Britannica Student Encyclopedia - 2010

Protozoans are found all over the world,

on land and in water. Protozoans living

on land especially like moist soil. Some

protozoans are parasites. They live inside

the bodies of animals, including

humans. Parasitic protozoans can cause

disease.

A protozoan is just a single cell. But it

can do all of the things that organisms

with many cells can. A protozoan can

The remains of a protozoan that lived long

ago are preserved in rock as a fossil.

BRITANNICA STUDENT ENCYCLOPEDIA Protozoan 159

eat, grow, reproduce, and get rid of

wastes. Most protozoans can move, too.

Protozoans have different shapes, but

they all have some features in common.

Like all cells, every protozoan is made

up of a jellylike material called cytoplasm.

Within the cytoplasm is at least

one nucleus. The nucleus directs the

functions of the cell. The cytoplasm also

contains special organs that do certain

jobs, such as digestion or making proteins.

Some protozoans have hairlike or

whiplike structures that help them

move.

Most protozoans reproduce themselves

without a partner. Usually the nucleus

pinches in the middle to create two

halves. The halves pull apart with equal

amounts of cytoplasm to form two separate

organisms.

..More to explore

Cell • Living Thing • Parasite • Protist

Providence

Population

(2000 census)

173,168;

(2007 estimate)

172,459

Providence is the capital of the U.S.

state of Rhode Island. It lies at the head

of Narragansett Bay, which is part of the

Atlantic Ocean.

Providence is a busy seaport. It is also

one of the main industrial centers in

New England. It is among the region’s

leaders in the production of machinery,

jewelry, and silverware. Government,

health care, banking, and other services

also bring money to the city. It is home

to Brown University and several

colleges.

The English settler RogerWilliams

founded Providence in 1636. He made

the town a center of religious freedom.

Providence played an important role in

the American Revolution. In 1775 the

city had a protest called a tea party.

People burned British tea to protest

against taxes on tea. During the war

many American troops lived in the city.

In 1854 both Providence and Newport

became state capitals of Rhode Island. In

1900 Providence became the state’s only

capital.

..More to explore

Rhode Island

Big houses stand on a hillside in Providence,

Rhode Island.

160 Providence BRITANNICA STUDENT ENCYCLOPEDIA

Prussia

Prussia was a historical region in Europe

that bordered the southeast coast of the

Baltic Sea. It was known for its powerful

army. In 1871 Prussia united several

German states to create the empire of

Germany.

Beginnings

The first Prussians were tribes of hunters

and cattle raisers. They were related to

the Latvians and the Lithuanians. In the

1200s the Teutonic Order, a group of

German-speaking knights, conquered

the Prussians. The knights brought

Christianity to the Prussians.

During the 1400s Poland and Lithuania

defeated the Teutonic knights in a series

of wars. Prussia was then divided into

East Prussia andWest Prussia. The king

of Poland ruled the western part directly.

He ruled the east through the Teutonic

Order.

In 1526 the grand master of the Teutonic

Order dissolved the order. He

accepted Polish rule and changed East

Prussia into the territory of a duke. The

territory merged with another German

state, called Brandenburg, in 1618.

Kingdom

In 1660 FrederickWilliam of Brandenburg

ended all Polish control over East

Prussia. In 1701 FrederickWilliam’s son

crowned himself as the first Prussian

king, Frederick I.

Frederick I’s grandson was Frederick II,

who is known as Frederick the Great.

He tookWest Prussia back from Poland

in 1772. Under his rule, Prussia became

a major power.

In 1848 some Prussians tried to start a

revolution against King FrederickWilliam

IV. They wanted the people to have

a say in the government. The king

stayed in power, but he gave Prussia a

constitution in 1850. The constitution

created a parliament, or legislature. The

people elected some of its members.

Empire

In 1862 Otto von Bismarck, a member

of the Prussian parliament, gained a

leading role in the government. He created

a plan to bring Prussia and some

other German states together as one

German empire. In January 1871 the

king of Prussia became EmperorWilliam

I of Germany.

Frederick II

also improved

Prussia’s

educational

system and

supported the

arts.

Otto von Bismarck was the Prussian leader

who created the modern country of Germany.

BRITANNICA STUDENT ENCYCLOPEDIA Prussia 161

The End of Prussia

William II, also known as Kaiser

Wilhelm, became emperor in 1888. He

led Germany into World War I.

Germany lost the war, and in 1918 the

winners forced William II to give up

his position. Germany became a

republic—a country led by the people,

not by a king. Prussia lost territory. It

also lost power in Germany’s

government. By 1947, after World War

II, Prussia no longer existed.

#More to explore

Frederick the Great • Germany

Psychology

Psychology is the scientific study of the

ways that people think, feel, and behave.

Like anthropology and sociology, psychology

is called a social science. Scientists

trained in psychology are called

psychologists. Psychologists study the

human mind and emotions to try to

understand the reasons behind people’s

actions.

There are several different branches of

psychology. Clinical psychology is the

largest branch. Clinical psychologists

treat people with mental illnesses and

emotional problems.

Psychologists who work in other

branches of psychology do experiments

and research. Some study what happens

in the brain when people think and feel.

Others study how people react to others.

Certain psychologists compare the

human mind to the minds of other animals,

especially apes and monkeys.

To do their work, psychologists often

observe, or watch, people. For example,

a psychologist may observe children at

play to see how they get along. Psychologists

also may ask people to answer

questions or to do different tasks. By

comparing the actions and responses of

many different people, psychologists

hope to find patterns. These patterns

Some kinds of psychologists talk with

people to help them deal with emotional

problems.

The Rorschach test is one tool that psychologists

use to learn about personality. The

psychologist shows a person inkblots, and

the person describes what they look like.

Different kinds of people see different things

in the inkblots.

162 Psychology BRITANNICA STUDENT ENCYCLOPEDIA

may help to explain why people think or

act as they do.

#More to explore

Anthropology • Mental Illness • Social

Science • Sociology

Pterodactyl

Pterodactyls were flying reptiles of prehistoric

times. They lived about 145 to

65 million years ago, at the same time as

the dinosaurs. Remains of pterodactyls

have been found all over the world.

As far as scientists know, pterodactyls

were the largest flying animals that ever

lived. Some pterodactyls measured more

than 36 feet (11 meters) across with the

wings spread out. But the smallest pterodactyls

were as small as a sparrow.

A pterodactyl’s back legs were long and

thin, like those of birds. Pterodactyls

also had long beaks. But unlike birds,

pterodactyls did not have feathers. Their

wings were made of skin, like those of

bats. Pterodactyls probably did not fly

by flapping their wings constantly.

Instead they probably glided on air currents.

Pterodactyls were meat eaters. Many had

hooked claws and sharp teeth that they

used to grab and hold onto prey. Pterodactyls

that lived near water fed mostly

on fish. Pterodactyls that lived far from

water ate small animals.

#More to explore

Dinosaur • Prehistoric Life • Reptile

Public Health

The term public health describes efforts

to keep a whole community healthy.

Local and national governments run

many public-health programs. These

programs improve living conditions and

give people longer lives.

Public health includes many different

health services. Some programs work to

prevent and to fight disease. Vaccination

is an important part of these efforts. A

vaccine is a substance given to people to

protect them from illness. Other programs

focus on fighting pollution or

keeping food and water safe. Public

health also involves teaching people

about exercise and healthy eating.

Public-health programs started to appear

in the 1700s and 1800s. Before that,

health was mostly a personal or local

issue. But as the populations of cities

and countries grew, the number of

health problems grew, too. Governments

began to see the need for keeping the

A fossil skeleton shows that pterodactyls

must have looked like giant birds. But scientists

do not believe that birds came from

pterodactyl ancestors.

Obesity, an

extreme form

of being overweight,

has

recently

become a

major publichealth

issue in

the United

States.

BRITANNICA STUDENT ENCYCLOPEDIA Public Health 163

public healthy. Today most countries

have their own public-health programs.

In the United States, the Department of

Health and Human Services oversees

many public-health agencies.

The World Health Organization

(WHO) promotes the health of people

around the world. It works to stop the

spread of polio, AIDS, and other diseases.

Its vaccination programs helped

rid the world of smallpox. The WHO

also warns travelers about diseases in

certain countries.

#More to explore

Government • Vaccine

Pueblo

The Pueblo are a group of Native

American tribes that live in northeastern

Arizona and northwestern NewMexico.

Early Spanish explorers gave them the

name Pueblo, which is Spanish for

“village” or “town.” The explorers were

impressed by the villages that the Indians

had built. Today the term pueblo is used

for both the people and their villages.

The Pueblo built large houses that had

several stories, like apartment buildings.

They used blocks of adobe, or sunbaked

clay. The Pueblo got most of their

food from farming. Their main crop was

corn. Early Pueblo also hunted and

gathered wild plants to eat.

The Pueblo are descendants of the

ancient Anasazi people. Some of their

villages were already hundreds of years

old when Spanish soldiers arrived in

1540. The Spanish gave the Pueblo

metal tools and cloth. They also brought

horses and new crops such as wheat and

chili peppers.

Later Spanish rulers were cruel to the

Pueblo. In 1680 a Pueblo leader called

Pope led a rebellion against the Spanish.

The Pueblo drove the Spanish from

their lands for 12 years. When the Spanish

returned they had more respect for

the Indians. Their rule was not as harsh.

People wait in line to get flu shots. Such

shots can prevent diseases from spreading

to many people in a community.

A photograph from the early 1900s shows

adobe houses built by the Zuni, a group of

Pueblo Indians.

164 Pueblo BRITANNICA STUDENT ENCYCLOPEDIA

At the end of the 20th century there

were about 60,000 Pueblo Indians. They

lived in 19 pueblos. Unlike many other

Indians, modern Pueblo have mostly

been able to keep their traditional way

of life.

#More to explore

Adobe • Anasazi • Native Americans

Puerto Rico

Puerto Rico is an island in the Caribbean

Sea. It is a commonwealth of the

United States. This means that Puerto

Rico governs itself but keeps some ties

with the United States. The capital of

Puerto Rico is San Juan.

Puerto Rico is part of the island group

called theWest Indies. The island is

roughly rectangular in shape. It is mostly

mountainous, but the land along the

coast is flatter. The weather is warm

year-round.

Most Puerto Ricans have Spanish ancestors.

People of African descent make up

a smaller group. Some people have

mixed European and African roots.

Most Puerto Ricans speak Spanish, and

many speak English as well. Most of the

people are Christian.

Puerto Rico’s main sources of income

are manufacturing, services, and trade

with the United States. Factories make

chemicals, medicines, electronics,

machinery, and clothing. Finance and

tourism are major service industries.

Farms produce sugarcane, tropical fruits,

coffee, beef, pork, chickens, milk, and

eggs.

Arawak Indians known as the Taino

arrived in what is now Puerto Rico by

AD 1000. The first European to reach

the island was Christopher Columbus.

He claimed it for Spain in 1493. In the

late 1700s the Spanish started to set up

large farms called plantations. They

brought in Africans to work on the plantations

as slaves. Sugarcane, coffee, and

tobacco were the major crops.

In 1898 Spain gave Puerto Rico to the

United States after losing the Spanish-

AmericanWar. In 1917 the U.S. government

made the people of Puerto Rico

People celebrate a religious festival in

Puerto Rico by putting on costumes and

masks.

BRITANNICA STUDENT ENCYCLOPEDIA Puerto Rico 165

citizens of the United States. Puerto

Rico became a commonwealth in 1951.

Puerto Ricans have most of the benefits

of U.S. citizenship. However, they cannot

vote for the U.S. president.

#More to explore

Arawak • Caribbean Sea • San Juan

• Spanish-AmericanWar • United States

•West Indies

Pulaski, Casimir

Casimir Pulaski was born in Poland, but

he became a military hero in the American

Revolution. He stated his reasons

for joining the revolution in a letter to

General GeorgeWashington: “I came

here, where freedom is being defended,

to serve it, and to live or die for it.” He

paid for his beliefs with his life.

Early Life

Pulaski was born on March 4, 1747, in

Winiary, Poland. In his 20s he fought

against the Russians, who threatened his

homeland. Pulaski later moved to

France.

Pulaski met Benjamin Franklin in Paris,

France, in December 1776. Franklin was

looking for experienced volunteers to

help fight for American independence

from Great Britain. Pulaski agreed to

help and sailed to America. He arrived

in June 1777.

Military Career

During the American Revolution

Pulaski impressed other soldiers with his

skills as a cavalryman. A cavalryman is a

soldier who fights on horseback. Pulaski

showed great courage at the battle of

Brandywine in Pennsylvania in September

1777. Pulaski led a cavalry charge

against the British, who were winning.

His actions allowed GeneralWashington

to escape with his troops.

In 1778 Pulaski formed a cavalry group

known as the Pulaski Legion. The division

included French, Irish, Polish, and

German soldiers. Pulaski trained them

in battle drills on horseback. He later

became known as the Father of the

American Cavalry.

Pulaski’s last battle was the battle of

Savannah in 1779. On October 9, 1779,

Pulaski was shot in the leg. He died two

days later on a ship on its way to

Charleston, South Carolina.

#More to explore

American Revolution •Washington,

George

Casimir Pulaski

166 Pulaski, Casimir BRITANNICA STUDENT ENCYCLOPEDIA

Puma

The puma is a large cat of North and

South America. It is also commonly

called a mountain lion, cougar, or panther.

It is about the same size as a jaguar.

Its scientific name is Puma concolor.

Pumas live in a wide variety of habitats

from southern Alaska to southern

Argentina. Most of the pumas in North

America live in the mountains of the

western United States and Canada.

Some pumas live in Florida.

Pumas can be up to 6 feet (1.8 meters)

long, not including the tail. They stand

about 2 to 3 feet (0.6 to 0.9 meter) tall

at the shoulder and weigh about 80 to

220 pounds (36 to 100 kilograms).

They may be yellowish tan, reddish

brown, bluish gray, or some other color.

Pumas are powerful jumpers who attack

their prey by leaping onto its back. From

the ground, pumas can jump to heights

of more than 18 feet (5.5 meters).

Pumas mainly eat deer, but their diet

also includes other small or mediumsized

animals.

For many years people killed pumas

because they sometimes attacked livestock.

Now pumas are protected in

many places by laws that limit or ban

hunting of the animals.

#More to explore

Cat • Jaguar

Pumpkin

Pumpkins are fruits that are commonly

grown for food. The inside is cooked

and eaten or used to make breads, soups,

and pies. Pumpkins are related to

squashes, gourds, cucumbers, and melons.

Some types of pumpkin are called

squashes.

Pumpkins are grown throughout North

America and Europe. They grow on

plants that have very long vines. The

plant has rough, heart-shaped leaves and

large yellow flowers.

Pumpkins usually weigh 9 to 18 pounds

(4 to 8 kilograms). The largest varieties

may weigh 75 pounds (34 kilograms) or

more. Pumpkins are generally round.

The puma is sometimes called the mountain

lion because it is at home in the mountains.

Pumpkins grow on long vines.

BRITANNICA STUDENT ENCYCLOPEDIA Pumpkin 167

But some may be flattened or stretched

out on the top and bottom. The color is

usually yellowish to orange. The rind, or

skin, is smooth. Ridges run from the top

to the bottom.

Pumpkins are picked in autumn. They

can be stored for a few months in a dry

place. In addition to using pumpkins in

cooking, people roast and eat pumpkin

seeds. They also feed pumpkins to animals.

In some countries a carved pumpkin,

called a jack-o’-lantern, is a familiar

Halloween decoration.

#More to explore

Fruit • Gourd • Halloween • Squash

Purim

Purim is the most festive Jewish holiday.

It is also called the Feast of Lots. The

holiday celebrates a time when Jews in

Persia (now Iran) escaped a plot to harm

them. Purim usually falls in late February

or early March.

In the 400s BCHaman, the Persian king’s

adviser, plotted to kill all the Persian

Jews.To choose a day for the killings, he

drew lots (which means that he picked a

day by chance). But the Persian queen, a

Jewish woman named Esther, convinced

the king to stopHaman. This story is

told in the Book of Esther in the Bible.

On Purim Jews go to a synagogue and

listen to a reading of the Book of Esther.

Afterward family and friends have a festive

meal. The celebration often includes

acting out the story and playing games.

People exchange gifts of food and give to

the poor. They also eat pastries called

hamantaschen, which means “Haman’s

pockets.” The pastries are supposed to

resemble Haman’s three-cornered hat.

#More to explore

Judaism • Persia

Puritans

Puritans were people who wanted to

“purify,” or simplify, the Church of

England. This church had broken away

from Roman Catholicism during a

period called the Protestant Reformation.

However, the Puritans felt that the

Church of England had kept too many

Catholic practices. Some Puritans, called

Separatists, formed their own churches.

Others just wanted to change the existing

church.

Many officials in England did not

approve of the Puritans. The king and

other English people often mistreated

the Puritans. They called the Puritans

“roundheads” because they wore their

hair short instead of in long curls.

Children dance in Jerusalem to celebrate

Purim.

168 Purim BRITANNICA STUDENT ENCYCLOPEDIA

Puritans in America

In 1620 a group of Puritan Separatists,

now called the Pilgrims, left England to

escape mistreatment. They crossed the

Atlantic Ocean in a ship called the Mayflower.

After reaching North America,

they founded Plymouth Colony in what

is now Massachusetts.

Several years later, another group of

Puritans left England to find religious

freedom. They set up the Massachusetts

Bay Colony in 1630. Both of these

groups eventually became known as

Congregationalists.

Puritans in England

In England the Puritan spirit spread

throughout society. Although the king

disapproved of the Puritans, many of the

common people shared their beliefs.

Many leaders in Parliament also listened

to the Puritans.

In 1642 civil war broke out between

supporters of Parliament and the king.

King Charles was defeated and later

executed in January 1649. The Puritan

leader Oliver Cromwell became

England’s new leader. Cromwell’s government

favored the Puritans. Several

new Puritan groups, including the

Quakers, first appeared during this time.

Cromwell died in 1658, and a new king

took power in 1660. Puritans were once

again mistreated. This period was called

the Great Persecution. Finally, in 1689

the Act of Toleration gave Puritans the

freedom to practice religion as they

thought it should be practiced.

..More to explore

Massachusetts Bay Colony • Plymouth

Colony • Protestantism • Quaker

Pyongyang

Population

(2005

estimate), urban

area,

3,351,000

Pyongyang is the capital of North Korea,

a country in East Asia. The city lies on

the Taedong River. It is North Korea’s

largest city. It is also a center of education

and culture.

Pyongyang is a major center of industry.

