Inventors and Inventions
Leonardo da Vinci
Leonardo da Vinci
Italian engineer and artist
The archetypal Renaissance man, Leonardo da Vinci
pursued interests in art, architecture, mathematics,
astronomy, anatomy, biology, botany, philosophy,
science, and engineering. In thousands of pages
of detailed notes and drawings, which included
hundreds of inventions, Leonardo examined the
physical world around him, leading the world
away from the superstitions of the Middle Ages
and into the modern era of science and reason.
Born: April 15, 1452; Vinci, Republic of Florence
(now in Italy)
Died: May 2, 1519; Cloux (now Clos-Lucé), near
Amboise, France
Also known as: Leonardo di ser Piero da Vinci (full
name)
Primary fields: Aeronautics and aerospace
technology; civil engineering; military technology
and weaponry
Primary inventions: Designs for making ropes, lifting
columns, threading screws, spinning and weaving
machines, flying machines, weaponry, boats, and
many other devices
Early Life
Leonardo da Vinci (lee-uh-NAHR-doh dah VIHN-chee)
was born on April 15, 1452, in Vinci, a small town located in the hills above the lower Arno River Valley in
the vicinity of Florence. Because he was the illegitimate
son of a wealthy notary, Ser Piero, and a local peasant
girl, Caterina, few records exist to document Leonardo’s
early years. In an era in which surnames were not yet in
common use, Leonardo’s birth name was Leonardo di
ser Piero da Vinci, which meant “Leonardo, son of
[Mes]ser Piero from Vinci,” later shortened to Leonardo
da Vinci, or Leonardo from Vinci. Leonardo apparently
spent his first five years in Anchiano, a small village just
outside Vinci, in the care of his mother, who may have
been the first to introduce the young Leonardo to the
beauty of the Tuscan countryside and to lay the groundwork for his later insatiable desire to understand the wonders of the natural world.
When Leonardo was age five, Ser Piero brought the
boy to live with him and his family in Vinci, where Leonardo was groomed to follow in his father’s occupation
as a notary. Before long, however, Leonardo’s artistic
talents were recognized as too impressive to be ignored,
and Ser Piero took his son to Florence, the hub of fifteenth century cultural and political activity. In 1466, Ser
Piero secured for Leonardo the position of apprentice in
the workshop of Verrocchio, one of the foremost artists
of the day. There, the young Leonardo met not only important civic leaders and patrons but also other young apprentices such as Perugino, Ghirlandaio, and Botticelli,
who, along with Leonardo, would later become some of
the greatest artists of their era. In this invigorating atmosphere, Leonardo learned skills that would serve him as
an artist and as an inventor and engineer as well, skills
such as the vital role of keen observation, the importance
of rational investigation, and the need for careful documentation. In 1472, when he was twenty, Leonardo was
admitted into the Guild of St. Luke, the organization that
oversaw both artists and doctors of medicine, a fortuitous
combination for a young man with Leonardo’s extraordinary proclivities.
Life’s Work
Upon becoming a master, Leonardo established his own
workshop, where, in 1473, he created his earliest extant
drawing, a view of his beloved Arno River Valley, drawn
from a bird’s-eye perspective, which reflected his lifelong interest in birds and flight. In 1482, on the advice of
Lorenzo de’ Medici, Leonardo traveled to Milan to visit
the court of Ludovico Sforza, known as Ludovico il
Moro. In a letter to Ludovico, Leonardo offered his services as a military engineer, listing the many warfare devices and military benefits he could proffer, including
portable bridges, mortars, mines, guns, cannons, covered
chariots, and catapults. At the end of the letter, almost as
an afterthought, Leonardo mentioned that he could also
serve Ludovico as an architect and painter. In an era
of intense rivalry, both in cultural status and military
prowess, Leonardo’s claims appealed to Ludovico, who
wisely hired the prodigious young man. Leonardo remained in the Ludovico court from 1482 to 1499, during
which time Leonardo worked intensely on mechanisms
for both defensive and offensive military purposes.
