Britannica Student Encyclopedia - 2010

1453. In 1472 Ivan III, the prince of

Moscow, married the niece of the last

Byzantine emperor. Ivan III’s grandson,

Ivan IV, was the first Russian ruler to

use the title of tsar. Known as Ivan the

Terrible, he had great power and ruled

harshly. Later tsars had similar qualities.

In 1721 Peter the Great stopped using

the title of tsar. Even so, Russia’s emperors

continued to be called tsars until the

last of them, Nicholas II, was removed

from the throne. Revolutionaries killed

Nicholas and his entire family in 1918

so that no descendants could claim the

title in the future.

#More to explore

Caesar, Julius • Ivan IV • Nicholas II

• Peter the Great • Russia

Tshwane

#see Pretoria.

Tsunami

Natural disasters, both on land and

under the ocean, may cause deadly

ocean waves called tsunamis. By the

time a tsunami reaches shore, it has

gained tremendous size and power. Tsunamis

can wipe out entire coastal villages

or towns.

Earthquakes, landslides, or volcanic

eruptions can trigger waves in a nearby

ocean. These waves may travel for thousands

of miles. They may move as fast as

500 miles (800 kilometers) an hour. As

they approach a coastline, the waves

move more slowly. They also rise, often

to heights as great as 100 feet (30

meters). As the first huge wave nears

Tsunami is a

Japanese

word.

Tsunamis used

to be called

tidal waves,

but they have

nothing to do

with tides.

Ivan IV, known as Ivan the Terrible,

was the first Russian ruler

to use the title of tsar.

BRITANNICA STUDENT ENCYCLOPEDIA Tsunami 103

 

land, the coastal water often draws back

dramatically. Then the tsunami hits the

land.

Tsunamis cannot be stopped, but there

are ways to defend against them. Scientists

around the world watch for early

signs of earthquakes. They also note

unusual changes in ocean levels.With

this information, scientists can warn

people to leave areas that a tsunami

might hit.

The Pacific Ocean is the site of many

tsunamis, but tsunamis can form in the

Atlantic and Indian oceans, too. A powerful

earthquake struck beneath the

Indian Ocean in December 2004. The

earthquake set off tsunamis that hit

about 10 countries. More than 200,000

people died.

#More to explore

Earthquake • Ocean

Tuberculosis

Tuberculosis, or TB, is a disease that

usually affects the lungs. Tuberculosis

used to be a leading cause of death in

Europe and North America. Today

tuberculosis is treatable.

Certain types of tiny living things called

bacteria cause tuberculosis. One type of

bacteria causes most cases of tuberculosis

in humans. It infects the lungs. This

may lead to coughing, chest pain, difficulty

breathing, loss of energy, and

weight loss. The person may even cough

up blood. Infected people spread the

disease to others when they cough or

sneeze.

Another type of bacteria causes a less

common form of tuberculosis. This

form of tuberculosis may damage the

bones and joints. Humans get it by

A doctor looks at the chest X-rays of

patients infected with tuberculosis.

A diagram shows the different elements of a tsunami. An undersea earthquake causes

waves to spread out in the ocean. As the waves approach a coast, they hit land under the

water. This makes the waves much larger.

104 Tuberculosis BRITANNICA STUDENT ENCYCLOPEDIA

 

drinking milk from a cow infected with

the bacteria. This form of tuberculosis

can be prevented by pasteurizing milk,

or heating it to kill the bacteria.

Tuberculosis spreads most easily in

crowded places where living conditions

are poor. In some countries people get

something called a vaccine to protect

them from tuberculosis. If people do get

tuberculosis, doctors treat them with a

medicine called an antibiotic. People

given antibiotics have a good chance of

recovering from the disease.

#More to explore

Bacteria • Disease, Human • Lung

Tubman, Harriet

In the middle of the 1800s Harriet Tubman

escaped from slavery in the southern

United States. She then helped lead

many other runaway slaves to freedom.

She also served the Union during the

American CivilWar.

Harriet Tubman was born in about

1820 in Dorchester County, Maryland.

She was one of 11 children of a slave

family. Her name at first was Araminta

Ross. She later changed her first name to

Harriet, which was her mother’s name.

In about 1844 Harriet married a free

African American named John Tubman.

In 1849, after hearing that she was to be

sold, she escaped to Philadelphia, Pennsylvania,

without her husband.

In Pennsylvania Tubman became a “conductor”

for the Underground Railroad.

The railroad was a secret network that

helped escaped slaves to find their way

to freedom. By 1857 she had freed hundreds

of slaves, including her own parents.

She said that she “never lost a

passenger,” even though slaveholders

offered large rewards for her capture.

During the American CivilWar, Tubman

went to South Carolina with the

Union Army. She served as a nurse and a

scout. She even led raids against the

Confederates.

After the CivilWar Tubman settled in

Auburn, New York, with her parents.

There she worked for racial justice and

also for women’s rights. She believed

that the two struggles were closely

linked. In 1908 she opened a home for