Factories in the city make fabric and

clothes, food products, machines,

chemicals, and other goods.

An artwork from the 1500s shows a Puritan

family. The Puritans lived simply, with little

decoration in their clothing or homes.

The Pilgrims

moved to Holland

(now part

of The Netherlands)

before

deciding to

move to North

America.

BRITANNICA STUDENT ENCYCLOPEDIA Pyongyang 169

According to legend, Pyongyang was

founded in 1122 BC. It is said to have

been built on the site of an even older

capital.

The first historical records of Pyongyang

are from 108 BC. It became the capital of

the Koguryo kingdom of northern

Korea in AD 427.

Pyongyang suffered several invasions

over the years. In the 1890s it was damaged

during a war between China and

Japan. The Japanese controlled the city

from 1910 to 1945.

In 1948 Korea was divided into two

countries, North Korea and South

Korea. Pyongyang became the capital of

North Korea.

#More to explore

Korea, North • KoreanWar

Pyramid

A pyramid is a large structure with four

sides that usually slope upward and meet

at a point. The base of a pyramid is a

rectangle, and the sides are usually triangles.

People throughout the world

have built pyramids at different times.

The most famous pyramids were built in

ancient Egypt more than 4,500 years

ago. The pyramids of Mexico, Central

America, and South America are also

well known.

Egypt

The pyramids of ancient Egypt were

tombs. Egyptian kings had themselves

buried with gold and other treasure.

They had pyramids built partly to keep

out people who would steal the treasure.

However, robbers broke into most, if

not all, of the Egyptian pyramids in

ancient times. About 80 pyramids have

been found in Egypt, but some are now

only rubble.

The Egyptians developed pyramids from

an earlier type of tomb called a mastaba.

Mastabas were rectangular tombs with

flat tops. In about 2650 BC King Djoser

had his architect, Imhotep, build a new

Young children file past a statue of North

Korea’s first leader, Kim Il-sung, in the city

of Pyongyang.

The pyramids of Giza were one of the

Seven Wonders of the World in ancient

times. They are the only one of the seven

still standing.

170 Pyramid BRITANNICA STUDENT ENCYCLOPEDIA

type of tomb. Imhotep stacked six stone

mastabas, each smaller than the one

beneath it. The result was a pyramid with

a stepped design. Less than 100 years

later King Snefru built the first pyramid

with smooth, sloped sides.

The Great Pyramid was built for King

Khufu in about 2550 BC. It sits in a

group with two smaller pyramids in

Giza, Egypt. About 100,000 workers

spent about 20 years building the Great

Pyramid. They stacked about 2.3 million

blocks of stone to a height of 471

feet (143 meters). Each of the blocks

weighed about 2.5 tons. The workers

probably hauled them up a dirt ramp.

The Americas

Many ancient peoples of Mexico and

Central and South America built pyramids.

They usually used dirt and stone.

These pyramids typically have a stepped

form with a temple or platform on top.

The Maya built a famous pyramid called

the Castillo in what is now southeastern

Mexico. The people of the ancient city

of Teotihuacan, in central Mexico, built

the Pyramid of the Sun and the Pyramid

of the Moon.

#More to explore

Egypt, Ancient • Maya

Pyrenees

The Pyrenees mountain chain forms a

high, rugged barrier between Spain and

France. The mountains stretch for 270

miles (430 kilometers) from the Mediterranean

Sea in the east to the Atlantic

Ocean in the west.

Many of the mountains in the Pyrenees

are more than 9,000 feet (2,740 meters)

tall. The highest peak is Pico de Aneto,

which rises 11,169 feet (3,404 meters).

Snow covers many of the peaks yearround,

especially those in the center

section of the chain. Ancient glaciers, or

moving sheets of ice, carved valleys

throughout the Pyrenees. There are also

many mountain lakes and some of the

highest waterfalls in Europe. Forests

cover the mountain slopes in the west.

Fewer trees and other plants grow in the

east, which is much drier.

Few people live at the Pyrenees’ highest

elevations. However, the tiny country of

Cows graze in the Pyrenees in Spain.

BRITANNICA STUDENT ENCYCLOPEDIA Pyrenees 171

Andorra is nestled among peaks near the

eastern end of the chain.

Farmers and ranchers tend crops and

raise animals in the valleys and on the

slopes of the Pyrenees. Major crops

include corn, potatoes, fruits, hay, olives,

grapes, and cereals. Animals include beef

cattle, sheep, and goats. Visitors come to

the mountains for their hot springs, as

well as for winter sports, hunting, fishing,

and hiking.

Throughout history the Pyrenees have

separated Spain from the rest of Europe.

The mountains made it difficult to

travel between the two by land. No one

made good maps of the Pyrenees until

the 1800s. For this reason the Spanish

became excellent sailors. They also

developed ties with North Africa, which

is separated from Spain by only a short

stretch of the Mediterranean Sea.

#More to explore

Andorra • Mountain

Python

Pythons are giant snakes of Africa, Australia,

South and Southeast Asia, and the

Pacific islands. Pythons are constrictors.

This means that they kill their prey by

wrapping themselves around it and

squeezing it until it dies. Boas also constrict,

but pythons and boas are different

kinds of snakes.

There are about 28 species, or types, of

python. They live in a variety of habitats,

from forests to open, rocky areas.

Many species live near water.

One type, the reticulated python, is the

world’s longest known snake. It reaches

a length of up to 32 feet (10 meters).

Smaller pythons include the ball, or

royal, python, which generally reaches a

length of only about 6 feet (2 meters).

Pythons tend to strike their prey

suddenly from a hidden position. They

grasp the prey in their teeth and then

kill the animal by squeezing it to death.

Large pythons generally eat small

mammals and birds. Smaller pythons

also eat amphibians and reptiles. After

eating a large meal, a python may not

need to eat again for weeks or even

months.

Like most other snakes, pythons reproduce

by laying eggs. After the female

lays her eggs she coils herself around

them until they hatch about two or

three months later.

#More to explore

Boa Constrictor • Snake

A green tree python coils around a tree

branch in Indonesia.

172 Python BRITANNICA STUDENT ENCYCLOPEDIA

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Student

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Volume 11

2010 Britannica Student Encyclopedia

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International Standard Book Number: 978-1-61535-363-7

eBook edition January, 2010

The rich country of Qatar was

once a land of wandering

herders and small fishing

villages.

(See Qatar.)

Members of the Society of

Friends, a Christian group, are

called Quakers.

(See Quaker.)

Workers use machinery and

explosives to take stone from a

quarry. The stone may be taken

in big blocks or in small pieces.

(See Quarrying.)

More than 80 percent of the

people of Quebec, a Canadian

province, speak French as their

usual language.

(See Quebec.)

The Australian state of

Queensland is nicknamed the

Sunshine State.

(See Queensland.)

Qq

Qatar

Qatar is a small country in theMiddle

East. It is an emirate, a country ruled by a

leader called an emir. The capital isDoha.

Geography

Qatar sits on a small peninsula on the

eastern coast of Saudi Arabia. The Gulf

of Bahrain and the Persian Gulf lie to

the north, east, and west.

Qatar’s land is mainly a low, flat desert.

The weather is hot during the summer

and warm the rest of the year.

Plants and Animals

Desert grasses and shrubs grow in

Qatar’s dry environment. Animals

include geckos, desert hares, jumping

rodents called jerboas, and many birds.

People

Most of the people who live in Qatar are

immigrants. They came from other Arab

countries, as well as Pakistan, India, and

Iran. Arabic is the main language. Most

people are Muslims.

Economy

Qatar is a rich country because of its

reserves of oil and natural gas. The

country also produces chemicals and

steel. Banking is important to the

economy as well. Qatar’s few crops

include dates, melons, and tomatoes.

Herders raise sheep, goats, and camels.

History

For centuries Qatar was a land of

nomads (wandering herders) and small

fishing villages. In 1868 the al-Thani

family gained power.

In 1916 Great Britain took control of

Qatar’s foreign affairs. Qatar gained

independence from Britain in 1971.

Emirs from the al-Thani family ruled

Qatar into the 21st century.

..More to explore

Doha • Middle East

Most men in Qatar wear traditional clothing.

The long white shirt is called a thobe. A

gutra is a headdress made of cloth and

held in place with a black rope.

Facts About

QATAR

Population

(2008 estimate)

1,448,000

Area

4,412 sq mi

(11,427 sq km)

Capital

Doha

Form of

government

Constitutional

emirate, or

kingdom

Major cities

Ad-Dawhah

(Doha),

Ar-Rayyan,

Al-Wakrah, Umm

Salal

4 Qatar BRITANNICA STUDENT ENCYCLOPEDIA

Quaker

Members of the Christian group known

as the Society of Friends are called

Quakers. They are dedicated to experiencing

God personally rather than

through clergy, such as priests or ministers.

Quakers call the presence of God

inside each person the “Inner Light.”

They believe that the Inner Light guides

them through life.

Practices

Quakers attend meetings to worship

God. These meetings are open to everyone.

The worshippers sit in silence, waiting

for a message from God.Worshippers

who hear a message share their

thoughts with the others.

Quakers have a long tradition of working

for peace and opposing war. They

also oppose slavery, cruel treatment of

prisoners, and unfair treatment of

women. Various Quaker groups organize

relief and service projects throughout

the world.

History

George Fox, an English preacher,

founded Quakerism in the mid-1600s.

He grew to believe that God could be

found inside people rather than in

church ceremonies. He and other

preachers established groups that shared

his beliefs. These groups later became

the Society of Friends. Its members were

called Quakers because many worshippers

quaked, or trembled, with emotion

during religious meetings.

The Quakers offended many Christian

leaders because they refused to honor

officials, take oaths, or pay for the

upkeep of English churches. Government

authorities fined some of the

Quakers, took their property, and put

them in prison. The Quakers flourished

nevertheless. A law passed in 1689

granted freedom of worship to the

Quakers and other groups in England.

At the same time some Quakers traveled

to the North American colonies. In

1681 King Charles II of England gave a

Quaker namedWilliam Penn land that

became the colony of Pennsylvania.

Many Quakers settled there. In the

1800s Quakers in the United States

founded several colleges and universities

that emphasized science. In the 1900s

Quakerism spread to Africa and Europe.

#More to explore

Christianity • Penn,William

Quaker service

groups in

the United

States and

Great Britain

shared the

Nobel peace

prize in 1947.

Quaker worship services are called meetings.

A drawing shows a meeting that took

place in the 1800s.

BRITANNICA STUDENT ENCYCLOPEDIA Quaker 5

Quapaw

The Quapaw are Native Americans who

once lived in eastern North America,

along the coast of the Atlantic Ocean.

They later moved westward along with

other related tribes, including the Osage,

the Kaw, the Omaha, and the Ponca.

The Quapaw eventually settled in what

is now Arkansas. The tribe itself is sometimes

called the Arkansas.

The Quapaw lived in rectangular, barkcovered

homes called longhouses. Longhouses

were big enough to house several

families. The Quapaw grew corn,

gourds, pumpkins, sunflowers, beans,

and squash. They also hunted such animals

as bison (buffalo) and gathered

nuts and berries.

In 1673 French explorers visited

Quapaw lands. The French and the

Quapaw became trading partners. But

the French also brought diseases, such

as smallpox and measles, that killed

many Quapaw.

American settlers soon arrived in the

area. In the early 1800s the U.S. government

got the Quapaw to give up their

Arkansas lands. The Quapaw went to

live among the Caddo Indians in Louisiana.

However, floods soon drove them

from their new home.

In 1833 the Quapaw moved to a reservation

in Indian Territory (now Oklahoma).

In the 1920s some Quapaw

became wealthy because they were able

to mine and sell lead and zinc found on

reservation lands. At the end of the 20th

century there were about 1,000 Quapaw

living in the United States.

#More to explore

Kaw • Native Americans • Omaha

• Osage • Ponca

Quarrying

Mining is the removal of minerals from

Earth’s crust. Quarrying is the mining

of stone, or rock used mainly for

building. A quarry is a hole or a pit in

the ground from which workers remove

stone. During quarrying, workers cut or

blast stone into smaller pieces. These

smaller pieces of stone are easier to

handle and can be used to make many

things.

A Quapaw sash is decorated with colorful beads.

6 Quapaw BRITANNICA STUDENT ENCYCLOPEDIA

Types of Quarried Stone

There are two basic types of quarried

stone: dimension stone and crushed

stone. Dimension stone is blocks or

slabs (big rectangles) of stone that have

been cut to a certain size. Granite and

limestone are popular types of dimension

stone. Crushed stone is much

smaller than dimension stone. It is stone

that has been broken into many small

pieces.

How Quarrying Is Done

Workers take stone from a quarry by

cutting, drilling, or blasting it. To get

dimension stone, they use machinery

that cuts or drills large pieces of stone

off the walls of the quarry. Each long,

heavy slab weighs thousands of pounds.

Workers cut the slabs into smaller blocks

before transporting them to the surface.

To get crushed stone, workers use explosives

to blast stone from the quarry’s

walls.

In ancient times people removed stone

from quarries without the help of modern

machines or explosives. For instance,

the ancient Egyptians used such tools as

picks, wedges, drills, and saws.

Uses of Quarried Stone

The ancient Egyptians quarried huge

blocks of stone to build pyramids. The

ancient Greeks and Romans created

many buildings and sculptures with

quarried stone, as did later peoples.

Today businesses all over the world use

quarried stone, and almost every country

has quarries. People still use dimension

stone to make buildings,

monuments, and sculptures. They use it

to build bridges, tunnels, and dams as

well. People use crushed stone mostly to

build roads and to make concrete.

#More to explore

Mining • Rock

A worker at a quarry cuts slabs of limestone

into smaller blocks.

Many different machines, including trucks

and cranes, are used in quarries.

BRITANNICA STUDENT ENCYCLOPEDIA Quarrying 7

Quebec

The province of Quebec is different

from the rest of Canada. The

language and traditions of most

of its people are French rather than

English. The name Quebec comes from

an Algonquian Indian word meaning

“where the river narrows.” It was first

used for the province’s capital, Quebec

city, which is located at a spot where the

Saint Lawrence River narrows.

Geography

Quebec is Canada’s largest province in

area. It borders Ontario and Hudson

Bay on the west. The Hudson Strait lies

to the north. To the east are the Gulf of

Saint Lawrence and the mainland part

of Newfoundland and Labrador. To the

south are New Brunswick and the U.S.

states of Maine, New Hampshire, Vermont,

and New York.

Most of Quebec’s people live in the lowlands

near the Saint Lawrence River and

in the region south of the river, which is

part of the Appalachian Mountains. The

Laurentian Mountains, north of the

lowlands, are the oldest mountain range

in the world. The rocky land north of

the Laurentians has many forests, lakes,

and rivers. In the far north, near Hudson

Bay and Hudson Strait, are barren

Arctic lands.

People

Most of Quebec’s people are of French

origin. More than 80 percent speak

French as their usual language. After the

French, people of British descent are the

most numerous. Other ethnic groups

include Irish, Italians, Haitians, Chinese,

Greeks, and American Indians.

Nearly half of Quebec’s people live in

Montreal or its suburbs. Located on an

island in the Saint Lawrence River,

Montreal is the second largest city in

Canada after Toronto.

Economy

Services and industry are the most

important parts of Quebec’s economy.

Most of the province’s workers are

employed in such services as tourism,

education, banking, real estate, and

sales. The next largest group works in

manufacturing. Factories in the province

produce food and drinks, aircraft and

other transportation equipment, electrical

goods, chemicals, and paper. Quebec’s

mines provide gold, copper, zinc,

James

Bay

8 Quebec BRITANNICA STUDENT ENCYCLOPEDIA

iron ore, and asbestos. River dams create

electricity, which Quebec exports to

other provinces and to the United

States.

Most farming in Quebec is done in the

south, near the Saint Lawrence River.

The province leads all others in dairy

farming. Quebec is also among the leading

provinces in poultry, hog, and vegetable

production. Maple sugar is a

Quebec specialty.

History

The first people in what is now Quebec

were American Indians and Inuit.

Indian groups included the Iroquois, the

Huron, and the Cree.

In 1534 the French explorer Jacques

Cartier sailed up the Saint Lawrence

River and claimed the lands he saw for

his country. The region was called New

France. In 1608 Samuel de Champlain

founded Quebec city. Montreal was

founded in 1642.

The French turned New France over to

the British in 1763, after losing the

French and IndianWar. The British

renamed the land Quebec. In 1791 the

British split Quebec into two parts:

Upper and Lower Canada. Lower

Canada was later renamed Canada East.

Canada East became the province of

Quebec in 1867. It was one of four

original provinces in the new country of

Canada. Upper Canada became the

province of Ontario.

Quebec’s borders changed in the early

1900s. Ungava, a huge region between

Hudson Bay and the Hudson Strait,

became part of the province in 1912.

But the province lost land to Newfoundland

(now Newfoundland and Labrador)

when a boundary line was drawn in

1927.

Quebec’s French Canadians have not

always gotten along well with Canada’s

English-speaking majority. In the 1960s

some people in Quebec began to

demand that Quebec become a separate

country. In 1976 Quebec voters elected

a government dedicated to independence.

However, in 1980 and again in

1995 the people voted for Quebec to

remain part of Canada.

..More to explore

Canada • Cartier, Jacques • Champlain,

Samuel de • French and IndianWar

• Saint Lawrence River and Seaway

Street signs in Quebec are

mostly in French.

Facts About

QUEBEC

Flag

Population

(2006 census)

7,546,131

Area

595,391 sq mi

(1,542,056 sq

km)

Capital

Quebec city

Motto

Je Me Souviens (I

Remember)

When Quebec

Became a

Province

1867

BRITANNICA STUDENT ENCYCLOPEDIA Quebec 9

Queensland

Queensland is the second largest of Australia’s

six states. (Western Australia is

the largest.) Queensland is known for its

sandy beaches, damp rain forests, open

plains, and rugged highlands. Its tropical

climate has earned it the nickname Sunshine

State. Brisbane is the capital.

Geography

The Pacific Ocean borders Queensland

on the north and the east. The state of

New SouthWales lies to the south, and

the state of South Australia lies to the

southwest. The Northern Territory

forms the western border of Queensland.

Mountains that rise 2,000 to 5,000 feet

(600 to 1,500 meters) line Queensland’s

coast. A mountain range called the

Great Dividing Range separates the eastern

third of Queensland from the western

part. The western part of the state is

mostly dry plains. Dense rain forests of

palms, pines, and other plants grow on

the eastern coast. Off the coast of

Queensland is the world’s largest coral

reef, called the Great Barrier Reef.