Whether it was out of his own innate interests or
because of the necessity of defending his homeland, Leonardo was always clearly involved in developing machines for warfare. Among his drawings, Leonardo included sketches for both a single sling and a double sling
to hurl stones, as well as a giant crossbow. Leonardo also
drew designs for a scything wagon, which, when pulled
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Leonardo da Vinci
Inventors and Inventions
sence, the forerunner of the modern
tank. Leonardo proposed the construction of a round, metal-covered
enclosure, which, when operated by
eight men protected inside, could be
turned and moved in any direction by
men on the lower level, while men
on the upper level of the machine
fired through narrow openings in the
top.
Leonardo was also interested in
innovations at sea. He drew plans for
fast boats that could ram and hold the
enemy’s craft while men protected
by shields attacked the enemy with
artillery. Leonardo also drew designs
for paddle-propulsion boats, with the
energy being provided by men in the
hull, whose power was increased
by a system of cogwheels and gears
that multiplied the revolutions of the
paddlers. He designed a ship with a
double hull that would minimize the
water intake if the ship’s outer hull
were damaged. In order to inflict as
much damage as possible on an enemy vessel, Leonardo designed ship
Leonardo’s sketch of an ornithopter with a pilot and a life preserver. (The Granger
bottom breakers to facilitate the sinkCollection, New York)
ing of enemy ships. Leonardo was
also concerned with spanning bodies
by horses, moves a system of gears that spin huge scythes
of water. He designed fast construction bridges to enable
protruding from the side of the wagon, capable of cutting
armies to quickly build bridges with a system of wood
down anything in their path. Leonardo missed no opporlogs and ropes. Leonardo also designed movable bridges,
tunity to enlarge and embellish upon current firearms. He
such as completely revolving bridges that could be turned
multiplied the efficiency of the traditional single-barrel
in case of enemy advances; parabolic bridges, which, seartillery by designing a three-barreled cannon, an eightcured to one bank, could be turned on vertical hinges; and
barrel machine gun, and even a thirty-three-barrel maan impressive design for a single-span bridge with a douchine gun. Each of these guns was designed to be mounted
ble support that would permit the bridge to be of suffion easily movable gun carriages that were adjustable
cient height to permit even vessels with tall masts to sail
both horizontally and vertically in relation to the desired
underneath. If a bridge was not available, Leonardo detarget. In order to lift heavier artillery, Leonardo devised
signed floats so that a man could simply walk across a
a winch in which the lifting and lowering was done with a
body of water. Leonardo even drew plans for a diving
worm screw and a spiral wheel. To improve the accuracy
suit that would allow a man to dive underwater and to
of his artillery, Leonardo explored the use of aerodybreathe through a system of respiration pipes that reached
namic projectiles to control the trajectory of the ammunithe surface of the water.
tion. Concerned with the challenge of rapid ignition of
The political and military events of the late fifteenth
the multiple artillery barrels he was designing, Leonardo
and early sixteenth centuries drove Leonardo from place
drew plans for automated igniting devices and automatic
to place. In 1499, Louis XII of France invaded Milan and
strikers. The covered chariot that Leonardo had promdefeated the ruling Sforza family. Leonardo was forced
ised Ludovico Sforza in his letter of 1482 was, in esto flee to Venice, where he used his talents to invent de714
Inventors and Inventions
Leonardo da Vinci
sketches of wings, both the natural wings of birds and
vices to defend that city from attacks by sea. The next
human-made wings that were worked by various mechayear found Leonardo back in Florence, where he rejoined
nisms. To assist the act of flight, Leonardo devised an inhis guild and resumed painting. During the ensuing years,
clinometer to control the horizontal positioning of the
Leonardo served as military engineer for Cesare Borgia,
craft and anemometers to show the wind direction. Leotraveling between Italian cities devising defensive mechnardo’s dreams of flight ranged from designs for flyanisms and designing a functioning canal up to the Porto
Cesenatico. Only after the Sforzas regained control of Milan in 1506 did Leonardo return once again to that city. In his
The Dream of Flight
later years, Leonardo lived and worked in
Florence, Rome, and Bologna, making
To fly like a bird was a lifelong dream for Leonardo da Vinci. Leothe acquaintance of his younger fellow
nardo said that he had a childhood memory of a bird flying down to his
artists, Michelangelo and Raphael. Leocradle and brushing its feathers against his face, and one of Leonardo’s
nardo spent his last years in France as the
earliest drawings was an aerial bird’s-eye view of the Arno River Valley.
court engineer, architect, and painter to
Throughout his life, Leonardo dedicated many in-depth studies to the
flight of birds, such as his 1505 Codex on the Flight of Birds.
