the Nobel Prize for Physics in 1903 for their work on radioactivity. After Pierre was killed in a road accident in 1906, Marie devoted herself to her work on radioactivity as well as teaching at the newly created Pierre Curie Institute. She was awarded the Nobel Prize for Chemistry in 1911 for discovering radium. Marie Curie is the first and only person to be awarded two Nobel Prizes for science.

During World War I, Curie devoted herself to using the controlled radioactivity of radium for medical purposes, helping develop the technique of radiotherapy to treat some cancers. Her legacy can be seen in hospitals throughout the world where this is now used. She strongly believed in the importance of science helping humanity.
Because no one knew about the dangers of radioactivity, Curie had been exposed during her career to massive doses of radiation. We now know that overexposure can destroy cells in the human body. She died on July 4, 1934, from leukaemia, almost certainly caused by the radioactivity of the radium she had discovered.