People

More than 3.5 million people live in

Queensland. Most Queenslanders can

trace their family history to Europe. A

small number of people are Australian

Aborigines. People from Southeast Asia,

especially Vietnam, also have settled in

Queensland.

More than 40 percent of Queensland’s

people live in Brisbane, in the southeastern

corner of the state. This big city is a

port on the Pacific Ocean.

Economy

Farming and mining are important to

Queensland’s economy. The main farm

products are beef, sugarcane, wheat, and

wool. Other crops include sorghum,

corn, pineapples, and bananas. Queensland’s

mines produce coal, copper, silver,

zinc, and lead.

Tourism also brings money to the state.

Tourists come for the warm climate and

sandy surfing beaches. Many visit the

Great Barrier Reef and the rain forests.

Queensland is home to many animals. Kangaroos

sometimes hop across roads, so

people must drive carefully.

10 Queensland BRITANNICA STUDENT ENCYCLOPEDIA

History

Aborigines have lived in what is now

Queensland for at least 40,000 years.

European explorers visited the area in

the late 1700s and early 1800s. In 1824

Great Britain set up prison camps in

what is now Queensland. Britain

shipped many prisoners to these camps,

which existed until 1840.

Free British settlers began to build settlements

in the area in the early 1840s. At

first Queensland was a part of the

colony of New SouthWales. In 1859

Queensland became a separate colony.

The population soared after gold was

discovered in the late 1850s. Many miners

went to Queensland in the hope of

striking it rich.

In 1901 Australia became independent

from Britain. At the same time Queensland

became a state of Australia.

..More to explore

Australia • Great Barrier Reef

Quito

Population

(2005

estimate), urban

area,

1,514,000

Quito is the capital of Ecuador, a country

in northwestern South America. The

city sits on the slopes of the Pichincha

volcano, in the Andes Mountains. It is a

center of education, culture, and business.

Ecuador’s major oil pipelines pass

through Quito. Banking, tourism, and

other service industries are important to

the city’s economy. Factories in Quito

make cloth, medicines, and metal and

wood products.

Quito is the oldest capital in South

America. In ancient times it was the

center of the kingdom of theQuitu

Indians. The Cara Indians took over the

area in the 900s. In 1487 the city became

part of the Inca Empire. Spain ruled the

region from the 1500s to the early 1800s.

In 1830 Ecuador became an independent

country withQuito as its capital.

..More to explore

Ecuador

Qur#an

..see Koran.

Spanish-style buildings surround a plaza in

Quito, Ecuador.

BRITANNICA STUDENT ENCYCLOPEDIA Qur#an 11

Raccoons live high in hollow

trees or at the tops of buildings

in cities.

(See Raccoon.)

A tropical rain forest has three

sections: the canopy made by

the treetops; the understory,

where smaller plants grow;

and the forest floor.

(See Rain Forest.)

The ancient Egyptians believed

that at sunrise the god Re—the

sun—began a journey across

the sky in his boat.

(See Re.)

Recycling reduces the amount

of paper, glass, plastic, and

other materials that people

throw away.

(See Recycling.)

Sally Ride was the first U.S.

woman to travel into outer

space.

(See Ride, Sally.)

Rrr

Ra

..see Re.

Rabat

Population

(2004

estimate), urban

area,

1,622,860

Rabat is the capital of Morocco, a country

in northern Africa. The city lies

where the Bou Regreg River flows into

the Atlantic Ocean.

Industries that provide services, such as

banking and trade, are important to

Rabat’s economy. Many people work for

the government. Factories in the city

produce cloth, food products, and

bricks. Craftspeople in Rabat make carpets

and leather goods.

In ancient times the Romans created a

colony in the Rabat area. In the 1100s

the Muslim rulers of Morocco founded

Rabat as a military camp. In the early

1600s Spain’s rulers forced all Muslims

to leave Spain. Many of them moved to

Rabat and the nearby city of Sale. Later

in the 1600s the area was a base for

pirates. The pirates attacked ships off the

coast of northern Africa.

In 1912 the French took control of most

of Morocco. They made Rabat its capital.

In 1956 Morocco became an independent

country with Rabat as its

capital.

..More to explore

Morocco

Rabbit and Hare

Rabbits and hares are mammals with

long ears. There are about 28 species, or

types, of rabbit and about 30 species of

Walls surround the oldest part of the city of

Rabat. The walls were built hundreds of

years ago to protect the city from invaders.

The jackrabbits of North

America are actually hares.

BRITANNICA STUDENT ENCYCLOPEDIA Rabbit and Hare 13

hare. They all belong to the same animal

family, called Leporidae. Because rabbits

and hares look similar, people sometimes

confuse them.

Where Rabbits and Hares Live

Different species of rabbit and hare live

in different habitats around the world.

Cottontails and jackrabbits live wherever

they can find brushy shelter. Other types

can be found on mountains, on plains,

in marshes or swamps, and even in the

snowy Arctic.

Physical Features

Both rabbits and hares have short tails.

They also have large eyes, strong teeth,

and sensitive noses. The upper lip is

split.

Hares are usually larger and heavier than

rabbits. Hares measure from 16 to 28

inches (40 to 70 centimeters) long. Rabbits

may be from 8 to 20 inches (20 to

50 centimeters) long. In general, hares

also have bigger ears and longer hind

feet than rabbits.

The fur of hares and rabbits is often

gray-brown in color. Many hares turn

white in the winter. Rabbits’ coats are

the same color year-round.

Behavior

Many rabbits and hares live alone. Some

rabbits live together in underground

burrows called warrens.

Rabbits and hares eat mostly plants.

They can cause great damage to gardens

and crops. Their natural enemies are

flesh-eating birds, mammals, and

reptiles. Rabbits and hares use their

speed and jumping ability to escape

from these predators.

Reproduction

Female hares may have two to three litters

of babies each year. The newborns

have open eyes and can hop within minutes.

They can take care of themselves

after only a few days.

Female rabbits also may have several

litters each year. Newborns are blind and

helpless. They stay with their mother for

about three weeks.

#More to explore

Mammal

Raccoon

Raccoons are mammals of the Americas.

They can be found in cities as well as in

the countryside. There are seven species,

or types, of raccoon. The most common

is the North American raccoon.

The North American raccoon can be

found in Canada, the United States, and

Many kinds of rabbits dig burrows, or

holes, for shelter.

14 Raccoon BRITANNICA STUDENT ENCYCLOPEDIA

South America. It prefers wooded areas

near water, but it will live in other areas,

including large cities.

Raccoons have short legs, pointed

muzzles, or snouts, and small ears that

stand straight up. Their small feet

resemble slender human hands. North

American raccoons are 30 to 36 inches

(75 to 90 centimeters) long from the

nose to the tip of the tail. They weigh

about 22 pounds (10 kilograms). A large

male can weigh more than 44 pounds

(20 kilograms).

Raccoons have a pattern of dark fur

around their eyes that looks like a mask.

They also have bushy tails that have

dark bands, or rings. Their bodies are

covered with shaggy, coarse fur that is

iron-gray to blackish in color. They are

nocturnal omnivores, which means they

are active at night and eat both plants

and animals. Raccoons eat crabs, frogs,

fishes, rodents, fruit, and plants, including

crops. In cities they tend to eat garbage

or anything else they can find.

Raccoons live high in hollow trees or at

the tops of buildings in cities. In captivity

raccoons can live up to 20 years, but

most do not live more than 5 years in

the wild. Many are killed by humans for

their fur or because they are considered

pests.

#More to explore

Mammal

Radar

Radar is a system that uses waves of

energy to sense objects. It can find a

faraway object and tell how fast it is

moving. Radar is very useful because it

can sense objects even at night and

through thick clouds.

How RadarWorks

A radar system is made up of a transmitter,

a receiver, an antenna, and a display.

The transmitter creates radio waves,

which are invisible streams of energy.

The antenna sends the waves out into

the air. When the waves hit an object,

they reflect, or bounce back, to the

antenna.

The waves then pass to the receiver,

which makes sense of them. By measuring

how long it takes the waves to

return, the receiver can tell how far away

the object is. The receiver can also tell

where a moving object is headed and at

what speed. Sometimes it can tell how

big the object is, too. The receiver sends

this information to a display, or screen,

for people to see.

Shaggy fur keeps a raccoon warm in the

winter.

The word

radar is short

for radio

detection and

ranging.

BRITANNICA STUDENT ENCYCLOPEDIA Radar 15

travel through empty space, like in outer

space. They can also travel through air

and even solid substances, such as glass.

Through empty space, the waves travel

at a speed of about 186,282 miles per

second (299,792 kilometers per second).

Like all waves, electromagnetic waves

have peaks and valleys. The distance

from the peak of one wave to the peak

of the next wave is called a wavelength.

Different kinds of electromagnetic waves

have different wavelengths.

From longest to shortest wavelength,

the types of electromagnetic radiation

are radio waves, infrared rays, visible

light, ultraviolet rays, X-rays, and

gamma rays. Radio waves are used for

sending signals, including television and

radio broadcasts. Microwaves are short

radio waves that can be used to cook

food in microwave ovens. Infrared

radiation, or heat, is given off by warm

objects. Infrared radiation from the sun

heats Earth. Visible light is all the

wavelengths of electromagnetic

radiation that the human eye can see.

Different wavelengths of visible light

are seen as different colors. Ultraviolet

radiation is used by the skin to make a

nutrient called vitamin D. X-rays are

used to make a picture of something

inside an object, such as bones inside

the body. Gamma rays are used in

medicine to kill cancer cells.

The shorter the wavelength, the more

energy the radiation carries. The types

with the most energy—ultraviolet radiation,

X-rays, and gamma rays—can be

harmful to the body.

Mechanical Radiation

Unlike electromagnetic radiation,

mechanical radiation cannot travel

through empty space. It can travel only

through a substance, such as air, water,

or solid objects. A common example of

mechanical radiation is sound. Sound is

produced by the back-and-forth motion

of a vibrating object. This motion produces

sound waves that travel away from

the object. Sound travels more slowly

than light does. This is why during a

storm, the sound of thunder follows a

flash of lightning. An earthquake produces

another form of mechanical radiation.

The shock waves created by an

earthquake travel through Earth and

cause the ground to shake.

Nuclear Radiation

Nuclear radiation comes from the

nucleus, or center, of atoms. It is produced

when the nucleus changes in

some way. The nucleus of some types of

By sending

sound waves

through the

body, doctors

can check on

the health of a

growing baby

inside its

mother.

Electromagnetic radiation travels in waves.

A wavelength is the distance from the peak

of one wave to the peak of the next wave.

Short wavelengths have a shorter distance

between peaks than long wavelengths.

BRITANNICA STUDENT ENCYCLOPEDIA Radiation 17

atoms is unstable. An unstable nucleus

can naturally change into another type

of nucleus. When it does this, it shoots

off nuclear radiation in the form of

small particles or gamma rays. Atoms

that give off radiation in this way are

called radioactive. Nuclear radiation

carries a lot of energy, so it can be dangerous.

Cosmic Rays

Cosmic rays are a type of radiation made

up of tiny parts of atoms that speed

through outer space. Cosmic rays can

come from the sun, but most come from

farther away in the galaxy. Some cosmic

rays travel almost at the speed of light.

Because they move so fast, they have

very high energy. Scientists study cosmic

rays to learn more about the makeup of

the galaxy.

#More to explore

Atom • Energy • Heat • Light • Nuclear

Energy • Radio • Sound • X-rays

Radio

Radio is a way of sending sounds or

other information through the air. The

information is carried by invisible radio

Radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays are all

types of electromagnetic radiation. Radio waves have the longest wavelength, and gamma

rays have the shortest wavelength.

Dish antennas pick up radio waves that

carry many kinds of communication.

18 Radio BRITANNICA STUDENT ENCYCLOPEDIA

waves. Radio waves are used for broadcasting,

or sending out, radio and television

programs. Radar, cell phones,

cordless telephones, wireless computer

networks, and other forms of communication

use radio waves, too.

How RadioWorks

Radio waves are a type of radiation.

Radiation is energy that moves. Like all

waves of radiation, radio waves have a

property called frequency. Frequency

describes the number of waves that pass

a given point each second.

Radio waves are sent out by a device

called a transmitter. The transmitter

turns talking, music, pictures, or other

information into electric signals. The

transmitter combines these electric signals

with radio waves of a certain frequency.

The waves spread out in all

directions from an antenna connected to

the transmitter.

The radio waves are picked up by an

antenna connected to a device called a

receiver. The receiver separates the electric

signals from the radio waves. Then it

turns the electric signal back into the

original sounds or pictures.

A receiver that picks up waves that carry

sound is called a radio. A radio sends the

electric signal through speakers so the

sound can be heard. Each radio station

sends out radio waves of a certain frequency.

A person changes a radio from

one frequency to another to hear different

stations.

History

In the late 1890s several people began

working on ways to send and receive

electric signals using radio waves. An

Italian scientist named Guglielmo Marconi

got much of the credit for developing

radio. In 1897 he started a company

that developed several uses for radio.

The first radio station started broadcasting

in Pittsburgh, Pennsylvania, in

1920.Within two years hundreds of

radio stations were started. Radio was a

major source of home entertainment

until the mid-1950s. Then television

became more popular.

In the early 21st century satellite radio

got many people interested in radio

again. Satellite radio was a new method

of radio broadcasting. Instead of using

antennas on the ground, satellite radio

stations sent broadcasts from satellites,

or spacecraft. Satellite radio stations

provided crisp, clear sound. They also

Families of the 1930s had no television to

watch. Instead, they gathered around the

radio to listen to their favorite programs.

BRITANNICA STUDENT ENCYCLOPEDIA Radio 19

could be heard over a much wider area

than traditional radio stations could.

#More to explore

Electronics • Marconi, Guglielmo

• Radar • Radiation

• Telecommunication • Telephone

• Television

Railroad

A railroad, also called a railway, is a type

of land transportation. In a railroad a

train travels along a path of two metal

rails, or tracks. A train is a row of

wheeled cars that are linked together.

The wheels of rail cars have a rim that

keeps them on the rails.

A vehicle called a locomotive pulls most

trains. A locomotive can be powered by

an engine that burns diesel fuel or by

electricity. The electricity comes from a

third rail or an overhead wire. The train

operator, called the driver or engineer,

usually sits in the locomotive.

Types of Trains

Trains can be divided into two types:

passenger and freight. Passenger trains

carry people. Freight trains carry goods.

Passenger trains have cars with seats.

Many passenger trains also have dining

cars, baggage cars, and even sleeping cars

with beds. The speed of many large passenger

trains is about 100 miles (160

kilometers) an hour. However, some

trains in Europe and Japan can go more

than 180 miles (290 kilometers) an

hour.

Commuter trains (trains that carry

workers into a city), subways (underground

trains), and monorails (trains

that run on one rail) are smaller passenger

trains. They carry people shorter

distances. These trains often do not have

a separate locomotive. Instead, some or

all of the cars have electric motors under

the floor. The train operator sits in the

front car.

Freight trains consist of locomotives and

freight cars. There are many types of

freight cars. Boxcars often carry packaged

goods. Open hopper cars often

carry coal. Covered hopper cars often

carry grain. Tank cars carry liquids. Car

carriers carry automobiles. Special flatcars

carry trailers or freight containers.

Some freight trains have 150 or more

cars. Because they pull so much weight,

freight trains usually move more slowly

than passenger trains.

High-speed trains leave their station in London,

England. They can go all the way to

France through a railway tunnel that runs

under the English Channel.

20 Railroad BRITANNICA STUDENT ENCYCLOPEDIA

History

Before there were trains and locomotives,

people used horses to pull carts

along tracks. Europeans began using this

early type of railroad in the 1500s. They

used it to carry heavy loads to and from

mines.

In 1803 Richard Trevithick, a British

engineer, planned and built a locomotive

that ran on steam power. Mining

companies used it. In the 1820s another

British inventor, George Stephenson,

designed and built the first steam train

to carry goods and passengers.

In 1869 the United States completed a

railroad system that stretched all the way

from the East Coast to theWest Coast.

This railroad was called the transcontinental

railroad.

Between the 1930s and the 1950s, diesel

engines replaced steam engines as the

power source in most locomotives.

Today freight trains operate throughout

the world. But in many countries trucks

carry much of the freight that trains

once did. Passenger trains are still common,

too. However, airlines have taken

passengers away from many railroads.

#More to explore

Transportation

Rain

Water has three forms. It may be a liquid,

a solid called ice, or a gas called

water vapor or steam. Rain is the liquid

form of water that falls from the sky in

drops.

Rain fills lakes, ponds, rivers, and

streams. It provides the freshwater

needed by humans, animals, and plants.

If too much rain falls, however, dangerous

flooding may happen.

How Rain Forms

Rain is a part of Earth’s endless water

cycle. At the beginning of the cycle, sunlight

heats up water on Earth’s surface.

The heat causes the water to evaporate,

George Stephenson of England built the

Rocket with his son, Robert, in 1829. It was

the fastest steam locomotive of its time, with

a speed of 36 miles (58 kilometers) per hour.

A tree frog enjoys the rain.

BRITANNICA STUDENT ENCYCLOPEDIA Rain 21

or to turn into water vapor. This water

vapor rises into the air. As the water

vapor cools, it turns back into water, in

the form of droplets. The droplets form

around dust and other particles through

a process called condensation.

Clouds form from large numbers of

these droplets. In a cloud, droplets come

together with other droplets to form

larger drops of water. Eventually the

drops become too heavy to stay in the

cloud. They fall to Earth as rain. Then

the water cycle begins again.

Sometimes drops of water freeze into ice

crystals in the clouds. Sometimes the ice

crystals melt as they fall toward the

ground. This is another way that rain

forms.

Where Rain Falls

Rain falls almost everywhere on Earth.

One of the world’s rainiest places is

MountWaialeale in Hawaii. It rains

about 350 days a year there. About 460

inches (1,170 centimeters) of rain fall

there every year. One of the driest places

on Earth is the Atacama Desert in Chile.

It receives less than 0.04 inch (0.1 centimeter)

of rain a year. It has not rained in

some parts of this desert in hundreds of

years.

Acid Rain

Rain washes dust and dirt from the air.

But rain itself is not always pure. Sometimes

polluting chemicals from cars,

factories, and power plants become

trapped in clouds. The rain from these

clouds contains those harmful chemicals.

This polluted rain, known as acid

rain, can damage plants, animals,

people, and property.