King Francis I. Throughout these tumulLeonardo’s designs for a flying machine progressed over time. His
tuous years, Leonardo recorded his obearliest designs consisted of machines in which the human pilot, laying
servations, insights, and inventive devices
prone in a wooden frame, placed his feet in stirrups and moved his feet toin drawings and notations that filled thougether, causing the downstroke of the wings; the pilot’s hands directed the
sands of notebook pages.
upstroke by means of a lever. Over time, Leonardo modified the moveIn addition to his copious studies on
ment of the pilot’s legs, having the legs slide up and down, assisted by the
military matters, Leonardo also turned
hands, in order to make the wings beat. A still further advance was the adhis attention to civil matters, with special
dition of a head harness that manipulated a rudder to control direction. Leattention to devising labor-saving devices
onardo drew numerous sketches of wing types, from a wing based on that
and improving on existing work-related
of a bat to adjustable tilt wings, beating wings, and articulated wings, each
machines. Leonardo drew intricate plans
in an effort to refine his flying machine. The most ambitious of his designs
included a large enclosed cabin, capable of holding two pilots who operfor machines for making ropes, lifting
ated the flapping bat wings with a complex system of screws and cranks.
columns, and threading screws. One of
As inspired as Leonardo’s designs were for his early flying machines,
his particular interests was the fabrication
two
factors would have prevented his designs from ever taking off. First,
of textiles, a major industry in Italy at the
the materials that were available at the time were just too heavy to be matime. Leonardo drew designs for several
nipulated by even multiple human pilots. In addition, Leonardo’s underspinning and weaving machines and instanding of the flight of birds was fundamentally flawed. Leonardo becluded plans for an automated bobbin
lieved that birds flew when the wing was moved down and back, as if the
winder. He also devised teasing machines
bird were swimming through the air like a swimmer through water. In acthat processed cloth by running the cloth
tuality, the lift required for flight is created when birds move their wing
over a series of rollers. He designed a
feathers up and forward.
winged spindle that would stretch, twist,
As time progressed, Leonardo replaced the flapping-wing designs
with designs for fixed-wing glider crafts. At first, Leonardo did not proand wind thread simultaneously. Although
vide a means for the pilot to control the machine through body movemost of the textile manufacture in Italy at
ments. Eventually, however, he enabled the pilot to balance the craft by
the time was done with wool, silk was
moving the body’s extremities, effectively inventing a predecessor to the
also a coveted material. Leonardo demodern controlled glider.
signed a silk-doubling machine that inLeonardo wrote a journal entry in which he stated that a great bird will
creased silk production output.
take flight from Mount Cerceri, a mountain near Leonardo’s residence at
Leonardo was always fascinated by
the time. Legends recount that one of Leonardo’s assistants piloted the
the possibility of locomotion, whether on
craft, crashed, and broke his leg. Whether one of Leonardo’s great birds
land or in air. It is his experiments with
ever actually took flight will probably never be known. What is known is
flight for which Leonardo’s inventive talthat in an era of holdovers of medieval traditionalism and superstition,
ents are perhaps best remembered. LeoLeonardo’s dream of flight opened up a new vision of possibilities for the
future.
nardo seemed obsessed with enabling humans to fly like the birds. He drew many
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Leonardo da Vinci
ing machines, hang gliders, and parachutes to a complex
rendering for an air screw, anticipating the future helicopter.
Impact
Leonardo was one of the foremost visionaries in history.
