War, Hayes entered the U.S. House of
Representatives in 1865. He was
reelected to the House in 1866. Hayes
then served three terms as governor of
Ohio.
Election of 1876
In 1876 the Republicans chose Hayes as
their candidate for president. His
Democratic opponent was Samuel J.
Tilden, governor of New York. Tilden
won the popular vote, but the results in
the electoral college were uncertain. The
Republicans said the voting results from
three Southern states were wrong. In
Hawthorn trees produce white or pink flowers
once a year.
Rutherford B. Hayes
BRITANNICA STUDENT ENCYCLOPEDIA Hayes, Rutherford B. 29
January 1877 Congress set up a commission
to decide the election. On
March 2 the commission, made up of
eight Republicans and seven Democrats,
decided in favor of Hayes. The decision
angered many Democrats.
Presidency
As president, Hayes ended the period
known as Reconstruction. This was the
period following the CivilWar when the
country worked to bring the Southern
states back into the Union. He took
U.S. troops out of the South. He gave
Southern states control of their elections.
He also appointed Southerners to
government offices. Hayes’s policies
toward the South angered conservative
Republicans known as the Stalwarts.
The Stalwarts also disagreed with
Hayes’s efforts to end the “spoils system.”
In that system the government
gave out jobs as political rewards. Hayes
wanted to give the jobs to people who
passed a test. Congress refused to change
the system, but people became more
aware of its problems.
Retirement
Hayes did not run for reelection in
1880. In retirement he was involved in
several causes. Most notably he worked
to improve prisons and to provide better
education for African Americans in the
South. He died in Fremont, Ohio, on
January 17, 1893.
#More to explore
Electoral College • Reconstruction
• United States
Heart
The heart is the organ, or body part,
that pumps blood through the body. It
is the main organ of the cardiovascular
system. The cardiovascular system carries
substances to and from all parts of
the body in the blood.
October 4, January 17,
1822 1868 1877 1877 1879 1881 1893
Hayes is born
in Delaware,
Ohio.
Hayes becomes
governor of
Ohio.
Hayes is
elected
president.
Hayes ends
Reconstruction
in the South.
Hayes signs a
law to allow
women lawyers
to practice
before the
Supreme Court.
Hayes retires
from the
presidency.
Hayes dies in
Fremont, Ohio.
T I M E L I N E
30 Heart BRITANNICA STUDENT ENCYCLOPEDIA
The Human Heart
The human heart is pear-shaped and
slightly larger than a fist. It is located
high in the chest, slightly to the left. The
heart of a grown-up person weighs
about 8 to 12 ounces (230 to 340
grams).
The heart is made of very strong muscle.
This muscle pumps blood by squeezing
and relaxing in a regular rhythm. This
rhythm is called the heartbeat. The heart
muscle beats an average of 70 times per
minute. More than 4 quarts (3.8 liters)
of blood pass through the heart every
minute.
The human heart is divided into right
and left halves. Each half is divided into
two hollow sections called chambers.
The upper chambers are called atria.
(Each of these chambers is called an
atrium.) The lower chambers are called
ventricles.
Blood from the body flows into the right
atrium. This blood carries a waste product
called carbon dioxide. The blood
then passes into the right ventricle. The
right ventricle pumps the blood to the
lungs. In the lungs, blood picks up oxygen
and releases carbon dioxide. The
oxygen-rich blood enters the heart’s left
atrium. The blood then passes into the
left ventricle. The left ventricle pumps
the blood throughout the body.
Problems with the heart include irregular
heartbeat and heart disease. Irregular
heartbeat is a heartbeat that is too slow,
Blood enters the right atrium of the heart. It
flows into the right ventricle, through the
lungs, and into the left atrium. Finally, it
passes into the left ventricle and then leaves
the heart.
A patient runs while a machine records his
heartbeats. The machine tells doctors
whether the patient’s heart is healthy.
BRITANNICA STUDENT ENCYCLOPEDIA Heart 31
too fast, or unsteady. Heart disease happens
when fatty substances build up
inside blood vessels. The fatty deposits
block blood from getting to the heart.
Heart disease can lead to a heart attack.
A heart attack happens when part of the
heart muscle dies. Exercise and eating a
healthy diet can help to keep the heart
healthy.
The Hearts of Other Animals
Like the human heart, the hearts of
mammals and birds have four chambers.
The hearts of other animals are different.
Amphibians and lizards have hearts
with three chambers. Fishes’ hearts are
folded tubes, with three or four sections
that are like chambers. Spiders and some
worms have hearts that are straight
tubes.
#More to explore
Blood • Lung • Muscle
Heat
Heat is a form of energy. Heat flows
from hot objects to cool objects. It flows
from one object to another because of
their difference in temperature. The cool
object absorbs the energy and becomes
warmer.
Objects are made of particles, or bits,
called molecules. Molecules are always
in motion. As an object is heated, the