#More to explore

Acid Rain • Cloud • Flood •Water

Rainbow

A rainbow is a multicolored arc, or

curved line, in the sky. Most rainbows

form when the sun’s rays strike raindrops

falling from faraway rain clouds.

Rainbows appear in the part of the sky

opposite the sun, usually in the early

morning or late afternoon. From inside

to outside, the colors of a rainbow are

violet, indigo, blue, green, yellow,

orange, and red.

Sunlight travels through space in the

form of waves. Scientists use an idea

called wavelength to describe these

waves. Some light waves have long wavelengths,

while others have short wavelengths.

Light waves with different

wavelengths appear as different colors.

Usually all light waves blend together to

form white light. But when light waves

A rainbow arcs over a beach in Hawaii. A

faint secondary bow is visible above the

bright primary bow.

The more raindrops

a cloud

contains, the

darker it

becomes.

22 Rainbow BRITANNICA STUDENT ENCYCLOPEDIA

pass through raindrops, they separate.

This happens because the raindrops

bend light waves with different wavelengths

by a different amount. The separated

light waves appear as the colors of

a rainbow.

The brightest and most common type of

rainbow is called a primary bow. Sometimes

a fainter rainbow forms outside

the primary bow. This is called a secondary

bow or, sometimes, a double rainbow.

A secondary bow forms when the

light bends twice inside the water drops.

The first bend makes the primary bow,

and the second bend makes the secondary

bow. The colors in the secondary

bow appear in the opposite order of the

colors in the primary bow.

#More to explore

Light • Rain

Rain Forest

Thick forests found in wet areas of the

world are called rain forests. Most

people are familiar with hot, tropical

rain forests filled with trees that stay

green year-round. But there are other

kinds of rain forests, too. Temperate rain

forests grow in cooler parts of the world,

such as the northwestern United States

and southern Australia. Monsoon rain

forests have a dry season and trees that

shed their leaves each year. They grow in

Southeast Asia. The rest of this article

will focus on tropical rain forests because

they are important to the health of the

entire planet.

Where Tropical Rain Forests

Are Found

Tropical rain forests grow around the

equator in the hot, wet region called

the tropics. They are found in parts of

the tropics that get more than 70 inches

(180 centimeters) of rain each year.

Parts of South and Central America,

western and central Africa, Southeast

Asia, and Australia have tropical rain

forests.

Features

Tropical rain forests can be divided into

several sections. At the top of the forest

is a thick layer called the canopy. It is

formed by the spreading branches and

thick leaves of tall trees. The canopy

blocks much of the sunlight from the

area below. The canopy can be between

100 and 170 feet (30 and 50 meters)

above the ground. A few very tall trees

stick up above the rest of the canopy.

They are called emergent trees. Many

Thick rain forest covers parts of the African

country of Cameroon.

BRITANNICA STUDENT ENCYCLOPEDIA Rain Forest 23

animals and insects live among the treetops

of the canopy.

The section below the canopy is called

the understory. It contains small trees,

shrubs, and plants. Many of these are

saplings (young trees). Their stems reach

up toward the light. However, these

smaller trees generally do not receive

enough sunlight to grow into adult trees.

On the forest floor, bacteria, fungi, and

insects help to break down dead plants

and animals. This process creates a thin,

rich top layer of soil that provides nutrients

to the roots of the plants and trees.

Because this layer of soil is thin, most of

the trees have shallow root systems.

Life in Tropical Rain Forests

The trees found in tropical rain forests

stay green all year, though they do shed

their leaves sometimes. Palms are among

the most common trees.

Below the thick canopy, other plants

have to compete with each other to get

enough light. As a result, many plants

use other plants to reach toward the

sunlight. For example, woody plants

called lianas attach to the stems of other

plants and climb from the ground to the

canopy. Mosses, ferns, and orchids may

also attach themselves to larger plants.

Each area of the rain forest has thousands

of species, or types, of animal.

Many plant-eating animals live in the

canopy—for example, monkeys, flying

squirrels, and sharp-clawed woodpeckers.

At the lower levels of the forest are

animals that run, flutter, hop, and climb

in the undergrowth. On the rain forest

floor are such animals as chimpanzees,

gorillas, elephants, pigs, deer, and

leopards.

Tropical Rain Forests in

Danger

Tropical rain forests grow in many poor

countries. Some poor countries sell the

wood and other resources of rain forests

to make much-needed money. This

often means that entire sections of the

forest are destroyed. The loss of rain

forests endangers many plants and animals

that live nowhere else in the world.

Some of these plants and animals may

become extinct if their rain forest habitat

is destroyed.

The destruction of tropical rain forests

also affects the environment of the rest

of the world. Through the process

Different kinds of plants grow at different

levels of a tropical rain forest.

24 Rain Forest BRITANNICA STUDENT ENCYCLOPEDIA

called photosynthesis, plants produce

oxygen and absorb carbon dioxide gas

from the atmosphere. Because the

number of plants in tropical rain forests

is so huge, the forests produce much of

the world’s oxygen, which all animals

need to live. When forests are burned,

massive amounts of carbon dioxide

escape into the atmosphere. This

carbon dioxide leads to a problem

called global warming.

..More to explore

Equator • Fern • GlobalWarming

• Palm

Raleigh

Population

(2000 census),

city, 276,093;

(2007 estimate)

375,806

Raleigh is the capital of the U.S. state

of North Carolina. It is one of three

cities—Raleigh, Durham, and Chapel

Hill—that make up an area called the

Research Triangle. Each of these cities

has a large university that conducts

scientific research. Raleigh is home to

North Carolina State University and

five other schools for higher education.

The area also has many companies that

conduct research and develop hightechnology

products. They are located

in a group of offices called Research

Triangle Park.

Most people in Raleigh work in government

or in research, education, health

care, and other service industries. Factories

in the city make such products as

paper, processed foods, electronics,

medicines, and computers.

Raleigh was created in 1792. It was built

to be the new capital of North Carolina.

In 1865, during the American Civil

War, the Union Army took control of

Raleigh. During the 20th century the

city grew greatly.

..More to explore

North Carolina

Ramadan

In the religion of Islam, the holy month

of Ramadan marks when the prophet

Muhammad received the words of the

Koran. The Koran is the holy book of

the Muslims, as the followers of Islam

are called. Muslims observe Ramadan

by praying, reading the Koran, and

fasting.

The North Carolina state Capitol is in

Raleigh. It was built between 1833 and

1840.

BRITANNICA STUDENT ENCYCLOPEDIA Ramadan 25

Muslims fast by refusing to eat or drink

anything during daylight hours. Small

children, very old people, and people

with illnesses are excused. After sunset,

Muslims break their fast with prayer

and festive nighttime meals. The end of

the monthlong fast is celebrated as a

festival.

Ramadan is the ninth month of the

Islamic calendar. Since the Islamic calendar

is based on the moon, Ramadan

may occur in any season of the year. The

27th night of Ramadan is celebrated as

the Night of Power, or Lailat al Kadr.

On that night, it is said, God revealed

the Koran. Ramadan officially ends

when religious officials first see the new

moon.

#More to explore

Islam

Rap

The musical form called rap is basically

rhythmic, rhyming speech. Rap is the

most important part of a way of life

called hip-hop culture. Many people call

the music that rappers use hip-hop

music.

Rap songs often tell stories about rappers

and their backgrounds. Some rappers

speak about racism and its effects

on African Americans. Most rappers

have been men. Some women, such as

Queen Latifah, have become successful

rap artists as well.

Rap began in the early 1970s in African

American neighborhoods in New York

City. The first rapper was probably a

Jamaican deejay named Kool Herc.

(Deejays play recordings at dance clubs.)

Kool Herc used two turntables, or

record players, to create sound for parties

in the Bronx section of New York.

As the music played he would “rap,” or

talk, to the audience.

In time other deejays developed the

rhyming musical speech that became

rap. Early rappers included Afrika Bambaataa

and Grandmaster Flash. In 1979

the Sugarhill Gang’s song “Rapper’s

Delight” became the first hit rap song.

Boys in Pakistan help to prepare meals that

Muslims will eat after sunset during

Ramadan.

Rap artists perform for a crowd at an

awards show.

26 Rap BRITANNICA STUDENT ENCYCLOPEDIA

During the 1980s rap mixed with other

forms of popular music, including rock

and soul. Some popular rappers during

this time were LL Cool J, Run-D.M.C.,

the Beastie Boys, and De La Soul. Public

Enemy performed rap songs with strong

political messages.

In the 1990s a form of rap known as

gangsta rap became popular. Gangsta

rap songs by N.W.A., Ice-T, and other

performers described the drug use,

gangs, and violence found in inner cities.

Other rappers continued to mix rap

with other forms of music—for

example, the Fugees used reggae, and

OutKast used funk.

#More to explore

Hip-Hop • Popular Music

Raptors

#see Bird of Prey.

Raspberry

Raspberries are delicate, juicy fruits.

They are eaten fresh. They are also

canned, processed for jams, put into

pastries, or frozen. Raspberries are a

source of vitamin C, vitamin A, and

iron.

Raspberries grow in the United States

and Europe. They thrive in places where

summer is not very hot and winter is

not very cold.

Raspberries are usually red, purple, or

black. They grow on prickly bushes

called brambles. The bushes produce

small flowers that develop into the

berries.

Botanists (people who study plants) do

not consider raspberries to be true berries.

True berries, such as cranberries and

blueberries, are single fruits that develop

from a single flower. But a raspberry is

actually a cluster of small fruits that

develop from a single flower. The small

fruits are attached to a firm core. When

a raspberry is picked, the core stays on

the plant. This is why a picked raspberry

is hollow inside.

Raspberries are similar to blackberries.

But when a blackberry is picked, the

core stays inside the fruit. Another difference

is that raspberries are hairy but

blackberries are smooth.

#More to explore

Blueberry • Cranberry • Fruit

Each raspberry is actually a

cluster of tiny fruits.

BRITANNICA STUDENT ENCYCLOPEDIA Raspberry 27

Rat

Rats belong to the group of mammals

called rodents. They live throughout the

world, either in the wild or around

people. They usually stay out of sight by

squeezing into tight hiding spaces.

Rats look like mice but are usually

larger. A rat is usually about 7 to 10

inches (18 to 25 centimeters) long, not

including the tail. The fur can be gray,

white, black, or brown. Rats have sharp

teeth. They use their teeth to defend

themselves against birds, snakes, and

other enemies.

Rats are most active at night. Rats in the

wild eat leaves, branches, seeds, and

roots. Some eat small animals. Rats living

near people will eat almost anything

that people eat. They also gnaw on all

kinds of objects other than food, such as

walls and telephone cables.

Rats can reproduce quickly. Females that

are only a few months old can have

babies. A rat can have as many as 150

babies every year.

Many people think rats are pests.With

their big appetite, rats can destroy crops

and stored grain. Rats also can spread

diseases, such as the plague. But rats can

be useful, too. Medical researchers use

them in experiments. Some people keep

rats as pets.

#More to explore

Mammal • Plague • Rodent

Rattlesnake

Rattlesnakes are poisonous snakes that

have rattles in their tails. A rattlesnake

shakes its rattle to threaten, or warn off,

other animals.

There are about 30 species, or types, of

rattlesnake. They live in the Americas,

from southern Canada to Argentina.

They are most common in the deserts of

the southwestern United States and

northern Mexico.

A mother rat protects her babies in the corner

of a barn.

A western diamondback rattlesnake shakes

its rattle.

28 Rat BRITANNICA STUDENT ENCYCLOPEDIA

Most rattlesnakes are gray, tan, or brown

with diamond-shaped patches or crossing

diagonal bands. They are usually

between 1 foot (0.3 meter) and 8 feet

(2.5 meters) long. The head is shaped

like a triangle.

Rattlesnakes belong to a group of snakes

called pit vipers. Between each eye and

nostril, a rattlesnake has a heat-sensing

organ called a pit. It uses these pits to

find prey. Rattlesnakes eat rodents, lizards,

and birds. When a rattlesnake

bites, venom, or poison, flows through

its fangs into the prey.

When threatened, a rattlesnake raises

and shakes its tail rattle. The rattle is

made up of several hollow, loosely connected

segments. It makes a buzzing

sound when the segments rapidly hit

each other. The sound warns intruders

to back off.

Most rattlesnakes are shy and try to stay

away from people. But if disturbed, a

rattlesnake will bite a person. Rattlesnake

bites are painful and can be lifethreatening.

But prompt medical

treatment can usually stop the effects of

the venom.

#More to explore

Snake • Viper

Raven

Ravens are large, black birds that are

closely related to crows. They belong to

a scientific group of birds called songbirds.

However, their voices do not

sound very musical. They make a variety

of noises, such as caws, croaks, and

gurgles. People in some cultures think of

these dark birds as symbols of death and

bad things to come. However, some

people admire ravens for the birds’ great

intelligence.

Ravens and crows are in the same family

as jays and magpies. There are several

different species, or types, of raven. The

common raven is found in parts of North

America, Europe, Asia, and Africa.Other

types of raven also live in those four

continents as well as in Australia.

Ravens are very hardy birds. They are

found in a variety of habitats, including

forests, mountains, deserts, and frozen

plains.

Ravens look a good deal like crows.

However, ravens are heavier and have

bigger bills. They can measure up to 26

inches (66 centimeters) in length. Ravens

also have shaggier feathers than crows do,

especially around the throat. Ravens’

feathers are all or mostly black, often with

a blue or purplish shimmer. Several types

Ravens are larger and heavier than crows.

BRITANNICA STUDENT ENCYCLOPEDIA Raven 29

have some white or brown markings. The

common raven is all black.

Ravens eat a varied diet that includes

mice, insects, grain, and the eggs of

other birds. They also feed on dead animals

and garbage.

#More to explore

Bird • Crow • Magpie • Songbird

Ray

A ray is a fish with a flattened body and

large, winglike fins. Rays belong to the

same large group of fishes as sharks.

Both rays and sharks have skeletons

made up of cartilage (elastic tissue)

instead of bone. Rays are found in all

oceans of the world.

There are more than 300 different species,

or types, of ray. These can be

divided into several groups: skates, electric

rays, sawfishes, and stingrays.

Rays vary in size. The little, or hedgehog,

skate is less than 20 inches (50 centimeters)

long. The Atlantic manta, or

giant devil ray, has a wingspan of up to

23 feet (7 meters).

Most rays have rough skin. It may be a

solid color or patterned. Electric rays,

however, have smooth skin. They also

have electric organs near the head. These

give powerful electric shocks to enemies

or prey. A ray’s tail is slender and sometimes

long and whiplike. Stingrays have

a poisonous spine on the tail. They use

it for defense. Sawfishes have a long

snout shaped like a saw. They use it

mainly for hunting.

Rays often lie partly buried in sand or

mud on the ocean floor. They feed on

small fish and such crustaceans as crabs

and shrimp. When prey gets close, rays

quickly lunge out of the sand and snatch

it up.

The females of most species give birth to

live young. However, skates lay eggs.

#More to explore

Fish • Shark

Re

In ancient Egyptian mythology Re was

the chief sun god. (His name is sometimes

spelled Ra.) The sun god was very

important to the Egyptians. The ancient

pharaohs (kings) said they were related

to him.

According to legend, Re created the

universe. Time began when his sun disk

rose out of the darkness for the first

time. At creation, Re made Shu (air)

Two southern stingrays swim in shallow

water.

30 Ray BRITANNICA STUDENT ENCYCLOPEDIA

and Tefnut (moisture). They gave birth

to the sky goddess Nut and the Earth

god Geb. From the marriage of Nut

and Geb came the gods Osiris, Isis,

Seth, and Nephthys. These gods were

the main figures of Egyptian

mythology.

The Egyptians believed that at sunrise

Re—the sun—began a journey across

the sky in his boat. At sunset Re sailed

his boat to the underworld. There each

night he fought an evil snake named

Apopis. Apopis tried to prevent the sun

from rising again. But each night Re

won. Each morning he began another

journey across the sky, and the sun rose

again.

#More to explore

Egypt, Ancient • Isis and Osiris

• Mythology

Reagan, Ronald

Ronald Reagan was elected in 1980 as

the 40th president of the United States.

Reagan was a conservative who cut some

kinds of government spending but

strengthened the military. He strongly

opposed the Soviet Union and other

Communist countries.

Early Life and Career

RonaldWilson Reagan was born in

Tampico, Illinois, on February 6, 1911.

His parents were Jack Reagan, a shoe

salesman, and NelleWilson. At high

school in Dixon, Illinois, Reagan played

football and acted in school plays.

After graduating in 1932 from Eureka

College, Reagan became a radio sports

announcer in Iowa. In 1937 he moved

to southern California, where he became

a successful movie actor. His first film,

Reagan’s good

speaking skills

earned him

the title The

Great Communicator.

Re was the sun god of ancient Egypt.

BRITANNICA STUDENT ENCYCLOPEDIA Reagan, Ronald 31

Love Is on the Air, was released in 1937.

Reagan went on to appear in more than

50 movies and several popular television

shows.

DuringWorldWar II Reagan joined the

Army Air Corps but did not see combat.

In 1940 he married the actress Jane

Wyman. They had a daughter and

adopted a son before getting a divorce in

1948. Reagan married the actress Nancy

Davis in 1952. They had a daughter and

a son.

Political Career

Reagan was a Democrat during the

1940s. After growing more conservative,

he switched to the Republican Party in

1962.

Reagan was elected governor of California

in 1966 and in 1970. In 1980 he ran

for president with George Bush as his

running mate. Reagan defeated President

Jimmy Carter that year. He took

office in January 1981. Reagan ran for

reelection in 1984. He easily defeated

his opponent,Walter F. Mondale.

Presidency

Reagan worked to reduce the role of the

federal government. Congress approved

many of his proposals to cut spending,

except for defense, and to lower taxes.

February 6, June 5,

1911 1966 1980 1981 1986 1989 2004

Reagan is

born in

Tampico,

Illinois.

Reagan is

elected

governor of

California.

Reagan is

elected

president.

Reagan

survives an

assassination

attempt.

The Irancontra

affair

becomes

public.

Reagan retires;

George Bush

becomes

president.

Reagan

dies in Los

Angeles,

California.

T I M E L I N E

Ronald Reagan was the 40th president of

the United States.

32 Reagan, Ronald BRITANNICA STUDENT ENCYCLOPEDIA

On March 30, 1981, a man shot Reagan

in the chest inWashington, D.C.

Reagan recovered after surgery.

In foreign affairs, Reagan built up the

military to protect the country from the

Soviet Union. He also proposed a system

that would destroy missiles in space. He

called the system the Strategic Defense

Initiative. Reagan later improved relations

with the Soviets. His historic meetings

with Soviet leader Mikhail

Gorbachev led both countries to destroy

some nuclear weapons.