In addition to creating such masterpieces as The Last
Supper and Mona Lisa, Leonardo is credited with being
one of the most prolific inventors of all time. His inventions were based on careful observation and copious documentation. Leonardo was unique for his time in that he
explained not only the purpose of machines but also how
machines actually worked. Leonardo was the first to conceive of machines as both a whole and a sum of its parts,
realizing that the parts, such as flywheels, cogs, and
gears, could be modified, improved upon, and utilized in
innovative new ways. With this realization, Leonardo
was able to combine individual parts into hundreds of
new machines.
In his designs, Leonardo anticipated many modern inventions. He drew diagrams of a hydrometer that anticipated the modern science of hydraulics. His plans for devices for the canalization of rivers are still in use today.
His designs for diving suits, parachutes, flying machines,
and helicopters inspired generations of later inventors. In
1903, the Wright brothers achieved Leonardo’s dream of
heavier-than-air human flight. A few years later, the
modern helicopter was developed. His plan for a singlespan bridge, conceived in 1502 for the sultan of Istanbul
but never realized because it was thought to be impossible, was brought to reality in 2001, when a smaller bridge
based on Leonardo’s design was constructed in Norway.
On May 17, 2006, the Turkish government commenced
construction of Leonardo’s bridge over the Golden Horn
at the mouth of the Bosporus, just as Leonardo had originally planned 504 years earlier.
Recognized now as some of the most farsighted inventions ever devised, Leonardo’s achievements are displayed in museums around the world, chief among them
the Leonardo da Vinci National Museum of Science and
Technology in Milan, Italy, and the Leonardo da Vinci
Museum at the Château du Clos Lucé in Amboise,
France. His notebooks are the highlights of major collections in the Louvre, the National Library of Spain, the
Ambrosian Library of Milan, and the British Library.
Only one of Leonardo’s notebooks is in a private collec-
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Inventors and Inventions
tion: The Codex Leicester is owned by Bill Gates, an acclaimed inventor of the late twentieth century. Five centuries later, inventors can still draw inspiration from
Leonardo da Vinci, the most prodigious of Renaissance
men.
—Sonia Sorrell
Further Reading
Laurenza, Domenico, Mario Tadei, and Edoardo Zanon.
Leonardo’s Machines: Da Vinci’s Inventions Revealed. Cincinnati, Ohio: David & Charles, 2006.
Using detailed diagrams and color illustrations, the
authors show how Leonardo’s inventions could have
been constructed, how they would have functioned,
and how they had an impact on subsequent inventors
and inventions.
Nicholl, Charles. Leonardo da Vinci: Flights of the
Mind. New York: Viking Penguin, 2004. The author
examines the phenomenon of the Renaissance in Italy
and explores the social and political events that both
fostered and frustrated Leonardo’s creative impulse.
Richter, Irma A., ed. Leonardo da Vinci Notebooks. New
York: Oxford University Press, 2008. This updated
edition of selections from Leonardo’s notebooks includes a preface by world-renowned Leonardo expert
Martin Kemp, a chronology of Leonardo’s life, new
notes on the manuscripts, and seventy line drawings,
all of which serve to enhance the understanding of Leonardo’s inventive genius.
Suh, H. Anna, ed. Leonardo’s Notebooks. New York:
Black Dog & Leventhal, 2005. Leonardo scholar
H. Anna Suh has compiled a superb selection of significant notebook entries and drawings, carefully
gleaned from the nearly six thousand extant notebook
pages and drawings by Leonardo. This monumental
publication contains stunning reproductions of the
originals along with insightful translations of Leonardo’s own, often cryptic, notations.
See also: 4Abbas ibn Firnas; Aristotle; Roger Bacon;
Giovanni Branca; George Cayley; Hero of Alexandria; Al-Jazart; Louis-Sébastien Lenormand; JosephMichel and Jacques-Étienne Montgolfier; James
Nasmyth; John Augustus Roebling; Igor Sikorsky;
John Tyndall; Faust Vran5i6; An Wang; Otto Wichterle; Wilbur and Orville Wright.
Inventors and Inventions
Libby, Willard F.
Willard F. Libby
American chemist
Libby, a chemist who specialized in the study of
radioactive elements, developed the carbon-14 method
used to determine the ages of archaeological artifacts.
