The French explorer known as the Sieur
de La Salle was the first European to
travel down the Mississippi River to the
Gulf of Mexico. He claimed for France
all the land that was drained by the
river.
Early Life
La Salle was born on November 22,
1643, in Rouen, France. His original
name was Rene-Robert Cavelier. In
1666 he went to Canada and traded for
furs. Native Americans told him of a
broad river that ran from the Great
Lakes region to the sea. This was the
Mississippi.
Explorations
In 1669 La Salle traveled south from
Lake Ontario. He did not reach the Mississippi,
but he may have reached the
Ohio River. In 1673 he helped to build
Fort Frontenac on Lake Ontario.
Larches’ needle-shaped leaves change color
and fall off in the autumn.
An illustration from the late 1600s shows
the Sieur de La Salle at the coast of the Gulf
of Mexico.
BRITANNICA STUDENT ENCYCLOPEDIA La Salle, Sieur de 109
In 1674 and 1677 La Salle visited
France. King Louis XIV gave him the
title of Sieur de La Salle, which means
Sir La Salle.
In 1682 La Salle reached the Mississippi
from the Illinois River. He floated all the
way to the river’s mouth at the Gulf of
Mexico. There, on April 9, 1682, he
claimed the entire Mississippi River valley
for France. He named it Louisiana
after his king.
Last Voyage
La Salle then returned to France. The
king gave him permission to build a fort
at the mouth of the Mississippi and to
invade the Spanish land of Mexico.
La Salle’s expedition set out from France
planning to sail through the Gulf of
Mexico to the mouth of the Mississippi.
On the way, several of La Salle’s ships
were lost. Many men became ill.Worst
of all, La Salle could not find the Missis-
A map shows the route taken by the Sieur de La Salle down the Mississippi River. It also
shows the route of La Salle’s last, failed voyage.
110 La Salle, Sieur de BRITANNICA STUDENT ENCYCLOPEDIA
sippi River. He finally landed at Matagorda
Bay, in what is now Texas. His
men grew so angry that they murdered
La Salle on March 19, 1687.
#More to explore
Louisiana • Mississippi River
Laser
A laser is an instrument that can produce
a powerful beam of light. The
word laser stands for the scientific words
that explain how a laser beam is produced:
“light amplification by the stimulated
emission of radiation.”
In the 1950s scientists in the United
States and the Soviet Union came up
with the ideas needed to build lasers. A
U.S. scientist built the first laser in
1960. Since then scientists have built
many more types of lasers.
How LasersWork
A laser is usually made up of a tube with
mirrors at both ends. One mirror is
partly transparent (see-through). Inside
the tube is some type of material, such
as gas, crystal, or liquid.
A powerful lamp or some other source
of energy adds energy to the material.
Then the material produces light. The
light bounces back and forth between
the mirrors at the ends of the tube. As it
does so, it causes the material in the tube
to produce more light. Some of this
light escapes through the partly transparent
mirror.
The escaped light is known as a laser
beam, or laser light. Laser light is different
from sunlight or light from a lamp,
which is called white light. White light
contains a mixture of all the wavelengths,
or colors, of light. Laser light
contains only one color. In addition,
white light spreads out and gets weaker
as it travels away from its source. Laser
light travels from its source in a straight
line. This helps it keep its strength over
very long distances.
Uses
Construction workers and scientists use
lasers to measure distances. Laser light
can also carry telephone signals and
other information over long distances.
In this case it travels through special
cables, called fiber-optic cables.
Doctors sometimes use laser beams
instead of scalpels (knives) to cut into
people. The energy of a laser beam can
also close cuts without stitches.
Another common use of laser light is to
make and read compact discs—CDs and
Laser radar
measured the
distance from
Earth to the
Moon in the
1960s.
The light that escapes out of one end of a
laser’s tube is called a laser beam.
BRITANNICA STUDENT ENCYCLOPEDIA Laser 111
DVDs. Some types of computer printers
use lasers, too.
#More to explore
Compact Disc • Energy • Fiber Optics
• Light
Latin America
Latin America is a region made up of
Mexico, Central America, and South
America. Some of the islands of the
West Indies, in the Caribbean Sea, also
are included. The area is known as Latin
America because most people speak languages
that came from Latin (the language
of the ancient Romans). These
languages include Spanish, Portuguese,
and French.
People
Many Latin Americans have a mixture of
American Indian, European, and African
ancestry.Most people speak Spanish or
Portuguese. People in French Guiana
and parts of theWest Indies speak
French.Millions of American Indians
speak their native languages.Most Latin
Americans are Roman Catholic.
History
American Indian peoples lived in what is
now Latin America for thousands of
years before Europeans arrived. These
peoples included the Maya, the Aztec,
the Inca, and many others.