In 1986 the public discovered that officials

who worked for Reagan had illegally

sold weapons to Iran. The officials

hoped that Iran would help to free U.S.

hostages in Lebanon. They had then

secretly sent money from the weapons

sales to anti-Communist rebels (contras)

in Nicaragua. The Iran-contra affair

embarrassed Reagan, but he soon

regained his popularity.

Later Years

Reagan retired in 1989. In 1994 he

announced that he had Alzheimer’s disease.

Reagan died on June 5, 2004, in

Los Angeles, California.

#More to explore

Alzheimer’s Disease • Bush, George

• Union of Soviet Socialist Republics

• United States

Reconstruction

After the American CivilWar ended in

April 1865 the United States went

through a period known as Reconstruction.

The Union (the Northern states)

had defeated the Confederacy (the

Southern states that had left the Union).

From 1865 to 1877 the two sides

worked to put the United States back

together.

During Reconstruction, people disagreed

on how to readmit the Southern

states, or bring them back to the Union.

They also disagreed on what to do about

African Americans who had won freedom

from slavery.

Radical Reconstruction

While the war was still going on, President

Abraham Lincoln made a plan to

readmit Confederate states quickly. Lincoln

was killed in April 1865. Andrew

Johnson then became president. He

wanted to carry out Lincoln’s plan.

An illustration shows African American men

lining up to vote for the first time. Men who

had been slaves gained the right to vote

during Reconstruction.

BRITANNICA STUDENT ENCYCLOPEDIA Reconstruction 33

Some members of the U.S. Congress,

called Radical Republicans, disagreed

with Lincoln and Johnson. They wanted

to punish the South. They also wanted

to protect African Americans. In 1867

the Radical Republicans took control of

Congress. The period that followed is

called Radical Reconstruction.

During Radical Reconstruction, lawmakers

put the South under military

rule and removed most white Southern

leaders from power. This left control of

the Southern states in the hands of African

Americans and whites loyal to the

Union. Some of these whites were criticized

by Southerners, who called them

carpetbaggers. The term referred to the

idea that they were Northerners who

came to the South carrying only what

they could put in a small bag. Southerners

also accused them of coming to take

advantage of the situation. Some white

Southerners cooperated with the blacks

and carpetbaggers. Other Southerners

accused those who cooperated of doing

so in order to further their own interests.

They called them scalawags.

Congress also required Southern states

to ratify (approve) the 14th Amendment

to the Constitution before they

could rejoin the Union. This amendment

guaranteed citizenship to African

Americans. By 1870, all 11 former

Confederate states had approved the

amendment and rejoined the Union.

Freed African Americans

Meanwhile, nearly 4 million former

slaves tried to start new lives in the

South. A government agency called the

Freedmen’s Bureau helped them. It provided

medical care and food. It also built

more than 1,000 schools.

In 1870 the 15th Amendment to the

Constitution guaranteed African Americans

the right to vote. These new voters

helped to elect African Americans to

many offices, including seats in Congress.

Despite these gains, most African

Americans in the South were still poor.

They had no way to buy land and ended

up working on farms for low pay.

Reconstruction Ends

Reconstruction gradually came to an

end for several reasons. Some radical

leaders died. People accused some

A cartoon from the 1870s makes fun of a

Northern politician. It shows him as a carpetbagger,

or a Northerner who moved to

the South with only what he could carry in

a small bag. (At the time, traveling bags

were commonly made of carpet.)

34 Reconstruction BRITANNICA STUDENT ENCYCLOPEDIA

Reconstruction governments of

dishonesty. New terrorist groups like

the Ku Klux Klan stopped African

Americans from voting or running for

office. As a result, Southern Democrats

(who had supported the Confederacy)

took back control of governments in

the South.

The final blow came with the presidential

election of 1876. The vote was so

close that both Republicans and Democrats

claimed victory. The Democrats

allowed the Republican winner, Rutherford

B. Hayes, to become president only

after making a deal. Hayes promised to

remove U.S. Army troops from the

South. The troops left in 1877. Southern

Democrats were then in complete

control of the South. Reconstruction

was over.

#More to explore

African Americans • American CivilWar

• Hayes, Rutherford B. • Johnson,

Andrew • Ku Klux Klan

Recycling

Recycling is a way to reduce the amount

of garbage that is thrown away. Every

year the United States produces millions

of tons of garbage. The garbage is sent to

landfills, where some of it pollutes the

land and air. As a result of recycling,

some things that would have been

thrown away are reused instead in new

products.

What Gets Recycled

Many items can be recycled, including

aluminum cans, glass bottles, newspapers,

magazines, and plastics. Composting

is also a form of recycling. It involves

saving certain food wastes and mixing

them with grass clippings and leaves.

This creates a nutrient-rich mixture that

can be used in gardens. Even water can

be recycled. Before water is reused, it is

cleaned and purified at a wastewater

treatment plant.

Types of Recycling

There are two types of recycling: internal

and external. In internal recycling,

the waste products from manufacturing

processes are reused within the same

factory. For example, when copper tubing

is being made, the ends of the tubes

are usually trimmed. These copper ends

are melted down and used to make new

tubing.

In external recycling, people collect recyclable

materials. The recyclables are

brought to a recycling facility, where

they are sorted, cleaned, and prepared to

be sold. Industries then buy the material

and use it to make new products.

Recycling starts when recyclable materials

are sorted and left to be picked up.

BRITANNICA STUDENT ENCYCLOPEDIA Recycling 35

Importance of Recycling

Governments and groups that try to

protect the environment have encouraged

people to recycle. They say that

recycling is important in several ways. It

reduces pollution of air, water, and land.

It also protects natural resources such as

trees, minerals, and oil. These do not get

used up as quickly if people can reuse

existing products made from these

resources.

#More to explore

Environment • Natural Resource

• Pollution

Red Cross and

Red Crescent

The International Movement of the

Red Cross and Red Crescent is a

collection of groups that help people

during times of war and natural

disasters. The groups are not religious.

However, the Red Cross is the name

used in mainly Christian countries. The

Red Crescent is the name used in

mainly Muslim countries. (A cross is a

symbol of Christianity and a crescent is

a symbol of Islam.)

More than 180 Red Cross and Red

Crescent societies, or groups, exist

throughout the world. For example,

there are an American Red Cross, a British

Red Cross, and a Pakistan Red Crescent.

Each society is independent and

offers its own services. The societies provide

medical help, food and water, and

shelter to victims of earthquakes, floods,

and other natural disasters. They also

help people during times of war. During

peacetime, the societies teach first aid

and safety skills. Many also run blood

banks.

The International Committee of the

Red Cross (ICRC) was the first Red

Cross group. It is based in Switzerland.

The ICRC helps people affected by wars

or other violent conflicts. Because it

never takes sides in wars, most countries

trust this group. Countries often allow

the ICRC to work in areas where other

groups are not allowed.

A Swiss man named Jean-Henri Dunant

started the Red Cross movement. In

1863 he helped to form an international

group of people to help wounded soldiers.

These helpers began using a red

cross as their symbol. The group became

known as the ICRC in 1875. In 1901

Red Cross workers in South Korea prepare

aid kits to be sent to North Korea. North

Koreans needed help after a train accident

injured many people.

A woman

named Clara

Barton

founded the

American Red

Cross in 1881.

36 Red Cross and Red Crescent BRITANNICA STUDENT ENCYCLOPEDIA

Dunant shared the first Nobel peace

prize for his work.

#More to explore

Nobel Prize • Switzerland

Red Sea

The Red Sea separates the Arabian Peninsula

from northeastern Africa. It was

named for the changing color of its

water. Normally the water is blue-green.

Sometimes, though, red algae turn the

water reddish brown.

The Red Sea is long and narrow. On the

east it is bordered by the Arabian countries

of Saudi Arabia and Yemen. The

African countries of Egypt, Sudan, and

Eritrea lie to the west. In the south a

passageway called a strait connects the

Red Sea with the Gulf of Aden and then

with the Arabian Sea. In the north the

Suez Canal connects the Red Sea to the

Mediterranean Sea.

The Red Sea is one of the world’s

busiest trade routes. Ships carry

passengers and goods between Europe

and Asia through the Suez Canal. The

sea also contains deposits of oil and

other minerals.

The Red Sea is one of the first large

bodies of water mentioned in recorded

history. Egyptians used the sea for trade

as early as 2000 BC. The Suez Canal was

opened in 1869. It made trade and

transportation on the sea much easier.

#More to explore

Arabian Peninsula • Suez Canal

Redwood

The redwood is the world’s tallest type

of tree. One tree was measured at 367.8

feet (112.1 meters) tall. Many redwoods

grow to heights of more than 300 feet

(90 meters).

The redwood grows in Oregon and

California. It is found in foggy areas

near the Pacific coast. A related tree is

the dawn redwood. It grows in central

China. Two other trees are sometimes

called redwoods: the giant sequoia of

There are a number of coral reefs in the

Red Sea.

BRITANNICA STUDENT ENCYCLOPEDIA Redwood 37

California and the Japanese cedar of

eastern Asia.

The redwood has a huge trunk. It can be

10 to 20 feet (3 to 6 meters) across. The

trunk may have no branches for the first

100 feet (30 meters). This is because the

redwood sheds its lower limbs as it

grows. The leaves on the lower branches

are dark green and pointed. Short

needles grow near the tree’s top. The

redwood has small cones. They are only

about 1 inch (2.5 centimeters) long.

A redwood may live for more than

1,500 years. Its long life is partly due to

the tree’s thick bark. Redwood bark can

be more than 12 inches (30 centimeters)

thick. It helps the tree to resist disease

and parasites, or harmful animals. The

bark also resists fire.

Redwood timber is used to make furniture,

shingles, and fence posts. Several

state parks have been created to protect

the trees. In 1968 Redwood National

Park was established in California.

#More to explore

Giant Sequoia

Reformation

A religious movement known as the

Reformation swept through Europe in

the 1500s. Its leaders disagreed with the

Roman Catholic church on certain religious

issues and criticized the church’s

great power and wealth. They broke

away from the Catholic church and

founded various Protestant churches.

Today, Protestantism is one of the three

major branches of Christianity. As the

Reformation spread across Europe, it

also inspired movements for political

and social change.

Origins and Spread

In the early 1500s almost everyone in

western and central Europe was Roman

Catholic, and the church was very

powerful. The Reformation began in

1517. In that year a German priest

named Martin Luther circulated a list

of doubts he had about certain Catholic

beliefs and practices. Soon after, Luther

came to reject the authority of the

church and its leader, the pope. He

thought that people could learn all

religious truths directly from the Bible.

Luther also believed that people are

saved by their faith alone, not by works

they do. He called for the end of most

of the sacraments, or rituals, of

Catholicism.

The redwood tree that grows in California

and Oregon is sometimes called the coast

redwood. Its scientific name is Sequoia sempervirens.

38 Reformation BRITANNICA STUDENT ENCYCLOPEDIA

The pope condemned Luther’s

teachings. But Luther’s message spread

quickly. Huldrych Zwingli called for

even greater changes in Christian

worship. He converted many people in

Switzerland to Protestantism. John

Calvin helped bring the Reformation to

France and made Geneva (now in

Switzerland) into a Protestant city-state.

In 1534 King Henry VIII established

the Church of England, with himself as

leader. Influenced by Calvin, John

Knox helped found the Presbyterian

church in Scotland. By the mid-1600s

Europe was mostly divided into

Protestant and Catholic regions. Most

of these divisions have remained in

place. In the 1600s the settlers of the

British colonies brought Protestantism

to North America.

Counter-Reformation

The Roman Catholic church tried to

stop the spread of Protestantism with its

own movement, the Counter-

Reformation. Members of a religious

order known as the Jesuits spread

Catholicism through their teaching and

missionary work. A Catholic court system

called the Inquisition punished

Catholics who disobeyed church teachings.

From 1545 to 1563 a Catholic

body known as the Council of Trent

made many changes to the Catholic

church in an attempt to correct its problems.

The Counter-Reformation won

back many people who had left the

Catholic church.

#More to explore

Calvin, John • Henry VIII • Luther,

Martin • Protestantism • Roman

Catholicism

Refugee

When people leave their country to seek

refuge, or protection, in another country,

they are called refugees. Sometimes

governments force people to leave their

country. Other people leave their coun-

An illustration shows Martin Luther (right)

meeting with Roman Catholic leaders.

Luther was a major figure in the Reformation.

A refugee camp in Kyrgyzstan houses

people who escaped violence in their home

country of Uzbekistan. Many refugees must

live in temporary homes, such as tents.

BRITANNICA STUDENT ENCYCLOPEDIA Refugee 39

try because they belong to a group that

is being mistreated. Still others leave

their country to escape wartime conditions

or starvation.

Even though they seek shelter in a new

country, refugees often continue to

think of the old country as their home.

They may want to move back if conditions

change. This makes refugees different

from other migrants, who want to

change their homes permanently. Refugees

are also different from displaced

persons. These are people who are forced

from their homes but not out of their

country.

Refugees Before the 1900s

Before the 1900s, many refugees were

people who disagreed with their country’s

religion. In the 1400s a Roman

Catholic court called the Inquisition

forced the Jews out of Spain. Beginning

in 1685, French Catholics expelled

French Protestants called Huguenots

from France.

These refugees often moved to new

countries with few problems. There were

not many rules about movement from

one country to another. This situation

changed when modern nations developed

in the 1800s. Refugees from modern

nations needed to ask permission to

enter another country. The new country

then decided whether to offer asylum, or

protection, to the refugees. (Asylum

prevents refugees from being handed

back to the country that mistreated

them.)

Refugees in the Early 1900s

The battles ofWorldWar I (1914–18)

forced many refugees from Belgium,

France, Italy, and Romania. These refugees

resettled in their homelands after

the war. However, the Russian Revolution

of 1917 forced more than 1.5 million

out of Russia permanently.

Meanwhile, Turkey forced more than 1

million Armenians to move to Syria and

Palestine between 1915 and 1923.

The new international organization

called the League of Nations decided to

deal with the growing problem of refugees.

It appointed a Norwegian explorer

named Fridtjof Nansen to help refugees.

Nansen created a League of Nations

Passport to allow refugees to move freely

across national boundaries. He won the

Nobel peace prize (an important international

award) in 1922 for his work.

WorldWar II and Its

Aftermath

WorldWar II (1939–45) created more

than 60 million refugees. Jews fleeing

the Nazi leaders of Germany made up a

large portion of them. Many entered the

United States, and others moved to

South America and other places. Hundreds

of thousands of people left Poland

for the Soviet Union. In Asia, Japanese

attacks forced more than 30 million

Chinese people from their homes.

In Europe, many events that followed

the war created still more refugees. Millions

of Germans had to move out of a

region called East Prussia when it

became a part of Poland. In addition,

One goal of

the

organization

called

Amnesty

International

is to help

refugees find

asylum.

40 Refugee BRITANNICA STUDENT ENCYCLOPEDIA

the Soviet Union began setting up Communist

governments in eastern European

countries. People left those

countries because they were afraid of

losing their freedom.

The United Nations (UN) replaced the

League of Nations in 1945. In 1950 the

UN created an office to help refugees.

The office, called the Office of the High

Commissioner for Refugees, won the

Nobel peace prize in 1954 and 1981.

Refugees SinceWorldWar II

The two world wars were not the only

events that created many refugees. In

1947 the British divided their colony of

India into two new independent countries:

India, where the main religion was

Hinduism; and Pakistan, where the religion

was Islam. Eighteen million people

crossed the borders in order to live with

others of their own religion.

During the 1900s, many Jewish

migrants and refugees settled in the

Middle East in the region called Palestine.

They created Israel as a Jewish

homeland in 1948. After that, many

Arabs who had been living in Palestine

became refugees themselves.

Millions of refugees fled Asian wars.

One such war was the KoreanWar of

1950–53. Another was the VietnamWar

that ended in 1975. Another was the

invasion of Afghanistan by the Soviet

Union in the 1980s. More than 1 million

refugees left Iraq during the Persian

GulfWar in 1991.

Events in Africa, the Americas, and

Europe also created refugees. Civil wars

in Africa forced millions from their

homelands. When the Caribbean nation

of Cuba became Communist in 1959,

more than 1 million refugees left the

island. The breakup of Yugoslavia in the

1990s set off fighting between its different

groups of peoples. Two million

people had to leave their homelands.

In the early 21st century, the UN estimated

that there were still about 10 mil-

World War II refugees cross a wrecked

bridge in Germany in 1945.

A family of refugees from Afghanistan

seeks help from the UN High Commissioner

for Refugees.

BRITANNICA STUDENT ENCYCLOPEDIA Refugee 41

lion refugees in the world. Many of

them lived in crowded camps because

they were unable to find permanent

homes in the countries that they fled to.

#More to explore

Migration, Human • United Nations

Reindeer

Reindeer are mammals of the deer family

along with moose and elk. They are

also called caribou. All reindeer grow

pairs of antlers, which are large bony

growths on the head. Female reindeer

are the only females of the deer family to

grow antlers.

Reindeer live in the far northern

regions of North America, Europe, and

Asia. They live in forests and the Arctic

tundra, or treeless plains of the far

north.

Compared to other members of the

deer family, reindeer have thicker bodies

and shorter legs. Reindeer stand about

2 to 5 feet (0.6 to 1.5 meters) high at

the shoulder. They can weigh as much

as 700 pounds (320 kilograms). They

have thick coats of brown, gray, or

whitish fur. Their feet have wide

hooves.

Reindeer live together in herds. The

herds travel long distances between their

summer and winter homes. Reindeer eat

grasses, other plants, and a plantlike

material called reindeer moss.

Reindeer breed in autumn. The males

often battle each other for mates. The

females usually give birth to one baby at

a time.

Some people, including the Sami of

northern Europe, keep herds of reindeer.

They use the animals to pull sleds over

the snow. They also raise reindeer for

their meat, milk, and skins.

#More to explore

Deer • Tundra

Religion

People often use the word religion to

mean the worship of a god or gods. But

some religions do not have gods. One

thing that all religions have in common

is that they help their followers to find

meaning in the world. Many people

want to know where the world came

from. Many also want to know what

happens after death. Most religions

offer some sort of answer to these great

questions. The major world religions of

today are Christianity, Islam,

Hinduism, Buddhism, Sikhism, and

Judaism.

Some reindeer are found in the Arctic tundra,

while others are forest animals.