He also pioneered the use of radioactive elements to
trace hydrological and geophysical processes.
Born: December 17, 1908; Grand Valley, Colorado
Died: September 8, 1980; Los Angeles, California
Also known as: Willard Frank Libby (full name)
Primary field: Chemistry
Primary invention: Carbon-14 dating
Early Life
Willard Frank Libby was born on a farm in Grand Valley,
Colorado, on December 17, 1908. His parents, Ora Edward Libby and Eva May Libby, soon moved to California, where Libby attended grammar school in Sebastopol. There, he received his high school education at
Analy High School, where he played on the football
team. Libby entered the University of California, Berkeley, in 1927, where he was awarded a B.S. degree in
chemistry in 1931. He received his Ph.D. in chemistry in
1933 and was appointed an instructor at the university’s
Department of Chemistry. Over the next decade, he was
promoted to assistant professor and later to associate professor of chemistry. His major research during this period was focused on building sensitive Geiger counters,
electronic devices that are used to measure the decay
of natural and human-made radioactive elements.
Libby married Leonor Hickey in 1940. Together they
had twin daughters, Janet and Susan, in 1945.
Life’s Work
In 1941, Libby was awarded a Guggenheim Memorial
Foundation fellowship to conduct research at Princeton
University. However, the start of World War II interrupted
his efforts. Shortly after the attack on Pearl Harbor on
December 7, 1941, Libby joined the Division of War Research at Columbia University in New York. He worked
on the Manhattan Project to develop the atomic bomb. At
Columbia, Libby worked with Harold Urey, who won the
Noble Prize in Chemistry in 1934 for isolating deuterium,
a heavy isotope of hydrogen. Under Urey’s direction,
Libby was responsible for developing the gaseous diffusion technique to separate and enrich uranium 235, which
was used in the atomic bomb dropped on Hiroshima.
In 1945, at the end of World War II, Libby was ap-
pointed professor of chemistry at the University of Chicago, where he worked in the university’s Institute for
Nuclear Studies. In 1946, Libby showed that when cosmic rays (charged particles moving through space at
nearly the speed of light) strike the upper atmosphere of
the Earth, they produce trace amounts of tritium, a rare
radioactive isotope of hydrogen having an atomic mass
of three units, and carbon 14, a rare radioactive isotope of
carbon. This tritium can be incorporated into water that is
present in the Earth’s atmosphere. Since tritium has a
half-life (the time required for half of the starting amount
of an isotope to decay away) of only twelve years, it can
be used to trace the presence of atmospheric water. If
water has been isolated underground for many years, all
the tritium that was added while the water was in contact
with the atmosphere will have decayed. By measuring
the tritium concentration, Libby developed a method to
determine the last time atmospheric water was added to
underground water, such as well water. He applied the
same technique to measuring the circulation pattern and
Willard F. Libby. (©The Nobel Foundation)
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Inventors and Inventions
Libby, Willard F.
bon 14 to the stable carbon 12 decreases. By
measuring this ratio, Libby suggested that he
could determine how long ago the plant or
Carbon has two stable isotopes, carbon 12 and carbon 13. A small
animal had died. In 1947, Libby and Ernest
amount of carbon 14, a radioactive isotope of carbon, is also found on
Anderson performed an experiment demonEarth. Since carbon 14 has a half-life of only 5,730 years, any carbon
strating that Libby’s idea was correct. They
14 present when the Earth formed has decayed away. However, cosshowed that the methane gas from Baltimore
mic rays interact with nitrogen in the Earth’s atmosphere, producing
carbon 14. If the number of cosmic rays is constant, the ratio of radiosewage had measurable carbon 14, while
active carbon 14 to stable carbon 12 stays at a constant value, with the
methane produced from old petroleum deproduction just balancing the decay. The carbon 14 reacts with oxygen
posits (produced from organisms that lived
in the atmosphere, forming carbon dioxide, which spreads around the
millions of years ago) did not. In 1949, Libby
world. Plants take in atmospheric carbon dioxide during photosyntheand James Arnold, a research associate at the
sis, so, while plants are alive, their carbon 14-carbon 12 ratio is the
Institute for Nuclear Studies, demonstrated
same as the atmospheric ratio. Animals ingest carbon 14 by eating
that the carbon-14 dating technique worked
plants or other animals, so the carbon 14-carbon 12 ratio in living anion archaeological samples: Their carbon-14
mals is also the same as the atmospheric ratio. However, as soon as the
technique was as accurate as other dating
plant or animal dies, it stops taking in carbon dioxide, and the carbon
methods used on objects such as wood from
14 decays away. The carbon 14-carbon 12 ratio serves as a clock, tickthe coffin of an Egyptian mummy.
