Britannica Student Encyclopedia - 2010

fighting the VietnamWar. In 1967 Ali

refused to join the armed forces because

of his religion. He was convicted of

breaking the law. His title was taken

from him and he was not allowed to box

again until 1970. In 1971 the U.S.

Supreme Court cleared Ali of all criminal

charges.

In a match against George Foreman in

1974, Ali regained the world heavyweight

title. In 1979 Ali announced that

he would retire. He came out of retirement

for matches in 1980 and 1981,

but he was defeated both times. In later

years Ali suffered from Parkinson’s disease,

which affects the brain and the

muscles.

Allegheny

Mountains

The Allegheny Mountains, or the

Alleghenies, extend from Pennsylvania

to Virginia in the eastern United States.

They are noted for their scenic beauty.

At one time these mountains were an

obstacle to settlers who wished to move

westward.

Muhammad Ali fights Ernie Terrell

in 1967.

82 Ali, Muhammad BRITANNICA STUDENT ENCYCLOPEDIA

 

The Alleghenies are part of the Appalachian

Mountains. They stretch more

than 500 miles (800 kilometers) and

consist of two nearly parallel ridges.

At Mount Davis near the Maryland border,

the Alleghenies rise to 3,213 feet

(979 meters), the highest point in Pennsylvania.

The highest point inWest Virginia

is 4,863 feet (1,482 meters), at

Spruce Knob.

A large amount of coal is mined from

the Allegheny range. Heavy forest cover

makes the Alleghenies a rich source of

timber, too.

#More to explore

Appalachian Mountains

Allen, Ethan

Ethan Allen was a patriot and a soldier.

He won an important early victory in

the American Revolution. Allen led a

band of fighters called the Green Mountain

Boys against the British at Fort

Ticonderoga, in what is now New York.

Ethan Allen was born on January 21,

1738, in Litchfield, Connecticut. In

1757 he fought in the French and

IndianWar. In 1762 Allen became an

ironworker. Several years later he moved

to what is now Vermont.

Vermont was not a separate colony at the

time. NewHampshire and New York

both claimed the territory.To aid the

NewHampshire side in the dispute,

Allen organized the GreenMountain

Boys. (The name of Vermont comes from

the French words for “green mountain.”)

After the start of the American

Revolution, the group fought the British.

On May 10, 1775, the Green Mountain

Boys captured Fort Ticonderoga. Later

that year Allen was captured by the British

during an unsuccessful attack on

Montreal, Canada. He was released in

1778. The Army then made him a colonel,

but he fought no more in the war.

The Allegheny Mountains become very colorful

in the fall as the leaves on the trees

begin to change.

A picture from the 1800s shows Ethan Allen

capturing Fort Ticonderoga.

BRITANNICA STUDENT ENCYCLOPEDIA Allen, Ethan 83

 

Allen spent his later years trying to make

Vermont a state. New York still wanted

the territory for itself and interfered with

his efforts. After the war Allen even

talked with the British about making

Vermont part of Canada. This hurt his

reputation as an American patriot. He

died on February 12, 1789, in Burlington,

Vermont.

#More to explore

American Revolution • French and

IndianWar • Vermont

Allergy

An allergy is the human body’s negative

reaction to certain foreign substances.

Some allergies are commonplace. Many

people suffer from hay fever when pollen

is in the air. Some develop skin

rashes when they touch certain substances.

Others experience stomach

cramps after eating particular foods.

When a person reacts in these ways to

any outside substance, that individual is

said to be allergic to it.

Allergies and the Immune

System

Several things happen to cause an allergic

reaction. First, a person is exposed to

a substance such as pollen. The bodies of

most people would simply ignore pollen.

Some people’s bodies, however, treat it

as a harmful invader. When this happens,

the person’s immune system produces

substances called antibodies to

fight the pollen’s effects.

The antibodies produced in the body

tend to stay in the blood. Because of

this, the immune system remembers and

recognizes the specific substance that

attacked the body. The next time the

body comes in contact with the substance,

the antibodies react to it again.

Signs of an Allergic Reaction

The antibodies react by releasing a

chemical called histamine. Histamine

causes fluid to build up in the body and

cell tissues to swell. That is why the eyelids

of a person with hay fever become

red and puffy. Histamine also affects

muscles. This can cause breathing difficulties

or stomach cramping and pain.

One severe type of allergic reaction is

known as anaphylactic shock, or anaphylaxis.

Some people have this reaction

if they take certain drugs, eat foods such

as nuts and shellfish, or get stung by

certain insects. Anaphylaxis has very

severe symptoms and sometimes leads to

death.

Treatment

Most people quickly learn which allergies

they have. When possible, they try

Sneezing is a common sign of some allergies,

such as hay fever.

Pets are a

common cause

of allergies.

Skin cells and

saliva of cats,

in particular,

can cause

sneezing, itching,

and

watery eyes.

84 Allergy BRITANNICA STUDENT ENCYCLOPEDIA