42 Reindeer BRITANNICA STUDENT ENCYCLOPEDIA

Types of Religion

Throughout history there have been two

main types of religion. One type has a

single, all-powerful god. Judaism, Christianity,

and Islam are the major religions

that say there is one god. Other religions

with one god include Sikhism and

Baha#i.

In the other main type of religion, followers

believe in more than one god.

The religions of this type include Hinduism,

Jainism, Shinto, Zoroastrianism,

Native American religions, and traditional

African religions.

Followers of other religions do not focus

on worshipping gods. For example, followers

of Buddhism search for a higher

state of being, which means freedom

from suffering. Followers of Daoism

focus on acting in a certain way.

Common Elements of Religion

Religions usually have rituals, or special

patterns of actions, that followers perform.

They often have prayers that followers

say and holidays on certain days

of the year. Many religions have written

works that are considered holy, such as

the Bible or the Koran. Many religions

also have special buildings, such as

churches or temples, where followers

gather for worship.

Religions set out rules or guidelines for

how followers should live. Different

religions have different rules. However,

many religious rules have to do with

treating others well and doing the right

thing. Religions also have sets of beliefs

that followers accept as true—for

example, belief in a god and life after

death.

Religions have played a very important

role in the history of people all over the

world. They have affected almost every

part of people’s lives. For example, religions

have affected the way governments

are set up, how families are formed, and

the way people teach their children.

#More to explore

Baha#i Faith • Buddhism • Christianity

• Daoism • Hinduism • Islam • Jainism

• Judaism • Shinto • Sikhism

• Zoroastrianism

Rembrandt

The Dutch painter Rembrandt is one of

the most famous of all European artists.

He created many historical and biblical

paintings known for their rich color and

masterful use of light and shadow. He is

also known for his drawings and etchings

(a type of print).

Rembrandt was born on July 15, 1606,

in Leiden, the Netherlands. His full

Major World Religions

Religion Number of Followers in

the World, Mid-2005

Christianity 2,133,806,000

Islam 1,308,941,000

Hinduism 860,133,000

Buddhism 378,808,000

Sikhism 25,377,700

Judaism 15,073,000

Source: Britannica Book of the Year, 2006

Nearly three quarters of the people on

Earth follow one of six major world religions.

Religions that

focus on the

belief in one

god are called

monotheistic.

BRITANNICA STUDENT ENCYCLOPEDIA Rembrandt 43

name was Rembrandt Harmenszoon van

Rijn, but he is usually known simply by

his first name. He attended the University

of Leiden but left to study painting.

By the time he moved to Amsterdam in

1631, he was already a successful

painter. Many wealthy people hired him

to paint their portraits. An early masterpiece

of his was The Anatomy Lesson of

Dr. Nicolaes Tulp, a group portrait

painted in 1632. He completed another

famous group portrait, The NightWatch,

in 1642.

Around that time Rembrandt’s work

began to go somewhat out of fashion.

With fewer orders for portraits, he

began to have money problems. In the

late 1650s he sold his house and many

of his belongings to pay his debts. But

he continued his work, producing portraits

of biblical figures, local people,

and himself. Rembrandt died on October

4, 1669, in Amsterdam.

#More to explore

Painting

Renaissance

The Renaissance was a period in European

history. It began in the 1300s, during

the late Middle Ages. It ended

during the 1500s, when the modern era

began. Renaissance means “rebirth” in

French. During the Renaissance there

was a rebirth of interest in ancient

Greece and Rome. The Europeans of the

Renaissance took ideas from the ancient

people and developed their own. They

also made scientific discoveries and created

great art.

Background

During the Middle Ages there were two

institutions that controlled much of

Europe. The Holy Roman Empire influenced

the political life of the people.

The popes of the Roman Catholic

church controlled the religious life. Both

of these institutions began to lose power

by the 1300s. Individual European

nations also grew stronger. People

started writing in their own languages

instead of Latin (the language of the

Catholic church). People felt freer to

think in new ways.

Humanism

Before the Renaissance, most people in

Europe placed great importance on God

and religion. During the Renaissance,

some people began to think about the

Rembrandt painted his own portrait at

age 63.

44 Renaissance BRITANNICA STUDENT ENCYCLOPEDIA

importance of humans as well. For this

reason these thinkers were called

humanists. Humanists wanted to make

the most of their lives on Earth. They

also wanted to understand the world

around them.

One of the first humanists was

Francesco Petrarch, an Italian poet who

died in 1374. Petrarch was interested in

what ancient writers had to say about

humanity. He got many other people,

including the great storyteller Giovanni

Boccaccio, to share his interests.

The Printing Press

In about 1450 a German named

Johannes Gutenberg invented the printing

press. This allowed people to make

many copies of written works. Printed

books soon spread the ideas of the

Renaissance all over Europe. One of the first thinkers to have his

writings printed was Desiderius Erasmus

of Rotterdam (now in The Netherlands).

Erasmus was a humanist scholar.

Science

The spirit of inquiry and discovery also

led to a Renaissance in science. In the

Middle Ages, scholars usually took their

scientific knowledge from books. During

the Renaissance, however, people began

to experiment and observe for

themselves.

Nicolaus Copernicus, who was born in

Poland, was one of the greatest astronomers

of the Renaissance. He showed that

Earth revolves around the sun. For more

than 1,000 years before that people had

An illustration shows Andreas Vesalius, a

doctor during the Renaissance. Vesalius cut

open dead bodies to learn how the human

body works.

A map of the Western Hemisphere from the

1500s shows that people during the Renaissance

were still discovering how the world

looked.

BRITANNICA STUDENT ENCYCLOPEDIA Renaissance 45

believed that everything in the universe

revolved around Earth.

Andreas Vesalius was a medical doctor

from Brussels (now in Belgium). Vesalius

found out about the human body by

carefully dissecting, or cutting apart,

dead bodies.

Art

Some of the greatest Renaissance artists

worked in Florence and in other cities in

Italy. The rulers of Florence, the Medici

family, spent great amounts of money to

have artists create pictures, buildings,

and statues.

Leonardo da Vinci worked during the

late 1400s and early 1500s. He painted

two of the world’s most famous works:

the Mona Lisa and the Last Supper.

Leonardo also made statues and

designed weapons. He even drew up

plans for a helicopter.

Michelangelo and Raphael were also

important artists of this period. They

painted religious figures but gave them a

realistic, human quality.

Exploration

The Renaissance also led people in

Europe to explore parts of the world

they had never seen. Christopher

Columbus and others from Spain and

Portugal discovered two continents—

North and South America—that had

been unknown to Europeans. This led

to other voyages of discovery.

Late Renaissance

No one event marks the end of the

Renaissance. The spirit of discovery that

defined the period led people to try new

ideas in all areas of life. Slowly artists

turned to new styles. New ways of

thinking about other fields, such as government

and politics, also developed.

#More to explore

Copernicus, Nicolaus • Gutenberg,

Johannes • Leonardo da Vinci • Medici

Family • Michelangelo • Middle Ages

Reproductive

System

All living things reproduce, or create

offspring. Animals’ offspring are often

called babies. The body parts that allow

animals to create babies belong to the

reproductive system.

A painting from the early 1500s

shows the realistic style of art

that was popular during the

Renaissance. It also shows the

type of dress worn by wealthy

ladies in Italy.

46 Reproductive System BRITANNICA STUDENT ENCYCLOPEDIA

Types of Reproduction

Some animals can create offspring

through asexual reproduction. This

means that one animal creates offspring

on its own. For example, corals, hydras,

and sea anemones can reproduce

through a process called budding. In

budding, a growth called a bud breaks

off from the animal to make a new animal.

A few animals, including some

worms, can break in half to create two

separate animals.

Most animals use sexual reproduction

to have babies. This means that two sex

cells, one from a male and one from a

female, join together to create a baby.

In some animals, including many types

of fish, the male and female sex cells

join together in water, outside the

female’s body. In other animals the sex

cells join together inside the female’s

body.

After the sex cells join they grow into a

baby. The babies of some animals, such

as birds and many reptiles, develop in

eggs outside the female’s body. The

babies of most mammals develop inside

the female’s body.

Human Reproduction

Like other mammals, humans reproduce

sexually. A woman’s body supports a

baby as it grows. For these reasons men

and women have different reproductive

organs.

Male Reproductive System

In men the main reproductive organs

are the testes. The two oval-shaped

Men and women have different reproductive

organs. A woman’s ovaries produce

egg cells. A man’s testes produce sperm.

BRITANNICA STUDENT ENCYCLOPEDIA Reproductive System 47

testes sit behind the penis in a pouch

called the scrotum. The testes make the

male sex cells, called sperm. Sperm are

too tiny to see without a microscope.

They are shaped like tadpoles with long

tails. The tail of a sperm is what moves

it forward.

The sperm travel through a tube toward

the penis. They mix with other fluids to

form a liquid called semen. During

sexual intercourse a small amount of

semen passes through the tip of the

penis into the woman’s body. This

semen contains between 200 and 300

million sperm. The sperm then travel

toward the woman’s sex cell, or egg.

Female Reproductive System

In women the main reproductive organs

are the ovaries. The two almond-shaped

ovaries sit inside the lower belly. When a

girl is born her ovaries contain up to

500,000 egg cells. Two tubes, called

fallopian tubes, connect the ovaries to

the uterus. The uterus is a muscular

organ that holds a growing baby.

Beginning when a girl is about 12 years

old, one ovary releases an egg once a

month. This process is called ovulation.

The egg travels from the ovary through

the fallopian tube to the uterus. If the

egg does not meet a sperm cell on its

journey, it dies. The egg and some blood

One of a woman’s ovaries releases an egg each month. If the egg meets a sperm cell, it

may become fertilized. The fertilized egg travels to the uterus, where it grows into a baby.

48 Reproductive System BRITANNICA STUDENT ENCYCLOPEDIA

then pass out of the uterus and through

the vagina, a muscular tube that leads

out of the body.

Fertilization, Pregnancy, and Birth

Sperm enter the woman’s body through

the vagina. The sperm swim up through

the uterus and into the fallopian tubes.

If an egg is in one of the fallopian tubes,

the sperm try to join with it. Only one

sperm can enter, or fertilize, the egg.

The rest of the sperm die.

Once the egg is fertilized, pregnancy (or

gestation) begins. The fertilized egg

moves into the uterus. As it travels it

starts to divide into many more cells.

After about five or six days these cells

burrow into the wall of the uterus.

There the cells begin to develop into a

baby. At first the developing baby is

called an embryo. After about eight

weeks the baby is called a fetus.

In the uterus the baby grows inside a

pouch called the amniotic sac. The

amniotic sac is filled with clear liquid.

The liquid protects the baby and lets it

move around. A bundle of blood

vessels, called the umbilical cord,

connects the baby’s belly to the

placenta. The placenta is a structure

A human pregnancy lasts about nine months. A developing baby goes through many

changes during the first three months.

BRITANNICA STUDENT ENCYCLOPEDIA Reproductive System 49

that lines part of the uterus. The

placenta brings nourishment from the

mother’s body to the baby. It also takes

away wastes from the baby.

After about nine months of development

the baby is ready to leave the

woman’s body. The bottom end of the

uterus, called the cervix, expands to create

a wide opening into the vagina. The

muscles of the uterus contract, or

tighten, to push the baby downward.

The baby moves slowly through the

vagina and out of the mother’s body.

When the baby is born the umbilical

cord and the placenta also leave the

mother’s body. The newborn baby is cut

free from the cord and the placenta.

After several days the stump of the cord

dries up and falls off the baby’s belly. It

leaves behind an indentation called a

navel, or belly button.

#More to explore

Egg • Gestation

Reptile

A reptile is an air-breathing animal that

has scales instead of hair or feathers.

Reptiles have lived on Earth for more

than 280 million years. Scientists consider

them to be the ancestors of birds

and mammals.

Over the years many kinds of reptiles

have become extinct, or died out. The

dinosaurs are well-known reptiles that

became extinct about 65 million years

ago. Today there are about 6,000 species,

or types, of living reptile. They

From the fourth month to the ninth month of pregnancy, the developing baby grows much

larger. The mother’s uterus and belly greatly expand.

50 Reptile BRITANNICA STUDENT ENCYCLOPEDIA

include snakes, lizards, turtles, alligators,

and crocodiles.

Where Reptiles Live

Reptiles are found all over the world,

except in very cold areas. The greatest

number and variety are in the hot,

humid tropics. Snakes and lizards live in

many different kinds of places. They can

live on land, in trees, in underground

tunnels, or in water. Most turtles live in

water but spend some time on land.

Tortoises live only on land. Alligators

and crocodiles spend most of their time

in water, but they can make short trips

on land.

Physical Features

Reptiles are vertebrates, or animals with

a backbone. Except for snakes, most

reptiles have four limbs. Reptiles vary

greatly in size. Some snakes and lizards

are less than 2 inches (5 centimeters)

long. The largest crocodiles, pythons,

and anacondas can grow to more than

30 feet (9 meters) long. The largest lizard

is the Komodo dragon, which

reaches a length of more than 10 feet (3

meters). Leatherback turtles grow to

more than 7 feet (2 meters) long.

Reptiles have dry skin that is covered

with scales. Scales are hardened folds of

the upper layer of skin. The scales of

many lizards overlap. They are arranged

side by side in snakes and alligators and

crocodiles. Scales also cover the bony

shells of turtles.

Reptiles shed and replace their scales

throughout their lifetime. Some species

shed often. Others shed several times a

year. Snakes shed all their scales at once.

Lizards, turtles, alligators, and crocodiles

shed their scales one by one or in

patches.

Behavior

Reptiles are cold-blooded animals. This

means that their body temperature

changes when the temperature around

them changes. Reptiles warm or cool

themselves by moving to warmer or

cooler places. Most reptiles are inactive

during winter. This is called hibernation.

Crocodiles lie on grass in Madagascar, a

tropical island in the Indian Ocean.

The flashy pattern of an adder’s scales may

warn predators to stay away. Adders are

venomous, or poisonous, snakes.

BRITANNICA STUDENT ENCYCLOPEDIA Reptile 51

Some are inactive during parts of the

summer. This is known as estivation.

Most reptiles are meat eaters. They eat

many kinds of animals, including

insects, birds, frogs, mice, and fish.

Some reptiles follow their prey. Others

hide and wait for the prey to approach.

Certain snakes shoot venom, or poison,

into their prey. A few lizards and turtles

eat only plants.

Reptiles have different ways of protecting

themselves from their enemies.

Rattlesnakes shake their tail rattle when

they feel threatened. A cobra spreads its

neck to look bigger. Some turtles hide in

their shells. Crocodiles, turtles, and

some lizards and snakes hiss loudly.

Most reptiles bite when threatened.

Senses

Alligators, crocodiles, and most lizards

hear fairly well. Snakes and turtles have

trouble hearing. Instead they can feel

vibrations in the ground. Some reptiles

have poor eyesight. This is true of snakes

and lizards that tunnel underground.

Reptiles taste and smell using special

organs in the mouth or nose. Some

snakes also have organs that are sensitive

to heat. These organs can sense prey

even in total darkness. This is because

the bodies of mammals and birds give

off heat.

Movement

Reptiles use various methods to move

from place to place. Most lizards walk

on four limbs. Some use only their hind

limbs when running. Certain snakes and

legless lizards move by pushing their

belly scales against rough surfaces and

pulling the body forward. Some desert

snakes use a type of movement called

sidewinding. They repeatedly bend and

lift the body to move across the sand.

Flippers or webbed feet help sea turtles

swim. Sea snakes use their flattened tails

like paddles in the water. Alligators and

crocodiles swim by whipping their tails

from side to side.

No living reptile can fly. However, some

tropical snakes and lizards can glide

from tall trees by flattening their bodies.

Life Cycle

Most reptiles lay eggs. Some lay just one

egg. Others can lay up to 200. It usually

takes about 60 to 105 days for the eggs

to hatch. Certain snakes and lizards give

birth to live young.

Most reptiles take at least a year to

mature. Unlike mammals, reptiles may

grow throughout their lives. Some reptiles

live longer than any other vertebrates.

Many species of reptile can live

Flying lizards cannot really fly. But they can

glide down easily from high places.

Some snakes

and the stinkpot

turtle let

out foul odors

to chase away

enemies.

52 Reptile BRITANNICA STUDENT ENCYCLOPEDIA

for more than 20 years in zoos. Certain

turtles have lived for more than 100

years.

#More to explore

Alligator • Animal • Bird • Crocodile

• Dinosaur • Lizard • Snake • Turtle

Republic

A republic is a form of government in

which the people elect, or choose, their

leaders. In most countries with a republican

government, the people elect the

head of the government, such as a president.

They also elect other people, called

representatives, to make laws.

The leaders of a republic are responsible

to the people who elected them. If the

people do not like the way their leaders

govern, they can vote them out of office.

This means that the people are the

source of power. This sets republics apart

from countries led by a king or another

all-powerful ruler.

Republics Today

Today most countries are true republics,

meaning that the people choose their

leaders. These republics practice a form

of democracy. A democracy is any government

in which the people have a say.

The United States, Mexico, India,

France, Kenya, South Korea, Peru, and

Indonesia are only a few of the world’s

many true republics.

Some countries call themselves republics

simply because a monarch (a king or a

queen) is not the leader. They are not

always democracies. For example, China

calls itself a people’s republic. But the

Chinese people have no choice in who

their leaders are.

Other countries practice democracy but

are not really republics, either. In the

United Kingdom the people vote for

representatives in Parliament (the country’s

lawmaking body). But they also

have a monarch. However, the monarch

has little real power.

An eastern box turtle gets its first look at the

world after hatching from a leathery egg. It

is on its own and will get no care from its

parents.

The president of Finland, Tarja Halonen,

ran for reelection in 2006. In a republic,

people elect their leaders.

BRITANNICA STUDENT ENCYCLOPEDIA Republic 53

History

The first republic was in ancient Rome.

In 509 BC the Romans set up a republic

that lasted for almost 500 years. A group

of elected leaders called the Senate was

the highest power in the government.

The next important democratic republics

formed in the late 1700s. In 1788

the United States set up the first modern

republic. An elected president leads the

U.S. government. Groups of elected

leaders called senators and representatives

make the laws.

#More to explore

Democracy • Government • Monarchy

• Rome, Ancient • United States

Government

Respiratory

System

All animals need a steady supply of oxygen

in order to live. Oxygen is a gas

found in air. It helps to turn food into

energy. This process creates another

gas—carbon dioxide. Carbon dioxide

must be removed from the body. The

respiratory system is the body’s way of

breathing in oxygen and breathing out

carbon dioxide.