ing away the time since the organism died.
A fresh sample of carbon 14 produces about fourteen disintegraLibby used the radiocarbon dating techtions per minute per gram of carbon. When the sample is isolated from
nique to determine the ages of linen wrapnew input of carbon 14, the number of disintegrations per minute per
pings from the Dead Sea scrolls, bread from
gram of carbon decreases exponentially. After 5,730 years, one-half
the village of Pompeii buried by the eruption
of the original amount of carbon 14 remains, and the carbon-14 decay
of Mount Vesuvius in 79 c.e., charcoal from
rate is only about seven disintegrations per minute per gram of carbon.
a campsite at Stonehenge, and corncobs from
After another 5,730 years, one-fourth of the original amount remains,
a cave in New Mexico. He also used radioand after another 5,730 years, only one-eighth of the original amount
carbon dating to determine that the last North
remains.
American ice age ended about ten thousand
Carbon 14 decays by the emission of an electron, which can be deyears ago, not twenty-five thousand years
tected with instruments such as proportional counters or scintillation
ago as had been believed.
counters, electronic devices that detect the individual decay products.
However, the cosmic rays produce only a very small amount of carbon
Libby remained on the faculty at the Uni14. In the Earth’s atmosphere, there is only one carbon-14 atom for evversity of Chicago until 1954, when President
ery trillion carbon-12 atoms, so these devices require a relatively large
Dwight D. Eisenhower appointed him to the
amount of carbon, typically about one gram, to measure a decay rate
U.S. Atomic Energy Commission (AEC).
accurately.
Libby had previously served as a member of
The sensitivity of carbon-14 dating increased with the developthe Committee of Senior Reviewers of the
ment of accelerator mass spectrometry. With this technique, the carAEC from 1945 to 1952. Libby, the first
bon is vaporized and separated into its isotopes, which are counted dichemist to serve on the AEC, headed Eisenrectly rather than by decay counting. This method allows dating of
hower’s international “Atoms for Peace” proonly a few milligrams of carbon. The carbon-14 dating technique program, which supplied equipment and inforvides reliable ages on samples dating back a few hundred years to
mation on the peaceful uses of atomic energy
about eighty thousand years.
and radioactive materials to schools, hospitals, and research institutions around the
world. Libby also studied the effects of rathe mixing of water in the ocean, and to determining the
dioactive fallout. He served on the AEC until 1959, when
age of wines.
he became professor of chemistry at the University of
In the same research paper that reported the tritium
California, Los Angeles (UCLA). He was appointed diproduction, Libby noted that the radioactive carbon 14
rector of the Institute of Geophysics and Planetary Physproduced by cosmic rays would be incorporated into livics at UCLA in 1962, a position he held until his death.
ing organisms. However, once an animal or plant dies, it
While serving on the AEC, Libby held a position as a retakes in no more atmospheric carbon, so the ratio of carsearch associate of the Carnegie Institution’s Geophysi-
Carbon-14 Dating
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Inventors and Inventions
Libby, Willard F.
cal Laboratory in Washington, D.C., so that he could
continue his scientific research.
During the Cold War, Libby opposed efforts to ban
testing of nuclear weapons. He proposed that every home
should have a fallout shelter in case of nuclear war. In a
widely publicized event, Libby built his own fallout shelter in his home. From 1959 to 1961, he served as consultant to the Office of Civil and Defense Mobilization. In
1961, he wrote a twenty-seven-page pamphlet published
by the Associated Press titled “You Can Survive an
Atomic Attack.”
