Britannica Student Encyclopedia - 2010

became buried beneath Earth’s surface.

The trees eventually decayed and disappeared.

But the resin hardened further,

until it became amber.

Many pieces of amber contain the

remains of insects or plants in the form

of fossils. These living things were

trapped in the resin before it hardened

into amber. Scientists study these creatures

to learn how living things have

changed over millions of years.

People have found amber throughout

the world. However, most of it comes

from the shores of the Baltic Sea in

northern Europe. This amber is buried

in sands that are 40 million to 60 million

years old.

Ancient people valued amber for its

beauty. They used it to make beads and

carvings. The ancient Greeks and

Romans also believed that amber had

magical and healing properties. Artists

today turn pieces of clear amber into

jewelry and other objects.

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Fossil • Jewelry and Gems

Millions of years ago, insects were trapped

in resin. The resin eventually hardened into

amber.

92 Amber BRITANNICA STUDENT ENCYCLOPEDIA

 

Ambulance

An ambulance is a vehicle used to transport

people who are sick or injured.

Most ambulances are either trucks with

space for patients or cargo vans with

raised roofs. Ambulances usually take

patients to a hospital.

Specially trained people called emergency

medical technicians, or EMTs,

ride in ambulances. They give sick or

injured people emergency medical care

before they reach the hospital.

Ambulances have many types of

equipment that are used to move and to

treat patients. Equipment for moving

patients includes stretchers and cots with

wheels. An ambulance’s medical

equipment helps to treat breathing

problems, heart attacks, broken bones,

and burns right away.

Large cities have hundreds of ambulances.

They are owned by public and

private hospitals, fire departments, and

private emergency medical services.

Some places use airplanes or helicopters

as ambulances. These air ambulances

have the same equipment as ground

ambulances. Air ambulances reach

people in out-of-the-way areas. They

also transport patients more quickly

than ground vehicles.

Most ambulance developments took

place during wartime. In the early 1800s

the French army used two-wheeled,

horse-drawn wagons to bring soldiers to

battlefield hospitals. In the 1860s public

hospitals began keeping their own horsedrawn

ambulances. The first motorized

ambulance was built in 1899. Airplanes

were used as ambulances for the first

time duringWorldWar I (1914–18).

Helicopters first served as ambulances

during the KoreanWar (1950–53).

#More to explore

Hospital • Medicine

Amendment

A change or addition to a law is called

an amendment. The word usually refers

to a change to the constitution of a government.

In the United States there have

been 27 amendments to the Constitution.

The most famous of these are the

first 10. They are known as the Bill of

Rights.

Emergency medical technicians treat a

patient in an ambulance.

BRITANNICA STUDENT ENCYCLOPEDIA Amendment 93

 

Passing an amendment to the U.S. Constitution

is a two-step process. The first

step is for two thirds of the members of

the Senate and two thirds of the members

of the House of Representatives to

vote for the amendment. The second

step is for the amendment to be ratified,

or approved, by the legislatures of three

quarters of the states.

Every U.S. state has its own constitution,

and almost all of them have been

amended more times than the U.S.

Constitution. The constitution of Alabama

has more than 700 amendments.

In many states voters must approve

amendments.

#More to explore

Bill of Rights • Constitution • United

States Constitution

American

CivilWar

In the 1860s the northern and southern

parts of the United States fought the

American CivilWar. The war started

after 11 Southern states separated themselves

from the United States and

formed their own government. Their

army fought the forces of the U.S. government.

The CivilWar threatened to

break up the United States. It is also

called theWar Between the States.

Buildup toWar

The North and the South had been

divided for many years over the issue of

slavery. The Southern economy was

based largely on cotton, which was

grown on large farms called plantations.

African slaves did most of the work on

the plantations. The North had small

farms that used paid workers. The

Northern economy also relied more on

manufacturing.

Neither side wanted the other’s ideas to

spread to new states being created in the

West. Northerners wanted to stop the

spread of slavery. But Southerners

believed that the U.S. government did

not have the right to decide whether or

not slavery should be allowed in a state.

They feared that the government’s next

step would be to stop slavery altogether.

Missouri Compromise

In 1819 the U.S. Congress had to decide

whether to allow Missouri to become a

state. Missouri wanted to join as a state

that would allow slavery. Some North-

The only way

to repeal, or

cancel, an

amendment to

the U.S. Constitution

is to

pass another

amendment.

Only one

amendment to

the U.S. Constitution

has

ever been

repealed.

The 19th Amendment to the U.S. Constitution

gave women the right to vote.