Insects breathe through holes in the

sides of their bodies. Fish and young

amphibians have organs called gills to

take in oxygen from water. Mammals,

birds, reptiles, and adult amphibians

breathe through lungs.

The Human Respiratory

System

The human respiratory system includes

several parts: nasal cavity, throat, voice

box, windpipe, bronchi, and lungs. Air

enters this system through the nose. It

then moves into the nasal cavity, a hollow

space behind the nose. Air also

enters through the mouth. These two

airways meet at the upper part of the

throat, called the pharynx.

Insects have no lungs. They use holes called

spiracles and air sacs to breathe.

Fish have gills instead of lungs. A fish takes

in oxygen as water flows past its gills.

54 Respiratory System BRITANNICA STUDENT ENCYCLOPEDIA

From the pharynx, two passageways

open downward. One is for food, and

the other is for air. The passage for air

contains the voice box, or larynx. Below

the voice box is the windpipe, or

trachea.

The trachea separates into two main

branches, or bronchi—one for each

lung. Within the lungs, the bronchi

divide into smaller and smaller

branches. The branches end with tiny

air sacs called alveoli. There are more

than 600 million alveoli in the lungs.

The alveoli contain tiny blood vessels

called capillaries.

The Breathing Cycle

The brain controls breathing. It controls

the diaphragm, a muscle at the base of

the lungs. It also controls the muscles

between the ribs.

When the diaphragm moves down and

the ribs move out, the area inside the

chest grows larger. Air then flows into the

lungs and makes them expand. Blood in

the capillaries picks up oxygen from the

air in the alveoli. The blood then brings

the oxygen through the cardiovascular

system to all parts of the body.

As the blood picks up oxygen, it also

brings carbon dioxide from the body to

the alveoli. The rib muscles and the diaphragm

then relax. As the area inside the

chest shrinks, the lungs decrease in size.

The smaller size forces out air, including

the carbon dioxide.

Newborn babies breathe up to 44 times

a minute. Adults breathe only about 16

Tiny structures in the lungs called alveoli

and capillaries exchange oxygen for carbon

dioxide.

BRITANNICA STUDENT ENCYCLOPEDIA Respiratory System 55

times per minute. When people are

asleep, they breathe more slowly, about

six to eight times per minute. If people

are afraid or worried, they can breathe

up to 100 times per minute.

Problems with the Respiratory

System

Hiccups are a harmless problem with the

respiratory system. They happen when

the diaphragm moves in a fast, jerky

way. Colds and influenza (the flu) are

infections that start in the nose and the

throat. Bronchitis is a swelling of the

bronchi. Pneumonia is an infection of

the lungs. Tuberculosis, emphysema,

and lung cancer are serious diseases of

the lungs.

#More to explore

Lung • Pneumonia • Tuberculosis

Reunion

The island of Reunion is a department

(a type of province) of France. It lies

near Africa in the Indian Ocean.

Reunion’s capital is Saint-Denis.

Geography

Reunion is about 420 miles (680 kilometers)

east of Madagascar, an island

country to the southeast of Africa.

Reunion has many mountains. Some of

them are active volcanoes. The island

has a warm climate with dry and rainy

seasons. Tropical storms called cyclones

are common.

Plants and Animals

Reunion has many flowering plants and

tropical fruit trees. Tropical forests grow

in the higher areas. Animals on the

island include chameleons, frogs, birds,

and butterflies.

People

Many of the people of Reunion have a

mixture of African, European, and South

Asian roots. Whites and South Asians

form other large groups. There are small

groups of Chinese and Africans.

French is the language of government,

but Creole is the language of everyday

Diaphragm, ribs, and lungs all move when

a person breathes in and out.

A green valley lies between mountains in

Reunion.

56 Reunion BRITANNICA STUDENT ENCYCLOPEDIA

life. Roman Catholicism is the main

religion. Most people live in cities or

towns.

Economy

Services, especially tourism, are the most

important part of Reunion’s economy.

The island also produces sugar, rum,

and lobsters. Farmers grow sugarcane,

fruits, vegetables, vanilla beans, tobacco,

and geraniums, which are used to make

perfume. Reunion trades mainly with

France.

History

Portuguese explorers discovered the

island in the 1500s. No one lived there

until the 1600s, when the French built a

settlement. The French brought Africans

to work as slaves on coffee and sugar

plantations. After slavery ended in 1848,

workers from Asia arrived.

Reunion was a French colony until

1946, when it became a department of

France. The people of Reunion then

became citizens of France.

#More to explore

France • Indian Ocean

Revere, Paul

Paul Revere was a hero of the American

Revolution. He is most famous for

riding his horse through the countryside

near Boston to warn the colonists that

the British were coming. Revere was also

a skilled silversmith (maker of silverware).

Paul Revere was born on January 1,

1735, in Boston, Massachusetts. His

father’s family was French and the family

name was changed from De Revoire

to Revere. Paul learned silversmithing

from his father.

As a young man Revere joined the Sons

of Liberty, a club for colonists who disliked

British rule. Such people were

known as patriots. In 1773 he and other

patriots protested a tax on tea by throwing

British tea into Boston Harbor. This

action became known as the Boston Tea

Party.

On April 16, 1775, Revere rode to warn

the patriots of Concord, Massachusetts,

to hide their weapons from the British.

Two days later he rode again, from Boston

to Lexington, Massachusetts. This

time he warned the patriots John Han-

A painting shows Paul Revere holding a

silver teapot that was made in his own

workshop.

BRITANNICA STUDENT ENCYCLOPEDIA Revere, Paul 57

cock and Samuel Adams that the British

were coming to arrest them.

He also warned the Lexington minutemen

that the British were coming. The

minutemen were fighters who boasted

that they needed only a minute to get

ready. On April 19, the Lexington minutemen

fought the battle that started the

American Revolution.

During the war Revere set up a factory

that made gunpowder for the military

forces. He also served in the army,

defending Boston Harbor. After the war,

Revere returned to his work as a silversmith.

He also manufactured copper

sheeting. Paul Revere died on May 10,

1818, in Boston.

#More to explore

American Revolution • Minuteman

Revolution,

American

#see American Revolution.

Revolution,

French

#see French Revolution.

Revolution,

Russian

#see Russian Revolution.

Reye’s Syndrome

Reye’s syndrome is a serious disease of

children. Luckily it is not very common.

But when doctors do not treat it right

away, it can cause brain damage or even

death. Some doctors believe that Reye’s

syndrome is brought on by a medicine

called aspirin.

Reye’s syndrome often strikes children

who are getting over influenza, the common

cold, or some other disease that is

caused by a virus. The first symptom, or

sign, of Reye’s syndrome is frequent

vomiting. Then the person might

become tired and confused. Some

people breathe rapidly and have violent

muscle movements called convulsions.

The person may finally fall into a coma,

which is like a deep sleep from which

someone cannot be awakened.

Doctors think that aspirin triggers

Reye’s syndrome. Some of a person’s

cells might have a problem that does not

appear until the person takes aspirin. To

prevent Reye’s syndrome, doctors recommend

that children under 12 do not

take aspirin.

Reye’s syndrome is a serious disease that

requires a hospital stay. In the hospital,

doctors give the person fluids and medicines

to reduce brain swelling. The person

also gets help with breathing. If the

disease is treated early enough the person

can usually make a full recovery.

#More to explore

Virus

Henry

Wadsworth

Longfellow’s

poem Paul

Revere’s Ride

made that

event an

American

legend.

58 Revolution, American BRITANNICA STUDENT ENCYCLOPEDIA

Reykjavik

Population

(2008 estimate)

119,000

Reykjavik is the capital of Iceland, an

island country in the North Atlantic

Ocean. It is Iceland’s largest city by far.

The name Reykjavik means “bay of

smokes.” It refers to the steaming-hot

water that spouts from the ground at

nearby hot springs.Water piped from

the hot springs is used to heat the city.

Reykjavik has many businesses and

industries. The city is a fishing port. It

has factories that process fish, other

foods, and aluminum. However, most

people work in service industries such as

sales, banking, and health care.

According to legend a Viking founded

Reykjavik in 874. It was a small fishing

village until the 1900s.

Denmark began to rule Iceland in the

late 1300s. In 1786 Reykjavik became

the island’s capital. Iceland’s lawmakers

have met in the city since 1845. In 1944

Iceland became an independent country

with Reykjavik as its capital.

..More to explore

Iceland • Vikings

Rhinoceros

Rhinoceroses are heavy mammals with

thick skin and hooves. There are five

species, or types, of rhinoceros. Illegal

hunting has left most of them in danger

of dying out.

The Sumatran, the Javan, and the great

Indian rhinoceroses are found in Asia.

The black rhinoceros and the white, or

square-lipped, rhinoceros are found in

Africa.

Most rhinoceroses live by themselves.

They generally live in grasslands or in

marshes. The Sumatran rhinoceros prefers

the forest.

Rhinoceroses weigh 3 to 5 tons. They

are about 8 to 13 feet (2.5 to 4 meters)

long. Some have one horn on the top of

the head. Others have two horns. The

animals cannot see well, but they have a

good sense of hearing and smell. They

eat grass, reeds, and twigs.

..More to explore

Mammal

The black rhinoceros of Africa has two

horns and is known for its bad temper.

BRITANNICA STUDENT ENCYCLOPEDIA Rhinoceros 59

Rhode Island

Rhode Island is the smallest U.S.

state. It was one of the 13 original

American Colonies. Its official name,

The State of Rhode Island and Providence

Plantations, dates back to colonial

times. Providence was the first settlement

and is now the state capital. Rhode

Island’s nickname, the Ocean State,

comes from its coastline along the Atlantic

Ocean.

Geography

Rhode Island lies in the northeastern

part of the United States. It is one of the

states in the New England region. The

Atlantic Ocean borders the southern

part of the state. Connecticut is to the

west and Massachusetts is to the north

and east. The eastern half of Rhode

Island is indented by the waters of Narragansett

Bay.

Rhode Island has two natural regions.

The western two thirds of the state lies

within the Appalachian Mountains. It is

a rough, hilly region with many forests

and lakes. The rest of the state is a shallow

lowland area that extends into

southern Massachusetts. The lowlands

include numerous islands, sandy

beaches, and salt marshes. Rhode Island

has a damp climate with short summers

and long, cold winters.

People

Whites of European heritage make up

more than four fifths of Rhode Island’s

population. The Hispanic population in

Rhode Island has grown a great deal. It

doubled between 1990 and 2000. During

that period, Hispanics went from

about 4.5 to almost 9 percent of the

population. African Americans make up

more than 4 percent of the population.

Economy

Tourism is one of the state’s important

service industries. Businesses in financial

services, insurance, and real estate are

also major parts of the economy. Rhode

Island’s most notable manufactured

products are jewelry and silverware.

Harvesting shellfish and fish from the

waters off Rhode Island is a vital industry.

The most valuable shellfish are lobster

and hard-shell clams. Plants grown

in nurseries and greenhouses are Rhode

60 Rhode Island BRITANNICA STUDENT ENCYCLOPEDIA

Island’s leading source of income from

agriculture.

History

The Narraganset tribe was the largest

Native American group living in the area

before Europeans arrived. Portuguese,

Italian, and Dutch explorers and traders

visited the region in the early 1500s.

RogerWilliams, a minister, and his followers

founded Providence in 1636.

They had left Massachusetts in search of

religious freedom. In 1663 the king of

England granted a charter that officially

created the new colony in Rhode Island.

Before the American Revolution started

in 1775, Rhode Islanders took part in

the first violent protest against the British

government. In 1772 a group of

townspeople burned a British customs

ship that had run aground in Narragansett

Bay.

Rhode Island was one of the original 13

states of the Union. In 1790 it was the

13th, and therefore the last, state to

ratify, or officially accept, the U.S. Constitution.

The state ratified the Constitution

only after the document included

the Bill of Rights, which guaranteed

individual liberties.

Rhode Island served as an operations

center for the U.S. Navy duringWorld

War I (1914–18) andWorldWar II

(1939–45). As the home of the Naval

War College, the state continues to play

a role in military affairs.

..More to explore

Bill of Rights • Narraganset • Providence

Boats anchor in Newport Harbor in Narragansett

Bay, Rhode Island.

The Breakers mansion overlooks the Atlantic

Ocean in Newport, Rhode Island. It is one

of several grand homes that draw visitors to

the state.

Facts About

RHODE ISLAND

Flag

Population

(2000 census)

1,048,319—

rank, 43rd state;

(2008 estimate)

1,050,788—

rank, 43rd state

Capital

Providence

Area

1,545 sq mi

(4,002 sq km)—

rank, 50th state

Statehood

May 29, 1790

Motto

Hope

State bird

Rhode Island red

State flower

Violet

BRITANNICA STUDENT ENCYCLOPEDIA Rhode Island 61

Rhododendron

Rhododendrons are plants with beautiful

flowers and glossy leaves. The name

rhododendron comes from the Greek

words for rose (rhodon) and tree (dendron).

There are more than 800 species, or

types, of rhododendron. They can be

found throughout the world except for

Africa and South America. Many are

found in the Himalayas and the mountains

of Malaysia in Asia.

Most kinds of rhododendron are evergreen,

meaning that they keep their

leaves all year. However, some kinds lose

their leaves each autumn. These kinds

are usually called azaleas. Rhododendrons

also vary greatly in size. Some are

tiny shrubs or groundcover that are only

4 inches (10 centimeters) tall. Others are

treelike plants that grow more than 40

feet (12 meters) tall.

Most rhododendrons have thick, leathery

green leaves. The leaves can be round

or oval. The flowers are usually shaped

like a tube or a funnel. They may be

white, pink, red, purple, yellow, or blue.

Some plants grow large clusters of flowers.

Others have single flowers or smaller

clusters of two or three blooms. A number

of species are known for the strong

fragrance, or smell, of their flowers.

#More to explore

Himalayas

Rhubarb

Rhubarb is a vegetable. It grows in long

stalks with large leaves at the top. There

are several species, or types, of rhubarb.

They originally grew only in Asia. The

plants are now found throughout the

world, but they grow best in places with

cool weather. Rhubarb plants are also

called pieplants.

Rhubarb plants have green, heart-shaped

leaves. Some of the leaves may have large

veins or wrinkles. The leaves grow at the

end of pink, green, red, or red-green

stalks. In some types, the stalks can

Gardeners prize rhododendrons for their

beautiful flowers.

The red stalks of a rhubarb plant can be

cooked and eaten. The leaves are poisonous.

62 Rhododendron BRITANNICA STUDENT ENCYCLOPEDIA

reach up to 2 feet (60 centimeters) long.

After the leaves have grown, sometimes a

separate flower stalk may appear. It may

have tiny white, yellow, or greenish red

flowers at the end of it.

Rhubarb stalks grow from a stem called

a crown that grows under the soil. The

roots also grow from the crown. Rhubarb

roots can live through the winter.

Fresh stalks will grow every year starting

in early spring.

People use rhubarb in a variety of dishes.

Only the stalks of the plant are eaten,

however, because the leaves contain a

poison. The stalks are crisp and have a

tart flavor. Rhubarb is often cooked with

sugar and used like a fruit in pies and

preserves.

Rice

Rice is a grain that is the main food of

about half the world’s population. It

belongs to the grass family. Its scientific

name is Oryza sativa. The grain known

as wild rice, despite its name, comes

from a different plant.

Rice was first planted and grown in

India more than 4,000 years ago. Today

90 percent of the world’s rice is grown

in Asia.

Most rice is grown underwater in paddies.

A paddy is a bed of mud with low

mud banks around it. The paddy is

flooded with 2 to 4 inches (5 to 10 centimeters)

of water. The paddy is kept

flooded for most of the growing season.

The rice plant grows to about 4 feet (1.2

meters) tall. It has several stalks with

long, flattened leaves. At the end of each

stalk is a fan-shaped head made up of

green and yellow flowers. These flowers

produce the grains of rice.

After harvesting, rice must be processed,

or milled. Milling removes outer layers

of the rice grains. To produce brown

rice, only the first layer, called the hull

or husk, is removed. Another layer,

called the bran, is removed to create

white rice. Brown rice is much higher in

nutrients than white rice. Enriched

white rice has added B vitamins and

minerals.

Rice is eaten alone and in a great variety

of soups, side dishes, and main dishes.

In eastern Asia people grind rice into

flour to make rice cakes and pastry. The

people of Japan, China, and India use

rice to make liquor. The parts of the

plant that are not eaten can be used to

make mats, garments, baskets, fertilizer,

fuel, and other products.

#More to explore

Grain • Grass

Workers plant rice in a paddy in India.

BRITANNICA STUDENT ENCYCLOPEDIA Rice 63

Richmond

Population

(2000 census),

city, 197,790;

(2007 estimate)

200,123

Richmond is the capital of the U.S. state

of Virginia. It lies on the James River. It

is a historic city that played an important

role in the American Revolution

and the American CivilWar.

Richmond has a number of notable

buildings. The state Capitol was

designed by Thomas Jefferson, the third

president of the United States. The home

of JohnMarshall, the fourth chief justice

of the U.S. Supreme Court, dates from

1790. St. John’s Church is where the

patriot Patrick Henry gave his famous

“Liberty or Death” speech in 1775.

Most people in Richmond work in government

or in trade, banking, or other

service industries. Factories in the city

make tobacco and food products,

chemicals, metals, and other goods.

In 1637 American colonists set up a

trading post where Richmond is today.

The town was built there in the 1730s.

During the American Revolution, Richmond

became the capital of Virginia.

British troops raided the town in 1781.

Just before the American CivilWar, Virginia

and 10 other Southern states withdrew

from the United States. In 1861

they formed a separate government

called the Confederate States of

America, or the Confederacy. Richmond

became the capital of the Confederacy.

In 1865 U.S. troops captured Richmond.

Most of the city’s business district

was destroyed. After the war

Richmond recovered rapidly.

..More to explore

American CivilWar • American

Revolution • Confederate States of

America • Henry, Patrick • Virginia

Ride, Sally

Sally Ride was a U.S. astronaut. In 1983

she became the first U.S. woman to

travel into outer space.

Sally Kristen Ride was born in Encino,

California, on May 26, 1951. She

graduated from Stanford University in

northern California with four degrees,

including a doctorate in physics.

In 1978 the National Aeronautics and

Space Administration (NASA) selected

Ride to train as an astronaut. After com-

Grand houses line a street in Richmond, the

capital of Virginia.

64 Richmond BRITANNICA STUDENT ENCYCLOPEDIA

pleting her training in 1979, she worked

as a space shuttle mission specialist. On

June 18, 1983, Ride made her first voyage

into outer space aboard the space

shuttle Challenger. The shuttle was in

space for six days.