Libby divorced his wife in 1966 and married Leona
Woods Marshall. He continued to explore applications
of radioactive decay to geological problems. In 1977, he
developed a method to monitor the emission of radon gas
from earthquake-prone areas, detecting the alpha particle
emitted when radon decays by using sensitive film. He
suggested that an increase in radon emission might signal
an upcoming earthquake. Libby died of a lung illness on
September 8, 1980, in Los Angeles.
technique is the Shroud of Turin—believed by some to
be the burial cloth of Jesus Christ. Records of the shroud
date back to the mid-fourteenth century. The presence of
pollen spores from Israel on the cloth suggested that it
might be a genuine relic. However, in the 1980’s, small
samples of the cloth were dated independently by three
laboratories in Tucson, Oxford, and Zurich. Their results
showed the cloth was made around 1300 c.e. and could
not be a burial shroud from the time of Jesus Christ.
Monitoring the radiocarbon age of the water in a well
system can aid in determining if overuse is depleting a region’s water supply before the problem becomes so severe that there is a shortage. Oceanographers employ the
carbon-14 method to date recent sea sediments. Carbon14 dating has made accurate determinations of the rate of
turnover of the deep water of the Earth’s oceans. These
results play an important role in studying one of the central problems of physical oceanography: determining
how water circulates in the oceans.
—George J. Flynn
Impact
In 1960, Libby was awarded the Nobel Prize in Chemistry for his development of carbon-14 dating. Introducing
Libby for the award, Professor Arne Westgren said that
Libby had “succeeded in developing a method that is indispensable for research work in many fields and in
many institutes throughout the world. Archaeologists,
geologists, geophysicists, and other scientists are greatly
indebted to you for the valuable support you have given
them in their work.”
Although archaeologists and geologists had other
methods to determine the ages of certain types of samples, the carbon-14 method quickly proved more rapid
and more accurate. Thus, Libby’s radiocarbon dating
method quickly attracted attention from the scientific
community, and more than one hundred carbon-14 analysis laboratories were established around the world.
Archaeologists were able to establish time lines for
human development and settlement that preceded the
written record. Egyptologists, for example, employed
Libby’s technique to create a chronology of Egyptian
rulers dating back to about 5000 b.c.e. The charcoal from
campfires in Iraq was dated, showing that people lived in
Iraq twenty-five thousand years ago. “Ötzi the Iceman,”
a frozen body found in the mountains of northern Italy in
1991, was also dated using Libby’s technique. Samples
of the iceman’s bones, boot, leather, and hair show that
he lived about fifty-five hundred years ago.
The most famous object dated using the radiocarbon
Further Reading
Bowman, Sheridan. Radiocarbon Dating. Berkeley:
University of California Press, 1990. A sixty-fourpage, well-illustrated account of Libby’s contribution
to radiocarbon dating and how the technique has reshaped archaeologists’ knowledge of the past, including as examples Stonehenge and the Shroud of Turin.
Leroy, Francis. A Century of Nobel Prize Recipients:
Chemistry, Physics, and Medicine. New York: Marcel Dekker, 2003. An account of the career and accomplishments of the Nobel Prize winners, including
a section on Libby and his development of radiocarbon dating.
Libby, Willard F. Life Work of Noble Laureate Willard
Frank Libby. Simi Valley, Calif.: Geo Science Analytical, 1982. This collection of Libby’s scientific papers
illustrates the progression of his ideas on radiocarbon
dating, beginning with the recognition that carbon 14
was produced in the atmosphere and culminating with
his efforts to date a variety of archaeological artifacts.
Taylor, R. E. “Fifty Years of Radiocarbon Dating.” American Scientist 88 (January/February, 2000): 60-67.
The author, an archaeologist, describes Libby’s contribution to the origin of radiocarbon dating, the advances that have made it possible to date samples that
contain only milligrams of carbon, and the important
contribution the technique has made to archaeology.
See also: Hans Geiger; Ernest Orlando Lawrence.
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