Archimedes [ar' ki mE' dEz] scientist and inventor
Archimedes was born in
Syracuse, a Greek colony on the island of Sicily,
about 287 B.C. He lived and worked there all his
life except for a few years of study in
Alexandria.
His Discoveries
Pi.
Archimedes' only surviving published works are
his mathematical treatises. In Measurement of
the Circle he worked out the ratio of the
length of a circle's circumference to its radius
to a degree of accuracy never before achieved. He
did this by a technique which would not be
replicated again until the discovery of
differential calculus by Isaac Newton
nearly 2,000 years later.
Buoyancy.
Archimedes made his bestknown discovery as the
result of his friendship with Hieron II, ruler of
Syracuse, who often turned to the mathematician
for advice and guidance. On one such occasion
Hieron had bought a gold crown from a local
goldsmith. Hieron doubted the goldsmith's honesty
and wanted to be sure the crown was actually made
from pure gold, so he asked Archimedes to check
the gold content without damaging the crown in
any way. Although he spent several days on the
problem, Archimedes couldn't come up with an
answer. Then, while stepping into a full bathtub
one day, he suddenly noticed a wash of water
overflowing the sides. Upon further thinking he
realized that the amount of water displaced from
the bath was equal to the volume of his own body
entering it. He had finally found the answer to
Hieron's problem. If he immersed Hieron's crown
in water and measured the volume displaced, he
would know the volume of the crown. To determine
whether it contained any metal other than gold,
he had simply to compare the total weight of the
crown with the weight of that given amount of
gold.
According to legend, Archimedes
was so excited by his discovery that he ran naked
from his bathroom into the streets of Syracuse
crying "Eureka!" (meaning I have
discovered it!).
Archimedes did indeed
perform a buoyancy test on Hieron's crown, and
found that it contained a far higher percentage
of base metal than the goldsmith had promised,
and Hieron promptly had the goldsmith executed.
Archimedes later extended his
buoyancy principle to show that a body in water
received an upward force, called an upthrust,
equivalent to the weight of water it displaced.
This explains why heavy objects can float. For
example, a modern ship built of steel can float
because it displaces a large volume of water,
while a single bar of the same metal will sink in
an instant.
Lever.
Archimedes' fascination with mechanisms led him
to explore the principle of the lever. He
showed how a lever, pivoted about a fulcrum,
could lift a heavy weight with a relatively
gentle force applied to the end of the lever's
arm. He reportedly told a friend: "Give me a
place to stand and a lever long enough and I will
lift the world!"
His Inventions
The Archimedean Screw
is a device still used to lift water for
irrigation. As the handle is turned the water is
carried upward within the spiral chambers as the
screw revolves. The water comes out of the upper
end of the screw.
Siege Defenses.
Archimedes spent his final years helping defend
Syracuse from invading Roman armies, which had
been besieging the town for three years. Time and
again their attacks were beaten back by strange
machines designed by Archimedes. One of these
machines was a catapault, a weapon that
shot rocks at the enemy. Writers of his day
claimed that Archimedes invented grappling hooks
that could seize ships and disable them. They
also said he designed a system of mirrors that
concentrated the sun's rays to set enemy ships on
fire.
His Death
Despite Archimedes' machines,
Syracuse finally fell in 212 B.C. and the city
was sacked. The Roman commander Marcellus gave
orders that Archimedes was to be brought to him
and treated with honor and kindness. According to
a contemporary story, one of the Roman soldiers
came across Archimedes as he was deep in thought.
When the soldier tried to get Archimedes to come
with him to see Marcellus, Archimedes impatiently
waved the soldier away saying "Go, do not
disturb me!" Furious at the implied insult,
the soldier reportedly drew his sword and struck
Archimedes dead.
Isaac Newton
Lever
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