Ride took a second trip aboard the Challenger

in 1984. During this mission

Ride’s friend Kathryn Sullivan became

the first U.S. woman to walk in space.

In 1986 the Challenger exploded as it

was taking off for another mission. Ride

was one of the astronauts who helped to

investigate the explosion. Ride left

NASA in 1987.

Ride later worked as the director of the

California Space Institute at the University

of California, San Diego. She also

wrote several children’s books about

outer space. In 2003 Ride helped to

investigate another space shuttle disaster

after the shuttle Columbia broke up as it

was returning to Earth.

..More to explore

Space Exploration

Riga

Population

(2008 estimate)

717,371

Riga is the capital of Latvia, a country in

northeastern Europe. It is Latvia’s largest

city by far. It is also a major port. The

city lies on theWestern Dvina River

near where it flows into the Baltic Sea.

Latvia’s economy depends heavily on

Riga. The city is a center of shipping

and manufacturing. Factories in Riga

make chemicals, cloth, processed foods,

and wood products. Banking, trade, and

other service industries are important to

the city’s economy.

Riga was established as a trading settlement

in 1201. Poland took control of

the city in 1581. Sweden captured Riga

Sally Ride sits in the cabin of the space

shuttle Challenger.

People gather at outdoor restaurants and

cafes among the old buildings of Riga.

BRITANNICA STUDENT ENCYCLOPEDIA Riga 65

in 1621. However, the Poles and the

Swedes let the city govern itself. Russia

took over Riga in the early 1700s.

In 1918 Latvia became an independent

country with Riga as its capital. But the

Soviet Union took control of Latvia in

1940. In 1991 Latvia broke away from

the Soviet Union and became independent

again. Riga remained its capital.

..More to explore

Latvia

Ring of Fire

A chain of volcanoes surrounds the

Pacific Ocean. Because the volcanoes

frequently erupt in fiery explosions, the

region is known as the ring of fire. Many

earthquakes occur in the region as well.

The chain passes along the west coast of

North and South America. It runs along

the Aleutian Islands and the islands of

East and Southeast Asia. Then it extends

east and south to New Zealand.

The ring of fire surrounds the edges of

the giant Pacific Plate. A plate is a section

of the rocky outer layer of Earth.

Earth’s plates move at different rates and

in different directions. As the Pacific

Plate and the plates around it grind into

each other, they cause earthquakes and

volcanoes.

..More to explore

Earthquake • Volcano

Rio de Janeiro

Population

(2007

estimate), city,

6,093,500;

urban area,

11,563,302

Rio de Janeiro is a large city in Brazil, a

country in South America. It is the second

largest city in the country, after Sao

Paulo. The city lies on the Atlantic

Ocean. It is often called Rio for short.

Tourists flock to Rio for its beautiful

beaches and for a yearly festival called

Carnival. The city celebrates Carnival

for four days before the Christian

season of Lent begins. Lively parades

and parties last day and night. People in

colorful costumes sing and dance in

Rio’s streets.

Places of Interest

A large statue of Jesus called Christ the

Redeemer overlooks Rio de Janeiro. It

66 Ring of Fire BRITANNICA STUDENT ENCYCLOPEDIA

stands on Mount Corcovado. A rock

called Sugar Loaf is another major landmark.

The rock offers great views of

Rio’s beaches below. Two of its bestknown

beaches are called Copacabana

and Ipanema.

Economy

Tourism is a major part of Rio de

Janeiro’s economy. Banking, trade, and

other services are also important. The city

is one of Brazil’s main manufacturing

centers. Factories in Rio make clothing,

medicines, metal products, and processed

foods. The city is also a major port.

History

Portugal took control of Brazil in the

1500s. Many American Indians already

lived in the Rio area. Portuguese sailors

entered the area’s harbor in January

1502. They thought it was the mouth of

a river. Because of this they named the

site Rio de Janeiro, which means “river

of January.” Portuguese settlers began

moving there in the 1560s.

In the 1700s the Portuguese used Rio as

a port to ship out gold and diamonds.

In 1763 they made it the capital of their

colony of Brazil. The city grew greatly.

Brazil became an independent country

in 1822. Rio was its capital. In 1960 the

capital was moved to the city of Brasilia.

However, Rio de Janeiro remained

important to Brazil’s economy.

#More to explore

Brasilia • Brazil • Sao Paulo

River

A river is a large, natural stream of water

that flows over land. Rivers shape the

land by carving out canyons and other

valleys. Humans have used rivers in

many ways. Many ancient civilizations

grew up near rivers.

River Courses

A river begins as a tiny trickle of water

on high ground. The water may come

from rainfall, from melting snow or ice,

or from underground. The trickle com-

Rio de Janeiro lies on a bay of the Atlantic

Ocean. A towering rock called Sugar Loaf

stands at the entrance of the bay.

A boat pushes barges on the Mississippi

River.

BRITANNICA STUDENT ENCYCLOPEDIA River 67

bines with other trickles as it flows

downhill. It may be called a stream, a

brook, or a creek.

Eventually the creek grows into a river.

In its upper course the river flows rapidly.

It cuts through the land and picks

up soil and gravel. In its middle course

the river flows down gentler slopes. It

gets larger and slower. Soil, gravel, and

sand begin to sink to the bottom.

In its lower course the river flows even

more slowly. It drops still more solid

material. Some material is carried all the

way to the mouth—the place where the

river enters the sea. This material may

build up to form a piece of land called a

delta.

River Systems

A river receives water from the smaller

streams that flow into it. These streams

are called tributaries. A river and its

tributaries make up a river system. The

area that a river system covers is called a

basin. Rivers that are the same length

may have basins of different sizes. The

Amazon River is slightly shorter than

the Nile River, but the Amazon has a

basin more than twice as large.

Importance to Humans

Humans drink river water. They catch

fish from rivers. They also use river water

to grow crops. They often do this by

digging ditches that carry water to farm

fields. This practice is called irrigation.

Before modern times, people often

traveled on rivers. Large riverboats called

barges still carry grain, coal, and minerals.

Flooding creates problems for people

who live near rivers. People have built

dams across many rivers to control

floods. As water flows through a dam it

often runs through generators that create

electricity.

People also put waste into rivers. This

practice has made river pollution a serious

problem.

#More to explore

Canyon • Dam • Delta • Flood

• Irrigation

Rivera, Diego

The Mexican artist Diego Rivera is

known for creating large murals, or wall

paintings. In his murals he represented

Diego Rivera painted a mural in San Francisco, California, that combines images of traditional

Mexican art with images of modern North American technology.

68 Rivera, Diego BRITANNICA STUDENT ENCYCLOPEDIA

scenes from Mexico’s history, telling of

its cultures, farming and industry, wars,

and politics. His paintings feature bright

colors and are crowded with people and

symbols.

Rivera was born on December 8, 1886,

in Guanajuato, Mexico. At age 10 he

earned a scholarship to study art in

Mexico City. In 1907 he won a scholarship

that allowed him to travel to

Europe. He studied art in Spain and

then settled in Paris, France.

In Paris Rivera began painting in a style

called cubism. In this style the subject is

broken apart into basic shapes, such as

squares, triangles, and circles. In about

1917 his style changed. He began to use

simple forms and bold areas of color.

In 1921 Rivera returned to Mexico. He

and the Mexican painter David Alfaro

Siqueiros hoped to create a new kind of

art especially for Mexico. They wanted

to paint murals on buildings where

everyone could see them. The murals

would tell the stories of the Mexican

people.

Rivera completed his first important

mural in 1923. He was soon hired to

paint murals on several public buildings

in Mexico. Between 1930 and 1934

Rivera painted murals in the United

States. He died on November 25, 1957,

in Mexico City. Frida Kahlo, his wife,

also was a famous painter.

..More to explore

Kahlo, Frida • Mexico • Painting

Riyadh

Population

(2007

estimate), urban

area,

4,465,000

Riyadh is the capital of Saudi Arabia, a

country in the Middle East. It is the

largest city in Saudi Arabia. Huge

amounts of oil were discovered in the

country in the middle of the 1900s. The

Saudi government used money from the

country’s oil industry to turn Riyadh

into a very modern city.

Factories in Riyadh process oil, cement,

metals, and foods. The city is also a

major center of business and banking.

Riyadh became the capital of the Sa!ud

family lands in the early 1800s. In 1881

the Rashid family took control of the

A robed man walks in a garden in Riyadh,

Saudi Arabia. The water tower behind him

is a city landmark.

BRITANNICA STUDENT ENCYCLOPEDIA Riyadh 69

city. The Sa!ud family recaptured Riyadh

in the early 1900s. They established

Saudi Arabia as a unified country in

1932. Riyadh was the capital.

During the 1900s Riyadh grew greatly.

Money from the oil industry was used to

build modern hospitals, roads, and

gleaming new office buildings. In the

early 21st century the city was the site of

several violent terrorist attacks.

#More to explore

Saudi Arabia

Road

Cars, trucks, buses, motorcycles, and

bicycles travel on strips of land called

roads. Some roads are made of dirt or

gravel. A firm, strong material called

pavement covers most modern roads.

Types of roads include city streets, country

roads, and long-distance highways.

How Roads Are Built

There are many steps in road building.

First, road builders choose a route, or

path, for the road. They must carefully

study how the road will affect the businesses,

homes, traffic, plants, and animals

of the area. Next, road builders buy

the land on which they will build the

road.

Construction of unpaved roads (roads

without pavement) is simple. Builders

clear away trees, bushes, and plants from

the roadway—the strip of land over

which the road will pass. Then they

smooth out the roadway and press the

surface down with a machine called a

roller. This type of road is suitable for

areas where few cars travel.

Roads that many cars will use must be

stronger than roads that have less traffic.

These roads are paved. Paving materials

include asphalt and concrete. Asphalt is

a thick, dark, flexible material made

from petroleum, or oil. Concrete is a

mixture of cement, water, sand, and

gravel. When it dries it becomes as hard

as stone.

A strong road may start with a layer of

asphalt. On top of the asphalt is a layer

of sand, gravel, or crushed stone. A final

layer of asphalt or concrete finishes the

road. The concrete may have steel rods

or mesh inside it for extra strength.

Most major modern roads are built with

a gentle slope downward from the center

of the road outward. This slope is called

a crown. The crown allows water to run

off the road. These roads also have a

system for draining water away from the

sides.

An unpaved country road makes a pretty

picture. But such a road turns to mud in wet

weather, and it cannot handle heavy traffic.

The first major

road was the

Persian Royal

Road in western

Asia. It

was more than

1,700 miles

(2,700 kilometers)

long and

was used from

about 3500 to

300 BC.

70 Road BRITANNICA STUDENT ENCYCLOPEDIA

History

Peoples in ancient Egypt and western

Asia built the earliest roads more than

4,000 years ago. Later the ancient

Romans became famous as road builders.

They built roads paved with stone

across Europe. The Spanish built the

first roads in North America along

Native American trails. Early roads in

colonial America were usually dirt,

sometimes covered with rows of logs.

Before automobiles were invented in the

late 1800s, people used roads to travel

by foot, by horse, and by wagon. As cars

became popular in the early 1900s,

people began building more roads paved

with concrete and asphalt. In the 1950s

the United States began building a system

of large roads, called highways,

across the country. Today highways cross

many countries. But some poor countries

still have mostly unpaved roads.

#More to explore

Automobile • Concrete

Roadrunner

Certain birds in the cuckoo family are

called roadrunners. Roadrunners can fly,

but they are rather clumsy in flight and

get tired quickly. They prefer to dash

around on their powerful legs. A roadrunner

sometimes reaches speeds of

more than 15 miles (24 kilometers) per

hour. While running, it stretches out its

neck, spreads out its short wings, and

jerks its long tail up and down.

There are two kinds of roadrunner. The

greater roadrunner lives in Mexico and

the southwestern United States. The

lesser roadrunner is found in Mexico

and Central America. Most roadrunners

live in deserts and other open areas without

many trees.

The greater roadrunner is about 22

inches (56 centimeters) long. Its feathers

are streaked in olive-brown and white.

The lesser roadrunner is somewhat

smaller and less streaked. Both kinds

have a short tuft of shaggy feathers,

called a crest, on the head.

Drivers use the ramps of a cloverleaf intersection

to get on and off a long-distance

highway. Cloverleafs cost so much money

and take up so much land that they are usually

spaced far apart.

Roadrunners are usually seen on the

ground, where they feed on small animals.

BRITANNICA STUDENT ENCYCLOPEDIA Roadrunner 71

Roadrunners chase and catch lizards,

snakes, mice, and insects for food. A

roadrunner often holds an animal in its

bill and pounds it to death against rocks.

#More to explore

Bird • Cuckoo

Robin

Robins are familiar and much-loved

songbirds with reddish chest feathers.

Several species, or types, of bird are

called robins. The best-known types are

the American robin and the European

robin. Early European settlers in North

America named the American robin

after the European bird. Both these

types belong to the thrush family, along

with bluebirds and nightingales. But

American and European robins are not

closely related.

American and European robins were

originally woodland birds. They are now

also commonly found in gardens, on

lawns, and in parks. American robins are

found throughout most of North

America. Most of them fly south for the

winter. European robins are found

throughout Europe and in parts of western

Asia and northern Africa. Some of

the robins of northern Europe fly south

for the winter.

The American robin is about 10 inches

(25 centimeters) long. It has an orange

or dull reddish breast and belly. The

head is black, and the upper parts are

dark gray. Females and young males are

paler than adult males.

The European robin is much smaller,

with a length of about 5.5 inches (14

centimeters). It has orange-red feathers

on its breast, throat, and face. The belly

is white, and the upper parts are brownish

olive.

Both types of robin are often seen hopping

across lawns. They look for worms

or insects to pull up from the soil.

American robins eat worms, insects, and

The American robin has a reddish breast

and belly.

The European robin has a reddish face and

breast.

72 Robin BRITANNICA STUDENT ENCYCLOPEDIA

fruits. European robins eat mainly

insects but also some worms, fruits, and

seeds.

#More to explore

Bird • Bluebird • Nightingale • Songbird

Robinson, Jackie

Jackie Robinson was the first African

American to play baseball in the modern

era of the major leagues. He played as an

infielder and outfielder for the Brooklyn

Dodgers from 1947 through 1956.

Early Life

Jack Roosevelt Robinson was born on

January 31, 1919, in Cairo, Georgia. He

grew up in Pasadena, California. He was

a star athlete in football, basketball,

track, and baseball at the University of

California at Los Angeles (UCLA).

From 1942 to 1945 he served in the

U.S. Army.

After leaving the Army Robinson played

baseball for the Kansas City Monarchs.

The team belonged to the Negro American

League. At that time only white

players were allowed in the major

leagues.

Major League Career

Branch Rickey, president of the Brooklyn

Dodgers, was interested in making

major league baseball open to black

players. He knew that the first African

American brought into the majors

would have to be very special. When

Rickey met Robinson, he knew he had

found the right person. Robinson first

played for the Dodgers in 1947. At the

end of the season he was chosen as the

best new player in baseball. In 1949 he

was chosen as the most valuable player

in the National League.

Although Robinson played well, things

were not always easy. Players and people

in the crowd often shouted hateful

things at him. Pitchers sometimes threw

the ball at him on purpose. But Robinson

refused to quit.

Robinson helped the Dodgers win six

National League pennants and one

World Series title. He retired from baseball

in 1957.

Later Years

Robinson then became a businessman

and worked for civil rights. In 1962 he

became the first black player in the Base-

Jackie

Robinson’s

tombstone

reads, “A life

is not important

except in

the impact it

has on other

lives.”

Jackie Robinson played 10 seasons

for the Brooklyn Dodgers.

His lifetime batting average was

.311.

BRITANNICA STUDENT ENCYCLOPEDIA Robinson, Jackie 73

ball Hall of Fame. Robinson died in

Stamford, Connecticut, on October 24,

1972.

In 1997 Major League Baseball honored

Robinson by retiring his number 42

jersey. No other major league player can

wear that number.

#More to explore

African Americans • Baseball

Robot

A robot is a machine that does tasks

without the help of a person. Many

people think of robots as machines that

look and act like people. Most robots,

though, do not look like people. And

robots do only what a person has built

them to do.

How RobotsWork

Most robots are computer-controlled

devices with many parts. An industrial

robot, for example, is an armlike

machine that can turn at several joints.

It has a handlike part to grasp and hold

things. Motors move the parts.

Some robots can be “taught” to do a job.

For example, a person might guide an

industrial robot through the movements

needed to do something. Sensors on the

robot send signals about the movements

to the computer. The computer stores

the pattern of movements. Later the

computer can retrieve the pattern and

tell the robot what to do.

Uses

Most industrial robots are used in factories.

Some robots load, move, and

unload materials. Others are used on

assembly lines to help build things such

as cars and appliances.

Robots are especially useful because they

can do things that could be dangerous

for people. For example, they can be

sent deep underwater or into space.

Robots can also handle dangerous materials

such as radioactive waste or harmful

chemicals. They can even dispose of

bombs or do spy work for the military.

History

Writings from ancient Greece and China

tell of toys called automatons, which

were like robots. They were set in

motion by steam, air, water, or falling

weights. In the late 1700s and early

1800s complex automatons could play

music or write with a pen on paper.

During this time people also built

machines to help do certain kinds of

work. Modern robots only came about

Sony Corporation built a robot

that can throw a baseball.

74 Robot BRITANNICA STUDENT ENCYCLOPEDIA

after computers were invented.With

computers, people could program robots

to do tasks on their own.

Robots in Science Fiction

Robots often appear in science fiction,

or stories set in the future or in another

world. Robots in science-fiction books,

television shows, and movies can often

think, listen, talk, and walk easily on

two legs. Science-fiction robots that look

exactly like humans are known as

androids. Although real robots are

becoming more complex, they still are

not like these imagined robots.

#More to explore

Computer • Machine • Science Fiction

Rock

Rock, or stone, is a hard material made

up of one or more minerals. Rock makes

up the outer layer of Earth, called the

crust. The lower parts of this layer are

solid rock, or bedrock. Broken bits of

rock lie on top. The tiniest bits of rock

make up sand and soil. Underneath

Earth’s crust is a layer of melted rock,

called magma.

Types of Rock

There are three types of rock: igneous,

sedimentary, and metamorphic. These

names describe how each type of rock

was formed.

Igneous rock is hardened magma.

Magma may escape through cracks in

Earth’s crust. It may also come to

Earth’s surface when a volcano erupts.

As the escaped magma cools, it hardens