are important to the economy. Conakry
is also the country’s center of industry.
A people known as the Susu lived in the
Conakry area before Europeans arrived.
French traders and soldiers took over
Tombo Island in the 1880s. Their settlement
later became the capital of the
colony of French Guinea. In 1958
Guinea became an independent country
with Conakry as its capital.
..More to explore
Guinea
Concord
Population
(2000 census)
40,687; (2007
estimate)
42,392
Concord is the capital of the U.S. state
of New Hampshire. The city lies on the
Merrimack River.
Many people in Concord work for the
government. Others work in health care,
insurance, and other service industries.
Factories in the city make electronic
equipment and other products.
The site of Concord was settled in 1727.
It was named Penacook Plantation and
later Rumford. The city was part of
Massachusetts for several years. It
became Concord, New Hampshire, in
1765. Concord became the capital of
New Hampshire in 1808.
The State House of New Hampshire
was built in Concord with granite from
a nearby mine. For many years
Concord granite was a popular building
material.
..More to explore
New Hampshire
Concrete
Concrete is the world’s most widely
used building material. Concrete is an
artificial, or man-made, stone. It is
strong and long lasting. It can be made
into almost any shape. Concrete is used
to make driveways, patios, roads,
bridges, and even entire buildings.
How Concrete Is Made
One of the main ingredients of concrete
is a fine powder called cement. Concrete
The State House of New Hampshire in Concord
was built with local granite.
BRITANNICA STUDENT ENCYCLOPEDIA Concrete 175
is made by mixing cement with sand,
gravel, and water. The water and cement
form a thick paste that holds the sand
and gravel together. The water also
causes a chemical reaction that makes
the mixture dry and harden. Before concrete
dries it can be poured into forms to
make many different shapes, including
blocks, bricks, flat slabs, and arches.
After the concrete dries, it lasts a very
long time.
Advantages of Concrete
Concrete does not burn and it stays
strong during a fire. Materials can also
be added to make the concrete stand up
to heat, water, or chemicals. It can be
made light or heavy in weight. Some
types of concrete will even harden
underwater.
Concrete with metal bars running
through it is called reinforced concrete.
It is even stronger than regular concrete
and can support heavy loads. Reinforced
concrete is used to make roads, bridges,
and very tall buildings.
History
Concrete has been around for a long
time. Thousands of years ago the ancient
Babylonians used clay to hold sand and
gravel together. Ancient Romans used
ash from a volcano to make the concrete.
The ash, when mixed with water,
acted like glue, just like modern cement
does. The Romans used concrete to
build their domes, aqueducts, and
bridges. In the 1800s cement was
invented and became the main ingredient
in concrete.
#More to explore
Cement
Condensation
#see Evaporation and
Condensation.
Confederate
States of America
The Confederate States of America was
formed after Abraham Lincoln was
elected president of the United States in
November 1860. Lincoln was against
slavery. For many people in the Southern
states slavery was a part of their way
of life. They were afraid that the new
government would end slavery and
make them give up that way of life.
Therefore a group of these states withdrew
from the United States and formed
their own government. To defend this
government they fought the American
CivilWar from 1861 to 1865.
A construction worker moves a slab of concrete.
The metal bars in the concrete make it
especially strong.
176 Condensation BRITANNICA STUDENT ENCYCLOPEDIA
Member States
The first states to withdraw from the
Union were Alabama, Florida, Georgia,
Louisiana, Mississippi, and South Carolina.
Representatives from these states
organized the Confederate States, or
Confederacy, on February 4, 1861.
Texas joined a month later. After the
first shots of the war were fired, Arkansas,
North Carolina, Tennessee, and
Virginia also joined. Part of Virginia
later decided to split off and form the
new state ofWest Virginia. That state
joined the United States in 1863. Other
slaveholding states stayed in the Union.
Organization
Jefferson Davis of Mississippi was
elected president of the Confederacy,
and Richmond, Virginia, was made the
permanent capital. The government
ordered a flag to be created and issued
postage stamps and money. The Confederate
States had a constitution similar to
the U.S. constitution. The government
was also organized into branches and
departments much like those of the
United States.
The CivilWar
After withdrawing from the Union, the
Confederate States took possession of
the forts and other public property of
the United States lying within their borders.
U.S. troops, however, continued to
occupy Fort Sumter, located in the harbor
off Charleston, South Carolina. On
April 12, 1861, the Confederacy opened
A map shows how the issue of slavery divided the United States.
BRITANNICA STUDENT ENCYCLOPEDIA Confederate States of America 177
